68s

My 350 is in the shop. Kind of been there for a while but now the ball is rolling.

Stock heads redone. I believe they are #6 heads.

When i got the heads done it was a different shop. They put bronze guides.
The guy building the motor says cast guides is the way to go.

Didnt know which route i was going when i got the heads done.
Didnt know much about the car or where to go either.

So now im doing a whole rebuild. The shop that did the heads asked which cam i was going with. They recommended the RV cam. I asked to go 1 step higher and they said i needed new springs. 490 lift?

Got that done.

As far as the motor goes. He wants me to get a new block since the left side has thin walls. Only going .30 over.

This is going into a 68 cutlass supreme. I just want to do a stock rebuild with a few minor upgrades here and there. Still have the car looking stock.

When i talked about headers he said stick to stock manifolds. Headers always leak.

Im in northern california and there really isnt many shops that deal with olds. So my question is... Can i go with headers? will they leak? what can i do to prevent any problems with headers?

I figured a nice cam rebuilt motor and full exhaust should make a fun cruiser. Im also keeping the stock intake manifold. Having someone he knows build me a carb. Let my buddy use the stock 4 barrel quad and he sold it.

appreciate any feedback.

don71

I think headers are a pain and cause grief. I say skip 'em, you don't need 'em.

DoubleV

American Racing headers or no headers for me. ARH don't have the usual problems associated with cheap, mass produced headers. Their only downside is cost. With that said, I don't believe headers offer much on mild builds ( though they do help ), but I'm not sure how 'mild' your engine actually is.

ah64pilot

I think headers make power and any engine with performance modifications will see some degree of performance improvement. As with anything, it's knowing what to get and how to work with it.

coppercutlass

I disagree with the mass produced header comment. I have ran the same blackjack headers that i might add are from the 70's for 6 years with no issues. i also agree with ah64pilot. Case and point is the 307 thats in my 72 right now since my 350 pooped out. I ran the headers from my 350 and the 650 double pumper and that little 307 could smoke em and scratch second pretty hard. it stopped pulling at 4000 rpm but still impressive for a 307 that is stock intake to oil pan. Also headers arent that much more difficult than manifolds. It's the process of installation people screw up. If you dont use a mini starter then you leave the dr. side header with the fron bolt loose but tight enough to hold the header onto the block. You slide your starter in bolt it up and the bolt the header up. the pass side you do with out the oil filter adapter attached. You install your header on the pass side then bolt your oil filter adapter on. thats about as hard as it gets.

DoubleV

Coppercutlass, you are free to disagree of course, but there's a reason why some headers fit well for some and why the same model/brand headers fit like crap in others. It's because they're not made to very close standards. Some are just made better than others. This is a quality issue. How else do you explain one guy who says his Flowtechs fit like a glove and others say they weren't even close for the same application? My friends Hooker headers ( supposed decent quality header ) fit like CRAP in his 78 Cutlass. Others have had no problems though. We won't even mention all of the other header headaches that are a very real thing to most header users.

I've done track comparrisons when I installed my AR headers vs my ported manifolds and had the exact same exhaust system. Results were nothing spectacular and I didn't actually notice any gain on the street. As I said, yes they do add some power, but not as much as many like to claim and I'm talking about headers on very mild builds like a stockish 350, not a stout 455 or high performance 350 screamer. Will the OP see big gains from headers? Depends on the build.

coppercutlass

I added an x pipe and gained almost 1.5 tenths. I agree that some headers are made poorer than others I also think it's a risk one is taking when buying cheaper brands than the more expensive. You get what you pay for. Making things fit is part of the game sometimes. I ran full length headers on a very very mild 350. I dont think i would have gone into the 13's with manifolds. I went from 14.00 to 13.86 with an x pipe. the car ran 14.3's with the straight pipes and mufflers, 14.00 with open headers. Then i went 13.86 through the mufflers with an x pipe. So even on a mild build i still think headers help greatly. I might add i had to squeeze every ounce of power i could to get that car to run in the 13's . So i tinkered with alot of things like that I highly doubt the car would have seen 13's with manifolds.

oldcutlass

Headers are for people who like headers, I agree they are a pain in the butt, leaks, bolts coming loose, fitment issues. But hey, I'm masochist and love pain.

There is not much gain with an exhaust system attatched with headers over stock manifolds,it's with open exhaust that you realize the gain. There is also the sound difference and the looks.

coppercutlass

Oldcutlass i have to disagree. That particular combination liked the exhaust system. I could not crack into the 13's with open exhaust. Then i decided to try an x pipe with mufflers. and it ran 13.8's all day. It all comes down to what the engine needs. Even race engines benifit from an x pipe . The diffrence between running an open x pipe and running mufflers for me is exactly a tenth. Open headers put me between the open x pipe and muffler set up et. wise. That was my experience.

joe_padavano

Headers will always be better than the crappy stock SBO manifolds. I would also keep the bronze valve guides. These are preferable to cast.

oldcutlass

I agree Joe, most headers are better. The question is the percentage of better vs the headache on a relatively stock engine with a somewhat restrictive exhaust system. I think the old rule of thumb was a 4-7% increase with intake, mods, and port matching.

DeltaPace77

I've run long tube headers on my engines for years, and have little problems with leaks. Find it more of a gasket problem, but not with Mr Gasket Ultra Seals. Torque em' once, and you're done.

cutlassefi

I'd keep tabs on your builder, I'm not sure his advice is the best at this point.
Depending on your ultimate compression ratio, hopefully your cam is something around a 215-220@.050. Let us know what you picked.

joe_padavano

What Mark said. I MIGHT be concerned with wall thickness on a 1977-1980 WMW 350, but not on a 68-76 block. 0.060 over should be a no-brainer.

As for headers, get good gaskets (copper) and use locking fasteners to prevent loosening that causes leaks.

coppercutlass

I have not run copper but have had great success with felpro blue's , and flatout gaskets. You might also want to check remflex.

68s

He measured the block. He said he can bore .30 but doesnt like how one side is very thin. Also dont kno the specs on the cam but it is a step higher than the rv cam.

Same guy built my buddys 425.

Im only 27 and dont kno too much about rebuilding an engine. He has a 455 that came out of a boat but i want to keep it small block.

Ill keep u guys updated. He really wanted to swap the bronze guides for cast.

cutlassefi

Exactly what year block is it?

And just an FYI, it's .030, not .30.

Thanks.

DoubleV

Well .30 over would explain the thin walls!

ah64pilot

Good gaskets - yes

But:

Forget the locking fasteners...too much work. When you put your headers on, get all the bolts started. Then pull each one individually and put Ultra Copper on the first half of the threads that will go into the head. Guaranteed not to back out. I've retorqued after doing that but have never had any loose bolts. Works like a charm, but I can't remember where I learned it.

68s

Yes .030 excuse me. I wanted to get more out of it but when he checked it he said .030 is the most. The block n car is completely stock and original. Th reason for me rebuilding is when i bought it he said the car overheated and blew a gasket. Went to 1 shop with the heads....... Result was 1 cracked head getting a complete rebuild. When i checked the oil in the motor it was like chocolate milk. So since i was this far with the heads i pulled the motor. Then took that.to the shop where it is now. I took everything apart when i took.him everything! 2 bent rods. At this time i was online trying to find any info i could. Reason why i am on here. I appreciate all the info

I drive an 06 dodge charger hemi dd
04 z06 Corvette
I kno how helpful the forums can be.

68s

68 cutlass supreme.