See attached photos, how can I get the exhaust to be the same on both sides? Motor mounts are in the same location left & right in the chassis.....IMG_1377.JPGIMG_1378.JPG
Your headers to the footboxes looks pretty normal. It is typically much tighter on the DS. Do you have the body centered, front splash guards installed, and wraparound under the sides attached with the doors installed? The body can move in and out a lot, especially in that area where the pipes exit. More important than the exits IMO are how parallel and even distance from side to side the pipes are from the body.
Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.
edwardb nailed it. There are wedges and spacers available if you need to adjust. I made some AL spacers myself. Just a copy of the gasket, to get further away from the body.
If you're talking about how the header to sidepipe flange is farther out on the driver's side the answer is FFR 4 into 4 headers on a 351. The headers have been that way on every 351 based car I've done. Doesn't occur with 302 based engines (needless to say the headers are different).
Can you take a picture of the driver side pipe? Looks like its pretty close to the body yet you can clearly see the flange sticking out past the body. Not normal. If it was my car, i would have that side header shortened as long at the side pipe was far enough from the body.
Mike
Wow that looks like crap. I have seen many, many cars where the driver's side was higher than the passenger but I wasn't aware the the 351 driver's side is too long. Jeez FFR.
FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.
Jeff,
How did you address the situation previously? Should I consider shortening the DS header (Mike Everson)if installing the splash shield (EdwardB)doesn't have any effect or have a spacer made for the PS header? Can I buy spacers that are made already?? Very surprised that FFR has never addressed the issue with a design mod!!
I had the same issue with the header flange seeming to long, but with a 302. Took the forum advice and once I installed the splash guards it pushed the body way further out than I thought it would. Get those installed first then see where you are at.
See attached photos, how can I get the exhaust to be the same on both sides? Motor mounts are in the same location left & right in the chassis.....IMG_1377.JPGIMG_1378.JPG
That's how it looks for my 351w also. PS tucked in closer while the DS bolts show. Thought I had set the engine wrong.
Mk4 Roadster 20th Anniversary #8658. 04 of 20. 3.31 IRS.
Forte 427 Dart, TKO 600, Quick Fuel 780 carb. Delivered 9/2/2015, First start/Go Cart 2/18/2017.
Road Legal August 31, 2017
The FFR headers for my 302 where the same. I thought it might be the heads I used that caused the problem. The drivers side was too high, even after tilting and lowering the engine, and I had the flange machined on an angle to lower it. I had to add a spacer on the passenger side and made my own out of aluminum plate.
Breeze sells (or they did) wedges and spacers to make everything fit. We have shimmed the motor mount a lot of times also. It is a fixable situation. In the case in the picture make sure the splash guards are installed. Also the body is NOT centered over the hood opening it is centered by measuring the shock mounts to fender. HTH, Richard.
Need help finishing your project we can help here or at your shop.
FFR GTM #34 first GTM with working AC. 400 hp LS1 w/G50
FFR coupe 3617CP 331 Stack EFI T-5 IRS Cobra brakes, AC/heat.
Both cars by NRC, we can build (and have built) any FFR product.
We also make and sell a ton of great parts for the FFR community.
Brake kits, AC systems, #1 supplier of Team III wheels.
Also realize that the bolts that attach the body under the rocker panel area also affect this. Most people end up slotting the holes in the fiberglass so the side of the body can be pushed in and out to help align it flush to the door. Since the body is pretty solid (due to the curvature to fit it under the frame) from the rear wheel opening to the exhaust cutout that entire length moves as a whole.
FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.
The FFR headers for my 302 where the same. I thought it might be the heads I used that caused the problem. The drivers side was too high, even after tilting and lowering the engine, and I had the flange machined on an angle to lower it. I had to add a spacer on the passenger side and made my own out of aluminum plate.
HTH
Norm
Norm,
You wouldn't happen to have the template for the spacer you made, otherwise I'll just us a gasket for the dimensions!
I would balance the end of the headers first. You mentioned the motor mounts are in the same location but the correct position to look at is the end of the header to the floor. There is about a 1/4 inch play in the engine position(by motor mount) which can change the end of the header by almost an 1 1/2. Balance the engine first by the header flanges to the floor and then check the side pipe run out. The side pipe run on each side may be different but will look appropriate per side.
