Been looking at various options for upgrading the 396 in my 1972 K10 to something with more power. I am finding out that the header options for a big block 1967-1972 conversion are really limited.
If I am stuck using exhaust manifolds, is there a "why bother" point where it just doesn't make sense to invest in a bigger engine only to choke it off with manifolds? Let's say I'm shooting for something with 18" of idle vacuum that can use a stock converter. From the following options:
(1) Keep my 396, flat tappet, 702 head engine. No cam specs (bought used) but not a big cam.
(2) Cheap rebuild on a peanut port 454 - keep crank and heads, cheap flat tappet, sell the 396 on craigslist.
(3) Less cheap rebuild on 454 - 4.25 forged crank, H beam rods, find some 781's, hydraulic roller.
(4) Brodix block 540 with the crank, rods, and heads as described in (3).
Is there a "sweet spot" here? Does (3) even make sense with exhaust manifolds, will it run noticeably stronger than (2)? I assume (4) is just way too much money to spend if you are gonna run manifolds.
BBC exhaust manifold limitations
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novafornow
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rustbucket79
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Re: BBC exhaust manifold limitations
I’d build the 496 with budget aluminum oval port heads and focus on a sub 5000 rpm build that will be hard on tires and a blast from stoplight to stoplight. Although the exhaust manifolds would be a restriction, I don’t think they would be a major power killer. I wonder if a set of shortie’s would fit your chassis.
Re: BBC exhaust manifold limitations
thought about ‘em, read some reviews that they didn’t fit that great and not sure how much power they would be down compared to full length headers?
Re: BBC exhaust manifold limitations
interesting. i did some poking around on the 67-72 site and some have had better luck than others fitting those on a 4x4. but I did find that stan’s makes a tri-y header that seems to fit perfectly!
Re: BBC exhaust manifold limitations
i am hoping some of the tri-y headers mentioned above (dougs or stan’s) will fit. i bet a 496 oval port with tri-y headers would make a fantastic truck engine!rustbucket79 wrote: ↑Mon Dec 06, 2021 9:49 pm I’d build the 496 with budget aluminum oval port heads and focus on a sub 5000 rpm build that will be hard on tires and a blast from stoplight to stoplight. Although the exhaust manifolds would be a restriction, I don’t think they would be a major power killer. I wonder if a set of shortie’s would fit your chassis.