81-84 Olds Exhaust Manifolds

kdkmac92 · Nov 10, 2013

Hi,

I'm looking to upgrade my 86 442 (307) motor this winter. I already grabbed intake (A4) and heads (5A) out of a 84 Hurst Olds, but the donor engine had no OEM exhaust manifolds. I plan to use my existing 307 and rebuild the top end and keep the CCC, so I'm looking for a set of exhaust manifolds out of a 81-84 olds with the O2 sensor hole. So I have 2 questions

Does anyone have a decent set of 81-84 Olds 307 exhaust manifolds?

I'm up in the air on a new cam, so some input on a new mild cam or keep the original type 86 442 cam?

Kevin

86-blk442 · Nov 10, 2013

Early 307's had flat tappet cams 81-85, and the later had roller cams. The roller motors use different diameter lifters iirc, so don't know about a cam swap. Its cool you want to upgrade the 307 but you really are better off with at least a 350. There's really nothing to gain by swapping heads and intake. The swirl port motors ran great (for what they are) and were only rated at a few hp less than the older 307's. You probably won't notice a difference in power after doing all that work.

Just keep it stock for now and get a 350 down the road. The CCC system will run a mild 350 no problem. More power, and no one will know its not a 307 unless they look at casting #'s.

69hurstolds · Nov 10, 2013

Assuming you have an 86 442 stock exhaust system, your 442 should already have the cast iron exh. manifolds as used on earlier model engines and should bolt right up. Non-VIN 9 roller engines used the stupid stainless logs (useless).

Also, just to be clear, 85 VIN Y were roller cammed, VIN 9 was flat-tappet. Only year of the "dual-existence" types of cammed engines.

olds307 and 403 · Nov 10, 2013

You will gain some flow and about .25 to 1 compression with the head swap. Now mill the heads, port, polish with 350 valves and 1.7 to 1 rockers, would make a big difference. Add a custom grind roller cam and you get a good running 350 for about the same. The manifolds should be the same and dump that lousy cross over and converter. Both are very restrictive and should be replaced with duals.

kdkmac92 · Nov 10, 2013

Thanks for all the comments and help. I see so many internet posts on ditching the 307 for a 350 that it seems to be the direction I move toward. I just was looking to keep the under hood look as a sleeper (which can be done with the 350 and satin blk paint) and get to 275 - 300 hp with investment but not breaking the bank. I've seen the Tom Lentz comments (very helpful) and will try to make the right decision for a very streetable fun 3000 lb sled

I could grab the Hurst 307 block, but that sound like more $ than the 350 route. Well I'm having the trans redone at the end of the month to handle more beef under the hood. So the engine will be the next project after that is complete.

DoubleV · Nov 11, 2013

I'll put a vote in for not bothering with the 307. If you did, it would put a very small smile on your face for all of 5 minutes before you realize it just really ain't that fast and you wasted alot of money/time/ and effort for such little return in your investment. If you lived near me you could just buy my current engine. I'm going with something a bit more mean...

olds307 and 403 · Nov 11, 2013

Your goals are very easy with a 350. Plus you will gain a lot of torque over the 307 which means tire melting fun

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81-84 Olds Exhaust Manifolds

kdkmac92

n00b

86-blk442

G-Body Guru

69hurstolds

Geezer

olds307 and 403

Geezer

kdkmac92

n00b

DoubleV

Royal Smart Person

olds307 and 403

Geezer

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