ADM

Hi guys, a question to those who have experience with rebuilding LS1 motors.

What bearing clearances should I go for on the rods and mains? ARP rod bolts are going in, the mains will reuse the stock bolts.

Oil pump is going to be upgraded to a Melling HP/HV.

Also, what brand of bearings are recommended? What oil weight with the bearing clearances recommended?

The heads are 241. After inspecting them at the machine shop today we found them warped around the centre area and they need to be milled probably 0.010" to make them flat again.

Will I have PTV clearance problems installing an MS4 cam and milling them 0.010"? I intend to use a GMPP 0.056" MLS head gasket to avoid having a big bump in compression due to having not so high quality fuel at the pumps here.

I am reusing the stock pistons, just going to hone the liners and install new piston rings.

This is a budget rebuild for a daily driver that won't see high a lot of high RPM, but some WOT fun every now and again.

ADM

58 views and no one has a clue? Come on guys, if this was a which cam question we would be on page 17 by now! Haha!

M1SERY

Piston to valve clearance must be verified –the minimum clearance is .080" on the intake side and .100" on the exhaust side. The easiest method of verifying piston-to–valve clearance is to check using modeling clay on top of one of the pistons.

Some will run clearances as tight as .060"/.080" (Not uncommon ). I believe that the clearance on a LS1 using the MS4 with the 241 heads on them is already under the .080 for the intake side with the stock head gasket, but this usually is never a problem, mill an extra .010 it doesn't sound like much but, if you bounce it off the rev limiter a lot it might kick you in the head.

I know my set up is a little different than yours (look in signature), but when I milled my heads down (.026) I cut my pistons .085 on the intake side.

GET THE CLEARANCES WRONG OR OVER REV THE ENGINE AND BAD THINGS CAN OCCUR, as can ASSUMING THE CLEARANCES ARE CORRECT IF YOU DON,T CHECK

ADM

I will be checking the PTV, but I needed to know how much clearance would be safe. An option to move change the cam to a Torquer 3 is available if the PTV clearance is not going to be safe.

Still interested in the bearing clearances

SS10Tech

0.0021-0.0025 mains, 0.0020-0.0028 rods with 0.002-0.008 front to back thrust bearing clearance max.

KCS

iTrader: (20)

How much power? Auto or manual? Will it see more street miles, or drag racing or autocross?

Usually .001" per 1" of shaft diameter is a good general rule of thumb and will be safe for 99% of the engines out there, but with an aluminum block you can get away with being a little tighter on the mains.

97FormulaWS-6

iTrader: (1)

I ended up a little tighter on the mains with the motor I just assembled last week. Mains ended up at 0.0018.

Everything else I'll completely agree with.

ADM

It's a manual GTO with 3.90 gears in the rear and a spec 3 clutch assembly.

Car is going to be a daily driver but it doesn't really see a lot of mileage maybe 40 miles per week. It's might see the track once or twice a year and a 100 shot of N2O once in a while.

KCS

iTrader: (20)

Oh, well then .0020-.0024 is what I would shoot for on both main and rod bearings. I like ACL, but really just about any brand (even OEM) would be fine for what you're doing.

Just for reference, I went with .0024 on the mains and .0022" on the rods with coated ACL bearing in my iron block and I see 40psi idle and 60-65psi at WOT hot. I used a Melling 10296 HV oil pump with the low pressure blue spring too.

southernculture

iTrader: (1)

as far as oil my machine shop recommends Valvoline VR1 20w-50 only 6 bucks a quart and the only other oil that offers better protection is the VR1 not street legal oil. They had an independent oil analysis and it protects leagues above amsoil or royal purple.

97FormulaWS-6

iTrader: (1)

20-50?!?!?!? on these motors seems extremely thick and un-needed. AFAIK most are running in the 5-30/10-30 range.