Visit The Dirt Forum for More Information

Author Topic:   porting
stealth
Member
posted December 02, 2002 11:07 PM
I have a 355 Chevy smallblock with flattop pistons and 305 heads of camaro. I was told this would be a good combination for higher compression and less expensive way to build engine. I'm not getting the rpms up to where I need them to be to finish in top five. I have identical car to competitor running a 383 and he runs about 700 rpm more than me. My thought is the heads aren't flowing because I put 194 valves in and the air isnt able to flow around back side of valve. I'm going to do some porting on heads and am looking for advice on where to do the porting and if this is a good idea. Does anybody have any ideas, thoughts, or experience on this topic??


KPLugnut
Member
posted December 03, 2002 08:26 AM
It's not only going to be a matter of unshrouding the valves, but the ultimate limiting factor is the tiny runners in those 305 heads. You didn't mention what carb you have either, or intake, and they may not be helping as well.
Cam choice, heads, valvetrain beefy-ness, and intake and carb, all will play a major role in where that "ceiling" of rpm is for you.

That's the one downfall of the 305 heads. Sure, they make compression, but quickly run out of steam when the need for more airflow takes over.

Hope that helps,
KPLugnut


jhon hollomon
Member
posted December 03, 2002 10:25 AM
Plus your competitors 383 will more likely turn quite a few more rpm's anyways because of the stroke.


stealth
Member
posted December 03, 2002 06:19 PM
I have to run a rochester 2 brl carb and stock intake. I'm working on the carb and am going to put high rise bowtie intake on it this year. Would I be better off running different heads even with the flat top pistons? I dont have an extreme cam so to speak.


outlawstock17
Member
posted December 03, 2002 06:29 PM
jhon holloman, generally speaking, a short stroke engine is capable of more rpms than a long stroke engine. ideally, the best setup is usually a long rod, short stroke, big bore engine to get to the cubic inch limit.


KPLugnut
Member
posted December 03, 2002 08:37 PM
I would not recommend that intake with those heads and that carb. It's much more intake than the carb and heads are going to perform best with.
If you can find either some old double hump heads (461,462,441,487,041,186, etc etc), they will breathe much better than the 305 heads, and will work much better with that intake. You'll need a REAL healthy carb to feed it tho, even if your cam is not that radical.
And many a race has been won with flat tops and heads like that which have been angle milled .100" or so. No lack of compression there at all.
Another good combination would be the Vortec heads, a quadrajet intake and a good 2bbl with an adapter placing the carb over the rear of the intake plenum.

Hope that helps.

KPLugnut

Back to the Archives