1970_Holiday_Coupe

Hello all. I am a new member and a long time fan of oldsmobile. i have wanted one for the last 10 years or so and i finally got one. I have a 1970 Oldsmobile cutlass s holiday coupe vinyl top. when i digging for numbers i found something quite interesting. the engine is from a 1973. the heads are the dreaded number 8 heads casting number 411929. the engine is a 350 casting number 395558 - 2. and the vin derivative is a 33 which tells me its a 1973 and the third digit is a l or a 1 cant tell its a little worn.

i would like to raise the compression ratio to 9:1 or higher but no higher than 10.5:1. put an edelbrock performer rpm cam and edelbrock performer rpm intake and a 650 cfm carb. i have not checked on the rest of the driveline. i assume that it is a t350 trans and 3.55 gears in the rear. i could be wrong but i have to check yet.

am i on the right track? and where do i get a pair of heads w/o dropping 1800 on a pair of edelbrock heads.

oldcutlass

I moved your thread here so you can get an answer to your questions. Post a new intro in the newbie section with some pictures when you get a chance. Welcome to the site.

L69

Welcome aboard

L69

If it is a stock 73 engine u won't ever get 10.5 comp, not wit those deep dish pistons. Also edelbrock heads r approx 80 cc so that won't help compression either. Ur best bet is to find a set of pre 72 heads and the thinnest head gaskets they make. Then u might be able to get up to high 8s. Considering motor is tired and u don't have much info on her I would consider a rebuild so u can have her all microed up and cced and really know what she is and how much compression you have in the end. That way u can put the correct deck height on her pending what compression u want and the correct pistons including flat tops. The right way to do this is to rebuild it and I am sure most members on this site will tell you the same thing. Drive the car now till the motor is beat and then rebuild it or drive it and considering u pretty much need everything new inside, buy a core 350 and rebuild that while ur 73 continues giving u cruising fun. Enjoy and Godspeed

cutlassefi

Yes you can do it that way but a 73 will have the 14cc pistons in it, not the 24cc so an earlier head will put you in the low 9's compression wise.
Then from there you can decide just how much your budget can handle. Maybe it's rebuilding a core as mentioned, or redoing what you have.
But stay away from the generic grind cams, you probably don't have 3.55 gears, and keep the compression at a max of 10.0:1.

Keep us posted on your project. Welcome!

Smitty275

Welcome aboard. Congrats on getting your Olds. There are a lot of ways to go about achieving your goals. Core engines are cheap. You might want to get a good core and make it into what you want while leaving the current engine in the car so you can enjoy it. Then you do the swap and are only without your ride for a couple days instead of weeks or months.