Help Identifying Pistons

[pjmoreland]

The engine in my truck is seriously wimpy, and I'm trying to decide whether it is worth it to replace the heads or if I should just replace the entire engine. It is a two bolt 3970010 block from 1979 with 991 smogger heads. Compression ranges from 170 to 185. It consumes a quart of oil about every 2000 miles. I took some photos of the pistons using a scope. If these are flat top pistons, then I'm leaning toward putting on some 64cc heads. Is that a good idea, or would I be wasting money on this engine? Are these flat top pistons?

[gmc684x4]

Decent compression
Cam change and better flowing heads will help wake up your 350

Vortec heads could help wake it up
With vortec heads you also need vortec intake

With good compression I would check your valve seals for leakage

A vortec 350 flows better then the old high hp camel hump heads guys pays big bucks for you can if looking scrounge a used set cheap

Yes aftermarket heads can flow better they also cost more

[pjmoreland]

Originally Posted by gmc684x4

Decent compression
Cam change and better flowing heads will help wake up your 350

Vortec heads could help wake it up
With vortec heads you also need vortec intake

With good compression I would check your valve seals for leakage

A vortec 350 flows better then the old high hp camel hump heads guys pays big bucks for you can if looking scrounge a used set cheap

Yes aftermarket heads can flow better they also cost more

Thanks for the reply. I went to the local pick-n-pull this morning and pulled a set of 10239906 Vortec heads off a 1998 C1500 with 148,000 miles on it. Summit sells a reasonably priced Vortec carb intake manifold. I'll give that a try.

[garyd1961]

Some will say the 906 head don't flow as well as the 062 heads but don't pay that any mind it has been proven false. Are you sure they came off a c1500? The 906 heads are the HD version and came on the 2500. They should have harden valve seat inserts which is good because these heads are prone to cracks around the valve seats. The cracks don't seem to make a difference on a running motor but it's not recommended to reuse heads with the cracks. I have 906 heads on my motor and it runs great.

[pjmoreland]

Originally Posted by garyd1961

Some will say the 906 head don't flow as well as the 062 heads but don't pay that any mind it has been proven false. Are you sure they came off a c1500? The 906 heads are the HD version and came on the 2500. They should have harden valve seat inserts which is good because these heads are prone to cracks around the valve seats. The cracks don't seem to make a difference on a running motor but it's not recommended to reuse heads with the cracks. I have 906 heads on my motor and it runs great.

They do appear to have hardened exhaust valve seats. Here is the vehicle they came out of.

1gtec19r1we515721

[pjmoreland]

I finally finished installing Vortec heads and an XE268H cam on my 350 last night. Woke my neighbors up at 8:30 when I started it up for the first time and broke in the cam and lifters for half an hour. This engine has some get up and go now! I am seriously impressed. I hope my bottom end holds up to the abuse. Thank you gmc684x4 for suggesting Vortec heads.