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Thread: Holley carb questions

  1. #1
    Senior Member Paparazzi's Avatar
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    Holley carb questions

    Felt that my 351W wasn't running as well as she might, so checked out the timing and carb settings. A couple of questions for the engine guys:

    (1) I set the distributor to idle at a mark on the balancer that's at 12 degrees before TDC. To get the total degrees I revved the engine and was expecting to be able to read the value. But it goes further back from TDC into a region (BDC) that's not even marked. I was expecting it to go to the ADC area - is my balancer on backwards? Should I just put some tape on it that's reversed from the current markings, ie line up the 0 and just count back into the BDC zone? She's idling easily at about 1100 (stock cam and heads) and #1 plug is clean with a good vacuum reading. But I'd expect to be able to get a reading when at, say 3000 RPM.

    (2) When warmed up (which this time of year in 85F heat is almost immediate) shouldn't the electronic choke butterfly be fully open - ie vertical? It goes to about 80 degrees but won't open completely. If I press down on the red plastic cam it will open fully and the idle drops and she sounds much better. But if I blip the throttle it closes up a little and the revs go up again at idle. Is this the 'fast idle' on the carb? The throttle idle setting isn't even making contact at this point I've backed it out so much. Should I adjust the fast idle on the carb?

    Here the butterfly isn't completely open. The 12v feed is disconnected, but makes no difference to the position.

    20190817_144910.jpg

    By pressing down on the red cam the throttle cable is allowed to 'relax', the revs drop, and the engine sounds more comfortable. Blipping the throttle immediately closes the butterfly a little and puts the revs back up.

    20190817_144928.jpg
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    Seasoned Citizen NAZ's Avatar
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    You have two questions: one about ignition timing and advance, the other about carb operation. Let's take the carb first. With the 12V power removed from the electric choke the choke butterfly and fast idle will be positioned to the max adjusted limit and will stay that way regardless of the engine temp. The 12V power energizes a heating coil that heats a bimetallic spring to open the choke. It's a simple and robust system but needs to be properly adjusted to work correctly. If you want the choke to come off sooner, loosen the three screws on the choke cap and rotate it clockwise. You already know where the fast idle cam is located so I'm guessing you could figure out how to adjust it. I'm sure you can find several YouTube videos on how to adjust the choke.

    Now for the ignition. When you set the static timing did you remove and plug the vacuum source for the vacuum advance? Have you confirmed the zero mark is aligned with the pointer at TDC (requires a TDC finder)? Don't just assume it's correct.
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    BadAsp427's Avatar
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    I'll try to help you here to start;
    - when checking your timing, are you disconnecting and plugging the vacuum advance on the distributor? When checking for your total advance, you are actually checking the mechanical total advance, not the vacuum advance.

    - I'm going to take a guess at this as it is hard to diagnose from a couple photos but I think your elec choke needs to be relaxed just a bit more. Ie, loosten the three screws and turn it a couple notches clockwise (toward the front of the engine) Your carb is not letting it go completely off of the fast idle cam. And by the way, you can also adjust the fast idle speed with the screw that is riding on the red cam... but I don't think that is the problem because you are describing the idle at a good speed for it on the last (slowest) fast idle cam

    Not sure if this helps, I'd be happy to talk on the phone if needed... PM me if needed.

    Carl

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    Senior Member Paparazzi's Avatar
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    Thanks guys - you both mention disconnecting the vacuum advance on the distributor. I'm running MSD with Digital 6AL - no vacuum advance. Probably should have mentioned that, huh?

    Regarding the timing - I haven't checked TDC. I'll do that next to rule out any issue there on the timing mark.

    For the carb - I'll reconnect the 12v and since you both suggest an adjustment, I'll go for that too.

