correct 69 427 engine mounts

[Greg L.]

I need to replace one of my mounts.

These are what I had on the car and I have no reason to think they were ever changed so I'm 99% sure that they are original.


The problem is that Paragon shows this design as a 70-82 safety type and the 63-72 no safety type(which by the catalogue is correct for a 69) is very different.

So the question is, are these my original mounts or should I order the other 63-72 ones?

Thanks

[Joe L.]

Re: correct 69 427 engine mounts

Greg------

First, 2 questions for you:

1) What is the build date of the car?

2) Check the mounts over very carefully to see if there are any kind of numbers embossed on either one. These might be very small.

[Greg L.]

Re: correct 69 427 engine mounts

Joe,

The car's build date is Jan 31/69.

I've looked one of the mounts over and can't see any marks, numbers, etc other than the green paint. I'll check the other mount this evening. Would the numbers be stamped in the steel or raised in the rubber?

Greg

[Joe L.]

Re: correct 69 427 engine mounts

Greg------

Generally, if numbers are present, they'll be seen as raised characters in the rubber portion of the mount.

As far as the mounts you've removed go, it's my opinion that they are a replacement engine mount. However, they may have been installed at a very early stage in the car's life. 1969 Corvettes are generally acknowledged to have been supplied with non-locking engine mounts. Also, there was no difference between the big block and small block mounts for any given year---they were the same. My September, 1969 built small block was originally equipped with non-locking style mounts.

There was some sort of a recall or service bulletin issued sometime for 1969 engine mounts. I believe that this recall involved the installation of a "cable and bracket" kit to limit engine movement in the case of a motor mount failure. However, I never receieved such a recall and my motor mounts remained the non-locking style without any "cable and bracket" kit until I changed them to the locking style in 1975.

One caveat here: the AIM specifies that there was a change in engine mounting issued sometime during the 1969 model year (the date of the revision is not clear in my copy of the AIM; however, it looks like it's a 1968 date). The original mount was GM #3886466, the same mount used for 1966-68 Corvettes. I have NOS examples of this mount and it is a non-locking style mount, likely the same as was originally installed on my car.

The revised engine mounting was a GM #3967767. I do not know what the configuration of this mount was like. I do not have any NOS examples of this mount. It was only briefly available in SERVICE from about March, 1969 through October, 1969 when it was replaced by the GM #3980701. I do have NOS examples of the latter mount and it is a locking style mount.

Incidentally, the GM #3980701 mount is similar to the mount you have, but the configuration differs in certain ways. So, I know that what you have is definitely NOT the 3980701. However, it's possible that it's a GM #3967767. If so, then they are most probably original to the car. Perhaps, for 1969, the locking style mount was phased into PRODUCTION and was used on big blocks prior to its use on small blocks.

There could be 2 reasons for this: first, the big block with its higher torque could have been considered to be more vulnerable to engine mount breakage. So, with a then-limited supply of the locking style mounts, it may be that the decision was made to use what were available on big blocks. Second, the locking style mounts on small blocks required revised lower ignition shielding. Perhaps, the revised shielding was not released coincident with the locking style mounts. So, small blocks may have continued to use the non-locking mounts.

This is why I'm so interested in confirming if there are any numbers on the mount. The question is was the 3967767 mount an improved non-locking mount (and, perhaps, what was originally installed on my car) nad the last iteration of the non-locking mount or was it the first of the locking style mounts? Enquiring minds want to know. I've been trying to get to the bottom of this for years.

[Michael H.]

Re: correct 69 427 engine mounts

I joined the original discussion on this about a year ago and suggested that the new locking style mount was introduced in production some time during the 69 run. My post was ignored and everyone agreed that the new style locking mount entered prod for SOP of the 70 MY, so I gave up.

The motor mount campaign was a BIG deal around GM at that time. I still have some of the paperwork on it. (not here, unfortunately) Seemed like a new "urgent" instruction sheet arrived almost weekly.

[Steve Antonucci]

Re: correct 69 427 engine mounts

Joe, Mike,

I have an early build big block Camaro and I would expect that the mounts
are the same as far as the engine goes. Perhaps either of you can correct
me if I'm wrong.

Point is that early big block mounts used what I consider to be a strange
design in that only a bolt was used vs. the standard bolt & nut. The far
side of the mount had a threaded receiver with a pronounced rubber bulged
area. Did this provision come on early Vettes as well?

This is what I am referring to:

[Joe L.]

Re: correct 69 427 engine mounts

Steve-----

1967-68 Camaros with 350 cid engines or 396 cid engines used the same motormounts as Corvette. Obviously, these were a non-locking style mount.

1969 and later Camaros used different motor mounts than Corvettes.

[Michael H.]

Link To Old Discussion

I just found the original discussion on the motor mount. I had forgotten that in that discussion, it was mentioned that GM sent letters of owners of just about every model that Chevrolet sold from 69 on back, EXCEPT Corvette. Wonder why?? (hope the link works)

https://www.ncrs.org/forum/archive21.cgi?review=169758

https://www.ncrs.org/forum/archive21.cgi?review=169758

[Greg L.]

Re: correct 69 427 engine mounts

Joe,

I did find some numbers but I don't think they are GM numbers.

Anyways, here they are:

2267AHN5 and 2267AHN10

The green paint markings are why I was thinking that they were original but maybe they got upgraded like you said early in it's life.

Let me know if these numbers have any meaning to you.

Thanks

Greg

[Joe L.]

