Stage II Clearances

[65vette396]

Guys, I just bought a 86 Grand National with a 274 in. stage II engine in it. The car has a broken ring or broken ring land in the number 6 cylinder (haven't pulled it apart yet). But at any rate I was gonna go ahead and check all of the clearances in the bottom end when I pull the motor apart I wanted to check all of the bearings and clearances while I'm in there. What clearances do you guys typically run on these things (Rods, Mains, and ring end gap). Also, What torque specs are used (rods, mains, heads) car is supposed to have H-beam carillo rods and ARP bolts in the mains and heads (has M&A alum. heads) If you guys need more info. just let me know. I am only going by what I was told when I bought the car. I'll get more specific when I actually pull it apart, but I was curious as to what most of you guys used here. BTW, I am very mechanically inclined and have built many 109 blocked buicks, even more big block chevy's, ect........ Thanks, in advance. Drew

 

[750H.P.V6]

Drew,

I'll take a stab at this but I will start off by saying that clearances will vary depending on who built the engine and of course how much wear is on the components. Rod an main bearing clearance should be somewhere between .0015" and .0025" personally I like .002". Piston to wall clearance will .006" + depending on H.P. level. Rod side clearance .010" to .020". Ring end gap around .025"on both top and 2nd rings. Rod bolt torque will depend on which bolts you have in the Carrillo rods. The SPS Carr 7/16 bolts will take 80-85ft lbs. Main studs 95-100 ft lbs. head bolts or studs 80ftlbs with ARP moly lube. Keep in mind this is just a guideline and not the gospel. I hope it helps.

Neal

 

[65vette396]

Neal, thanks for the insite. That is exactly what I was looking for is just some simple guildlines. I won't be pulling the motor for another couple weeks as my in-laws are in from out of town and the wife would kill me, lol. I will be sure and post exactly what is in the motor when I get the car apart then so we can get closer to specifics. Just for your information, Lawrence Conley built the car and the motor. I plan to call him as well when I get into it. Thanks again, Drew