    Will post updates - thank you both!
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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    Seasoned Citizen NAZ's Avatar
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    You'll need a piston stop such as this one in the thread size for your heads: https://www.summitracing.com/parts/pro-66792/overview/

    Once you ensure the zero mark is at TDC, use a timing light again after the engine is warmed up and off the fast idle cam. Carefully check that the advance is going the correct way and you don't have the MSD box programmed to retard the timing. If I remember correctly, the programmable 6AL can be set-up retard the timing above an RPM threshold. I just ordered one and haven't used the programmable version before but that's one of the features I was looking for.
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    Senior Member CraigS's Avatar
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    Assuming your balancer is stock or stock type, you can get a rough check on the timing marks just working w/ a 1/4 inch dowel. In other words, variations in timing mark locations for different models are usually far apart. A balancer may have 2 sets of marks but they are maybe 90 degrees apart. So you can check to see if you are on the right marks w/ a dowel but it's not accurate enough to verify the marks are exactly correct. RE; the carb. It's usually hard to see but there is a small screw on the linkage that works on the red cam. So the choke has two adjustments. choke on idle speed (that small screw) and richness or length of time choke stays on (rotating the black housing). To start the engine needs to be run long enough so the choke is fully off (the electric heater inside the black cover). While you mess w/ it you can turn the black to see which way closes the choke. I don't mess w/ these often enough so I painted a small arrow on mine to remember. BTW a good start point is when the electrical tabs are close to vertical. I know some guys are happy w/ these chokes but I never have been. Back in the day chokes had coolant run to them so they actually reacted to engine temp. These electric heaters act on their own w/ only slight connection to actual engine temp. Years ago I converted mine to a manual choke operated by a push pull cable.
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    Senior Member Paparazzi's Avatar
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    Ordered the TDC locator and some timing tape to make those markers easier to read. Looks to be a few days shipping so will report back and play with the carb setup in the meantime.

    J.
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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    Quote Originally Posted by Paparazzi View Post

    To get the total degrees I revved the engine and was expecting to be able to read the value. But it goes further back from TDC into a region (BDC) that's not even marked. I was expecting it to go to the ADC area - is my balancer on backwards?

    But I'd expect to be able to get a reading when at, say 3000 RPM.


    I'm running MSD with Digital 6AL - no vacuum advance.

    It's working "perfect" - the centrifugal advance throws in more advance, and should move toward the BDC area.

    It is easiest to read this with an adjustable timing light - mark TDC and adjust the degree wheel on the back of the timing light to "move" TDC to the timing mark - then read your degrees of advance off the timing light.

    You are looking for 30 to 34 degrees total advance when all the centrifugal advance is "swung in" - probably by about 3000rpm - if it's higher than 3000rpm you probably need lighter springs on your centrifugal advance.


    Quote Originally Posted by CraigS View Post

    Years ago I converted mine to a manual choke operated by a push pull cable.

    +1

    Best advice.

  9. #9
    Senior Member Paparazzi's Avatar
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    Quote Originally Posted by mike223 View Post
    It's working "perfect" - the centrifugal advance throws in more advance, and should move toward the BDC area.

    It is easiest to read this with an adjustable timing light - mark TDC and adjust the degree wheel on the back of the timing light to "move" TDC to the timing mark - then read your degrees of advance off the timing light.

    You are looking for 30 to 34 degrees total advance when all the centrifugal advance is "swung in" - probably by about 3000rpm - if it's higher than 3000rpm you probably need lighter springs on your centrifugal advance.





    +1

    Best advice.
    Can you recommend an adjustable timing light that works with MSD? I have a basic battery powered one now since I read that the MSD can confuse the digital ones.

    Regarding the markings on the balancer - given that the amount of adjustment would go more towards the BDC area, why then would it have about 40 degrees marked after and only about 15 before? Wouldn't you want it the other way around? Or is it just that I need to make my own markings? (I ordered the MSD tape too so not such an issue now).

    I'll look into a manual conversion.
    UPDATE: I see that conversion kits are < $10. I think I can get that without having to go through wife approval. ;-)
    Last edited by Paparazzi; 08-18-2019 at 11:37 AM.
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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    Seasoned Citizen NAZ's Avatar
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    Please confirm which MSD ignition box you have -- the 6AL or the 6AL-2. Rereading your post I may have misunderstood which box you have. And if you have a part number for your MSD distributor it would be helpful. Last thing, what is the max BTDC degree marking on your damper?
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  11. #11
    Senior Member Paparazzi's Avatar
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    Quote Originally Posted by NAZ View Post
    Please confirm which MSD ignition box you have -- the 6AL or the 6AL-2. Rereading your post I may have misunderstood which box you have. And if you have a part number for your MSD distributor it would be helpful. Last thing, what is the max BTDC degree marking on your damper?
    I have the 6AL PN 6425 with a Blaster 2 coil. The distributor doesn't have any immediately visible identification. Looking at the Summit site, it's either 8584 or 85840. Given that it was built by a shop for a previous customer as a packaged motor, I'm going to say it's probably the cheaper 8584.

