MKIV Complete Kit Build Thread - Wisconsin

[cheverett]

Any luck figuring out what went wrong with the master cylinders? I've read that some people have them fail in the 500 to 700 mile range. I've also read that people received units with scratch's and grooves cut in the cylinder. I wouldn't think that you'd be that unlucky though. Maybe taking one apart would give you some insight.

Have not taken the MC's off yet.

I did talk to a Wilwood rep and he did not like that we used a pressure bleeder. I do wonder if moving the pedal (and pushrod) while under any pressure from the pressure bleeding tank could wreck anything? Otherwise, he speculated that maybe the seals dried out over time if they were older and sitting around for a while.

FF emailed back and said to not use the wrong fluid (I was using DOT 3 as directed) and make sure pushrods are not at an angle (they are not).

I have 3 new ones and will try this again without the pressure bleeding. Will take apart the worst one and see if anything looks wrong.

[edwardb]

Have not taken the MC's off yet.

I did talk to a Wilwood rep and he did not like that we used a pressure bleeder. I do wonder if moving the pedal (and pushrod) while under any pressure from the pressure bleeding tank could wreck anything? Otherwise, he speculated that maybe the seals dried out over time if they were older and sitting around for a while.

FF emailed back and said to not use the wrong fluid (I was using DOT 3 as directed) and make sure pushrods are not at an angle (they are not).

I have 3 new ones and will try this again without the pressure bleeding. Will take apart the worst one and see if anything looks wrong.

If pressure bleeding, you should never move the pedals while under pressure. If you did, plus the 15 PSI you mentioned earlier, agree the seals probably took a beating. I've used pressure bleeding on numerous builds. At around 5 PSI as I mentioned before. Has always worked with little/no fuss or damage. Many others have the same experience. Nothing to be afraid of.

[cheverett]

If pressure bleeding, you should never move the pedals while under pressure. If you did, plus the 15 PSI you mentioned earlier, agree the seals probably took a beating. I've used pressure bleeding on numerous builds. At around 5 PSI as I mentioned before. Has always worked with little/no fuss or damage. Many others have the same experience. Nothing to be afraid of.

Thank you again! My 16 year-old son and I are learning the hard way on some of this. We will be fixing the master cylinders, but for now have been learning a lot about carburetors. We adjusted the floats (they were very high) successfully and actually got the engine started but it won't stay running. With more carburetor adjustments and learning coming it would be a lot easier if our tachometer functioned properly.

Our tachometer will not zero out. Sits at 1800 rpm with key off or on. When doing the calibration sequence for our type of coil the tach needle will move smaller intervals through the first few steps for each button push and then move the normal amount right on 5,6,7,8. But won't go below 1800. Tried unplugging it. Gauge bad? Wiring harness issue?

Thank you again!!

[Mike.Bray]

If it's a Speedhut tach you can remove it from the dash, unscrew the lens cap to expose the face & needle, and manually move the needle to zero. I had to do this to mine as it was at 900 instead of zero. I think I posted about it somewhere. Speedhut even has a video on this.

[cheverett]

QUESTION: CARBURETOR OR FUEL LINE ISSUE??

(Mechanical fuel pump using -6AN PTFE braided line with post-pump filter at fuel rail to Holley Street Avenger carburetor)

Engine ran well last couple nights as we have made choke, float, idle mixture screw and fast idle screw adjustments. Looked at everything last night after cooled down a bit and front carb bowl is empty and we definitely have fuel in our oil. Rear bowl looks good. Both bowls were good at low end of viewing window when checked while initially running.

Did we vaporize some fuel heading into the fuel rail? I did not look at the carb window while at peak temperature. Are our filter and fuel line close enough to heater hose or anything else to cause this? See photos. We have been leaving the heater valve open while running to allow flow through heater hoses and get any air out. The filter and fuel line do not touch anything hot but probably 1/4 inch from heater hose. Before we change our heater hose return route with a 90 degree barb and move our fuel filter down closer to the pump, I am wondering if this could be more likely something else within the carburetor.

8A8D9771-1825-41A7-BDA1-49F7CD17F8A1_1_201_a.jpg
1A5AEEC2-94F3-481B-9B55-FE42C52ACEF7_1_201_a.jpg

[Railroad]

