Thread: can i put 350 heads on a 307 ????????

Tweet

I have a 1984 307 and i was wondering if i could put some higher performance/less restricted 350 heads on it? I think the bore for 307 is around 3.875", and was wonering if 350 bore 3.900" heads would fit without the valves hitting the block? and would this really help anyway?

Are you talking Buick?? cause I don't think they made a 307 in '84


Alan

Delray, go get an Olds book man. As for the 307, its possible to put any SBO heads on it with the exception of 206/307 7A(85-newer) without changing the intake. As for your flow question, it would indeed breathe better. However, this effect would be immediatly canceled out by low compression. Unless you plan to shave the heads to re-gain compression, it wont help. Your best option for a 307 is a Cam, a good exhaust, and a set of 442 307 heads. Remember that in 85 Oldsmobile went swirl port, and these heads are just plain restictive. I believe that the Hurst olds from 83 are larger valved heads, so this represents an option. If you dont like this, just have your current heads checked for cracks/stress and have them mached for larger valves. Hoped this helps. The 307 has a lot of potential if you have the time

I don't think you will have a problem, but get them checked if you don't know how to do it yourself...machine shops can check that usually, just call in advance. .30, port and poslish, match the intake to the heads better, see how much bigger valves will fit, sometimes your best off doing this to the original heads to the motor. What's the numbers on the 350 heads?

nothing specific just a hypothetical

why is this thread in the small block Chevy section

Originally posted by drg84
Delray, go get an Olds book man. As for the 307, its possible to put any SBO heads on it with the exception of 206/307 7A(85-newer) without changing the intake. As for your flow question, it would indeed breathe better. However, this effect would be immediatly canceled out by low compression. Unless you plan to shave the heads to re-gain compression, it wont help. Your best option for a 307 is a Cam, a good exhaust, and a set of 442 307 heads. Remember that in 85 Oldsmobile went swirl port, and these heads are just plain restictive. I believe that the Hurst olds from 83 are larger valved heads, so this represents an option. If you dont like this, just have your current heads checked for cracks/stress and have them mached for larger valves. Hoped this helps. The 307 has a lot of potential if you have the time

Sorry, I guess I didn't answer that correctly. I assumed he was talking 307 chevy which was built from '68-'73. That was why I said Buick. I realize Buick and Olds made 307's as well.

Alan

Buick never had a 307, but some Buicks had 307 Olds engines

Good eye both of you. Yes, there were Oldsmobile engines in Buicks. They also found their ways to some caddies. Devilles with Towing packages also had 307s with the good heads. You may want to look into 5.0 Caddies. As for the 307 you have, heres a few suggestions. Bump the timing up a few degrees. Oldsmobiles always ran high timing, so there is a tendancy towards pinging, but theres still some advance to be found. Replace the O2 sensor if you plan to keep the Q-jet, or just replace the Q-jet and get it over with. I personally reccomend an Edelbrock 600. Hollys might look good on this engine, but they perform horribly. Too little engine for too much carb. A good coil is a must. The EGR should be replaced or unhooked if you dont have to worry about emissions. The PCV is usually clogged on these motors. Pull the hose from the base of the carb, and blow through it. After you pull it from the passanger side valve cover of course. Then spray a bit of WD-40 down into the Valve, or replace it. It only costs somewhere around$2, so its your call. Finally, check for vacuum leaks. With a car that age, the hoses for all the vacum controlls are usually dry. Pull them and replace them. The Olds will run much better with the AIR pump engaged. Otherwise it will run lean at higher RPMs. This is due largely to the Computer controlled mixture. If you go to replace the carb, this isnt much of a problem. But its always a must if you dont have that great of a budget.

Originally posted by stepside454
why is this thread in the small block Chevy section

Oh well, I totally agree........its all FUBAR

Actually, i hate to tell you this Denny, but the 350N is an Oldsmobile creation too. As for the 307s in Deltas, they are usually the 140HP incarnation found in the Standard Issue Cutlass. Pointless to swap with unless you want a spare pair of heads.