Bundle of Snakes Advice

#1
The stainless steel bundle of snakes I received with the RCR GT40 project I purchased turned out not to fit the car. Everything is too high and too wide to fit under the fiberglass rear clip. I'm in the re-design stage of re-working the exhaust and am looking for opinions on what clearances are necessary from the fiberglass clip and from the transaxle. I'm running a G50-52 transaxle which sits pretty high and right now it looks like I'll have in places less than 1/2" clearance from the collectors to the ribs of the tranny...too tight? I'm not sure what else to do as room is at a premium. Also, the pipes, right now are running anywhere from 33" to 40" in length. Is there a basic rule for pipe length or difference in pipe length in making a crossover system? This is going to be a very tricky project...I've never attempted to tackle this complicated of an exhaust modification. I plan to cut, fit and tack and have a pro do the tig welding. Any other tips to make this go smoothly will be met enthusiastically!

Thanks!

Kim
 
#2
Making these headers is tough. I started with what would the the longest tubes, and then made all other tubes the same length through various twists and turns. My inverted 930 gives a lot less room behind the block, and then you have the slave cylinder in that area as well, which all makes this very difficult. Luckily, the GT40 at least has some room above the transaxle, which was not a luxury for my body style.
 
#5
Is there a better alternative transmission which would allow room? I'm in the planning stages, so I'm wide open to suggestions to avoid problems like this from potentially happening. I was considering a Porsche, either G50 or 996 variant. But I've seen the Audi 01E, the UN1 as well as the good old ZF trans. But I definitely would be wanting a cable shifter as I want to do a right hand drive car with shifter on the right like the original.
 
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#6
But I definitely would be wanting a cable shifter as I want to do a right hand drive car with shifter on the right like the original.
RHD with a ZF uses a rod shifter and as the ZF input shaft is below the output (unlike the Aude/Renault/Porsche units) you have a very low powertrain and thus lots of header room.
 

New Member
#7
Hi, I’ve got an Audi 01E in my RCR GT40 with the engine mounted one inch higher to get decent driveshaft angles. The RCR headers fit absolutely fine. The only mods I’ve made are to thin down the heads of a couple of the socket head bolts to make the fitting easy and a slight tweak to the tailpipes to get them perfectly central in the body rear aperture.
Personally, I’d explore every option before cutting the headers because I guess RCR make them on an accurate jig.
Cheers
Roger Allen
 
#8
Hi, I’ve got an Audi 01E in my RCR GT40 with the engine mounted one inch higher to get decent driveshaft angles. The RCR headers fit absolutely fine. The only mods I’ve made are to thin down the heads of a couple of the socket head bolts to make the fitting easy and a slight tweak to the tailpipes to get them perfectly central in the body rear aperture.
Personally, I’d explore every option before cutting the headers because I guess RCR make them on an accurate jig.
Cheers
Roger Allen
The exhaust was not made by RCR to my knowledge.
 
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Jac Mac

Active Member
#9
The stainless steel bundle of snakes I received with the RCR GT40 project I purchased turned out not to fit the car. Everything is too high and too wide to fit under the fiberglass rear clip. I'm in the re-design stage of re-working the exhaust and am looking for opinions on what clearances are necessary from the fiberglass clip and from the transaxle. I'm running a G50-52 transaxle which sits pretty high and right now it looks like I'll have in places less than 1/2" clearance from the collectors to the ribs of the tranny...too tight? I'm not sure what else to do as room is at a premium. Also, the pipes, right now are running anywhere from 33" to 40" in length. Is there a basic rule for pipe length or difference in pipe length in making a crossover system? This is going to be a very tricky project...I've never attempted to tackle this complicated of an exhaust modification. I plan to cut, fit and tack and have a pro do the tig welding. Any other tips to make this go smoothly will be met enthusiastically!

Thanks!

Kim
Dont see why the trans should be sitting high as porsche trans run input shaft below output driveshafts like ZF. I wonder if the header set you have were actually made for a 351w (1.280" higher deck height than the 302 based 363 you have been given with car ) easy mistake for a vendor if only told its cu-in size rather than actual engine block used.
 
#10
Dont see why the trans should be sitting high as porsche trans run input shaft below output driveshafts like ZF. I wonder if the header set you have were actually made for a 351w (1.280" higher deck height than the 302 based 363 you have been given with car ) easy mistake for a vendor if only told its cu-in size rather than actual engine block used.

Its possible the headers were made for a 302 block with standard height heads, my Z head ports are about 3/4" taller I don't think the Boss block is much taller than a 302...right now the height dimension is almost 3" too tall...and 2" too wide on both sides. If they were fashioned on a 351 wouldn't that give me the opposite problem? The headers would drop down on a 302.
 
#11
Correct. The deck height on a 351 is @1.3" higher (9.503" vs 8.2") than a 302. So if designed for a 351, they would be lower bolted to a 302 based engine. Even an early 351 block has a 9.48" deck height.
 
#12
Kim,
Can you post a couple of pics of how your engine and tranny sit in the chassis? I have a 306 and a g50 in mine, (RCR) and can give you an idea or send some pics. Scott
 
#13
IMG_2401.JPG

IMG_2402.JPG

Thanks Scott... here are a couple of photos of the exhaust I have now and where the transmission sits in the Horse shoe. I talked to Fran yesterday and he thinks I should abandon these headers and build a new system. He said it's near impossible to make a 2 inch header system that will fit this application and recommended I go to a 1 5/8" or a 1 3/4" at the most. Anyone in the market for a 2 inch bundle of snakes?
 
#14
Wow! 2" exhaust pipes. That's usually reserved for 450+cid big blocks. And 1-3/4" would be for a 408W or similar.

With a 302 based engine, I would think the 1-5/8" would be your best bet.
 
#15
Yup, big diameter sits high and looks nice but !!!!. I have 1 7/8 427 W in a CAV and have interference with the clam. I'v lowered the engine as much as possible. What to do, it may be a little tacky but I'm about to cut another window in the clam! Any one out there done this, I can't think of any other option. The pipes are tight to the cross member, no point in looking in that direction.
 

Rick Merz

Lifetime Premier Supporter
#16
Bill,

I feel your pain. Fran 's guy did a beautiful job making my headers but the #4 and #7 pipe came in contact with the rear clam and the pipe that crosses over going into the collector was a 1" higher than the rear clam under the window area. My solution was to cut and modify pipes #4 and #7 to clear the rear clam and to put a hump in the clam under the window area to clear the crossover. I still have to weld the pipes together (they are taped for now) but you can see what it will look like when finished.

Rick
 

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Jac Mac

Active Member
#19
Kims engine is 363 cu in, Those headers appear to be stepped so at a guess with 2" tailpipes it would be 1.75"OD primary size at port. When I built the 346 in the TVR I was told it was going to be 331/4'' bore & fabricated headers accordingly so exh ended up actually being a tad small for the 346 it ended up with ( 1.625/1.75/1.875 ), when driving it does go a bit flat at top end, but bottom end is OK on tracks it runs on. So what Im saying if Kim intends to run his 363 up to 7500+ ( which I hope he wont with the hyd roller cam ) those headers might be OK ( with a 4bbl ) and re-fabricated at collector end to take advantage of the huge gap between top of horseshoe collar and collector underside ( bottom pic above post #13 ). BUT if its only gonna be a cars n coffee deal go smaller & start over.
 
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#20
My headers are RCR supplied and, like the above pictured ones, are too high and contact the rear clip requiring a small "divot" be removed from the clip area under the window. Fit is tight at the transaxle but it works. Thinking about adding a temp controlled fan to blow air past that area for low speed/traffic operation.
 
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