olds 350 rocket questions

[historyg]

Hey i have the chance to get a 1968 350 rocket, still running, for around 200, should i get it, I have little knowledge on the 350 rocket, is the 1968 one any good. Does all my the stuff from my 307 change over?

 

[Oldsmoletick]

The 68 350 is a very good find, if it is an unmolested one it will have the #5 heads on it, which are said to be the best flowing heads in factory form, they basically come in two forms large valve and small valve. You can run the casting numbers to find out which you have, also the block casting numbers to find out if it is a high compression engine. As far as everything swapping over, not exactly. You will either have to get headers (I recomend hedman for fit) or get a pair of 350 manifolds. There is a diifference between 307 and 350 manifolds but I can't remember what it was, it's been a long time since I did a 307 to 350 swap, I do remember having to make a parts run for the 350 manifolds though. Use the 350 intake manifold, if it only has a 2bbl, either buy new or find a 350 manifold. The 307's have different coolant passages in the heads, there are block off plugs available, but you would be better off finding the proper intake. It will bolt up perfectly otherwise, all your accessory brackets and pulleys will fit. The other thing to look at though would be your water pump, some were short, some long, so you may want to use your 307 pump if using that pulley set up. Use the 307 engine mounts, or buy new ones for the swap. If you don't have to worry about emmision laws, I would ditch the computer controlled distibutor for a pre 1980 HEI one out of an Olds V8 and use a non computer carb. Other than those couple of things it should be a direct fit, be sure to compare oil pans as well, it shouldn't be an issue, but it wouldn't hurt to double check. If the engine runs well for only $200, I'd jump on it. Good Luck.

 

[jae]

Agreed - I would get it. $200 for a running '68 350 is a bargain, a "good" running 350!! (if you don't tell me where it's at and I'll buy it). I would verify all the casting numbers on the block and heads to be sure.

Didn't know there were long and short water pump versions for the Olds 350 (familiar with the Chevy), makes sense.

 

[joe_padavano]

The 68 350 is a very good find, if it is an unmolested one it will have the #5 heads on it, which are said to be the best flowing heads in factory form, they basically come in two forms large valve and small valve. You can run the casting numbers to find out which you have, also the block casting numbers to find out if it is a high compression engine.

Sorry, the casting numbers will not tell you the valve size nor the compression ratio. All 1968-1969 350 motors used no. 5 heads. All have the same casting number. Only the W-31 motors got the big valves and there is no external indication of the valve size. If you have to ask whether or not it's a W-31, then don't worry, it isn't. All 1968-1976 350 blocks used the same casting number. The compression ratio was changed by using pistons with a larger dish, not by changing the combustion chamber size. That is, at least until 1973, when all heads got the larger chambers.

As far as everything swapping over, not exactly. You will either have to get headers (I recomend hedman for fit) or get a pair of 350 manifolds. There is a diifference between 307 and 350 manifolds but I can't remember what it was, it's been a long time since I did a 307 to 350 swap, I do remember having to make a parts run for the 350 manifolds though.

The early 307s (with the 5A heads) use normal cast iron manifolds with the same port sizes as all Olds 350 motors and will work fine. The roller cam 307s with the 7A heads have tiny ports and the crappy welded tubular manifolds. Do not use these.

Use the 350 intake manifold, if it only has a 2bbl, either buy new or find a 350 manifold. The 307's have different coolant passages in the heads, there are block off plugs available, but you would be better off finding the proper intake.

News to me. The A4 intake on the early 307s is a cheap aluminum alternative to the iron 350 intakes and has been used by many. The A5 intake on the roller cam 307 has tiny ports like the exhaust manifolds and should not be used.

It will bolt up perfectly otherwise, all your accessory brackets and pulleys will fit. The other thing to look at though would be your water pump, some were short, some long, so you may want to use your 307 pump if using that pulley set up.

The Olds water pump, pulleys, and accessory brackets MUST be used as a set or the grooves will not align. All your 307 parts bolt right up.

Use the 307 engine mounts, or buy new ones for the swap.

Just be sure to buy new 307 mounts for your chassis.

 

[historyg]

wow thanks guys, I plan on bulding it before putting it back, but i didnt want to hassle looking for alternator brackets ext. I will be changing the manifold ext ext. yes it is a good deal, but i have to wait a little hopefully ill get it and ill let you guys know and take some pics of it. Thanks guys/girls for helping.

 

[historyg]

Dude decided not to sell it, he found out it was a 1970 350 sbo with a6 heads, and decided to keep it for himself. 😢

Thanks for all the help anyways.