I'm trying to install a set of Flowtech headers on an 84 TA with a stock 305 lg4. The driver side header bolts right up but the pass side does not.

For some reason the rear most exhaust manifold bolt hole in my 305 pass side head is further back towards the firewall and wont line up with the hole in the header.

The other 5 holes line up just fine. Will it be ok if I just use 5 bolts and leave the last one out? All the exhaust cutouts line up perfectly. Any ones else run into this? Surely I can't be the only one. Called Summit Racing and the guy didn't really know what to tell me!

 

Sounds like you got the wrong headers. There is a difference between heads and thus exhaust manifolds between some of the years. Exhaust manifolds from a 1992 305 TBI car won't bolt to a 1985 305 carb car, etc.

You'll have an exhaust leak if that last bolt isn't put in. Chances are with headers, you'll have an exhaust leak anyway - they always do - that's why everyone spends the extra for the locking header bolts, because otherwise they back out all the time. Even then, anyone with headers knows that once a month the bolts need retightened. Even with my Bresslen bolts I have to retighten every oil change and I always find a loose one. One other thing that helps alot is deadsoft aluminum or copper header gaskets - they are real thick, get squished alot when installing, and thus seal well.

But you'll need to get different headers for sure.

 

Can you just drill another hole in the header flange? Its been a while but I seem to recall my L98 heads having 2 last bolt holes. One was used by factory manifolds and one by headers. Maybe LG4 heads don't have that second hole.

I've put headers on 4 cars and never had a bolt come loose or exhaust leaks in any of them. I know people have trouble all the time but I have no idea why. Its just like any other parts. Use decent parts with decent gaskets with decent hardware that is TORQUED TO SPEC and you should never have any problems. My SLP headers have been on my car for 7 years and I have never had an exhaust leak or a bolt come loose. And I just used the supplied gaskets and hardware.

 

Thanks guys! I took a closer look at the pass side head and it does indeed have an extra hole drilled into it that lines up perfectly with the header bolt hole. I guess Chevy used 2 different bolt hole patterns for pass side exhaust manifolds.

 

Yes they did. And when some parts dealers sell parts like that they will sometimes say 6 bolt exhaust or 7 bolt exhaust. I know it's too little to late but next time you will know, or help the next guy or friend out.