Shovelhead motor shimming

[mudmane]

Hi guys

I'm in the process of lining up my shovelhead motor and trans for my open belt to go on. From searching I found the correct way to go about this but have a question on shimming the motor.

I have the motor loose in the frame and before even tightening the rear mount bolts I have a gap on the left side of 0.035" between the motor and frame. This seems alot, should I be shimming this gap before torquing the rear to check the gap at the front? Last thing I want is to blow a mount!

And also should I loosen all motor mounts when I install the inner primary to get it all square? Or leave the rear motor bolts torqued?

[Dcar1]

Torque the rear down, then shim the front, then torque those. GM starter shims from pep boys work great. I’ve always toqued the motor down front and back before doing anything with the primary.

[Dragstews]

Engine Mount Shim .036"
Retail Price:
$23.88
IN STOCK NOW!
VT No 31-1306

[rockman96]

What Dcar1 said. You'll have to shim the trans too.

When determining your shims, use feeler gauges and check out McMaster Carr. They have lot's of shim stock... I have found I needed slightly different amounts from side to side sometimes.

[mudmane]

I guess what I'm trying to say is that the mounting surface on the rear of my case isnt perfectly flat. Should I not be worried torquing the rear down if the right side is flat on the mount and the left side has a 0.035" gap??

[JBinNC]

Rear motor mount pad needs to be flat. Why is it not?

It is possible that the front mounts or frame are not square and that's rocking the motor at the back. You might try snugging the front mount and see if that pulls the rear of the motor up. If so, you need to shim the REAR mount first, and it's best to use a full width shim so the rear mount is anchored solid. Then shim the front ears individually.

You can chase your tail with this stuff. I recently had an aftermarket frame where the REAR of the motor had to be shimmed up almost 1/2", to get the primary to fit properly. Good luck with it.

Jim

[Tater66]

My pan frame would allow the engine to rock side-to-side. Pulled fresh rebuilt engine out thinking the case had sealer squished out at the seam. Nope. Just an engine rocking and rolling. Had to shim all mounts to get it right. Yes, starter shims in front, beer can shim at both back bolts.




JBinNC, would that have been a Paughco frame ? I had to shim rear engine and rear trans to get a primary to line up on their junk.

[Tattooo]

Unless your planning on having your frame pads or motor mount pads leveled I would only shim what has a gap......... You will break the case if the motor is twisted...........

[pan620]

Engine Mount Shim .036"
Retail Price:
$23.88
IN STOCK NOW!
VT No 31-1306

I bet they are in stock at that price!!

[Dragstews]

I bet they are in stock at that price!!

I checked, they're in stock, comes five in a pack ...

[mudmane]

Unless your planning on having your frame pads or motor mount pads leveled I would only shim what has a gap......... You will break the case if the motor is twisted...........

Right on. I will shim the gaps on the rear mount and then torque it down then shim the front

[Tattooo]

Right on. I will shim the gaps on the rear mount and then torque it down then shim the front

When you get the rear level to the front you shouldn't need any shims in the front..................

[Dragstews]

I have a wonder .. ??

Are you dealing with a mismatched set of cases ... ??