Just a reminder, the cutouts are for J-pipes. Yes , driver side is higher then pass. And yes, D side is closer to the body. It's normal for me to move D side up about 2.5 in. Pass side about 1.3/4. Also, the pass side needs a deeper back-cut on the back edge of the hole. When all is said and done, "most".....not "all" will fit parallel to the body without the use of shims. Not the same on each side but passable......Happy Mediums is the name of this game.....Good luck should you choose this mission......this message will self destruct in 5.....4.....3....2....1....REALLY ! Your still here. Most guys leave when I get to 3......You got this ....da Bat
Just a reminder, the cutouts are for J-pipes. Yes , driver side is higher then pass. And yes, D side is closer to the body. It's normal for me to move D side up about 2.5 in. Pass side about 1.3/4. Also, the pass side needs a deeper back-cut on the back edge of the hole. When all is said and done, "most".....not "all" will fit parallel to the body without the use of shims. Not the same on each side but passable......Happy Mediums is the name of this game.....Good luck should you choose this mission......this message will self destruct in 5.....4.....3....2....1....REALLY ! Your still here. Most guys leave when I get to 3......You got this ....da Bat
da Bat,
So you don't use a spacer on the PS to get the header closer to the body, similar to the DS? Just elongating the PS hole is adequate?
My passenger side pipe was only 1/2 inch from the body. I made a spacer out of some 1/2 inch aluminum plate I had left over from another project. That’s about as thick as I can tackle with the tools I have. I would have to look to see if I have enough aluminum left for another. Away from home for work now and have 1 day at off between now and the 24th. Will look and let you know if have any left and can help.
How soon would you need it. Just checked the weather at home and it’s -14 Celsius or about 7 above 0 Fahrenheit. Won’t be doing anything in the shop for awhile unless it warms up.
How soon would you need it. Just checked the weather at home and it’s -14 Celsius or about 7 above 0 Fahrenheit. Won’t be doing anything in the shop for awhile unless it warms up.
Norm
Norm,
Thank you for the reply, I'm more like >1" away on the passenger side! Curious what FFR has to say about the differences side to side.
Just heard from FFR, they are sending a spacer & wedge to get the PS side similar to the DS.. Still don't understand why this condition exists on 351W builds and nothing has been done to address it from a engineering perspective!
jwebb, I am in the same position I think that you were. I have a 351w (408) and the flange is sticking out past the body. I cannot move the body at this point as its painted and mounted. What did you end up doing here? I am considering getting new headers, or modifying the FFR ones again.
Wow somethings wrong there. What are your particulars on the build?
Mike
Agree with Mike, My DS is inside the body by 1 inch and the PS is inside by 1.25 inches. Somethings not right.
2nd MK4 #10639 received 3-19-23. Wife's version. Street Snake - IRS, Willwoods, no roll bars, no hood scoop, no stripes, Blue Print EFI 306 with AOD trans, and under car exhaust. Ford Eruption Green with saddle leather interior.
1st build - Mk4 Roadster #9319, received 4-10-18. IL registration 8/6/19. Moser 8.8. 3 Link. Wilwood brakes. Blue Print 427, Holley 750, TKO 600, 0.64 OD. Paint Dec 2020. Ruby Red with Carbon Flash Black metallic stripes.
Agree with Mike, My DS is inside the body by 1 inch and the PS is inside by 1.25 inches. Somethings not right.
I disagree. Mine is just like Erstanl’s and I have seen many like it. Blueprint 427w. No adjustment possible. One shim on passenger side for alignment. That’s just the way they fit without serious modifications. The side clearance from the pipe to body is similar on both sides. (See Jeff Kliners post above.)
Last edited by BB767; 02-26-2021 at 09:54 AM.
Reason: Added note about Jeff’s post
I disagree. Mine is just like Erstanl’s and I have seen many like it. Blueprint 427w. No adjustment possible. One shim on passenger side for alignment. That’s just the way they fit without serious modifications. The side clearance from the pipe to body is similar on both sides. (See Jeff Kliners post above.)
Well, I guess I got lucky then...Blue Print 427 and mine is perfect. It's hard for me to understand why my DS is an inch inside the body when so many are sticking out? Something has to be different to cause it. Length of headers, body position, motor mounts, something??
2nd MK4 #10639 received 3-19-23. Wife's version. Street Snake - IRS, Willwoods, no roll bars, no hood scoop, no stripes, Blue Print EFI 306 with AOD trans, and under car exhaust. Ford Eruption Green with saddle leather interior.
1st build - Mk4 Roadster #9319, received 4-10-18. IL registration 8/6/19. Moser 8.8. 3 Link. Wilwood brakes. Blue Print 427, Holley 750, TKO 600, 0.64 OD. Paint Dec 2020. Ruby Red with Carbon Flash Black metallic stripes.
Here is another angle of the issue. I don't think its drivable as is. The flange will knock into the top of the cutout and bang up all the nice bodywork as is.
How does the height of the pipes compare side to side. I have 351 heads on my 331 and had to have the header flange milled on an angle to lower the drivers' side pipe. The problem you have is the body cutout has already been enlarged to allow for the higher pipe so my solution would leave a large gap above the pipe.
