496 Head/Cam Advice?

What I have is a 4.25 Eagle crank, 6.35 Scat rods, and 789 KB Forged pistons, 850 Demon, 2 1/8 Super comp headers. This is in a 70 Nova with 4.10 gears, turbo 400, and 3500 stall. I have a set of 781's but don't want to put the cash into them if square ports would be better. The cam i'm looking at is the Comp XS282S or bigger any other suggestions? Eight years ago I ran a 69 Nova 468 with a 294s Magnum cam, 800 Holley, 2in Comp headers, 781's and 2.19 / 1.88 valves and same trans converter package but 4.56 gears. I want more power than the 468! This car will be driven some weekends and to the track maybe 5 times a year. There will be no out of town within 15 miles of driving. I'm Looking for advice on the heads and cam also the buget is tight. I would rather buy new heads rather than spend the same amount on porting the 781's. Any help will be appreciated!

Just hang loose. Pat McCarthy is the resident BBC guru and will have an answer for you. I pay close attention to his posts. I also pay attention to Erik's advice, so look for answers from these 2 guys. They both know what they're doing.

Most 496 BBC motors i have seen built here are using a .648 lift cam either solid or hydrayilc rollers. the heads have been an aftermarket 320 rec port head. low compression 10.25-1 . both made around 648 Hp and 650 TQ nice street motor. Dont choke that motor off.

Thanks for responding! I have looked at the 320cc Pro Comp heads. I know everyone says they suck but the price is cheaper than having all the work done to my old heads. Theres also a guy in Indianapolis selling 088 square port heads for gen v but I dont know if you can use them on a gen iv?

you put an oval port head on that motor and it will be done by 5000-5500 dont waste money on old 781 heads when you can get aluminum for a little bit more.

march 2007, car craft did a 496 big block chevy, they used AFR 305cc heads with a xtreme energy roller cam with 292 dur., they made 700hp and 600ft lbs of torque, something to check out. good luck

I can't afford a retro roller setup so i'm stuck with flat tappet and much cheaper aluminum heads. Thanks for the suggestion though!

my openion is to get a bigger cam like XS290S will be much better in ur application and a set of Darts heads ( Iron Eagle) they are good heads or check racing junk for used heads

how much cam do you think them KB are cut for ?? you need to mock it up with your new heads and check the valves drop on the intake you may have to fly cut them. i see you have some gear to it if you want PM me i have a good comp cam soild roller cam and crower roller lifers/ springs that are in great shape i would not run a flat cam in it

howdy ,

I have built 496" motors for several projects :rolleyes: ... they like the longer 6.385 rods , seems the rod ratio just flat works !
my daily driver is a 37 chevy pickup , tunnel rammed 496" I run flattop k.b.`s and factory 107 c.c. chamber large oval port heads w/ 2.19 x 1.88 stainless valves ..with the flattops there is well over .120 thousand`th clearance between the valves and pistons ,, run no less than .100 ,, just in case something happens to cause the motor to rev ... I never rev this past 6500 ,, I know it will go well past that w/ h beam rods ,,I don`t think any big motor needs more rev`s ...cam is a small roller , .671 lift x .295 dur. ......this combo pulls strong to 6500 r.p.m. ...... my race truck is an 85 S-10 ,, same combo , big brodix 320 heads and a .714 cam ....... I know you will enjoy the torque and power these motors produce ............ have fun , ratso

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Originally Posted by 70Nova496

Thanks for responding! I have looked at the 320cc Pro Comp heads. I know everyone says they suck but the price is cheaper than having all the work done to my old heads. Theres also a guy in Indianapolis selling 088 square port heads for gen v but I dont know if you can use them on a gen iv?

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The 320 cc heads are to large.
I would look at the World Merlin II's cast iron head with a 269 cc port volume.
If you shop around you should be able to buy them for around $1,400.
No matter what you do keep the port volume at or less then 290 cc.

Quote:

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Originally Posted by erik erikson

The 320 cc heads are to large.
I would look at the World Merlin II's cast iron head with a 269 cc port volume.
If you shop around you should be able to buy them for around $1,400.
No matter what you do keep the port volume at or less then 290 cc.

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A novice question. Are the Merlin 269 oval any better than a well prepped set of 781's? I was under the impression from another member on here that the 781's with gasket match and proper port work, llarger vavles etc will flow just as well as Merlin cast iro 269 ovals..just a question?

All I have to say is GOD BLESS STROKER BB's.
I have a baby cam in my motor, not even .600 lift, with the 320 Pro Topline heads. High rise Weind single plane, 850 mighty demon.....ect.
I put down 610hp/645tq. I know this motor will wake up even more with a "real" cam.

you put an oval port head on that motor and it will be done by 5000-5500 dont waste money on old 781 heads when you can get aluminum for a little bit more.

I see this is a little dated and not to argue but I have to add that the 781 oval port heads will in fact rev and build HP to 7000. I have a set of 781 with 2.19 in 1.88 ex small port work and milled to creat a 110 cc chamber on my 427. Not much material left after milling but these heads and flat tappet solid Isky cam helped to produce 423 RWHP at 6600 rpm in a 67 Camaro, Tremec TKO 600 and 9" rear.
From what I have read these heads work good until you reach the 650 HP mark and then need better heads.

Quote:

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Originally Posted by SMOKSHO98926

you put an oval port head on that motor and it will be done by 5000-5500 dont waste money on old 781 heads when you can get aluminum for a little bit more.

I see this is a little dated and not to argue but I have to add that the 781 oval port heads will in fact rev and build HP to 7000. I have a set of 781 with 2.19 in 1.88 ex small port work and milled to creat a 110 cc chamber on my 427. Not much material left after milling but these heads and flat tappet solid Isky cam helped to produce 423 RWHP at 6600 rpm in a 67 Camaro, Tremec TKO 600 and 9" rear.
From what I have read these heads work good until you reach the 650 HP mark and then need better heads.

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A well ported 781 with 2.19/1.88 valves might make power to 7,000 rpm's on a 427 but not on a 496.

OOPS, sorry Grump and thanks Erik I didn't pay attention.