['ol Pinion head]

formula400, went and looked at pics on page 50 and read thru comments on the posts.

The bare crossover being painted heavily with thick black heat paint, haven't seen it on a low mile original engine. Have seen a thin black coating on two nos later date cast exhaust crossovers (both '69-71's). Mind you, they were service parts and the reasoning behind the coating was to not show surface rust after sitting forever at parts dist facility. My take on the thick black heat paint on the bare crossover, is someone painted it that way after the car was new.

On original crossover shields, have ran across a few with a thin black original coating. As they are stainless, there was no reason to coat them at supplier plant to keep them from rusting, so no idea what was up with that. They were on relatively original cars, so... Have also examined a few low mile original cars where there was no black hue on the clamshell type shields. Multiple production runs, multiple finishes???

Paint... On my most original & document-able '71, there is no '71-early '73 paint on the original choke stove, or was there any on any of the orig carb linkage. On my '72 T/A, the choke stove on the crossover currently has a bunch of blue paint on it, but the choke stove is not orig to the car (came off a '71 GP YS 400), I pieced the choke stove & elbow for this car.

Back on page 50, noticed several comments on the removed 71 exhaust system. The flat spotted head pipes appear original, at least further back. My only question was the design of the front of the headpipe. I guess I cannot remember examining an original '70-72 Firebird roundport headpipe. Thought it odd there was a flange just a few feet back. The later SD version uses a piece of mandrel bent pipe kicking back from the manifold outlet, & is it is factory (supplier) welded to the remainder of (flatspotted) head pipe, which is quite long. this headpipe then slides into the beginning of the pipe that goes to the crossflow muffler. Would love to hear more comments about this 70-72 F headpipe.

[2manyT/A'S]

Originally Posted by 'ol Pinion head

formula400, went and looked at pics on page 50 and read thru comments on the posts.

The bare crossover being painted heavily with thick black heat paint, haven't seen it on a low mile original engine. Have seen a thin black coating on two nos later date cast exhaust crossovers (both '69-71's). Mind you, they were service parts and the reasoning behind the coating was to not show surface rust after sitting forever at parts dist facility. My take on the thick black heat paint on the bare crossover, is someone painted it that way after the car was new.

On original crossover shields, have ran across a few with a thin black original coating. As they are stainless, there was no reason to coat them at supplier plant to keep them from rusting, so no idea what was up with that. They were on relatively original cars, so... Have also examined a few low mile original cars where there was no black hue on the clamshell type shields. Multiple production runs, multiple finishes???

Paint... On my most original & document-able '71, there is no '71-early '73 paint on the original choke stove, or was there any on any of the orig carb linkage. On my '72 T/A, the choke stove on the crossover currently has a bunch of blue paint on it, but the choke stove is not orig to the car (came off a '71 GP YS 400), I pieced the choke stove & elbow for this car.

Back on page 50, noticed several comments on the removed 71 exhaust system. The flat spotted head pipes appear original, at least further back. My only question was the design of the front of the headpipe. I guess I cannot remember examining an original '70-72 Firebird roundport headpipe. Thought it odd there was a flange just a few feet back. The later SD version uses a piece of mandrel bent pipe kicking back from the manifold outlet, & is it is factory (supplier) welded to the remainder of (flatspotted) head pipe, which is quite long. this headpipe then slides into the beginning of the pipe that goes to the crossflow muffler. Would love to hear more comments about this 70-72 F headpipe.

The headpipes were from a mid December build 72 W66 with TH 400.

Perhaps the stick cars got different plumbing? (need to check the parts book)

[giles]

Originally Posted by 2manyT/A'S

The headpipes were from a mid December build 72 W66 with TH 400.

Perhaps the stick cars got different plumbing? (need to check the parts book)

2many, your headpipes look just like mine. I'll attach a not-so-great photo but you'll get the idea. Pretty flat in spots. The set on my car were purchased from GM parts and installed on my car about 1980 or '81. I had them out again about ten years ago, sandblasted and painted with high temp paint. The headpipes go back to about the rear footwell. There is a junction and then another pair go up and over the axle. If memory serves only the headpipes were unique to RA manifold cars. No difference between automatic and manual trans. The over-the-axle pipes, muffler and tailpipes were common with all dual exhaust Firebirds of the era (except SD which had the extra resonators in the forward part of the over-the-axle pipes).

[formula400]

don't die H.O forum !!!!!