Easy Rhino

My '65, which was originally built with an L76 is missing its original block but has many of the external L76 assemblies such as the correct exhaust manifolds and water pump pulley.

It also came with the correct so-called "third design" '62-'65 8" finned SHP harmonic dampener. Since it was installed on a non-solid lifter engine, it was pressed on, and the crankshaft was not threaded for a balancer holding bolt.

I'm slowly assembling a nominal L76 using a correctly dated 327 short block, using as many correct external pieces as I can manage.

My donor short block has a correct small journal 2680 forged crank; however, it too does not have the threaded snout.

I thought, and Colvin's book seems to say, that all '65 SHP solid lifter engines had a threaded crankshaft and employed a harmonic dampener bolt with washer.

Q1: Am I looking at this correctly?

Q2: I'm guessing that I can have the local machine shop drill and tap the crank snout when I give it to them to polish and balance the rotating assembly.

Q3: Anybody know the dimensions of the correct crankshaft snout bolt?

pop23235

Easiest solution is to pick up a repop bolt from someone like ZIP. Then you have the correct bolt/threads. You'll need the heavy washer and lock washer. Not sure what comes together. If you just need a heavy washer, I have some NOS.

65 Pro Vette

Easy Rhino

Broke out the Paragon catalog - part 980K for $10, includes the bolt, lock washer, and hold down washer.

tbarb

If you want to know what this grade eight bolt looks like it's also used to retain the steering damper to the relay rod on non power steering cars. I believe the correct lock washer is a star washer then the thick washer.

Easy Rhino

Great tip, thanks.

Nowhere Man

the same bolt was also used well into the 70's before they went to metric

Pop Chevy

65 pro ws right , 7/16-fine th.

cardo0

If you have your rotating assembly balanced you should include the dampener with the assembly. The dampeners were "tuned" by GM for the motors they mounted on. Mostly for RPM range.

Well balancing is a good idea when you mix and match parts. Flywheel and dampener need to be included.

BTW I think returning to a solid lifter cam is a cool idea. Options and details building a sbc are endless but it makes it fun also. Good luck.

Easy Rhino

You triggered additional thoughts there.

I expected to balance the short block rotating assembly for two reasons; first, I have no idea about the state of its balance, never having run the crank. Second, I replaced the rods, pistons, and rings, which are marginally lighter than the originals.

I need to get back up with my machine shop - I expected to deliver only the crank, rods, pistons, and rings for balancing.

So then, I also need to take the balancer and flywheel, then?

Anything else in the rotating assembly also need to be included? Things like the clutch assembly? Pilot bearing?

I've got more homework to do.

tbarb

In addition to the complete rotating assembly make sure to take the pressure plate. When you get it back there will probably be a paint mark on the flywheel and P/P showing the correct clocking position to mount the pressure plate on the flywheel. No need to take the disc because it spins free inside the assembly.

W Guy

I don't agree. Pressure plates are already neutral balanced, as are flywheels and balancers. Only the internal parts need to be balanced as a unit.

Verne

cardo0

I would ask what the machine shop what they will do. But flywheel and dampener for sure. May want to ask a few different shops. You may be surprised to find some shops send a lot of work out and charge you their fee on top of another's. Out of 5 shops I visited in Vegas I only got one tour.

If you have a scale accurate within a gram you should be able to save a $100 or more by weighting everything your self. But let the shop weigh the rod big and small ends if they need as that's a bit difficult. BTW lighter is better for more than one reason. It's easier to remove metal than to add it to the crankshaft. Also lighter pistons & rods stress the rods much less. I believe tensile and compression stress increases exponentially with RPM/engine speed.

Easy Rhino

I think I'll start another thread on the techniques of engine balancing.

Even the commercial links I looked at on line seem to disagree.

tbarb

Verne,

I agree with you in theory, but any time you start stacking up parts like a bolted pressure plate to flywheel there is always a chance of mismatch. The flywheel will be zero balanced then the P/P bolted and weight added or removed to maintain this balance.

If not checked/balanced as a assembly and there is the slightest difference in the pressure plate then after it's bolted to the flywheel you have just installed a eccentric weight to the back of your motor.

DSR

I would think checking balance of all the parts together would be better, but what happens when the clutch, disc and sometimes the flywheel wear out. Most shops would just replace the parts with out disassembling the motor for rebalance.

BADBIRDCAGE

You are correct on replacement but there is no reason not to balance the entire assembly, including pressure plate, on first shot. In addition a quality balance shop will record the readings and be able to match an independent item later if necessary.

Easy Rhino. You need to take a pair of connecting rod bearings along for the balancing operation to make the bobweights.

Easy Rhino

Thanks.

Looks like the crank goes in first before balancing to confirm my journal measurements then.

I don't want to buy bearings until I confirm the sizes.

solidaxel

Soo. only the 65 SHP solid lifter cranks were threaded?

MikeM

All SHP 327's with the 8" balancer except the very early '62 model.