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Old 01-31-2013, 03:54 AM
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big block norminal port volume?

Hello.. what was the g.m. 454 say ls5 ls6
and or 454 ho or 454zz head port size in cc
try'n to figure out if the heads I have are really way to big..
some are saying like 40cc to big..
at one time this was going in a street strip chevelle, well life forced that change.. and the chevelle gone..
now it'll be going into a 3900 lb truck as a toy/ w-end fun vehicle.. still a high hp engine just not as strung out as the chevelle was going to be..

try'n to figure out what way to go.. as the bbc would be a 489...
and th400 /4:11 gears 29" tall tire..

or get a 350 vortec and save the bbc for something else down the road ..

the heads I have are 345cc ports.. and I'm being told I have more head than c.i.d. unless I'm building to a 8000rpm red line..
just how lazy will these heads make an engine thats 2000-6500rpm street runner..
some are say'n back the intake ports down to 305cc..

confused as when I bought the 345cc heads the ports didn't look all that much bigger than the ls6 heads he had beside them..

first bbc... and yes I might have gone overboard on the intact trac...
do I stick with these or try to sell them and get smaller cc heads..
the pistons are 10.2 with 118cc chambers.. so they'd need shaving or change pistons to bump the compression a little..

I could install a blower/turbo but that and the efi would be way over the no budget I have at the
truck will never tow..

but I'd not want a dog till 4500rpm either


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Old 01-31-2013, 12:56 PM
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put those heads on a mild 540.
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Old 01-31-2013, 03:17 PM
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Those heads will work fine provided you have a good carb and manifold on top that can keep good fuel suspension. They are a little on the big side, BUT many people run "way too big of heads" and actually make really good power with them. You'll also find you can go a hair smaller on the cam.
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Old 01-31-2013, 03:40 PM
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I believe stock oval port BBC heads (781 and 049) are 256CC ports. They are great for a street car. Even street strip into the 11's.
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Old 01-31-2013, 04:44 PM
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big block norminal port volume?

If you have 489 ci. keep the compression at 10.2. What is the brand name of the heads you have? Find a camshaft that the basic operating range is in the 2000-6000 rpms or 2500-6500 rpms. Howards Cams Mechanical Flat Tappet Camshafts 121742-08 - Get a Hughes 3500 stall converter to go with the TH400 and 4.11 gears. I would run a Victor Jr. with a 850 DP.
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