    I'll have to get the car back up on the lift to check the max BTDC marking and it's about 120F in the garage right now - will check later when it's cooled down a bit!
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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  12. #12
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    Mike223 is exactly right. Advance means the spark happens earlier, and yes, will go well into the BTDC area. You never want spark ATDC. Check the manufacturer of your distributor... thwey can tell you what springs and how to setup for how much advance at what rpm. It may not be exact, but this is not an exact science... your vac advance will be constantly changing spark anyways.
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    Seasoned Citizen NAZ's Avatar
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    My bad, somehow got the idea you had the programmable version of the MSD box. So once you confirm the zero it's easy to check the advance curve if you have enough degree markings before TDC. Or like Mike suggested, use a dial back timing light if you can find one that plays nice with the MSD system. I start at idle and slowly ramp up the RPM 500 at a time and plot the lead changes.

    You'll need to know what timing curve your particular engine likes and you can set-up the springs and bushing stops to get you close. MSD has a chart showing the curve for different spring combinations. And a chart showing the total advance for each bushing. I've had to modify weights and fab special size bushings to get closer to what I needed so don't be afraid to experiment -- it's easy to replace parts if you mess up. If your engine is completely OEM (except for the ignition of course) you can use the manufacturer's specs but if you've changed heads or intake or carb or cam it is likely that's no longer valid. Simply changing the carb size can affect the optimum lead across the operating range. However, a mechanical advance is a crude thing and you'll never get a perfect curve anyway.

    What Mike gave you is reasonable total lead but the "all in" by 3000 may be a bit too early. Pay close attention to pinging under load at lower RPM. The plugs will also tell you if you have too much advance -- look for peppering on the insulator. That peppering is pieces of aluminum from the piston -- a bad thing. Absent a known or computer generated curve I prefer to start with less lead and all in at as high of RPM as the heavy springs will allow as it's safer.
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    Quote Originally Posted by Paparazzi View Post
    Can you recommend an adjustable timing light that works with MSD? I have a basic battery powered one now since I read that the MSD can confuse the digital ones. I've heard of that effect, but I've never seen it - I use an older Craftsman as pictured with a MSD 6AL - no problems.

    Regarding the markings on the balancer - given that the amount of adjustment would go more towards the BDC area, why then would it have about 40 degrees marked after and only about 15 before? Wouldn't you want it the other way around? Or is it just that I need to make my own markings? (I ordered the MSD tape too so not such an issue now). I've never seen one marked as you describe yours, they're always marked with 5~10 degrees ADC and 30~40 degrees BDC (sometimes in three different places for SBF) - I have seen the outer part of the harmonic balancer separate from the rubber, or turned out of position on the rubber - but I would not imagine someone would attempt to put it back on - and especially not backwards.
    Attachment 112566

    Quote Originally Posted by NAZ View Post

    You'll need to know what timing curve your particular engine likes and you can set-up the springs and bushing stops to get you close. MSD has a chart showing the curve for different spring combinations. And a chart showing the total advance for each bushing. I've had to modify weights and fab special size bushings to get closer to what I needed so don't be afraid to experiment -- it's easy to replace parts if you mess up. If your engine is completely OEM (except for the ignition of course) you can use the manufacturer's specs but if you've changed heads or intake or carb or cam it is likely that's no longer valid. Simply changing the carb size can affect the optimum lead across the operating range. However, a mechanical advance is a crude thing and you'll never get a perfect curve anyway.

    What Mike gave you is reasonable total lead but the "all in" by 3000 may be a bit too early. Pay close attention to pinging under load at lower RPM. The plugs will also tell you if you have too much advance -- look for peppering on the insulator. That peppering is pieces of aluminum from the piston -- a bad thing. Absent a known or computer generated curve I prefer to start with less lead and all in at as high of RPM as the heavy springs will allow as it's safer.
    All this is true + agreed - but I think he's *probably* dead safe with all in by 3200 since he's not got the additional complication of vacuum advance to worry about.

    Fooling with the centrifugal advance curve definitely needs to be approached with great care + thought + probably more experience than the OP currently has (not abuse - just added words of caution).

