I have a 1949 303 Olds motor that I am building for my 32 deuce coupe project. I was able to get a pair of 1954 #7 cylinder heads for it to replace the original ones to have better performance with bigger ports and 1.8 ratio rockers. The only other performance upgrades were new pistons for higher compression ( 9.0 to 1 ), three two barrel carbs, .030 cylinder overbore, lake style headers, and a new mild performance cam with the following specs. Duration @ .050 lift: 218 deg. intake & exhaust Valve lift: .540 in. Lobe centers: 108 deg. w/ 2 deg. overlap My question is would it be worth it to swap the #7 heads for a set of #10 heads for the larger ports and bigger valves. Would there be a significant or noticeable performance gain with the #10 heads using the upgrades to the motor that I listed.
While I’m not sure that you would feel the difference in the seat of your pants, the numbers would indicate that they would provide a performance improvement. If you have already had the #7 heads done, and have to search for #10s, I would just run the 7s. If you haven’t had the #7s done and you have or can get a set of #10s, I would go that route.
Smaller ports and valves have higher intake velocity and probably better low end torque. Look at the nailhead. They had tiny valves for their displacement...but they had tons of torque. Bigger valves and ports mean higher rpm potential and more power up top. Are you going to wind it out and race it around? Probably not. It's already going to have great power/weight ratio. Unless you want bragging rights, or are trying to emulate what a hot rodder might have done in the good old days...dont bother. 7s are fine.
Thanks for the replies. I have no experience with these Olds motors, so I have no idea how they perform. I was afraid that I wouldn't be happy with the performance of the motor since they were not exactly high perf as compared to a small block chevy of that era. I was thinking I needed to get as much power from the build as possible. The #7 heads on the motor have been rebuilt with new valves, guides and springs, it would be a waste to not use them and have to spend more money rebuilding the #10 heads for a small gain.
Thanks Black Panther. If this motor puts out lots of low end torque with the #7 heads, I'll be real happy with it. That is the way I like my motors to perform. I'm not building this car as a racer just a cruiser. Thanks for confirming that this motor - car combination will give me what I'm looking for. I saw a complete 56 Olds motor and trans in the HAMB cl***ified that has the #10 heads for sale not far from where I live for a good price, and it got me thinking whether it would be worth it to by it for the heads and use them on my build. Thanks to you guys, I'll stick with what I already have and save myself time and money.
Stick with the 7's. You won't notice the difference and since there done it is the best bet. Now on to the next question?? What have you done for a rear seal? I have been through three of the Best conversion seals and have reached my limit trying to seal this Olds up so I went back to a rope seal. Pulled the engine and the crank to make sure it was done right without any follow on issues. Real Pain! Ross used to do the Best conversions but gave up on them after 3 of 5 engines he rebuilt leaked. He now machines the block for a replacement OE seal and ended the issue.
Ive got #10 heads on my 88, which is49 303 bored to 324.With the Hydramatic though its still more of a sleepy cruiser than a "rocket". It dynoed at 212 Hp with a flat torque curve. In normal road use there probably isnt much difference so use what youve got.
Just keep in mind that the 1.8 rockers put quite a bit more load on the cam than the 1.5's do. Watch your spring pressure, use the right lube and break in oil and follow cam break in procedures very carefully.
I ordered a full gasket set from Ross and it came with the two piece rubber rear seal. Is that what you are calling the Best conversion? I'll have to wait and see if it works, I thought that was a better option than the original rope seal. I'd like to know how the block is modified for an OE seal.
I ordered the cam from Ross Racing and he ground it to give a mild performance upgrade while maintaining good drive ability with the 1.8 ratio rockers
The engine builder that did the machining on my motor had some tricks up his sleeve for these Olds engines. He used intake and exhaust valves from two different sbc motors and machined the spring pockets for sbc springs that can handle the cam specs. I'll be using Isky Rev lube on the cam, lifters and pushrods and the high zinc breakin oil.
I have the rubber seals and cork pieces, but I didn't get the spacer strips that go under the rubber seals. Chances are that this won't work right without those spacer strips. Should I order another rubber seal set, or go with the Best rope seal kit.
I'd call Best and inquire. At one time they offered a Teflon rear seal. Or chat with Tony at Ross about what you have
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