nickd

Joe or somebody could you post me a good 425 build that would make about 500 hp. You said using roller rockers was easy could you example more for me. I'm thinking of boring 60, with a cam, roller rockers will I need to beef up the turbo 400 at all. It is a 65 425 out of a Starfire hopefully the crank is useable the guy told me it spun a bearing and I still need to tear it down I'm hoping to use that crank tho with some work done on it. It has A heads. I believe it has a 45 degree cam bank angle but I still have to verify it.

csstrux

Moved thread to appropriate forum. should get some activity here.

MN71W30

I think 400 hp would be much easier to attain and a more realistic goal unless you have alot of money to spend. I'm not saying it can't be done but your gonna head down the road to brokesville getting 500hp. Using the Starfire heads and a good cam, some headers, and your going to be close to 400 in a hurry. That last 100 hp is gonna hurt..JMHO
Dave

nickd

Well I have since changed my mind. I was thinking of puttin a set of A heads off the 425 on a 1975 455 which has J heads right now. Will the A heads work? The 425 is a 65' and almost positive it is 45 degree

88 coupe

Pushrod holes will need to be drilled oversize for clearance. Only took an extra .032" (.016" per side) for C heads to work on a 45° block.

Norm

Warhead

You can also mark where the pushrod will touch, and have that clearanced with a high speed grinder. Your machine shop should be able to do this, when you do the valve job. Always double check for adequate clearance when you assemble.
Do the A heads have a fresh valve job?
(I know that you are NOT going to slap on worn out heads, are you)
Do a .030 surface, and have them back cut the intake valves.
Use the thinnest head gasket you can find.
Cheap and easy and good power.

nickd

Yes I plan to get the heads done so I can run unleaded. Will there be a problem with this? They have the weird rocker style. The 45 degree won't make a difference? I'm thinking of getting them polished also will that help on the power?

88 I'm trying to put A heads off a 45 degree and put them on a 75' 455 with 39 degree do I still need to have the holes for the pushrods drilled out and which pushrods should I use the 455's or the 425's? The 455 is a running motor the 425 had a spun bearing. Thanks guys

88 coupe

If you are having it done, use Warheads recommendation.

They should be the same length. If so, use the ones that show the least wear. If not, use the ones that came with the heads.

Norm

cutlassefi

Norm - Are you sure it was .016 per side and not .015 or .017? And how do you know that all castings are exactly the same? Can you say for sure that he'll need to remove exactly .016 per side and no more and no less? Did you check all of them as they left the factory years ago? Please clarify and substantiate. We'll need written confirmation that it's exactly .016 and not maybe just less than .020 from someone other than yourself to believe the bullshit you're spewing.

Thank you
BTW - You still haven't directly answered a post on another topic, still waiting.

442_Mustang

I feel a throwdown coming on. Actually the holes for the pushrods are drilled from the factory. I'd say theres a more than good chanch that the holes have never been drilled after origional production. I've not measured them because the A heads I have are on a High shelf so I'm not climbing up there but I'd say he's right again . <S> Norm

cutlassefi

I never said he couldn't be right. What I was questioning was how can you say such a precise number when you're dealing with castings from long ago. That's all. I'd like to know how much you ultimately have to remove, I'll bet it's other than exactly .016. Get my point?

dan2286

The way I understood his post was that was his experience when he did it. He did not say all of them will need to be drilled that much.

88 coupe

They were drilled at a slightly different angle for use with 45° blocks.

No chance, unless it was done to make them compatible with a 39° block.

I used the "thirty second of an inch" figure because it would be more than enough to allow for production tolerances.

Norm

88 coupe

Without a proper link attached, this statement is useless.

For example:

https://classicoldsmobile.com/forums/86465-post21.html
https://classicoldsmobile.com/forums/88637-post37.html

Simple, and to the point.

Norm

MN71W30

Maybe it the post where you said the bolts that broke off a Ford V6 were too soft.
And I said Norm I'm thinking too hard.
And you responded with "think harder"

I'm thinkin Norm, I'm thinkin. and I'm still thinkin too hard of bolt.

nickd

Is Norm Warhead?
If so Norm I would like to hear more from you sounds like you know what your doing. Really what I wanna know is which pushrods I should use the ones in the 455 or the ones in the 425?
I just read back and 88 said they should be the same size I guess I can check when I go to do the swap

88 coupe

No. Warhead actually knows what he is talking about.

Internet myth, based on a couple of lucky guesses.

Norm

88 coupe

What I may (or may not) have said, has nothing to do with this thread.

Norm

88 coupe

If you are interested in longevity, new ones are available from a variety of sources.

Norm

cutlassefi

Simple Norm, Seth's 455 build. You said he could get the pistons he needed faster from his favorite machine shop than from Summit. Remember? Capt Jim pointed that out, referring to your statement on post #16. How conveniently you skipped answering this, hmmmmmmm.

I don't really give a **** now, I think I've made my point.

BTW do you understand the meaning of the words two-faced? Probably not.

442_Mustang

Norm, My statement about there being little to no chance the holes being drilled oversize meant that unless someone drilled them oversize for bigger pushrods somewhere along the line. I've done it before on a small block Chibbie. Then all bets would be out the window if some huckleberry busted out a Unabit thinking of Mores Law...

88 coupe

I read it again. That is exactly what you said.

Norm

88 coupe

I did not make that statement.

Norm

Warhead

No I am not Norm.
Norm is in California, I live in Phoenix.
Phoenix is in Arizona.
That is a whole other state.

Note the style of posting. I have to go back 2-3 times editing before I am done with a single post, because this site likes to kick me out of it.
Norm does not, he can say it correctly in 1 post, no editing.

There are actually 3 different pushrod lengths for the BBO engines. I know for a fact that the .921 lifter engines will have a bit shorter pushrod than the 455 units. Unsure of the 425/45 degree pushrod, off the top of my head.

I would start with the pushrods from the block you use, and make sure that you have about .025-.035 preload (if you want to use that word-the bridge should be about that far from the head while tightening it down when the lifter plunger starts to compress).

Thanks for the good words guys.
I feel that Norm has much practical experience, from years of wrenching on this stuff, as do many of the people who post here.
I find him funny as hell, in a "grumpy old men" kind of way.
I too, try to share what may help, although it may not be what someone wants to hear,
or I may come across as a grouch.
I am still learning, also.