# 428 question



## Steveh513 (May 3, 2020)

I have a 69 428 block with no crank but i do have a 67 400 crank will the swap work i figured the rods will be different and the block needs bored just seeing what will and will not work


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## O52 (Jan 27, 2019)

Mains are bigger on the 421-428-455. Rods are the same.


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## BearGFR (Aug 25, 2008)

Like O52 said, the cranks aren't interchangeable. 421/428/455 all had 3.250" mains while 326/350/389/400 all had 3.000" in mains. All stock Pontiac rods are the same length at 6.625" center to center, regardless of engine displacement. The various stroke lengths were accommodated for by different pin heights in the pistons. The pins in a 455 piston are "higher" (closer to the piston crown) than they are in a piston for a 400, for example. Pontiac engineers weren't dummies. Since all the different engines had different bore sizes and thus all needed specific pistons "anyway", it was more cost effective to make pistons with different pin heights because that allowed all the engines to use the same rod. Some of the performance engines used rods made out of different materials and with different processes (factory forged rods in the 455SD for example) but they were all the same length. 

Before aftermarket stroker cranks became commonly available, the way you built a 400 stroker was to take a 455 crank and have the mains cut down to 3.000" from 3.250".

Bear


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## Steveh513 (May 3, 2020)

Thanks 052, and BearGFR for this I'm appreciated of the help


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## Old Man Taylor (May 9, 2011)

BearGFR said:


> Like O52 said, the cranks aren't interchangeable. 421/428/455 all had 3.250" mains while 326/350/389/400 all had 3.000" in mains. All stock Pontiac rods are the same length at 6.625" center to center, regardless of engine displacement. The various stroke lengths were accommodated for by different pin heights in the pistons. The pins in a 455 piston are "higher" (closer to the piston crown) than they are in a piston for a 400, for example. Pontiac engineers weren't dummies. Since all the different engines had different bore sizes and thus all needed specific pistons "anyway", it was more cost effective to make pistons with different pin heights because that allowed all the engines to use the same rod. Some of the performance engines used rods made out of different materials and with different processes (factory forged rods in the 455SD for example) but they were all the same length.
> 
> Before aftermarket stroker cranks became commonly available, the way you built a 400 stroker was to take a 455 crank and have the mains cut down to 3.000" from 3.250".
> 
> Bear



Although that is correct, it is not complete. The thrust bearing (#4) saddle thickness is a different. Ken Keefer made a kit for this modification. It included an Olds 350 bearing set (only using #4), but for it to fit the crank, the bearing was a little too wide for the saddle. So he made a shim kit to go between the bearing and the saddle. The picture shows the shim, but this one was made with a radius that was too big. The pretty nails were my wife's. Now they make stroker cranks that drop right into a 400 block.


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## BearGFR (Aug 25, 2008)

Old Man Taylor said:


> Although that is correct, it is not complete. The thrust bearing (#4) saddle thickness is a different. Ken Keefer made a kit for this modification. It included an Olds 350 bearing set (only using #4), but for it to fit the crank, the bearing was a little too wide for the saddle. So he made a shim kit to go between the bearing and the saddle. The picture shows the shim, but this one was made with a radius that was too big. The pretty nails were my wife's. Now they make stroker cranks that drop right into a 400 block.
> 
> View attachment 136654
> View attachment 136655


Ah, yes - I forgot about the thrust bearing issue. That had to be addressed also.


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## michaelfind (Dec 14, 2018)

I learn so much from you guys. Thank you


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## EdGorman (Mar 26, 2020)

I do have a 1968 428 I was thinking about selling. If anyone is interested.
Ed


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## Steveh513 (May 3, 2020)

EdGorman said:


> I do have a 1968 428 I was thinking about selling. If anyone is interested.
> Ed


Whats your location and price just out of curiosity I'd hate to have something like that shipped cross the country


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## EdGorman (Mar 26, 2020)

I haven't thought of a price yet. I am in Oregon, and this engine has already been stripped, cooked, beed blasted and magnafluxed. the block and heads are generally ready to be machined. I would just polish the crank. I have the -.010 bearings for that It has been stored for quite a while. Heads are #670. My number is 503-348-2249. Ed


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## Steveh513 (May 3, 2020)

So will a 455 crank work in a 428 block sorry for all the questions


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## Old Man Taylor (May 9, 2011)

Steveh513 said:


> So will a 455 crank work in a 428 block sorry for all the questions


Yes.


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## Old Man Taylor (May 9, 2011)

However, it will require different pistons - and it will increase the compression ratio.


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