deltsanddueces

I’m swappin a 350 into my 84 98 coupe which headers would work the best g body headers or a body headers? since they don’t make anything for these cars specifically

olds 307 and 403

Try a set of the Chinese full length stainless off Ebay. Surprisingly I had to do mods on the 70S, another guy put them in with 0 issues on his G body. Very well made and cheap.

Olds64

I have full-length Hedman Hedders on my 71 98. They fit well but are a PITA to install and maintain. I recommend against installing headers. If you have to use A or G body headers then make sure you have a BFH handy to get them to fit.

joe_padavano

The 1977-1985 full size cars use a frame that is VERY similar to the frame under the 1973-77 A-body cars. The full size DO use a bolt-on frame stiffener behind the control arm locations that will likely interfere with headers. Personally I would hesitate to remove it since GM is not in the habit of increasing production costs by installing unneeded parts.

deltsanddueces

So y’all are sayin I’d probably be better off stickin with exhaust manifolds?
Are the ones from the 307 any different than the 350 besides that they have tht oxygen sensor?

olds 307 and 403

The cast iron manifolds, yes.

brownbomber77

All of the suspension components and rear axle mounting locations are the same 73-77 A body and 77-96 B Body. Good chance a set of 73-77 headers will work just fine. I suggest eBay ones and then installing, banging up, tacking the tubes together in the middle where they come together (so they move as one unit, less flex and leverage from the flange to the collector and everywhere in between. Prevents cracking and leaking). Then, sending off for ceramic coating.

As noted before, you'll have to remove the braces going from the cradle to the frame rail.

deltsanddueces

https://www.summitracing.com/parts/h...hoCQ2MQAvD_BwE

if i ran these headman shortys would I still have to remove the frame brace? I been removing the 307 and while I was under the car it seems like these would dump out in the same place the factory manifolds

olds 307 and 403

Go to the Hedman site and take the header dimensions down. The Hedman are a mid length header and you may be close to the ground, even with a tight bend. The other two options are Sanderson shorties, very similar but 1 5/8" tubes, much thicker 3/8" flange that only requires RTV. The collector is much shorter and gives good ground clearance. In mild steel and ceramic coated, more money to buy. I have used multiple sets, quality is hit and miss. The third choice is Thornton shorties. In stainless, a thicker flange like the Sanderson and bolt to existing A body down pipes. There is one flattened pipe and quality is also hit and miss. Good luck.