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Vortec 7.4 L21 engine parts id

Pmeeeeee

By Pmeeeeee
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Pmeeeeee New Member

Pmeeeeee

Posted
Posted

 

I bought a taken apart gen vi 454 L21 vortec engine block, crank, n rods/pistons. The guy who took it apart didn't label what cylinder rods/pistons came out of.
The rods/pistons are still assembled together but how do I tell what cylinder each came out of? There are many factory marks on inside of pistons but nothing obvious (to me). On the rod cap sides(both upper n lower)they have unique stamping marks.They are:
T053
V028
V272
X225
M029
L290
X254
L147
What does the stamping mean? Hopefully that translates to a certain cylinder or something.
Thanks for your help!

20210613_223510.jpg

20210613_223313.jpg

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted (edited)

Unfortunately, you're pretty much out of luck there. While it's not ideal to mix n match pistons and cylinders, it will still run. Hopefully it's not worn out to the point where it smokes. I suppose you could measure at least 6 points on each piston and cylinder, and match them up with whichever has the correct clearance, but with taper and everything that may be tough.

 

If it were me, I'd buy a whole new set of +1 or +2 (depending on what's in there now) pistons and rings, bring all of that plus the block to a machine shop and have them bored to match. Since it's already apart, that would be you're best bet. The engine will run PERFECT, and stay that way for a LONG time. Every piston/cylinder will be equal and to proper clearance. Finish it off with a new oil pump, and that engine will be ready to rock for DECADES to come. Every one of those  engines makes it 250k miles at a minimum without ever going into the engine, unlike most of today's junk. You may have to replace lifters or valve springs down the road, but that's a weekend job, instead of 20 hours labor just to reach them on an LS.

 

The stampings are just to match the end caps up - that's critical. Can't mix and match end caps. That brings us to another problem - which rods went to which journals? You're going to have to get some Plastigauge and do some clearance measurements. 

Edited by Jsdirt
Forgot about the stamping question ...
Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
1 hour ago, Jsdirt said:

Unfortunately, you're pretty much out of luck there. While it's not ideal to mix n match pistons and cylinders, it will still run. Hopefully it's not worn out to the point where it smokes. I suppose you could measure at least 6 points on each piston and cylinder, and match them up with whichever has the correct clearance, but with taper and everything that may be tough.

 

If it were me, I'd buy a whole new set of +1 or +2 (depending on what's in there now) pistons and rings, bring all of that plus the block to a machine shop and have them bored to match. Since it's already apart, that would be you're best bet. The engine will run PERFECT, and stay that way for a LONG time. Every piston/cylinder will be equal and to proper clearance. Finish it off with a new oil pump, and that engine will be ready to rock for DECADES to come. Every one of those  engines makes it 250k miles at a minimum without ever going into the engine, unlike most of today's junk. You may have to replace lifters or valve springs down the road, but that's a weekend job, instead of 20 hours labor just to reach them on an LS.

 

The stampings are just to match the end caps up - that's critical. Can't mix and match end caps. That brings us to another problem - which rods went to which journals? You're going to have to get some Plastigauge and do some clearance measurements. 

 

Jsdirt: While not on topic my question remains on point. Not intending to derail this thread just looking for parallel information. 

 

Why does GM think this is not an issue with the Ecotec 2.4 I4. TSB on the critter has them putting new pistons and rings in a 100K mile block without so much as a hone. In fact they say not to hone.

 

So the question is, how successful has this been in eliminating oil consumption? 

 

Was the strangest TSB I ever read. Defies everything I know about motor building. 

 

 

 

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Yep, totally defies logic. Must be a warranty job, otherwise they'd have everyone do it right.

 

The other reason for that could be if there's some coating on the cylinders, like Nikasil - Japanese motorcycle manufacturers used to do this in the day. You couldn't hone or bore, since it would wipe out this coating. Only cast pistons could be used, too, if I remember right, or they'd seize. I highly doubt GM would spend a nickel on this process, though. It wasn't cheap, even for single cylinder bikes.

 

If that were my car & I wasn't a tech, I'd take it to a private garage and have them do it right - take the block to a machine shop and hone each cylinder to as good as they can get it. Or buy +1 over pistons and have them matched (ideally).

 

I don't have any experience with that engine - most of my customers are truck or SUV owners. Very few cars.

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