# Engine help/opinions



## Pontiacpurebrred (Jun 22, 2011)

OK. I have found the following. 
Pontiac 400 WC block 
Casting number of XX481988 
Date code of K097

I have found some conflicting info ...
1978 400 220 HP WC M 8.1 402 6X 1-4 17058263 FB W72 Block Casting # XX481988
It is mated with a 3 speed and has the 6X heads, 2 bbl manifold and carb.

Now I have also found 
WC F-body 78 400 220 4-speed L-78 Z 1x4 568557
Trans Am motor.
I was told it was in a Firebird originally. 

Is there any other way to determine the origin of this motor? Definitively?

Second question, if I am comfortable with the price, is this a good candidate for a nice goat motor? Properly re-built ... cammed and dressed can this be a 400+ hp beast?


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## Thumpin455 (Feb 17, 2010)

The 988 block is better than the later 557 block because it hasnt been lightened. If you plan to build a stroker then the 988 is better. If you are only looking for 400hp and not planning on stroking it then the 557 block will work. Spray it and you run the risk of dropping the crank out the bottom or cracking the block. The 557 also might not have the holes drilled to fit the A body mounts, some were, some werent. I had one that wasnt.

The W72 used the heavier 988 block where the B body line and regular Trans Am/Formula got the 557 block. The chances of finding a W72 block with a 2 barrel intake are kinda rare, but people will swap almost anything around. The date code by the distributor and the two letter code under the passenger side head will tell you what it is out of. The casting behind the passenger side head tells you which block it is.


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## Pontiacpurebrred (Jun 22, 2011)

I think it was originally a 4bbl block, from everything I have found the XX481988 blocks were the better 79 400 the more dowdy block than the other 400 put in 78/79 Firebirds and TA's.

Guy says it has new plugs and wires and cap and rotor it runs but needs timed. 
I will of course be rebuilding it.

He's willing to trade it for my TH400 that I am not going to be using anyway. 

Good deal?


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## Instg8ter (Sep 28, 2010)

something you will use for something that will take up space in the garage is always a good deal.....wish i could get someone to trade me E-heads for my 326...


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## Pontiacpurebrred (Jun 22, 2011)

Instg8ter said:


> something you will use for something that will take up space in the garage is always a good deal.....wish i could get someone to trade me E-heads for my 326...


So opinions please....will this be as good of a starting block as any 400? I would prefer a 428 4 bolt block or a 67-70 GTO 400 block, but really in the final analysis is there any difference 400 to 400? Can I not cam, head and intake this bad boy and end up with an @$$ kicker?
:confused


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## BearGFR (Aug 25, 2008)

The 400 would be a better/stronger block than a 428/455. The larger main journals in the 421/428/455 result in less "meat" in the main webs and therefore less strength. Build a stroker with good quality parts (forged rods and pistons) and you have the best possible combination: same (or more) cubic inches as the 455 but without the drawbacks (larger main journal resulting in higher bearing speeds, weaker block).

Opinions vary on the point at which 4-bolt mains and a forged crank are "required", but in any case it's well north of 600 HP for either/both. 

These ain't ::cough - spit:: chevys we're dealing with here.

Bear


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## Pontiacpurebrred (Jun 22, 2011)

BearGFR said:


> The 400 would be a better/stronger block than a 428/455. The larger main journals in the 421/428/455 result in less "meat" in the main webs and therefore less strength. Build a stroker with good quality parts (forged rods and pistons) and you have the best possible combination: same (or more) cubic inches as the 455 but without the drawbacks (larger main journal resulting in higher bearing speeds, weaker block).
> 
> Opinions vary on the point at which 4-bolt mains and a forged crank are "required", but in any case it's well north of 600 HP for either/both.
> 
> ...


Well I agree with all that, I was more hoping for opinions on THIS 400 block. From everything I have been able to find this was Pontiac's last great performance 400 ... this particular 400 casting the XX481988 the W72 Firebird / TA motor. Based on an older casting (481988) from the late 60's. Only built in Michigan and only for about a year. When they were gone they were gone. Only the best team of engineers were assembling them, yadda yadda yadda. 

http://pontiacformula.free.fr/schema/W72pack.pdf

I think I almost HAVE to get it. I can trade a halfway tired TH400 I don't need or want for the complete engine. The only reason I wouldn't is if someone here has heard or seen anything I have missed that this may not be a good casting or good starting point for a good street 400. 

As always Bear, your opinions mean a lot, and thanks for chiming in!


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## DukeB-120th (Oct 19, 2009)

Do it, good sir!


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## Pontiacpurebrred (Jun 22, 2011)

It is done. I talked to the guy last night. I will be pulling my engine and tranny this weekend and then doing the swap next weekend. Thanks for the input everyone. 

It looks like it's all original except for the carb and intake manifold ... even has the 6X (4) heads. So it should run about 8.4:1 natural compression. May get these heads ported and rebuilt and just use them as they are the best late model Pontiac performance heads. We'll see once I get it home and torn down. 

So...anybody looking for a 1964 389?
arty:


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