Worn out 250 Straight 6

[jjester6000]

I am new to the forum, I am 18 years old, and I own a 1974 GMC C1500 Custom. It has a 250 Straight 6, 3 on the tree, and has at least 239,000 miles on it (the odometer indicates 39,000, and the original owner already put 140,000 on it by 1979).

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The engine seems to have never been rebuilt, that is very prevalent when you see how much oil it burns.

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One quart every 50 miles, and it fowells up the plugs every 250 miles.

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Anyways, my whole point is that I want to rebuild the top end, so should I put the head from a 194 in order to increase the compression, or should I just rebuild the existing one?

 

[skysurfer]

I wouldn't bother with just a top-end rebuild on an engine with that many miles. Drop in a long block and be done with it.

 

[DoubleDingo]

And hook up that breather on the driver's side. It goes to the air cleaner housing. Although you're missing the top of it, so there's that.

 

[legopnuematic]

I wouldn't mess with trying to up the compression if it's worn out, all the new found compression will promptly escape between the rings and end up in the crankcase. Luckily those 250s can be bored out a few times, I've seen them bored 0.080 over and still hold up fine

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[75Monza]

I would attempt a leak down test on the cylinders first to see if rings actually wore out. Could be it's just sucking oil by the valve stem seals since it's original. If it is, then you just need the air pressure fitting and the spring compressor tool and change the seals without removing the head.

 

[Remo76C15]

Fun

 

[Old77]

Not sure why this was posted in the Introduction section but I've moved it for you so you get better exposure.

 

[Wumbo]

What part of the state are you in?

 

[78C10BigTen]

I wouldn't mess with trying to up the compression if it's worn out, all the new found compression will promptly escape between the rings and end up in the crankcase. Luckily those 250s can be bored out a few times, I've seen them bored 0.080 over and still hold up fine

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Imho one of the best engines chevy ever made... along with the 350 and 4.3

 

[Wumbo]

Imho one of the best engines chevy ever made... along with the 350 and 4.3

You spelled 454 wrong.

 

[78C10BigTen]

You spelled 454 wrong.

Oh damn im sorry.... 502.... that better? Lol

 

[Wumbo]

Oh damn im sorry.... 502.... that better? Lol

 

[78C10BigTen]

 

[Dave 84]

If I had your truck and yes that 6 is a good engine but I would have it out of there so fast hell my father in law has been trying to sell me his straight 6 fully rebuilt engine that came out of his blazer for 12 years i say and in my opinion only find a v8 sbc parts rain from the sky just have to reach out and grab them!

 

[Snoots]

If you just want it simple, an overall rebuild, NOT a top-end rebuild.

That keeps it cheap and follows the KISS method.