Vortec 350 Questions

[CGT]

I highly doubt L31's came with .028" stock. More like .041" and one of the main reasons I used to hunt down Victor Reinz .035" gaskets during head ports/swaps and rebuilds.

.028 stock on those motors

[ProPower engines]

The stock vortec head gaskets GM part# 10105117 are the replacement head gasket. They are .028" compressed.
There is also a GMPP head gasket used on the 602 and 604 crate engines with a different part number but the same .028 compressed thickness.

The 10105117's are cheap from the dealer at about $38/pair. They are the same head gasket used in Mercury marine and Volvo Penta 5.7 engines as well.
I use them several times a week.
But if you are going to use a steel gasket the thin shim gasket will not work well the head castings are too flexible as is the deck of the block. Thats why GM never used them because there would be leakage issues.
I know guys say they have done it for a race car but a street vehicle I would never consider doing it cause I know there will be an issue down the road soon.

Get your machinist to leave you with .035 to .040 total deck. That is to say from the piston to the head with the gasket thickness included in the measurement. Since you have measured the block already its no big deal now to get it perfect

[midnightbluS10]

For inexpensive SBC replacement pistons, I can often find a Silvolite in standard compression height. Usually for mercruiser applications.

Summit has a set of flat top, 1.56 compression height pistons for 139. Available in standard and .030 over. +6cc piston head volume.

https://www.summitracing.com/parts/sum- ... /overview/


Sum-17350c-30 for .030 over

[Gashog]

I have new composite head gaskets also. I'll have to look at them because I don't remember thickness.
I've used those same steel shims and some copper head gaskets....never a leak. Not once.
Clean, smooth and flat. Gasket coating (take your pic), chambered bolt holes and proper torque.

[496s10]

Victor reins 5746 gasket's are .026. I bought a head set from rockauto with the rubber bonded over steel intake gasket's and multi layered steel header gasket's for $36.

[gmc406]

You will custom tune this correct?

[496s10]

And also why does everyone over look the lt1 pistons? They are cheap and have a low tension metric ring pack with a slipper skirt design. If you can find nos gm piston's were made by mahle

[groberts101]

My bad.. must have crossed wires for the 96+ vortec 4.3 stuff. Guess the older stuff is starting to blur together. Must have been trying to limit the misinformation and forgot to check my own facts first. Lol

[Gashog]

You will custom tune this correct?

No. Not for a while.
The local tuner quoted me $1000 for a street tune.
For that much, I'll buy efi live, pull the wide band out of my car and datalog with my tech2.
Since that shop doesn't seem to be able to fix my girlfriends random multiple misfire after a year, I don't have much faith in their Mustang dyno and HP tuners skills either.
I'll do it myself, but that means in my "spare" time!
Right after I fix my girlfriends car!
I was hoping the adaptive strategy functions of my stock black box will be able to trim such a mild build within the margin of safety.

[Gashog]

And also why does everyone over look the lt1 pistons? They are cheap and have a low tension metric ring pack with a slipper skirt design. If you can find nos gm piston's were made by mahle

I'll definitely remember this for the next one!

[gmc406]

Just trying to understand your set up. What year taho? I assume 96-99ish? I don’t quite understand what your doing with the PCM as you stated.

[Gashog]

Just trying to understand your set up. What year taho? I assume 96-99ish? I don’t quite understand what your doing with the PCM as you stated.

Correct. It's a '98.
Ultimately, the 0411 PCM swap is the solution.
I'll tune it myself.
That's another project and may need to wait until next winter. For now, the black box will do. I'm not racing.

[leahymtsps]

The stock vortec head gaskets GM part# 10105117 are the replacement head gasket. They are .028" compressed.
There is also a GMPP head gasket used on the 602 and 604 crate engines with a different part number but the same .028 compressed thickness.

602 gasket 10105117 .028
604 gasket 12557236 .054

Tom

[novadude]

And also why does everyone over look the lt1 pistons? They are cheap and have a low tension metric ring pack with a slipper skirt design. If you can find nos gm piston's were made by mahle

Stock 96-99 vortec engines have a 12cc dish piston with 1.5/1.5/3.0 ring pack.

[Newold1]

I would build it as a 383 and ditch that funky GM spider injection intake system and put a decent efi throttle body-port injector set up on it so you can make some real torque. A nice set of long tube tri-y headers and some spintron mufflers. JMO