I rebuilt a 1970 350 motor for my 1976 cutlass as some of you know. I have been busy sorting out the small stuff and have finally got most of that done. thanks for the help by the way. I have some questions about the motor I rebuilt. the guy I bought it from said it came out of 1970 rag top. here are some of the things I found while rebuilding it.
1. Why is the harmonic balancer way bigger then my 1976
2. The heads cc right at 64cc without having to be machined they are marked #6 on the corners.
3. the pistons had what seemed to be 4 small valve reliefs instead of a dish. they were cast. They were standard also.
4. the valves were 2.00 or so on the intakes is this right for 1970?
5. the crank does have the "N" on it because it is a 1970?
6. I did not get the intake or carb with motor, they were already gone.
7. The stock manifolds still have the dual outlet, one is plugged though.
8. When i had my probe pistons installed they were at .010 deck height without any machining.

Is this how must 1970 motors were, they differ quite a bit from my 76 I guess. The 76 motor has smaller valves, and quite a dish on the piston, the crank does not have the "N", and my balancer is quite a bit smaller. I am going to assume my 1970 started out at around 10.0 to 1 or so. sorry for all the questions was just wondering why all of the changes. Also do any of you guys have around 185psi cranking compression and if you do how is it on pump fuel, that is what mine is now. thanks

 

That's the difference between the musclecar era and the emissions era.
1 motor has ********* and the other has lima beans.

I've never heard of stock cast pistons having less than a 6 cc dish though. ??

 

1. My guess is to save money on steel, because cast cranks don't need as much of a dampener as nodular iron. Or because you have a W31 motor.

2.Big valve #6 heads are w31 specs. 64cc sounds stock to me with no milling.

3. w31 pistons? That would be rare and cool.

4. 2.0 valves are correct for 70 w31 specs. Could have been machined and installed later though.

5. N means nodular iron, it is not forged steel, or cast iron

6.That's a shame. probably worth some bucks.

7.I have no idea about exhaust manifolds, I use headers and the manifolds are the wheel chocks 1 was plugged to run true dual exhaust I'm sure.

8. that's pretty good. Stock is usually deeper than that.

 

Well i have the pistons still I guess I will hang on to them, thanks for the info the motor is no longer stock I just bought it for a good rebuildable core. I drove it the other day and it is wild compared to my stock engine, the car feels good to drive now. Here is what I did to the motor
1. probe flat top pistons
2. edlebrock 7111 intake
3. heads machined to 63 cc and ported at a reputable speed shop, new ss valves and seats.
4. carb shop holley 770 vacumm secondary carb
5. morroso oil pan and melling pump
6. comp cams 274XE cam with roller rockers and all new valve train
7. headman headers 230-236 duration 520-521 lift on 110 degreed at 106.5 on the wheel.
8. whole assembly balanced and ARP fasteners
9. COAN 3000 stall
10. Powermaster starter
cranking compression is 185 to 190 and it seems to get by on 93 pump in the temps around 45-55 degrees. snowing now so it is put away.