Mark A 91Formula

iTrader: (3)

I'm in the process of assembling my new engine, bottom end has gone together without issue after getting everything back from the machine shop, and then came the heads.......first I stripped out a hole while tightening the head bolts...ok so 1 hole had bad threads, helicoiled it tonight after getting back from the parts store, and proceeded to start assembling the heads again, only this time while tightening a head bolt it snapped off flush in the block. That is going to be a bitch to remove. Worse yet we're talking a fresh set of GM Performace Parts head bolts. I have a strong suspicion my torque wrench is about to be cut in to little pieces with a torch.

I decided moments ago while in a semi drunken brainstorm to test the accuracy of the torque wrench by clamping it in a vice, and hanging weights off the end. Measured out 12 inches and hung 2 35lb weights off a thin rope. While not the worlds safest exercise, nor exactly scientific the torque wrench only measured about 54-55 ft/lbs for what should have been 70, so while sneaking up on Darts recommended 70 ft/lbs of torque I probably exceeded that by a fair amount. What is the outlook for the rod bolts and mains that were torqued with the same wrench? I'm certainly going to replace the head bolts now. The assembly spun without much force so I dont think anything distorted, should I replace the mains and rod bolts too as they have probably been over torqued as well? Anything else I should check or worry about? Anyway sure way to check the rod bolts? They're lunati capscrew type rods $$$ not cheap to replace the whole set. I only have about 1/8 of a bottle of jack left, should I open a fresh bottle of scotch?

rough

that sucks and the damn wrenches are expensive to

Redlinerevver

Here you go. Go to a buddy (snap on guy) and borrow there rench and torq a bolt then use your rench and see if its the same at the same number of pounds. If you find that it was off take the hammer to it then fire up the torch then throw the remains in a river. then I would go and re torq every thing and check threads and posssibly new new bolts if it was off major.
Good luck!!

Fullsizewagon

Idk exactly what type of tq wrench you did this with, but I guess it's the kind with an open scale near the handle. If so, and your 12 inches was not outside the scale then it would seem to indicate too little because all of the arm was not allowed to bend. Try it again with the string near the handle, measuring the distance and doing a calculation.

Damon

Borrow a proper torque wrench that goes "click" when it hits the torque value you dial in.

The "bending arm" type drive me right up a wall- I'm never sure whether I've done it right or not.

ksith

well look at the bright side, at least you didnt waist 2500 on rebuilding an engine only to have it seize up in the first 20 miles. yeah took it to the machine shop and the block is no good. so im up craps creek without a paddle

Mark A 91Formula

iTrader: (3)

Well I just ordered a new head gasket, main bolts, and head bolts from summit, I'll be buying a new torque wrench on the way home today also. The rod bolts I'll remove and check, if all appear good they'll go back in. I redid the torque wrench tests sober using various methods and got the same results, lower values weren't off by too much so I'm not as worried about the rod bolts, higher values had a significantly higher discrepency though so I wont chance the mains or heads. Now I just have to remove the broken head bolt, the threads were cleaned and had sealer so hopefully it wont be to bad to remove.

jv9999

iTrader: (1)

Those head bolts are pretty soft. Even if you have to drill it, it won't be too bad. I've had days like that. :-)

Air_Adam

Were they the one-time-only TTY bolts?

Mark A 91Formula

iTrader: (3)

Nope, not TTY bolts but I can say for sure at just over 85 ft/lb they will certainly yield

RevItUpZ28

iTrader: (1)

Hell, I did the same thing while building my 383 last year. Started torquing down an ARP rod bolt and it snapped like a twig. The torque wrench was shot and wasn't even clicking anymore. What was strange is that the day before on the pre-assembly it worked fine. Invest in a very good brand-name torque wrench (At least that was my lesson learned.)

Air_Adam

A torque wrench is the ONE place you will save money later by spending money now on tools, especially when doing this kind of work. It doesn't have to be a $900-correct-within-1/4-ounce kinda TW, but getting a good quality TW and keeping it maintained and properly calibrated is definitely worth it.

Mark A 91Formula

iTrader: (3)

Got a new craftsman torque wrench. Back to back test with the two off by just under 10 ft/lbs at 40 and it only got worse at higher numbers. Parts come in today so hopefully all will start going a little smoother, this thing has to run before the snow flies.