Re: correct 69 427 engine mounts

Greg------

Some original GM motor mounts do have these "AHN" markings. Unfortunately, so do some aftermarket mounts of days-gone-by. The "AHN" is a designation of the manufacturer which I believe was a company called "Anchor" something-or-other.

The "2267" probably refers to their model number. However, are you sure that the "22" is actually that and not a "77"? If it were "77", then it would be the last 4 digits of the part number I mentioned prviously as being used on some 1969 Corvettes. If the number were "7767" and the last 4 digits of the GM part number, there's only 1 chance in 10,000 that, by chance, it could be a manufacturer's part number and also the last 4 digits of a GM part number.

[Greg L.]

Re: correct 69 427 engine mounts

Joe,

I just checked it again to make sure and it is in fact 2267 and NOT 7767.

The part number similarity is probably so that the jobber can easily relate his replacement mount to the original that it is replacing.

Looks like some previous owner was concerned enough to want the safety type mounts but didn't want to pay dealer price to have them installed and went with jobbers instead. Either that or the dealer was out of mounts and sourced some from a jobber themselves.

Either way you look at it these no longer look like they are original to the car. Thanks Joe.

Greg

[Joe L.]

Re: correct 69 427 engine mounts

Greg------

I would not rule it out completely. I think that there is a possibility that they are original. If the GM number had been on them, that would have confirmed it. As it is, just because there is no GM number does not mean, for sure, that they were not used in PRODUCTION by GM. I can tell you that all the GM motor mounts that I know of for Corvettes did have the GM part number on them EXCEPT for the current SERVICE piece, GM #6258154. However, for the short-lived 1969 piece, who knows?

Does the car have A/C and/or a left side motor mount shield? According to GM, the left side shield was used for all 1969 Corvettes with big blocks, although it's possible, I suppose, that it was used for only those with A/C. In any event, if the car has A/C then it should have the shield. 1969 Corvettes with C-60 did use a unique part relative to the engine mounting system and that part was a "V" shaped shim used under the motor mounts. If the car is A/C-equipped it should have these shims; if not, it won't. However, the shims were not specific to locking and not-locking style mounts like the heat shields; the same shims were used for both style motor mounts.

The 68-69 motor mount left side shield will not fit a locking style mount. The 1969 AIM indicates that this shield was used on big blocks and makes no mention of the 70 style shield which was reconfigured to work with the locking style mount.

If the shield is not present, it could indicate one of several things:

1) it was removed when the locking style mounts were installed post-PRODUCTION;

2) the factory used the locking style mounts in PRODUCTION and omitted the then-available shield since it would not fit the locking style mounts;

3) if the car is non-AC car, it, possibly, never had the shield in the first place, regardless of what motor mounts it had.

So, there's still nothing definitive here.

[Joe L.]

Addendum

One point that I should have been clearer on with reference to the fact that the AIM shows the 68-69 style motor mount heat shield being used on big blocks:

The AIM shows the revison for the motor mount part number from 3886466 (non-locking) to 3967767 (unknown configuration). If the 3967767 had been a locking style mount, then I would expect that there would have been a coincident revision to the page on which the shield was shown. I would expect that either the shield part would have been revised or, if no shield compatible with the locking style motor mount had been available, there would have been an instruction to delete the shield effective the same date as the revised motor mount part number.

Of course, it's possible that someone just forgot about this.

[Greg L.]

Re: correct 69 427 engine mounts

Joe,

Now I'm really confused...

The car does not have A/C or the "V" shaped shim that you are refering to.

It does however have the left side heat shield and from what I remember it looked like it fit properly even thought it was used with the locking style mounts.

I'll dig it out tomorrow and try and see if it has been altered to fit the locking style mounts.

Greg

[Joe L.]

Re: Link To Old Discussion

Michael------

As far as the reference to the 3980701 as being shown as being applicable to 1969 Corvettes in a 1969 edition of the Corvette P&A Catalog, I believe you may be referring to the October, 1969 edition of the catalog. The intial 1969 model year printing of the catalog, dated October 1, 1968 shows the 3886466 as being applicable to 1969 Corvettes. Subsequent editions show the GM #3967766 as being applicable to 1969 Corvettes. The final edition, dated October 1, 1969 shows the 3980701 as being applicable. That's because the 3967766 was discontinued from SERVICE on October 1, 1969 and replaced by the 3980701. Consequently, the final edition of the P&A Catalog would show the new number.

The final edition did not show the 3980701 as being applicable to 63-68 models since the 3886466 had not been discontinued as of that time. It was discontinued, though, on March 1, 1971 and replaced by GM #3990916. After that time, the 3990916 was shown as being the SERVICE part for all 63+ Corvettes. Incidentally, the 3990916 is exactly the same as the 3980701 except that it's a kit which includes hardware. The kit includes 1 GM #3980701 mount + hardware for installation; the 3980701 was supplied as a "bare" mount only.

Very, very interestingly, the April, 1970 edition of the Corvette P&A Catalog shows the GM #3967767 as being uniquely applicable to 1969 Corvettes, even though that part was discontinued on October 1, 1969. It also shows the 3980701 as being applicable to "69-70 Corvettes".

By the way, as far as the 3886466 non-locking style mounts go, not every one of these fails in service and causes problems. The vast majority probably do not fail or do not fail in a manner which causes problems. However, when one DOES fail in a manner which causes problems, then one SERIOUSLY wishes that they had the locking-style mount installed. Guaranteed.