jims95z28

I'm planning on freshening up my LT1 ('95 Z28 M6) and had a couple of questions on what it would take to reliably spin the motor to 6400 RPM. The short block is stock with 105k miles. I'm running LE2 heads with a matched cam, roller rockers, springs, etc. I'm pleased with how it runs and currently have the rev limiter set to 6100 rpm. The cam I'm running definitely has a couple of hundred usable rpm left in it.

Other than a cylinder with slightly out of spec compression, the engine is in good shape and doesn't consume oil. I've owned it since new and it's always been taken care of. I expect to be able to reuse the stock rotating assembly.

The car is more of a hobby than a serious race car, but it does make it to the track 5-6 times a year for test/tune nights. Just looking for a short block that can reliably live with 400-425 rwhp at 6400/6500 rpm.

I'm planning on upgrading to ARP rod bolts (maybe new rods). I was considering having the rotating assembly balanced, too. Assuming all clearances are brought into spec, is there anything else that I should consider an absolute requirement?

Thanks,
Jim

aroberson77

I would go ahead on put ARP main bolts on as well. What is causing the low compression? Are you getting a new block?

BALLSS

OP

the stock rod bolts are what you need to address so going with ARP fasteners and getting the rods re-sized is recommended. Most likely your crank just needs a polish and do all new rod, main & cam bearings.

Machine shop would advise cyl condition. You likely can get away with a hone & re-ring....assuming your one cyl with low compression is not a cyl issue.

You now would have a fresh short block and one that will put up with 6400 RPM use.

Obviously if your cyl need a .030 over bore to clean up you will need new pistons and would have a 355 motor. Get good pistons like Mahle, not some heavy cheap slugs if you do need pistons

jims95z28

Rings are the cause of low compression. A squirt of oil in the cylinder brought the compression into spec. I'll get it bored (if needed) and reuse the block, crank, and pistons (assuming it doesn't need boring).

Good call on the main bearing cap bolts. I'm using ARP head bolts and rocker arm studs - they make good stuff.

What about mods to the oiling system, other then a new pump and pick-up? I've already ditched the factory oil cooler.

Thanks for the feedback!

BALLSS

the stock oil pump will likely out live you let alone this motor. You can get the GM spring (white IIRC) for a higher pressure. Do get a ARP oil pump drive shaft. The plastic color on the stock one is old/brittle and prone to breaking once removed and re-used

cookseyb

The ARP rod bolts will need to be pressed in soooo the ends will need to be re sized and checked for straightness, good to do even if they are stock.You won't believe how much better the engine will run-perform if you balance it. I use ARP bolts every where so you don't gotta mess with the torque to yield BS. Just a way to sell more bolts...

aroberson77

is the melling pump any good, idk if I willbe able to use mine since it ingested some bearings

pantera_efi

iTrader: (1)

Hi Jim, yes a set of forged rods may only cost a little more that a "resize" with ARP bolts.
The 6" rod length is also a benefit of a lower piston weight AND a better R/L with the 3.5" crankshaft good for higher RPM torque.
An engine balance job is also a good idea.

The SBC/BBC thread "Speed Master ITB's" is similar to your needs.
I would like to here your comment after you view those pictures.
A piston @ +.003" OS may save the cost of the block bore labor.

Lance

jims95z28

Hi Lance,
I did a search on Speed Master ITB's and came back empty handed. Can you post a link?
Thanks,
Jim