348 Head Questions

[TIREDIRN]

I have these two 348 heads - 3758379 and 3781173. Apparently the 3781173 is a high performance head and the 3758379 is a stock 61 head.

I had the heads cleaned up and installed these valves and springs from Show Cars - 348/409 SS POLISHED VALVE SET 3/8 X 5.110 STEM 8 EXH 1.67 HEAD 8 INT 1.94 HEAD.

What makes the 3781173 a high performance head?

Are these heads compatible to use on the motor?

Thanks

 

[Don Jacks]

I've never heard of an 1173 head,high performance or otherwise,but from what I have learned,high performance heads all had bigger valves.High performance heads on the 348 had 2.065 intake ,1.725 exhaust,while standard and truck/industrial heads had the 1.94/1.67 valve size.

 

[Richard Martin]

There was a discussion on chevytalk at least 12 years ago about a discovery by Verne Frantz of an early 1960 FE code 335 horsepower 348 with 3781173 heads (dated Jan and Feb 1960) with 1.94/1.66 valves. The 2.06/1.72 348 valve heads were not released until April 1960.

info on the 2.06/1.72 heads release date from Alan Colvin's Chevrolet by the Numbers, 1960-64 Edition, page 77.

 

[Don Jacks]

That would make that 1173 head one very rare piece indeed! Thanks Richard.

 

[TIREDIRN]

Thanks for the info guys. So I'm guessing there is no problem running these heads as a pair.

Thanks

 

[Tom Kochtanek]

Those are two different heads that you have there (IMHO). Not sure how they will perform as a pair with the same set of valves and springs, perhaps others will have more insight.

As mentioned. the 1173s were a short term casting circa 1960 between the 250 horse 379s and the (up to) 350 horse 1147s.

I've got a set on the shelf all cleaned and crack checked. Can't remember the casting dates off hand, They do have "1147" cast into the underside if I remember correctly. I do recall putting an 1147 next to the 1173 and that except for the valve size they were similar.

Best, TomK

 

[Tom Kochtanek]

I remember seeing one 1173 head on Ebay some time ago, not sure if it ever sold. Might be worth investigating...

 

[LMBRJQ 60]

Valve size apart, what are the runner volumes and design, i was under the impression that apart from larger valves the 1147 head had a lot more HP friendly design behind the valves or do they just have more meat to carve out?

If thay are a different design and flow differently i would think that this may make the engine difficult to tune ?
Some one will let me know i am mistaken


Steve