Hey guys...

As stated this is probably a newbie(read stupid) question but before reading another post I had know idea that there were different heads for the 350R. How can I tell which # head I have? And which one is better for performance?

I've learned that #8's are crappy smog heads, and I've read that alot of people have #7's. Are they the best or just most common? All replies are appreciated.

Hey..... I'm out of newbie jail!!!

 

The #5 from 1969 and # 6 from '70 both have smaller combustion chambers I believe. I have worked on both and found that the #5 require almost no work on the short turn above the valves and none in the bowl area when porting. Perhaps a better casting from the factory.

Hope this sheds some light on your question.

Danny

 

Thanks for the info, I hope I have the #5's. Where would I look to find out?

 

If your alternator is on the drivers side look right under it. Attached is a photo of a set of heads, note the large number 5 on the left corner just to the left of the spark plug hole and under the head bolt hole. John

P1010962.jpg

 

#8 heads have a larger (80cc) chamber, but that is it. Otherwise identical to #7 (68cc) heads.
#5 heads (68-69) do have a lower port floor, also has a lower bowl. cross section is the same as #7's, flow about the same. You can not lower the #7 head floor as low as the #5 (68cc) without risking water.
I like the #5's, myself.
What year 350 (R???) block do you have?
Early heads use 7/16 head bolts, later 350's use 1/2 inch head bolts and require early head bosses to be drilled to 17/32nd's for the early heads to bolt onto late blocks.
Jim

 

Thanks guys for the info. It's a '72 350 that I have. I plan on getting some pics I can post tonight. The car is pretty straight, just sorta neglected due to no garage for the first 7+yrs I owned it. My plan is to do the exhaust and disc conversion, then make her look pretty again. Then later I'll do the engine, maybe a 455 so I can really be a 442 wannabe.

 

I've found that my heads are #7's. Not ready to do any engine work now, but this info will come in handy later.