Compression ratio on a 1974 Chevy 350 in a Nova was 8.5:1.
8.5 to 1 compression is factory stock.
The compression ratio of a 350 Chevy engine usually ranges from 8.0 and 9.0 to 1. This provides a good balance of fuel economy and power.
A 260 what, on a 350 what, might help us answer that.
Not a good idea. 350 heads will lower compression to 7 to 1 or less.
About 8.5 to 1
then youre running about 8.5:1 compression
A compression test.
The average compression test reading for a Chevy 350 small block engine is around 150 PSI. Lower pressure indicates that there is a leak in the engine.
WILL IT STLL RUN ?OR IS IT DEAD ?
I had one with 10:1 compression that was making close to 350 hp with decent heads.
The 3970010 number on a 350 was found on the back of your block. Its a base number for that cubic inch motor. Its been there on multiple years of 350. It is also used for all kinds of applications from light cars to heavy duty trucks. all with different compression. There is no way to get compression ratios with that number. Use the number on the front of the block by the head. It will give you year, make and model of the car it was put in and you can track down your compression numbers from there. What you want to see is the compression reading of all the cylinders be within 15 psi of each other.
Yes, but it increases compression a full point.
No. It lowers the compression ratio and reduces power output.
4.000x3.750 with 8.5:1 compression
Good compression, good heads, good cam.
If any two adjacent cylinders have low compression it's probably caused by a blown head gasket.
it all depends on the head chamber volume of the 307 heads and the 350 heads that are being replaced. if the 307 heads have a smaller chamber volume then yes, they will bump up compression.
Remove all the spark plugs and turn the engine over by hand. Place your thumb over the #1 plug hole and you will feel the pressure on the compression stroke. A compression gage will also tell you when you are on the compression stroke.
Has no compression needs new rings