805Cutlass

hey guys i just pulled my 350 out of my 72cs. This is my first time doing a rebuild of any kind, but thanks to this site ive learned alot. Im in the process of taking things apart and checking the overall condition. So it looks like i have a 72 block but my heads are different. one is a 7 and the other is a 7a? it might sound stupid but does this mean the motor has been rebuilt? my goal is to up the compression but still be able to run pump gas. A daily driver but still fast enough to smoke those ricer hondas ....here are some pics of what im looking at, im open to thoughts and suggestions

billmerbach

Well I can see you have the high comp pistons would I be correct in saying he has close to 300 HP or would the heads he has change this

805Cutlass

this motor was ruuning i had it in the cutlass it seemed peppy of the line but no ***** mid or top end....are you saying these are not the original pistons that came with the 72's?

billmerbach

No they are my 70 block has them I'm also doing a rebuild also plus I get my knowledge from these men on here still learning so if I'm not sure I'll tell you but I'm pretty darn sure these are the originals

coppercutlass

Bill those are the low comps bud. 23 cc's no god can't do much with em .

billmerbach

Well I feel stupid those look like mine and some others I've seen and was told high comps how can you tell the difference

coppercutlass

The size of the dish and deptn is what gives it away.

billmerbach

Just figured that out lol sorry 805Cutlass I screwed up

805Cutlass

bummer! the dish on them didnt look real deep but then again this is my first time doing this.

coppercutlass

It's big. It's hard to get any compression with em to run a decent cam to make power.

billmerbach

I see that now I just looked at mine and I can see the difference between my high comps and his low comps thanks copper for clarifying that for me

805Cutlass

no worries bill we're all learning. so as far as my heads go one 7 and the other 7a.. is this normal to see what exactly does this mean? where these two heads different sizes?

coppercutlass

They are very close in. Design if any diffrences .

billmerbach

All I know is # 6 heads are desirable I guess they have better flow

805Cutlass

i just ran into this kit on summit wondering if this would work with my block. it claims to be Approximate compression ratio 9.64:1 with a 70cc head.... or would it be better/ cheaper to buy a set of speedpro flattops and rebuild kit.
http://www.summitracing.com/parts/fe...-000/overview/

coppercutlass

Bill the flow numbers are almost the same between 6 7 and 7 A if I remember right. The 5's are the best in stock form .

billmerbach

Well I gotta get some 5 heads then I'm just gonna shut up then

Lars

them bores look deep, whats the # on the timing shelf

coppercutlass

The other thing I noticed is one of those pistons looks like it almost has no dish ? maybe the way the pic was taken but even on the other pics at the bottom of the bore you can see a dish.

805Cutlass

sorry lars dont really know what you mean. whats the timing shelf?

805Cutlass

i think its the way the picture looks coppercutlass....all the pistons looks like theyre the same size just the right side of the block has alot more crud then the left

tru-blue 442

The #'s Lars speaks of
are right under the front of the
intake manifold. There is a shelf
for the timing chain gearset, right
behind the waterpump. the by-pass
hose from the thermostat housing goes
right over the top of those #'s.

They will tell which block you have.

olds 307 and 403

The Speed Pro pistons will put you around that if your heads CC around 70 and you leave the pistons around .025" in the hole with a .041" gasket. Take your block and heads to the machine shop, see what needs done. I would get the heads CCed for sure. That kit is fine for the street and expect to use pump Premium when done. I believe the only difference on those heads is spring pocket depth and the 7A's have induction hardened exhaust seats. I have never heard of Olds heads wearing out exhaust seats.

ransomolds

looks like a great project!the best advice i can give is to invest in mondello's technical reference manual.it will help you in all steps of your project.it will explain the number locations for your block and heads and charts to look them up.