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The interference was about at the same elevation as the polyurethane engine mounts. So the driver side bushing would have to compress quite a bit to cause a contact.
Am I OK as it is or do I need to butcher the header even more?
Drivers side engine mount only compresses on deceleration with the motor. Would have to be real aggressive with a manual to get that. With an auto I don't even think you could do it.
Misses by an inch, misses by a mile. Those SS (look chrome coated) headers are going to VERY HOT for sure. A fair amount of heat transfer will take place there. If they were ceramic coated it'd be whole lot better for everything under the hood.
Thanks REELAV8R - all good info to know. It is a manual gearbox, but I'm not aggressive :-) I guess it'll be fine on the driver side then. I am still grinding a steeroids bracket on the passenger side for clearancing of the header.
As far as coating is concerned, coincidentally I have just gotten in touch with Ceramic Barriers | Shock Towers | Auburn, WA (performancecoatings.com). I want them to ceramic-coat the SS headers and side pipes inside and out. It'll be done after the engine's first start and break-in period.
Thanks REELAV8R - all good info to know. It is a manual gearbox, but I'm not aggressive :-) I guess it'll be fine on the driver side then. I am still grinding a steeroids bracket on the passenger side for clearancing of the header.
As far as coating is concerned, coincidentally I have just gotten in touch with Ceramic Barriers | Shock Towers | Auburn, WA (performancecoatings.com). I want them to ceramic-coat the SS headers and side pipes inside and out. It'll be done after the engine's first start and break-in period.
That's a good idea to coat them after break in. You'll also be able to have a before and after comparison of ceramic coated pipes for people who want to know.
I have mine Jet hot coated. The warranty is for life with them.
Last edited by REELAV8R; May 26, 2022 at 11:02 AM.
Engine Masters did a segment on how much they could dimple a set of headers before it would cause any performance changes during their dyno runs.
They totally mangled a set of headers and saw no performance loss during their dyno tests.
It is an amazing video to watch if you can find it.
If you are at all worried about engine movement and contact with the headers at the steering joint, then swap out the poly engine mounts for a set of Moroso solid mounts.
Nothing moves and you’ll have no vibrations.
You might even gain some needed clearance.
I considered poly engine mounts until I talked with Energy Suspension who told me that it is true that they have seen several cases where header heat will melt even their poly engine mounts on Corvettes.
There are also several threads here on the forum to support this, which caused me to contact Energy Suspension in the first place.
Just another option to consider.
That's a good idea to coat them after break in. You'll also be able to have a before and after comparison of ceramic coated pipes for people who want to know.
I have mine Jet hot coated. The warranty is for life with them.
Might be interesting to take some of that heat indicating tape and apply it in a few areas near the headers before the coating and after to see some real numbers.
Agree on the above dimpling and performance. It was surpising. I would give it a little more clearance while you are in there. Best to do it now while they are out. I would say 1/8" is a little close. You could also then use some header wrap afterwards to insulate it some. DEI makes some good stuff. Just do a small section.
On the driver side, I did a little more banging and I now have a bit more than 1/8" clearance around the steering U-joint. I have like 1/4" clearance where the pipes go underneath the chassis. I think that's all good.
On the passenger side, I had the grind & repaint a steeroids bracket to make room for one pipe. I think it has enough room.
The tightest spot though is where one pipe goes underneath the chassis. There is 1/8" clearance there.
Too little??
1/8” is a little tight for my liking but others might think it’s plenty.
You could put another small dimple to flatten the pipe just a little at that location to gain more clearance.
you’re getting close.
Side pipes are really just free flowing exhaust if the side part are not restrictive. They are NOT a tuned length or diameter. Poly engine mounts melt on performance engines from header heat. They also cook the grease inside of stockish type steering boxes.
The engine trys to pitch up on the driver's side and down and slightly outboard on the passenger side under hard aceration and or dropping the clutch hard. this is due to the direction of rotation of the crank.
Keeping this in mind your passenger side should be just fine.
Hard decell does little movement as crank is still turning the same way. However really hard deceleration can cause tail of transmission to lift and front of engine to tilt downwards and slightly forward.
In this case your right side could contact as the headers will lift at the rear of them. Hoping all this makes sense.
I have used Hedman hedders on 2 Corvettes and both times they fit like a glove and there was no need to re-shape the pipes or even grind down the Steeroids Parts on my 1968 C3. They slide right in and don't get close enough to anything under the hood. Those were both times made for a 427 using 2-1/8" pipes. They were the long tube headers made for the C3.
It is a great idea to "break in your engine" before putting on the coatings. Several companies that make and sell ceramic coated headers tell you not to break in a "new" or freshly re-built engine with them as it can discolor the pipes near the heads. If you have any serious compression it is even more important as the compression makes extra heat and the standard coatings will not tolerate the extra heat without damage.
4-vettes, it all made sense. I decided to dimple the passenger pipe closest to the chassis and ended with about 3/16" clearance:
derekderek, you're right - after coating it will be barely noticeable (I hope).
ctmccloskey, side pipe headers must be more prone to hitting parts of the steeroids system compared to regular headers. Mine are only 1 7/8".
My contact at performancecoatings.com also recommended that I do the coating after the first start & engine break-in period. So be it.
If you can, find someone who can coat those headers inside as well as the outside.
If you can’t, I believe Eastwood makes some good coatings for the inside of header tubing.
How much driver side header clearance needed?
