Islander90

Hey everyone... just bought my uncle's 77 L48 T-top and one of the first things I plan on doing is exhaust. It's already got some decent stainless mufflers, but I plan on running true duals up to them. My question is about headers. I called some exhaust shops yesterday trying to find someone who could connect all the pipes and do it all, but one guy said he didn't think headers were a good idea. He said that he had heard that early corvettes had problems with exhaust manifold bolts breaking off in the block and requiring to be drilled and tapped which would make it a lot more expensive. Now I figure he was either just trying to give a reason to give a more expensive price or he was trying to talk me out of it cause he really didn't want to do the install. But it got me thinking.... I'd hate to spend the money on headers, do the install myself, and have the last bolt snap on me. But I'd also hate to spend all the money on the exhaust and still have the stock manifolds too! haha

So my ACTUAL question is; if I spray PB Blaster on the manifold bolts for a few days before the install, what are the chances of these bolts breaking? Has anyone heard of this being any type of common thing?? I mean, I have horrible luck when it comes to working on my vehicles, so I could see it happening, but what do you guys think??

I've searched the forums looking for problems with the install and really didn't find any. Hopefully I'm just being paranoid... any words of advice would be greatly appreciated. TIA!

-Steven

Maymyvetteliveforevr

I've installed headers on my 75, L48 about 20 years ago with no problems what so ever. I can't really see them breaking while installing them, only possibly when removing them. Some brand of header are best installed from the bottom up, in other words raise the car and put them in place from underneath. Spraying it with Blaster never hurts. Anyone else have any suggestions?

Good luck.

grayhook

he just dont want to do the job. The exhaust manifold bolts are the same as on any other sb car or truck. Nothing's differint just becouse it's on a corvette. Any old car or truck you'll risk exhaust manifold bolts breaking off. Yeah, PB Blaster the manifold bolts a few time's each day for a few days before the install. As far as installing...nothing to it, if your use'n a/c may need a bracket for that.
the real question is what are you want'n to do with it? if it's just a street cruiser...use the stock exhaust manifolds and go duel's from there. You'll get a nice kick out of it. If your going to race it...go for it, thay'll give a small gane in tq. across the board and a get bigger improvment in higher rpm range. Allso thay hang down and scrape some times, and you have to keep a check on the bolts and gaskets.
Like i said what you want to do with it? For a street car? i'ed go stock manifold and duel's.

big_G

Put yourself in the shops position. He breaks an exhaust bolt during manifold removal. He calls you to tell you the head has to come off. Now your pissed, and his bay is tied up. No one wins. I work on 30 to 40 year old vettes every day. Bolts break. Part of the job, and we explain the risks to the customer before we start the job. Most understand. But in my opinion, muffler shops don't need the hassles. Their bread and butter is pipes and mufflers. G/L

grayhook

that's what he shoulda said...what he said was
That's the difference between a good mechanic shop and a bad one if you ask me. Thay take the time to explain the risks before thay start the job.

Empatho

sometimes the bolts brake because ot the age and what not ... just try to do it your self you could get lucky like I did and the bolts will be loose already from all the vibration and will come out easily

Islander90

it's just gonna be a street cruiser, but I'm trying to get as much sound out of it as possible too... I guess another good question for me to ask ya'll is ; how much more sound will i REALLY get with headers vs. stock manifold if I'm going to 2.5" true duals with hi flo cats?

maybe another time I'll care more about power and flow and numbers, but as for now; I'm just going for sound really

thanks for the responses so far too

Islander90

and yea; I realize bolts break cause of age... just kinda curious what the chances would be... c'mon; can't you guys see into the future?!?

big_G

Well, we broke 1 last week as for odds, I think maybe 1 bolt out of 200 will break on something older than a 78...

grayhook

a good set of mufflers will do that for you.
I dont think you'll hear much of a difference, but the cat's will muffle the sound some too.
Do thay test your emissions in your state? if not drop the cat's!

Islander90

I don't have emissions, but I'm pretty sure if it was on there stock, then it has to be on there for visual safety inspection. I'm getting my jeep inspected tomorrow, so I'll ask the guy there what REALLY has to be on it haha

Empatho

if you remove the old cat the car should be louder