67 Original engine motor mounts

[Mark P.]

Re: 67 Original engine motor mounts

Fred - I agree with you. Repo rubber parts seems to not be as good as original rubber parts and when you consider that original mounts failed at a higher than acceptable level, it is pretty clear that this would be the place to take a small point hit. I am planning to go with option 1 even though a lot of restorers probably use a reproduction original style motor mount.



Mark

[Fred Y.]

Re: 67 Original engine motor mounts

Mark, for a point or two hit I'll take it any day when safety is concerned.

[Mark P.]

Re: 67 Original engine motor mounts

Hi Joe - I found a set of the 70+ shields in my spare parts stash. The finish is dull and unlike the original chrome. In the photo I posted the part is brand new and the finish is similar to mine. Did they move away from chrome to a cad finish ?

Thanks,

Mark

[Joe L.]

Re: 67 Original engine motor mounts

Mark------


Yes, they did transition to zinc for the shields. I don't think it occurred for 1970, though. I think it happened somewhat later. The shields with 6 digit part numbers which appeared for PRODUCTION and SERVICE about 1974 are zinc plated, not chrome. It's possible some of the earlier shields changed finish about this time, too.

[David L.]

Re: 67 Original engine motor mounts

Attached are 2 photos of a NOS 3886466 engine mount (on the left) used on 1966-1968 Corvettes as per my research. The number 3886466 is molded into the rubber part at the top as shown more clearly in the bottom photo. GM # 3886466 was replaced with GM # 3990916 in March 1971 as per Chevrolet Parts History (service parts).
The 2249 mount (on the right) is an aftermarket replacement mount.

Dave

[Patrick H.]

Re: 67 Original engine motor mounts

I would still recommend the newer Corvette Central mounts as compared to generic aftermarket replacements. They fit MUCH better.

[John L.]

[Ray G.]

Re: 67 Original engine motor mounts

Hello Gentlemen;

Have the "3866466" style as in Dave Liukkonen post on my "67 Bow Tie Corvette and believe them to be original.
They are an anti-lift mount to some degree when considering the geometric line path as an engine would/will lift if the rubber fails.

just my .02
Ray

[Mark P.]

Re: 67 Original engine motor mounts

That 2249 mount looks very close. I still am planning to use the locking tab motor mounts. I had to shorten a set of trailing arm pivot bolts, strip the cad finish then blacken them. The repro bolts I had bought were too short to use with the motor mounts.

[Joe L.]

Re: 67 Original engine motor mounts

That 2249 mount looks very close. I still am planning to use the locking tab motor mounts. I had to shorten a set of trailing arm pivot bolts, strip the cad finish then blacken them. The repro bolts I had bought were too short to use with the motor mounts.

Mark------


You didn't need to go to all that trouble. The original bolts, GM #399803, were available from GM until very recently and there should still be some around. These bolts had a piloting tip to make insertion and alignment easier.

[Mark P.]

Re: 67 Original engine motor mounts

Joe - are those grade 8 bolts ? I made mine out of grade 5 bolts which are used for trailing arm attachment. I just ordered a set of the 399803 bolts and will use those. Are they the same bolts used to attach steering boxes for "64-88 GM NOS GM CHEVELLE CAMARO NOVA CORVETTE" ?

[Joe L.]

Re: 67 Original engine motor mounts

Joe - are those grade 8 bolts ? I made mine out of grade 5 bolts which are used for trailing arm attachment. I just ordered a set of the 399803 bolts and will use those. Are they the same bolts used to attach steering boxes for "64-88 GM NOS GM CHEVELLE CAMARO NOVA CORVETTE" ?

Mark----


Yes, these bolts are SAE grade 8. They were used to attach the steering box on some Chevrolet passenger cars. However, they were not used for that purpose on Corvettes. Corvettes use stove bolts for steering box attachment to the frame.