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    This is kind of an unrelated question but still a Holley carb question. If you have vacuum advance, ( 302 Ford) should you have the same amount of vacuum at the nipple on the carb for the vacuum advance and at the nipple on the back of the carb for the PCV valve? At idle of 1000 rpm I have 0 inches at the nipple for the vac advance but 15 inches at the PCV nipple? Bring RPM's up and I do have vac at the vac adavance nipple and more at the PCV nipple

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    Quote Originally Posted by duff33 View Post
    This is kind of an unrelated question but still a Holley carb question. If you have vacuum advance, ( 302 Ford) should you have the same amount of vacuum at the nipple on the carb for the vacuum advance and at the nipple on the back of the carb for the PCV valve? At idle of 1000 rpm I have 0 inches at the nipple for the vac advance but 15 inches at the PCV nipple? Bring RPM's up and I do have vac at the vac adavance nipple and more at the PCV nipple
    That's called "ported advance" - here you go: http://www.superchevy.com/how-to/add...gnition-timing

  18. #17
    Senior Member skidd's Avatar
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    And the general consensus.. including my own.. is don't use ported vac for advance.
    It's a byproduct of the early 70s emissions push. It increases combustion temps at idle and is designed to work with old emissions tech.
    It's not for performance. Use full manifold vac.
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    Senior Member Paparazzi's Avatar
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    Update.

    I bought a piston stop and checked TDC. The mark on the balancer was accurate.

    With the motor to temperature I've adjusted the base advance to 18° and with the choke flap held fully open she'll idle sweetly at 800rpm with 20" of vacuum. I need a helper to check total advance and my teenage son is still asleep, of course.

    I adjusted the carb mixture to maximise the vacuum.

    Now onto the choke. The flap is still not opening fully at temperature. So as soon as I release the throttle she'll return to fast idle and too rich.

    Checked the 12v switched power from the MSD 6AL. Ha! Bingo! No power coming from the ignition box. Not sure whether that can be fixed without replacing the 6AL which hardly seems worth it - thinking I'll just put in a manual choke as suggested.

    But for now - what to do? How can I disconnect the choke to keep the flap fully open and put up with a hard start? Will it damage the engine to start like that?
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  20. #19
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    Paparazzi,

    I wouldn't expect any issues/damage by not using the choke. Haven't run a choke in years, no horn, nothing. Holley sells many carbs w/o the choke system providing a much cleaner air flow.

    I start with 2 pumps and turn the key. Yes, it needs a bit of throttle to keep it running at 1,500-2,000 for the first minute or so.

    You can remove the choke plate or for initial testing just wire it open and disconnect the actuation linkage. If you choose to install a manual choke cable you'll have the option if the choke helps at certain times.

    Jim

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    I did not know it was correct to power the electric choke from the MSD.
    It seems I remember the choke being feed from a key on source, other than the ignition.
    ,,, I am sure a search will direct you to a better and correct source.
    The electric chokes are great, just need it wired correctly. Do not put it on accessory hot.
    It seems the alternator field wire was a source, but you had better check that.
    Removing the choke blade will not keep the fast idle cam from being active.
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  22. #21
    Master Builder
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    What size is that Holley ? You can run any 12V key on power to the choke coil. A manual choke is a PIA. Holley chokes work great when adjusted properly' You can pull power to the choke from your pos side of coil. Next time you think Carb go with Quick fuel ! Great improvement ! A 351, depending on modifications and RPM range can run a 650 CFM and UP . If your car is a manual trans, a Mechanical secondary carb would be better for performance than the Vacuum secondary unit you are using.
    Kenny
    Last edited by first time builder; 08-24-2019 at 11:00 AM.

  23. #22
    Seasoned Citizen NAZ's Avatar
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    Do not pull 12VDC for the choke off the MSD box or the coil. This should be a separate switched circuit from the ignition. Yes, running with the choke on continuously WILL cause problems. Besides running like crap, a rich mixture will wash oil off the cylinders causing the rings to wear prematurely. In the olden days that was the standard method for seating rings on a new overhaul -- run the choke closed and the idle up above 2000 for 1/2-hour. And be advised that the fuel getting past the rings gets into the oil what do you think that does over time?.