I took a screen shot of the last picture you posted and don't know if modifying the header length will be possible. It maybe an optical illusion created by the camera angle but, it doesn't look you can move the flange inside the body without the pipe getting close to the body. The two red lines on the attached picture are the same length.
It may take a combination of tilting the engine, moving the body out and a liberal sprinkling of the correct bad words to get it to the right spot.
HTH
Norm
Mk4 base kit 7721, 331 Stroker, Holley Sniper EFI, Wipers, Heater, Whitby Soft Top, Drop trunk mod and more
Here is another angle of the issue. I don't think its drivable as is. The flange will knock into the top of the cutout and bang up all the nice bodywork as is.
I have a 408W (351W Based) with the Factory Five Headers and my DS Header end is closer to the body, just like Kliner stated. Header Flange to DS Body 5/8 inch and PS to Body 2 inches. Now this is after pulling the underside of the DS body outward as much as possible and then riveting it in place underneath. It needed to pulled out anyway to assist in proper DS door fitment. I also adjusted the PS so that the body to side pipe distance was close to the same on both sides. It also meant enlarging the cut outs for proper clearance, which was required on both sides.
Like most, the body on the frame required tweaking to get the front end aligned with the hood frame openings and in my case I had to move the rear of the body over to the DS by about 1/2 inch to get it to sit over the rear wheels properly. I verified multiple times that the rear axle was centered because initially I thought that was the problem. All in all the body on the frame needs to be tweaked so that everything looks right to the eye and not by the measuring stick.
I think you have a difficult situation because your body is painted and positioned and the cut outs made. But I don't see anyway around not pulling the DS body out some and re-reviting the underside. A lot of folks place 2 revits one more forward which in my case helped get the body out further from the Header Flange. And enlarging the side pipe cuts outs where needed. The cut out raw edges could be touch up with brushed on black paint. The concern is that adjusting the body out might mess up your door alignment. Maybe even enough that additional body work would be required on the door and re-painting. Although not ideal maybe just making the cut out bigger where needed is the easiest way to go at this point.
Also make sure your side pipes are basically at the same height off the floor. If not, them maybe some engine movement could help.
As I said way back in post #5 this is a characteristic of the FFR headers on a high deck 351 based block. That was the case when I wrote it 3 years ago and is still true today although I'm hopeful that the new ball flange headers might be better. With the traditional 4 into 4s the driver's side flange is right at the body... sometimes beyond. The situation is exacerbated if wedges are required to align the pipes with the body because the stack up moves the pipe flange even farther outward. I hate it but my hands are tied when working the cutouts and I have to leave clearance. Most times I end up using buttonhead bolts to gain just a little vs. the socketheads. As Rich said this should have been addressed before paint---I always, always, always fit and align the pipes during mock up and massage the cutouts as required. If necessary you can reshape them after paint by working carefully with a 1 1/2" drum sander in a die grinder or drill.
If you can’t resolve your issue with all of the suggestions so far you could reach out to George at GAS-N. I have spoken with him about an issue with my set up (raised deck 351w based 427 with Z heads that FFR does not support with their standard headers) and he has an adjustable header jig that he can send you so you can get the side pipe flange exactly where you want them. Once set, you send the jig back and he will make a custom set of headers for you. His headers also offers an adjustable ball joint for side pipe adjustments now. I have ordered a set from him with the right flange for the Z heads. I should receive them next week and I am hoping that they will be even on both sides but after reading this post we will see.... George did say that if I need to have in/out adjustments he could build the side pipe flange to ball connection to any length if needed.
Here is another angle of the issue. I don't think its drivable as is. The flange will knock into the top of the cutout and bang up all the nice bodywork as is.
Looks like the header/pipe flange just needs to come in a bit. I've had both headers and pipes modified on various cars. Not really that tough or expensive to do, just need to find a good welder/fab shop and they should be able to fix you up.
You also might be able to replace the gasket with copper RTV which would save you a 1/8" and switch the top bolt to a hex or pan head and it might get you by? My 2 cents. Good Luck. Scott
FFR #3870 MK II, Spectra Blue/Arctic White, 1974 414W, 10:1, Eagle 4340 crank and rods, KB Pistons, Ported Performer RPM 2.02 heads & intake, QFT SS-650, Comp XR282HR, Quality Roadsters pan, Crane ignition, TKO600, 3.55 gears, 3 link, SA QA1's, Breeze LCA's, Heim joints & VPM F/R bars, Power steering with Hiedts valve, Power brakes, Fortes bump steer kit, 5 bolt axels, SSBC rear brakes, Oil cooler, Pusher fans, Halibrand Cobra III's with Nitto NT555 G2 245/285/17
Thanks: 
Likes: 
Reply With Quote
Originally Posted by jwebb