Really do not know where to start. Have not read back, except where you adjusted the carb.
Why do you think the front bowl is empty. Sight holes used to set fuel below hole. Had to rock car to see fuel come out. I would think clear sight holes use the same setting.
You probably got some gas in the oil with rich choke, wrong jet adjustments, pumping gas pedal, etc.
You do not really need a tach to adj carb.
With choke fully disengaged, fast idle screw should be clear of the fast idle cam. Set the idle speed screw to the desired idle. You know what is too fast or slow.
A vacuum gauge is good for setting air fuel adjustments. Highest vacuum at normal idle speed.
No need in trying to adjust it, if you cannot get your rpm down to a normal idle.
If the choke is off, fast idle not engaged, idle speed screw backed off, and you still have a fast idle, disconnect the throttle linkage.
If still too fast start looking for a vacuum leak. Most common issue is pcv valve. Either pinch the line closed or plug the line.
Short of having an uncapped vacuum source, you should be able to adjust idle speed with the idle speed screw on the drivers side, which contacts the carb throttle shaft lever.
Do not hard bottom out the air fuel adjustment screws, but start about 1 full turn off seat.
Adjust either air fuel jet for max idle smoothness and rpm. If you have an increase above a good idle level, correct with idle speed screw. Do the same with the other side of the carb and set idle speed as desired.
Hope all that makes sense. Post what you find and do, I will be glad to help.
good luck,

[cheverett]

Really do not know where to start. Have not read back, except where you adjusted the carb.
Why do you think the front bowl is empty. Sight holes used to set fuel below hole. Had to rock car to see fuel come out. I would think clear sight holes use the same setting.
You probably got some gas in the oil with rich choke, wrong jet adjustments, pumping gas pedal, etc.
You do not really need a tach to adj carb.
With choke fully disengaged, fast idle screw should be clear of the fast idle cam. Set the idle speed screw to the desired idle. You know what is too fast or slow.
A vacuum gauge is good for setting air fuel adjustments. Highest vacuum at normal idle speed.
No need in trying to adjust it, if you cannot get your rpm down to a normal idle.
If the choke is off, fast idle not engaged, idle speed screw backed off, and you still have a fast idle, disconnect the throttle linkage.
If still too fast start looking for a vacuum leak. Most common issue is pcv valve. Either pinch the line closed or plug the line.
Short of having an uncapped vacuum source, you should be able to adjust idle speed with the idle speed screw on the drivers side, which contacts the carb throttle shaft lever.
Do not hard bottom out the air fuel adjustment screws, but start about 1 full turn off seat.
Adjust either air fuel jet for max idle smoothness and rpm. If you have an increase above a good idle level, correct with idle speed screw. Do the same with the other side of the carb and set idle speed as desired.
Hope all that makes sense. Post what you find and do, I will be glad to help.
good luck,

Thank you. Clear window sight holes had fuel level at bottom edge past couple nights when running. Rear bowl still does but the front bowl has not a bit of fuel splashing around and the float is visibly very low in the window. We had no fuel in the oil after running the night before and both bowls were at the bottom edge of the window where we had set them last week. However, an hour after running last night - no fuel in front bowl and a lot of fuel in oil.

[Mike.Bray]

QUESTION: CARBURETOR OR FUEL LINE ISSUE??

(Mechanical fuel pump using -6AN PTFE braided line with post-pump filter at fuel rail to Holley Street Avenger carburetor)

Engine ran well last couple nights as we have made choke, float, idle mixture screw and fast idle screw adjustments. Looked at everything last night after cooled down a bit and front carb bowl is empty and we definitely have fuel in our oil. Rear bowl looks good. Both bowls were good at low end of viewing window when checked while initially running.

Did we vaporize some fuel heading into the fuel rail? I did not look at the carb window while at peak temperature. Are our filter and fuel line close enough to heater hose or anything else to cause this? See photos. We have been leaving the heater valve open while running to allow flow through heater hoses and get any air out. The filter and fuel line do not touch anything hot but probably 1/4 inch from heater hose. Before we change our heater hose return route with a 90 degree barb and move our fuel filter down closer to the pump, I am wondering if this could be more likely something else within the carburetor.

8A8D9771-1825-41A7-BDA1-49F7CD17F8A1_1_201_a.jpg
1A5AEEC2-94F3-481B-9B55-FE42C52ACEF7_1_201_a.jpg

Have you tried plugging into the carburetor to see what the data says?

[Railroad]

Front needle and seat, might be leaking, allowing too much fuel into the bowl and out the boosters into engine and oil.
Are you seeing a higher oil level, or fuel smell in the oil. The smell is not too much of an issue. If you have raised the level, you will need to change oil.
You might be percolating fuel into the engine due to fuel line heat, but not something that occurs that often.
Do what rerouting and isolating you can and watch the boosters in the primaries and see if fuel is dripping, while idling and after it sits and heat soaks.
It takes a lot of fuel to increase the oil level.
Seems I read, you have a manual fuel pump, should be good. If not manual, check your fuel pressure.
You can pull the front needle and seat, without taking the bowl off. Back it all the way out and check for trash. Reset the level and give it a try.

good luck,

[cheverett]

ADJUSTABLE DRIVER SEAT

We took a step away from trying to figure out our carburetor issue today and solved the 6 inch height difference between my son and me.
Nice product from Detroit Speed gives 7 inches of options for the driver's seat position.

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