    You must have a reliable 12VDC switched source of power to the choke when the ignition switch is on (and only when it's on) or you will never get the electric choke to work correctly. There is no need to go to a manual choke, just provide the power and adjust the choke correctly. However, if you see some other benefit to a cable operated choke -- go for it. I'd be surprised you actually need to use a choke unless you like driving in winter. Even here in snow country I don't run a choke on my hot rod. And that thing has a big high rise with a huge open plenum and 1050 CFM carb. I can get away with that because I only drive in fair weather, not when it's freezing out.
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  24. #23
    Senior Member Paparazzi's Avatar
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    The 6AL has a wire from it marked 'electric choke' so I kind of assumed that I could use that?! I disconnected everything and so I now have a fixed open choke blade and no high idle to worry about. Just posting this and then heading out to get new batteries for the timing light to check total timing.

    I live in NY so winters are ****** cold, but short of the occasional fun drive when it's dry, I typically don't take the car out if it's below 40F or thereabouts. I can deal with a more 'manual' start operation or switch to manual choke. As mentioned, does a car like this really need a 'winter start' option? I learned to drive in cars with manual choke and no syncro on 1st gear, so the electric choke was always something of a luxury for me.

    I'm not sure the model carb, I bought it as a 'carb to tranny' package from a Backdraft dealer who were upgrading a customer's car to a 427. It's a 600CFM Holley, I know that much. Other than that, I'm pretty sure everything is as stock as stock gets. New cam and heads are some point in my future, but not short term. Maybe a new carb then too (QuickFuel comment noted!). I currently have it limited to 6000 RPM which I've hit that on occasion with some 'enthusiastic' starts. I'm running IRS and 3.55 gearing so 1st is a blink of the eye.

    Before I took it off, the choke would come off partially, just never fully. I guess the heat from the block was actuating it to some degree. It was really more the fast idle not coming off that was bothering me.

    Heading out now for a ride - weather couldn't be more perfect! Will report back.
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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  25. #24
    Seasoned Citizen NAZ's Avatar
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    If you have a wire from the 6AL labeled "electric choke" I suspect someone other than MSD placed that label on there. I've run your same CD box for years and there has never been a wire off any of the ones I used that is intended to power the electric choke. Just re-read the instruction sheet -- nothing.

    I'm confident that if you power the choke from a reliable 12VDC source you can adjust it and make it work properly. Hundreds of thousands of OEMs used electric chokes successfully and you can too. Building a car is a challenge and learning experience. Don't give up when there's a bump in the road -- push through and you'll be rewarded.

    Good luck. Have fun with your car.
    Dart Little M 406" SBC 800 HP N/A & 1,100 HP on nitrous, 2-spd Powerglide with trans brake, 6,000 RPM stall converter, narrowed Moser 88 3.90:1 spool with 35-spline gun-drilled axles & Torino bearings, custom parallel four-link, custom tube chassis & roll cage NHRA certified for 8.5-sec (only two FFR Hot Rods have this cert).

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  26. #25
    Senior Member Paparazzi's Avatar
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    Quote Originally Posted by NAZ View Post
    If you have a wire from the 6AL labeled "electric choke" I suspect someone other than MSD placed that label on there. I've run your same CD box for years and there has never been a wire off any of the ones I used that is intended to power the electric choke. Just re-read the instruction sheet -- nothing.

    I'm confident that if you power the choke from a reliable 12VDC source you can adjust it and make it work properly. Hundreds of thousands of OEMs used electric chokes successfully and you can too. Building a car is a challenge and learning experience. Don't give up when there's a bump in the road -- push through and you'll be rewarded.

    Good luck. Have fun with your car.
    Just back from a quick trip. If the seat of the pants dyno is anything to go by, it's a big improvement. A bump on the throttle at 80 gives quite a nice neck snap of acceleration. I think I just graduated to my big boy trousers and took the training wheels off.

    I'll leave the choke assembly off for now, maybe will find another 12v source if I get bored of the troubled starts. I'll also re-check that wiring! I do wonder if it's never worked - it's only recently I've felt that this has started though.

    Speaking of bumps in the road - isn't that what makes us 'car enthusiasts'? I just had to get on my knees and reach behind my dash in the Home Depot car park after turning the key to ... nada. Realised my momentary 'security' hidden switch (clutch safety switch repurposed) had come loose. This afternoon's project.

    Got plenty of grins and thumbs up on the way home - life is good.
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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  28. #26
    Senior Member Paparazzi's Avatar
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    Update - hopefully final.

