Peanut port 454 build assistance/help

[coloradoceltic]

I'm going to start out with saying I'm a complete newbie to anything other than: rebuilding a transfer case, doing brakes, stock suspension replacements, and routine maintenance(ig water pump replacement)
I have loved obs burbs my whole life. I have 2 of them (350 tbi and 454 tbi) I wanted to rebuild my engines. The 350 I'm going to just do stock and I have a manual for that it's got 350k+ on it. But for the 454 I'd like to pep it up just a little bit. Not trying to broke. Got bills to pay. The only problem is, I have no idea where to start. I don't really wanna mess with carb stuff.

I read just throw a cam in or upgrade to the vortec heads. But that seems to leave out a lot of detail. It seems there is a lot more than pulling the engine and throwing a new cam in with stock everything else unless I'm wrong. Same with the vortec heads. I'd have to change the intake and fuel distribution system right? Can someone help me find what I'm looking for? Like a part # of things and what ancillary parts will have to be changed. Idk if the stock ECU can be tuned at all. I'm very lost and have spent countless hours on forums, but it seems I'm at a much lower level of knowledge basin than what I seem to need to accomplish a seemingly simple upgrade.

If someone can point me in the right direction to find part # or a guide on what lobe separation is and all of that so I can finally just bring a little more life to that aged 454 I got that would be great. I may not be the smartest guy, but I can read instructions. Thank you again for your time.

 

[Schurkey]

WHAT VEHICLE? Low- or high-pressure TBI?

Thousands of years ago, one of the Chevy magazines had an insert that detailed a Vortec-head conversion on a peanut-port engine.

Dead-stock Vortec heads gained horsepower and torque, although the gains were fairly mild. About 35 hp if I remember right. Downside is that the article was very poorly written. Not sure I trust much of it.

I put Vortec heads on my boat 454 (peanut-ported Mk IV) and ran it that way for a few years. It worked, but it was nothin' special. The Vortec heads are a straight bolt-on, nothing special needed provided you select the correct gaskets, the pushrod guideplates are the right size for the pushrods, and the valvesprings and such match the cam. Two details are that you'd want to scrap the valve rotators in favor of rotator-eliminator shims. My heads had rotators on both the intake and exhaust, so I needed 16 shims. The other is that in stock form, the Vortec doesn't have adjustable lifter preload. This "can" be OK, but most folks change the rocker bolts for special studs and nuts to make the system adjustable again.

Does Colorado have emissions testing? If so, you're going to need stock-appearing parts, or a blind guy doing the testing.

 

[L31MaxExpress]

I would go with 90s 366/427 heads over the Vortec heads myself.

 

[99xcss4]

I would go with 90s 366/427 heads over the Vortec heads myself.

how do they stack up compared to oval/large oval ports and how are they any different from any other big block truck head I know they were tall decks but other then that I do not see what is so special about them

 

[99xcss4]

now if you are saying to use a 366 or 427 tall deck block I 100% agree they can easy swallow a big stroker crank and rods and take the 4 ring pistons out and put standard 3 ring pistons in

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[L31MaxExpress]

how do they stack up compared to oval/large oval ports and how are they any different from any other big block truck head I know they were tall decks but other then that I do not see what is so special about them

They are a small oval port with a smaller open chamber. On par with a hard to find 781 head.

 

[Schurkey]

I would go with 90s 366/427 heads over the Vortec heads myself.

Be really careful. Some of those have TINY valves--small-block sized. They're like a built-in governor that restricts engine speed 'cause the air flow is so choked-off.

They've also been run really hard. The trucks that got the tall-deck engines would often run so hard that the exhaust manifolds would glow red. The exhaust ports and valves would get REALLY hot. Valve seat recession can be a big problem, as can cracked castings.

I don't know about chamber differences. Chevy had so many different BBC combustion chambers that I can't keep track of them all. Beyond that--I don't think they'd be much different from the heads he's got.

 

[Schurkey]

now if you are saying to use a 366 or 427 tall deck block I 100% agree they can easy swallow a big stroker crank

Again--be selective. I've never owned a 366, but I've had a bunch of tall-deck 427s. SOME 427 tall-deck castings have clearance built-in that will take a 4.25-stroke crank and steel rods with no modification. Some do not, gotta grind (and grind, and grind) the casting for clearance.

But I don't think the O. P. wants to change blocks.

For the record, GM built very few 482 cid "Turbo-Marine" engines for offshore boat racing using the tall-deck 427 block, ordinary (LS6?) 454 pistons, a 4.25" crank, and connecting rods to make up the difference, at 6.405" length. The oddball-length connecting rods are available in the aftermarket, or at least they were the last time I checked which was years ago.

 

[b454rat]

Are you sure on the 781 heads? Im by far an expert but my understanding that they are large oval port heads, like with the 049 heads. And tall deck heads were the peanut port....

 

[vr1967]

What block are you starting with, Mark IV, Gen 5, or Gen 6? Which ECU? What is the intended usage, towing or performance?

Casting 236 or 2360 (Gen 5) aka “peanut port” heads flow about 230cfm stock, and with very little work will support 550-600hp. On a street engine, they are great as they keep port velocity up. A “large oval” port flows about 260cfm stock.

The biggest problem I have found with BBCs that after about 1973 until 1995, they came with flat top pistons and open chamber heads, so their true compression ratio was about 7.7:1

Open chamber heads are said to be about 118cc, but I have seen them as big as 124cc

Closed Chamber heads average 96-100cc The several sets of Gen 6 aka Vortec heads I’ve messed with were 99-100cc Unlike the small block, BBC “Vortecs” share the same intake bolt pattern as the earlier engines.

Easiest way to gain some power with a flat top short block is to swap on closed chamber heads to get the compression up, be it either with 65-69 Mark IV or 96-up Gen 6 heads.