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J heads... dead horse!

Old January 8th, 2019, 11:42 AM
  #81  
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Originally Posted by coppercutlass View Post
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.
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Old January 8th, 2019, 02:20 PM
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Originally Posted by Firewalker View Post
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!
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Old January 8th, 2019, 02:21 PM
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Originally Posted by coppercutlass View Post
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.
what are you waiting for ???????
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Old January 8th, 2019, 02:27 PM
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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
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Old January 11th, 2019, 08:41 AM
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Smile Stock 'G' head flow

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
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Old January 11th, 2019, 09:25 AM
  #86  
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Stock C heads with back-cut 2.00 valve 1.678 exhaust valve

.50 29 na
.100 66 59
.150 101 83
.200 133 105
.250 156 121
.300 171 131
.350 187 141
.400 199 150
.450 208 157
.500 215 161
.550 222 165

J heads 2.07 valve tricky port work
.50 37
.100 69
.150 110
.200 148
.250 179
.300 205
.350 221
.400 227
.450 229
.500 231
.550 232

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.
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Old January 11th, 2019, 10:03 AM
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Yep, your ported J heads are really great at low to mid lifts and they hang on at the .550 numbers also.

With that much much difference in the numbers, those Jís would be putting out a lot more power than the Cís for sure!

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Old January 11th, 2019, 10:14 AM
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Talking

Originally Posted by Battenrunner View Post
Yep, your ported J heads are really great at low to mid lifts and they hang on at the .550 numbers also.

With that much much difference in the numbers, those Jís would be putting out a lot more power than the Cís for sure!

Thank you. I am convinced that I can get the same results from an Olds small block head. I just need a willing participant.
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Old January 12th, 2019, 04:07 PM
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Originally Posted by ChevyZ06 View Post
Thank you. I am convinced that I can get the same results from an Olds small block head. I just need a willing participant.
Check your PM
Thanks
Bernhard
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Old January 12th, 2019, 06:55 PM
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So... what is the port volume compared to the "C" head?
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Old January 12th, 2019, 09:06 PM
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Originally Posted by Lonnies Performance View Post
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!
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Old January 12th, 2019, 10:50 PM
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Boo Pontiac, Boo!

haha.....

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!!!
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Old January 13th, 2019, 05:58 AM
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With a small port & good low lift flow numbers, it looks like a great combination for low end torque if run with a smaller cam.
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