    So ... that 'electric choke' cable was bothering me. It wasn't 'tagged', it actually says it on the wire. So I traced it back and then realised that it's not part of the 6AL at all, it's from the Ron Francis harness. I have it going through the bulkhead behind the 6AL so it looks like it's part of it. Checked the RF wiring diagram - it's a fused supply. Checked the fuse box ... DOH! There it is - a blown fuse. Probably blew when it fell off the first time and it shorted.

    Sometimes I think I really overthink things and should consider the simplest solution first. Occam's Razor.
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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  29. #27
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    That is great news. I look forward to reading you having the elec choke up and working like it should.
    I seem to remember, the elec source was from the alt while it was running.
    This kept the key on, engine not running, choke coil from over heating, if you let the car sit with the key on, engine off for an extended length of time. I think there is an air circuit that gets pulled through the choke cap to prevent overheating and ruining the coil. All of this from a guy who cannot remember why he got up from his chair.
    Last edited by Railroad; 08-24-2019 at 02:16 PM.
    20th Anniversary Mk IV, A50XS Coyote, TKO 600, Trunk Drop Box, Trunk Battery Box, Cubby Hole, Seat Heaters, Radiator hanger and shroud.

  30. #28
    Senior Member Paparazzi's Avatar
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    I'll put the choke back on at some point, probably.

    So, that done, now I'm back to the timing. :-)

    Just took some readings. The battery powered timing light is tough to read in daylight, but:

    RPM Timing Degrees
    800 idle 17
    1000 18
    1500 20
    2000 25
    2500 29
    3000 34
    3500 38
    4000 38

    Which I'm going to say means that I have a 17 degree base and 38 total, 'all in' at 3500. Is that the correct way to interpret that, or do I subtract the base from the final to get total? If so, from what I've read it looks like I could use some adjustment in the mechanical advance?

    J.
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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  31. #29
    BadAsp427's Avatar
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    Those number all look real good, but I believe that 14 should be your idle advance and that would bring your top (all in) advance to about 36... These are the numbers that BluePrint Engines has me running on my 347 from them.

    Mk4 20th Anniversary #8690 (#8 of 20) Purchased 8/18/18----Build Started 8/19/18
    Build Thread Click Here / Registry Entry Click Here / BluePrint Engines 347ci / TKO600
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  33. #30
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    Looks good - I would drop the advance 3 degrees for 35 degrees total and keep an eye ear on it.

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  35. #31
    Seasoned Citizen NAZ's Avatar
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    You are interpreting the total advance correctly, base is 17, 38 total, all in by 3500. I'm with Mike, 38 total seems a bit too advanced but do you have a timing curve from the engine builder?
    Dart Little M 406" SBC 800 HP N/A & 1,100 HP on nitrous, 2-spd Powerglide with trans brake, 6,000 RPM stall converter, narrowed Moser 88 3.90:1 spool with 35-spline gun-drilled axles & Torino bearings, custom parallel four-link, custom tube chassis & roll cage NHRA certified for 8.5-sec (only two FFR Hot Rods have this cert).

    33 Hot Rod Super Pro Drag Racer Build: 33 HR NHRA Cert Roll Cage Build

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  37. #32
    Senior Member Paparazzi's Avatar
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    Great - thanks all!

    I'll bring the idle down to 14/15. I've no details on the engine at all other than it's a 351 roller, "Rebuilt 351w long block, built by same company Ford Reman uses" with 5500 miles since the build, which means next to nothing to me or probably anyone. I can't believe anything on the motor is anything other than the cheapest standard item that the builder could provide at the time. It was just a '351 option' on the original Backdraft. It wasn't an expensive option and I paid not a lot for it - always considered that it could be a 'beginner motor' for me and could stroke it out later down the road. I think they just wanted rid of it as used motors isn't their business.

    Just back from another trip out, 'just because' and she's going great.
    FFR6243RD, MkIII, 3.55, IRS, pin-drive width, carb'd 351W, T5, 1/2 dropped butt, Fortes hydraulic clutch, deep dish AC-III wheels by Team III. 9 year build; NY registered 7/18/2016 - "Sweet 16" winner at 2016 Taconic State Nationals 5 days later ... in 'rough as hell' gel coat for the foreseeable future! Build Blog - Leave me a comment!

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