425 block 455 guts

[biggraypig]

I have a 455 olds with a cracked block. Does anyone know if I can use a 67 olds 425 block for a rebuild of the 455?
Thank you

[Wet Dream]

www.realoldspower.com

[biggraypig]

I have decided to build the 425 instead.
Does anybody know a good place to buy an engine kit?
Thanks

[ghittner]

Yup, these are the guys. When I build my Toronado 425, this is where I'll go!
http://www.mondellotwister.com/

[LakesOnly]

I have a 455 olds with a cracked block. Does anyone know if I can use a 67 olds 425 block for a rebuild of the 455?
Thank youThe 425 and 455 Oldsmobile blocks are identical all the way down to the factory boresize.
The 425 Olds all came with a beautiful forged crankshaft. If you have not yet seen one of these cranks, you will love looking at it. I think you should use the 425 crank, absolutely. By the way, they have huge rod journals and you can offset stroke these Olds 425 crankshafts and have a nice forged stroker crank. Aftermarket piston/rod combos will need to be figured out by you, then stroke the crank accordingly. By the way, I'd recommend using fully-grooved bearings in your Olds boat motor so as to establish continuous oil feed to the rod bearings.
LO
p.s.: All 455 Ols cranks are cast. Supposedly, some say there were 30-40 forged 455 cranks out there, but this seems to be a mythical motor of sorts....

[biggraypig]

I do like the steel forged crank, and it is how you say beautiful. I have decided to build the 425 instead.
Could I Use any of the 455 parts that I already have to build the 425?
Thanks for all the input.

[SmokinLowriderSS]

Since the block is the same:
Heads, Intake, Exhaust, Distributor, etc, etc, etc.

[uselessgrant]

go to oldsfaq gives all specs and even casting numbers. your questions will be ansewered.

[Oldsquirt]

Couple things to watch out for.
The 425 lifter bores are machined at a different angle than the 455 lifter bores. This requires the use of a 425-specific cam. Using an off the shelf 455 cam will not work.
The crankshaft flange bolt pattern is different on the 425. The 455 PTO will not work. Looks like Glenwood Marine still has a 425 PTO in their catalog.

[oldselmn8tr]

I was told the lifter bore angles were different in my 67 425 when I called edelbrock for my cam and they said they didn't make a cam for it, I then called Engle cams and he said that was b.s. and shipped me cam and lifters. Worked great and no probs. So I am not sure if some did and some didn't or??? I do know I like my 425 and it screams for an Old's motor. The crank flange bolt pattern is definately different.

[Oldsquirt]

Could be true. What I remember from 25+ years ago was that you had to check the angle. Some had the later(455) angle and some didn't, and the difference in angle wasn't that big, but will affect valve timing. I probably shouldn't have said "will not work" but instead "will affect actual valve timing". :)

[Mark Sims]

Avoid mondello. over priced repackaged parts and since joe isnt there the tech sucks. Plenty of good olds venders at realoldspower.com

[Anthony75]

check your pm's

[biggraypig]

Thanks for everybodys comment and input they have been very helpful.
what I want to do is build me a 455 to run on for awhile, while I build a good solid monster 425.
This is what I have to start with:
Block: 389244D
Heads: C 394548 The underside of the heads have a 548 then looks like a tag that was screwed into the casting with 137 and then an 11 on one and a 12 on the other.
Intake: 397357 (2 brl)
Crank: 384722
It also has an F5 on the block behind the flywheel.
It will also be bored 30 over, and the heads will be redone with hardened seats. I would also like it to run 9.5 or 10.5 to 1 compression, with a mild cam.
Does anyone know of a good combination that will suit this application?
Where can I find parts for this build?