# 428 stroker to 461



## OneThumbTony (Mar 31, 2021)

Hey! Tony here

I have some questions about Buttler Perfomance 428 stroker kits. 

I have a 1967 GTO with a 1968 428 Engine that i have with. 0.30 over boar 

I was woundering if i can buy the 428 stroker kit from butlerperformance and overboar the cylinders to 0.35 so the boar ends up in 4.155 boar if i am right

The 428 crankshaft is damage because i had a coolingwater leak in the Oil and the bearing damage the crank


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## BearGFR (Aug 25, 2008)

The 428 is a 'large journal' engine with 3.25" mains like the 421 and 455 as opposed to the 326/350/389/400 3.000" mains, but there are still stroker kits made for 428's (and 455's).

You've got a couple ways to go here, depending on what you intend to do with the car.

The 428 is an excellent platform for a _race_ engine because it has a shorter 4.000" stroke (same as the legendary 421) which means you can spin it to higher RPM - and that combined with a cam that can take advantage of RPM is goodness. Horsepower = (Torque * RPM) / 5252 The 428 has enough displacement to make serious torque AND a short enough stroke that it can 'RPM' with the right parts.

On the street/stoplight to stoplight however, raw torque rules. In that case, yeah, the more displacement you have the more torque it's going to make. That spells stroker.

Your choice.

Bear


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## OneThumbTony (Mar 31, 2021)

Hello Bear

Street engine is what i am thinking about the engine had already Had a tuning 436HP om the wheels 

I have ported nr. 16 heads on it with New vavels it a 4 speed munshi i use and chevy 12 bolt rear axel, 
MSD ignition system and a edelbrock 800 thunder carburator

The camb is a flat tip performer from comp cambs 

I was thinking about the 461 stroke because det Block is already over bord to 4.150 
Stock is 4.120 for the 428

I was cheking the Butlerperformance Page for the stroker kit and it says i need a 4.155 i think because of the piston rings

This kit i was thinking about 



https://butlerperformance.com/i-31643246-butler-ross461ci-4-155-balanced-rotating-assembly-stroker-kit-for-428-block-4-250str.html?ref=category:1459547



Stroker kit


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## BearGFR (Aug 25, 2008)

The reason for the 4.155 bore is that the pistons are a 'standard size' for other applications that they buy in volume from Ross and are thus less expensive, as opposed to having them custom made. In your case, I'd recommend getting an estimate from a REPUTABLE machine shop that works on Pontiac blocks. Here's a key question to always ask: Do they have and use a torque plate for Pontiacs? -- If they don't have one, or if they try to tell you that Pontiacs don't need one, then cross that machine shop off your list and find another. Be prepared for a long search because these days, not many shops are equipped to work on Pontiac blocks, seeing as how they've been out of production for so many years. It's possible that when you add in the cost of having the block punched out an additional 0.005 that your total cost for that plus the stroker kit would be the same as if you went with custom pistons and didn't bore the block.

I don't know that for certain, but it's worth checking. 

For instance, for $200 more it appears that you can get this kit:
https://butlerperformance.com/i-245...-428-block-4-250str.html?ref=category:1459547
With size to your spec pistons and NOT have to pay for a re-bore.
I'd check with them.

Cheers,
Bear


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