When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have never over cammed an engine. The only reason i asked is because back in the stocker days head modifications where limited and many ran "cheater cams" i belive they had to measure at OE specs so i assume the ramp profiles where changed to help the heads flow better by . Just from what i know atleast.
Cheater cams were to cheat the cam specs used by the tech crews on teardowns back then to verify they met stock specks on durations and lift of the cam. Faster ramps on the cams meant more power, while still showing the same durations and lift. They were much much harder on valvetrains.
Better than what I suspect most do, and that is try and cheat the system with one step bigger.
I think it is only human for a person to think that bigger is better. Myself, when I build an engine I always have to fight the urge to use a large cam that sounds good (because thats what the customer wants) and use a cam that has good drive-ability(because thats what the customer really wants). They just don't know it!
i have never over cammed an engine. The only reason i asked is because back in the stocker days head modifications where limited and many ran "cheater cams" i belive they had to measure at oe specs so i assume the ramp profiles where changed to help the heads flow better by . Just from what i know atleast.
My 455 project will be just a budget hand me down build . thw J heads im running have been proven to work to atleast 11.50's so should work for me .Most wouldnt bother running them as they think they are junk
I've always said ported 'J' heads flow just as good as stock small valve 'G' heads, so why bother with 'J' heads. Ported 'J' heads N/A will get you about 400 shaft Hp which is good for the street but I would not pay someone to port them period. I had my stock 'G' heads flowed and the results are: Stock 2" intake, 1.62" Exhaust at 10"
You can find a very good listing of cylinder heads at Stan Weiss Web Site, my heads are the ones listed as 'Olds G Iron', he only took the info he wanted and he converted the 10" to 28" but I get a little more flow when converting to 28", 232 cfm on intake. One more thing I think is important is converting air flow to Hp at Air Flow to Hp. I am in the slow process of porting my 'G' heads as I find time and will be going with 2.15'/1.68" valves and twin 70mm turbos but, I have stock small valve 'G's on right now. I hope this helps.
Ray
Last edited by 74sprint; January 11th, 2019 at 08:42 AM.
Reason: oops
Same flow bench, same day, same operator. I also have a set of stock G heads. The C heads that I have listed here flow more than the G heads. My ported J heads will stomp a greasy mud hole in both of them in stock form. This i kinda what I found out porting the J heads. They are tricky.
So... what is the port volume compared to the "C" head?
My ported J heads have 169 cc on the intake ports. The C head that I listed the flow numbers from has 182 on the intake port. Just because, I checked the port volume on a #6 head that I have here, it was 155 cc. For anyone that would be interested I checked the port on a set of Pontiac 6X heads that I am building, they are 164 cc ported. Pontiac heads,,,, now there is another challenge!
Ok, so, since you have a dyno..... I vote for a stock J head chassis dyno test vs a ported J head dyno test vs. a stock c head dyno test vs. a ported C head dyno test. If you use Cometic gaskets, and you don't silicone the intake gaskets, it would be an easy and clean swap.... not like you aren't capable and you don't have a nice car to play with now!!!
January 8th, 2019, 11:42 AM
Stock 'G' head flow
