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Any difference between a '78 and '86 Small Block??

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Old Mar 12, 2009 | 08:14 AM
  #1  
andy625's Avatar
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From: Southampton UK
Car: Firebird 1987
Engine: 5.0
Transmission: Auto
Any difference between a '78 and '86 Small Block??

I have the chance to buy a small block V8 from a 78 Camaro - cheap. I'm thinking of buying it cleaning it up/rebuilding it just to give me something to do.

I just wondered whether I could potentially put it into my '87 Firebird if I ever had to? I appreciate that the sumps may be different, and I would need to transfer all my ancillaries etc, but would the basic block, engine mounts etc all be the same??
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Old Mar 12, 2009 | 11:21 AM
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Car: '87 IROC/'68 SS
Engine: 5.7L/350
Transmission: 700R4/Muncie 4-spd
Axle/Gears: 3.27 9 bolt / 3.31 12 bolt
Re: Any difference between a '78 and '86 Small Block??

Originally Posted by andy625
I have the chance to buy a small block V8 from a 78 Camaro - cheap. I'm thinking of buying it cleaning it up/rebuilding it just to give me something to do.

I just wondered whether I could potentially put it into my '87 Firebird if I ever had to? I appreciate that the sumps may be different, and I would need to transfer all my ancillaries etc, but would the basic block, engine mounts etc all be the same??
Your '87 has a two piece rear seal (which uses a different flexplate) and a roller cam. You can use the '78 block if you get the right flexplate.
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Old Mar 12, 2009 | 11:42 AM
  #3  
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Re: Any difference between a '78 and '86 Small Block??

Also, the oilpan isn't a problem, keep the '78 pan with the '78 block. The '78 heads won't accept your stock exhaust manifolds, but they will accept almost any headers for your car.
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Old Mar 12, 2009 | 12:19 PM
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From: Southampton UK
Car: Firebird 1987
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Re: Any difference between a '78 and '86 Small Block??

Thanks for the replies.

If I did ever fit it to my car, I think I'd change to headers in any case, even if it was just so I could get to the plugs easier!

Could I change the rear seal to a two piece type? Presumeably GM changed it as a 2 piece is better?

Also, I was going to do a search later, but if I changed to headers, does that mean I could remove the smog air pump and all teh associated plumbing? The smog rules are different over here, and an 87 car doesn't need all that stuff.
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Old Mar 12, 2009 | 12:32 PM
  #5  
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Re: Any difference between a '78 and '86 Small Block??

Smog pump. Do remove it, but save it, as laws do change, especially emissions laws as global warming gets more attention. Take photos first, don't butcher anything, label things, etc. Second, the '78 is 2-piece rear seal, which is not better. The '87 is 1-piece, which is better, and the '87 uses a roller cam. The '87 intake will require a bit of work to bolt to the '78 heads. GM went to the 1-piece to reduce warranty claims about oil leaks from the rear main seal. Now, if you're going to play with the '78 anyway, first be sure it is the 350, not a 305. 350 has 4" bores, 305 has 3.736". If the block has no damage, then consider stroking it. Doing a 383 couldn't be easier. and a stroker will need good-flowing aftermarket heads, preferably aluminum. Then you're on track for well over 400 horses.
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Old Mar 12, 2009 | 03:54 PM
  #6  
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Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
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Axle/Gears: 12B-3.73/9"-3.89
Your '87 305 heads are better than the '78 350 heads. Putting the 305 heads on the '78 block will solve about 75% of your compatibility issues.

1-piece rear main seal is better than 2-piece. But, that doesn't mean 2-piece is "bad". You will need a different flexplate, that's all.

The '78 will have the dipstick on the right side of the engine (looking at the engine from the front of the car). Stock intake manifolds get in the way of the dipstick tube. Headers solve that problem.
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Old Mar 12, 2009 | 04:49 PM
  #7  
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From: Southampton UK
Car: Firebird 1987
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Re: Any difference between a '78 and '86 Small Block??

The engine I'm looking at is a 305, but that's ok with me. Its cheap, and I'm just getting it as a project to keep me busy with the added bonus that I could use it in my Firebird IF my original engine dies (it's done 180000m, but otherwise runs ok at the moment). I've done loads of head jobs before, but I've never rebuilt a complete engine, so it'll be interesting.

Thanks for the info.
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Old Mar 12, 2009 | 11:17 PM
  #8  
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Silly me, assumed you were talking about a '78 350. . .

But, the '87 heads very likely are better than the '78 heads.
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