Gm 4.3 blocks

[tcombs115]

Hey guys, I have a 4.3 needing a new block. Current block is the newer style 234 casting numbers. Seems to be a tough block to find. Has anyone used a 090m block in replacement for the 234? If so, is there much difference in the two? I’ve heard possibly timing chain covers and oil pans may differ. Thanks in advance.

 

[Scott Danforth]

first, welcome aboard.

the "234" block is the 2007-2014 motor. base model Silverado and Siera trucks had them as well.

why do you say you need a new block? did you freeze bust it? if so, you also need new heads, intake manifold and exhaust manifolds

cheapest to get whole long-block at that point. suggest folks like Michigan Motorz

tell us the back story here

 

[tcombs115]

block is cracked from winter. I have a set of fresh machined heads, so I wouldn’t mind finding a decent block and having it machined and building myself. I have looked at and spoke with Michigan motors. Was just curious if anyone knew of any significant differences between the 2

 

[Scott Danforth]

you wont find a new block as GM moved from that platform in 2014.

even the old SBC you wont find new GM blocks, only aftermarket

your best bet is find a 2007-2014 GM truck and pull the motor. this is also about 1/3 the cost of rebuilding a motor. you can get a low mileage 4.3 from a late model wreck with a warranty for about $500.

there are plenty of changes between the prior 2003 and 2007 generation and the 2007-2014 generation. some are minor. Can you get the earlier block to work, yes.

 

[tcombs115]

Thanks for your input! I have a buddy that has an old 2011 Silverado with a 4.3 in it, that I could get for a deal and a half. But the truck has the 090m casting block in it. May just grab it and compare the two side by side, then have it machined if they are similar enough.

 

[Scott06]

Thanks for your input! I have a buddy that has an old 2011 Silverado with a 4.3 in it, that I could get for a deal and a half. But the truck has the 090m casting block in it. May just grab it and compare the two side by side, then have it machined if they are similar enough.

the 090M (m for metric) has metric fasteners on the starter, flywheel cover, and side motor mount holes. Don't ask me why GM mixed metric and SAE on the same block

I swapped a 090M 4.3 in my boat for a 5.0 that has all SAE fasteners- was no big deal about $45 worth of bolts. All the accessory bolt holds were SAE on both blocks.

Where I would look at if the oil pan and timing cover areas for differences. the 090M I had had a ribbed cast aluminum oil pan. Even if it is different between you cracked engine and donor engine just keep the parts (balancer and maybe flywheel too) with each engine. I would think you could take your accessories off your engine and put them on the new one no issue.

Edit - looking at the Mich Motorz site on the reman engines (options for the long blocks) looks like the oil pans are different part numbers between the 090/090M casting and the 243 casting. Not sure if the windage tray/oil pan is different for marine vs truck.

 

[tcombs115]

the 090M (m for metric) has metric fasteners on the starter, flywheel cover, and side motor mount holes. Don't ask me why GM mixed metric and SAE on the same block

I swapped a 090M 4.3 in my boat for a 5.0 that has all SAE fasteners- was no big deal about $45 worth of bolts. All the accessory bolt holds were SAE on both blocks.

Where I would look at if the oil pan and timing cover areas for differences. the 090M I had had a ribbed cast aluminum oil pan. Even if it is different between you cracked engine and donor engine just keep the parts (balancer and maybe flywheel too) with each engine. I would think you could take your accessories off your engine and put them on the new one no issue.

Edit - looking at the Mich Motorz site on the reman engines (options for the long blocks) looks like the oil pans are different part numbers between the 090/090M casting and the 243 casting. Not sure if the windage tray/oil pan is different for marine vs truck.

Thanks for the knowledge Scott!