long post, odd problem, need help please on a '78

[Barry K.]

Re: long post, odd problem, need help please on a '78

John
my '78 is an L82.
I can't imagine there would be a difference regardless of an L82 or L48 anyway.

[Jack H.]

Re: long post, odd problem, need help please on a '78

My recollection is Corvette motor mounts changed from non-locking to locking style in the 1969-70 era. Therefore, what's factory correct for a mid-year wouldn't be identical to those used on a late era Shark car as far as specific PN goes....

[Barry K.]

Re: long post, odd problem, need help please on a '78

My recollection is Corvette motor mounts changed from non-locking to locking style in the 1969-70 era. Therefore, what's factory correct for a mid-year wouldn't be identical to those used on a late era Shark car as far as specific PN goes....

thanks!
I didn't know when the locking or safety style mounts started

[Terry M.]

Re: long post, odd problem, need help please on a '78

Jack has it exactly right 1969 non-locking. 1970 locking. That said, either should be the same height because they are interchangeable. Some of the engine dress items won't fit without the proper mount, but the engine height should be the same.

I have heard that some of the off shore made mounts give fitment problems, and that is the reason I focused on them in response to your initial post. Thankfully I have no personal experience to illustrate the issue.

[John L.]

Re: long post, odd problem, need help please on a '78

Barry, L-82 damper is 8", L-48 is smaller, 7" or 7-12" need to check the TIMJ to be sure. Good you have a L-82 as that is what I have also, I just checked the gap between the frame and the balancer on mine it's 1-7/8".
From bottom of damper to bottom of frame measured with machinest square it s a total of 2-1/8", frame measures 1/4" at this location giving a clearance of 1-7/8". I also checked for shims at the frame to surround bolts, I have none there. I also found 1 good original motor mount (used) that you can have if wanted off my 79 L-82. I think it's an original one the part # showing is 330973. It did come off my 79 at 32,000 miles I think it's original. If you want it let me know.
John

[Barry K.]

Re: long post, odd problem, need help please on a '78

thanks John

I'm in the middle of making dinner so probably won't get a chance to check the measurements until tomorrow.

The part number off the motor mount is handy also in case I may need to get another set. Maybe GM still has them, i'll have to check, if not maybe I can find a set at Carlisle.

thanks for the offer but a single mount won't do me much good and if I need to replace them I'd rather do a matched set of new ones. Appreciate the offer much though!

EDIT: ok, just checked on GMPartsDirect.com and there were no results found for the motor mount p/n 330973. i'll check with my local dealer on Monday.

[John L.]

Re: long post, odd problem, need help please on a '78

Your welcome, I think I only have one as the other one was in bad shape from oil leaking on it for 17 years. I replaced both and thats why I have one. Check the clearance tomorrow, if thats what it is at least you will know its something you can readily fix. You might try Dr. Rebuild as he sometimes has NOS as well as I have found his quality to be one of the highest on his repo items.
Best of luck on your probem.

[Barry K.]

Re: long post, odd problem, need help please on a '78

I agree, probably 85%-90% of the parts I needed when I was working on the car 2 years ago all came from Dr. Rebuild.

god, I hate working on this car. There is always so much crap in the way whenever you need to get to anything. It's so much easier working on my '65.

[J M.]

Re: long post, odd problem, need help please on a '78

My recollection is Corvette motor mounts changed from non-locking to locking style in the 1969-70 era. Therefore, what's factory correct for a mid-year wouldn't be identical to those used on a late era Shark car as far as specific PN goes....

True. The part number I spoke of, 6258154, is locking. But since this is the only mount that was available from GM, I wasn't much concerned with factory correct.

[Edward M.]

Re: long post, odd problem, need help please on a '78

These people indicate that they have part 330973 in stock

LLEWELYN OBSOLETE GM PARTS
NORTHRIDGE, CA 91326 001 (818) 363-5094

And these have 6258154 in stock

DAN'S OBSOLETE GM PARTS
CHINOOK, MT 59523 001 (406) 357-2977

COLLECTORS AUTO SUPPLY.COM
OROVILLE, WA 98844 001 (800) 414-4462

COLLECTORS AUTO SUPPLY.COM
PEACHLAND, BC V0H 1X9 001 (800) 414-4462

CRAIG MOTORS
NAPA, CA 94559 001 (800) 224-8111

[Joe L.]

Re: long post, odd problem, need help please on a '78

ok, good news that that I won't need an engine hoist to change mounts if I floor jack will work.

Now I just need correct mounts but it sounds if that is going to be an issue. Just wonderful. you would think the repro manufacturers could get something as simple as an engine mount correct. SIGH

Joe Lucia, I haven't checked yet but do you know if the motor mounts are still available from GM thru their dealer parts counter and if so are they typically too thick also or just the aftermarket vendor mounts? If so, any suggestions? There surely is no point to replace these mounts if I'm going to send up with the same problem

I think while i'm at Carlisle this year I better search around for any NOS motor mounts

Barry-----

GM #6258154 was the last available part number for the motor mounts. It was discontinued about a year ago.

[Barry K.]

Re: long post, odd problem, need help please on a '78

Ed, thanks! if I need the mounts and can't find them at Carlisle I'll call that place in Ca..

Joe, thanks for the update on the parts #. If I can't find the #330973 I'll at least try to look for the # 6258154

[Joe L.]

Re: long post, odd problem, need help please on a '78

I agree, probably 85%-90% of the parts I needed when I was working on the car 2 years ago all came from Dr. Rebuild.

god, I hate working on this car. There is always so much crap in the way whenever you need to get to anything. It's so much easier working on my '65.

Barry----


More information. Pictured below is a GM motor mount identical to the ones originally installed on your car. The THICKNESS of this mount, as measured from the steel plate on one side to the steel plate on the opposite side is right at 1-1/8".

The dimension from the CENTERLINE of the upper block mounting holes to the CENTERLINE of the "oblong" holes through which the long bolt fastens the mount to the frame bracket is right at 1-1/2".

So, if the mounts you have match the aforementioned dimensions, then there is NOTHING DIMENSIONALLY wrong with the mounts you have. There may or may not be other problems with the mounts, but there is nothing that would cause the problems you are having with the shroud/fan. Under these circumstances, if you were to obtain and install original GM mounts, they're not going to result in resolution of the problem.

[Terry M.]

Re: long post, odd problem, need help please on a '78

It could also be possible the rear mount is lower than original and thus forcing the fan to ride higher. Just another thought.

[Joe L.]

Re: long post, odd problem, need help please on a '78

Ed, thanks! if I need the mounts and can't find them at Carlisle I'll call that place in Ca..

Joe, thanks for the update on the parts #. If I can't find the #330973 I'll at least try to look for the # 6258154

Barry------



GM #330973 and GM #6258154 are exactly the same. The GM #330973 is just the mount with no attaching hardware. It was used in PRODUCTION this way, but not available in SERVICE. GM #6258154 is a SERVICE UNIT which contains one GM #330973 mount + one through bolt + one lock nut + two flat washers.