Buying a 291 4.1

[czimpel]

I have a lead on a 291 block 4.1 with a couple hitches.

The engine was completely rebuilt for an N/A setup, so I know that this isn't a drop in piece for me. I'm looking strictly for the block.

Here is the issue. It was bored .040 by the rebuilder. Will this still work for a 4.1 turbo build?

Not sure if the rods and crank are from the stock block(filleted?)

The guy only wants $200 for carb to pan.

Is this worth the $200 investment?

 

[King MoneyBanks]

I have a lead on a 291 block 4.1 with a couple hitches.

The engine was completely rebuilt for an N/A setup, so I know that this isn't a drop in piece for me. I'm looking strictly for the block.

Here is the issue. It was bored .040 by the rebuilder. Will this still work for a 4.1 turbo build?

Not sure if the rods and crank are from the stock block(filleted?)

The guy only wants $200 for carb to pan.

Is this worth the $200 investment?

Yes.

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[ek02]

It's a good deal if the block is good, but have the block sonic tested and be sure it does not need to be bored any larger before you build it. .040 is close to the max unless you have really thick bores. It's a gamble until you are sure the block is good.

 

[czimpel]

Picked up the $200 291 4.1 this morning.

 

[ek02]

Nice. You got a good deal. There are over $200.00 worth of parts in the manifold, carb, heads, crank, etc. It will be nice if the block can just be honed for some forged pistons.

 

[czimpel]

Pulled it apart tonight, bores all look good at this point. Has the H471CP hypers in it, 2 dot rods, and a .020/.020 crank, doesn't look like a turbo crank. Not completely sure though as I have never seen one in person. It doesn't look to have much of a fillet on the rod journal. Timing cover has the numbers 1254992 cast in it right behind the balancer, not sure if this is a GM unit or not.

 

[Jay J]

looks like a good foundation.

 

[earlbrown]

If the timing cover has the crank seal loaded from the front it's not GM. Look at your main journals and note the groove on each side of the journals. If the rods have identical journals, it's a 'turbo' crank. If the rods have standard radiused transitions on each side, it's an 'N/A' crank.

could you read the O/S on the pistons?

 

[czimpel]

If the timing cover has the crank seal loaded from the front it's not GM. Look at your main journals and note the groove on each side of the journals. If the rods have identical journals, it's a 'turbo' crank. If the rods have standard radiused transitions on each side, it's an 'N/A' crank.

could you read the O/S on the pistons?

.040


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[czimpel]

Timing cover seal is from the inside, so I hopefully scored a good GM cover!

 

[earlbrown]

If it looks as good as the outside of the engine, you sould be good. The proof will be when you get it apart and take a look at the pump cavity and oil filter adapter.

 

[czimpel]

Non turbo crank.

 

[czimpel]

Oil pump. Doesn't look so good! .003" clearance from gear to wall.

 

[czimpel]

Timing cover.

 

[earlbrown]

Yeah, something huge went though that pump. That scoreline under the drive gear looks to be about .025" to 030" wide and just as deep!
With a set of GM gears that side clearance might close up, but it looks like the shaft bore is chewed up too. Almost like it was ran dry at one time and subjected to debris too.
From the pictures it looks like you have some significant scoring going on there.

 

[czimpel]

Usable?

 

[earlbrown]

If they cover looks as bad in real life as it does in the pictures, I wouldn't run that cover on an engine I cared about.