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Discussion Starter #1
i have two set's of chevy heads ,i'm needing some help to figure out what pair to run on my 505. the car is 3,500 pounds without driver , 10.5 tire ,stock suspension.
505 is 13.5:1 solid roller i can buy the right size cam to make heads work, 7,000 rpm shift point ,victor intake,1050 dominator,150 -200 hp shot big shot plate. turbo 400 ,4.10 gears

mild ported #990 rec.port open chamber heads with 1.880 and 2.250 valves

mild ported#781 same as #049 oval port open chamber heads with 1.880 and 2.19 valves

it is a 1/4 mile street car that runs mid 10's with a 8.5:1 454 and oval port heads ,plus a 180 shot going through the traps at 6,500 rpm

thanks
 

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Discussion Starter #3
990 heads for better flow on the topend ...
when you say topend what kind of rpm's are we talking about , i dont want to hurt my low end torque do to the fact my turd is heavy 3,700 pounds with me in it ,then again i dont want it to fall on its face half track . what kind of rpm's do you think the 781 head is good for and the rpm rang of the 990 head ?
 

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the 990's. the 781's do not have the port volume to feed that kind of cubic inches. they are barely 270cc the 990's are 310cc+. You are going to need the port volume trust me. Plus they already have the right sized intake valve in them.
 

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the 990's. the 781's do not have the port volume to feed that kind of cubic inches. they are barely 270cc the 990's are 310cc+. You are going to need the port volume trust me. Plus they already have the right sized intake valve in them.

I'm not trying to argue your point, but I think naturally aspirated the 781's have the volume to get it done. There is a guy not far from here who runs a 505 in a 3600 pound chevelle, he had 781's on it and was going 10.30's. Switched to brodix race rite ovals and now gets in into the nines. BUT, I agree that running nitrous he needs the bigger volume of the 990's.
 

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You dont want to argue my point, then you offer evidence to Support my side of the non argument? 781's do not have the cross sectional area to support 500 inches at 7000 rpm, Naturally aspirated, nitrous, or however else you wanna put it out there. Even if he said he was not going to spray it, i wouldve suggested the 990's anyway.
 

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You dont want to argue my point, then you offer evidence to Support my side of the non argument? 781's do not have the cross sectional area to support 500 inches at 7000 rpm, Naturally aspirated, nitrous, or however else you wanna put it out there. Even if he said he was not going to spray it, i wouldve suggested the 990's anyway.

I'm just saying I have seen 781's on a 505 run pretty fast. Now are those motors going 7k? Are they making power at that much spin? I dont know. But I know they can get a N/A car with a 505 to put down good enough times to require a chassis cert. Now, take that with a grain of salt, because I have not done it myself. But there are also a few 496's that are local with 049's and 781's that are running 10.0's at 3500 pounds. Now wether or not they are turning 7000, I dont know.

I'm interested in wht cam the op is running and intake and carb at 3500 and what he wants to get our of the swap.
 

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O ports 049s - 781s , is what I would go with. Under 7k rpm ,,,yea that just my .02s
 

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have friend with 049's on a 496 in a 78 camaro runs 10.50's
 

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You dont want to argue my point, then you offer evidence to Support my side of the non argument? 781's do not have the cross sectional area to support 500 inches at 7000 rpm, Naturally aspirated, nitrous, or however else you wanna put it out there. Even if he said he was not going to spray it, i wouldve suggested the 990's anyway.
What cross section should they have?
To the OP...
Is this 505 a MkIV block, 4.35 x 4.25 stroke? "Mild ported" always scares me...
 

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Discussion Starter #14
What cross section should they have?
To the OP...
Is this 505 a MkIV block, 4.35 x 4.25 stroke? "Mild ported" always scares me...
yes it is a mrkIV 454 4 bolt main fully studed .100 over, 4.25 stroke and 6.385 rods . forged scat crank , eagle h-beam,je pop up pistons 13.5:1
"mild port work" i should say bowls blended and smoothed out and a clean up on the ex. and int. runners .

trying to make around 700 +hp on motor with alot of torque to get the weight moving , i want to leave the light first and be moving out by half track so the other guys have to play catch up.
 

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yes it is a mrkIV 454 4 bolt main fully studed .100 over, 4.25 stroke and 6.385 rods . forged scat crank , eagle h-beam,je pop up pistons 13.5:1
"mild port work" i should say bowls blended and smoothed out and a clean up on the ex. and int. runners .

trying to make around 700 +hp on motor with alot of torque to get the weight moving , i want to leave the light first and be moving out by half track so the other guys have to play catch up.
The ovals would need some good port work. It could be done, but since you have some compression and you want to spray it, I'd probably just go with the 990's and a custom cam.
 
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