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Discussion Starter · #1 ·
I just bought a compression tested 350 SBC for $150. (off Craigslist) The mileage is unknown, however the compression tests looked good, between 135-150. The unknown, the block is I believe a GM crate or a Jasper. That's what I don't know. The block # is 3970010, the heads are 3417368 & 3417369. Can someone tell me the HP of this? Is this an aftermarket engine? The block numbers show they were made from 1968-1979, however the head numbers were from 1990 & newer. Anybody have any info on this?
 

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I just bought a compression tested 350 SBC for $150. (off Craigslist) The mileage is unknown, however the compression tests looked good, between 135-150. The unknown, the block is I believe a GM crate or a Jasper. That's what I don't know. The block # is 3970010, the heads are 3417368 & 3417369. Can someone tell me the HP of this? Is this an aftermarket engine? The block numbers show they were made from 1968-1979, however the head numbers were from 1990 & newer. Anybody have any info on this?
You'd like to see less deviation between the cylinders, 15 psi is over 10%.

Heads are 76cc smog chambers, supposedly made in Mexico but a heavier casting than many late sbc heads, 1.94" x 1.5" valves, pressed studs, etc.

A magazine test used a crate engine w/those heads (c/n 369) and made 335 hp w/a Comp XE268 cam. Valves had a 30 degree backcut, 0.015" shim head gasket to raise CR and give a good quench distance.
 

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Discussion Starter · #3 ·
unknown 350 update

Thanks for the info. This engine will repower a 1986 C-10. The current engine has piston slap going uphill & smokes 1 qt of oil every 100 miles. Time for an engine swap. I've learned this block is one of the most common castings for the SBC's & is also known for it's desirable high nickel content. I bought the a fore mentioned engine after compression test & listening to it run for 10 minutes.
 

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Thanks for the info. This engine will repower a 1986 C-10. The current engine has piston slap going uphill & smokes 1 qt of oil every 100 miles. Time for an engine swap. I've learned this block is one of the most common castings for the SBC's & is also known for it's desirable high nickel content. I bought the a fore mentioned engine after compression test & listening to it run for 10 minutes.

And you can't beat $150.00!!
 
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