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Author Topic: 1969 Z/28 motor mounts  (Read 9955 times)
sam
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« on: November 20, 2006, 09:16:23 PM »

Were the original 69 Z/28 motor mounts non locking? What was the part number on them?  Thanks,  Sam
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JohnZ
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« Reply #1 on: November 21, 2006, 03:12:01 PM »

Z/28 and L-48 used the same mounts - don't have the number handy - maybe Ed does.
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'69 Z/28
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Dave69x33
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« Reply #2 on: December 02, 2006, 11:33:56 PM »

According to Jerry MacNeish in is book, The Definitive 1969 Camaro Z/28-SS396 Fact Book, pp.202, the 69 Camaro motor mounts were P/N-3990518.  These mounts were used in combination with motor mount frame brackets P/N-3945507 and 3945508, which were redesigned for added strength for the 302 and 350 engines.

These frame brackets are on my 69Z but unfortunately, the original motor mounts were replace buy a previous owner during a partial restoration.
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69Z28-RS
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« Reply #3 on: February 14, 2013, 01:39:49 AM »

According to Jerry MacNeish in is book, The Definitive 1969 Camaro Z/28-SS396 Fact Book, pp.202, the 69 Camaro motor mounts were P/N-3990518.  These mounts were used in combination with motor mount frame brackets P/N-3945507 and 3945508, which were redesigned for added strength for the 302 and 350 engines.

These frame brackets are on my 69Z but unfortunately, the original motor mounts were replace buy a previous owner during a partial restoration.

I know the above is an old posting, but it seemed to be the latest and most detailed in the archives, and I believe there is an error in the '69 302 mount referenced.   I was investigating some *issues* with motor mounts for my '69 302, after having my headers hit my floor pan.  I changed the motor mounts from the mounts I was using (GM PN 3968700/3962748/3962740/3974735) and Yes, the parts had all these pn's emprinted in the rubber, and bought two parts store mounts, which lowered the engine about 1/2" and helped with the issue of headers hitting floor.   Doing some digging in ebay, I found that various sellers listed the above part numbers (3962748) as being correct for '69 Camaros.  I also found one or two ads for 3990918 pn as being NOS correct for '69 Z28, so I dug out my old 1970 P&A books and found the following:
1969 Chevy, Camaro (302, 350, 396) ...  PN  3990918
1970 Pass (S/W) w/2BC 350                   PN  3968700
1970 Police (454), All (396), Camaro w/Sp.H/Per (350)   PN 3968700
1970 Chevelle w/4BC (400, 454), MC (exc 400 w/4BC, 454), Chevelle (350)  PN 3962740
etc.   also some 70 models  PN 3962748

The McNeish book seems to have had a typo if 3990518 is listed for the '69 z28 mounts (I haven't got my book handy to check that).

If anyone has other or additional information to add to this, I'd love to hear it.   I want to make sure my 302 is sitting at the correct height in my Z28.
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
Ed Bertrand
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« Reply #4 on: February 14, 2013, 11:56:36 AM »

Quote
The McNeish book seems to have had a typo if 3990518 is listed for the '69 z28 mounts

That could very well be. I can't find that part number anywhere!

Ed
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69Z28-RS
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« Reply #5 on: February 14, 2013, 12:06:38 PM »

That was an old post by Dave69x33 (from 2006) which (no one ever corrected) which stated the incorrect PN for the mount, referencing McNeish's fact book.   Either he made a typo, or Jerry has corrected the mistake, because in the 4th edition (revised) of Jerry's fact book, the correct PN (3990918) is now correctly referenced!
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
1968RSZ28
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« Reply #6 on: February 14, 2013, 12:52:49 PM »

Yup, I believe Dave made a typo (3990518).  Jerry's 3rd edition also references the correct motor mount part number, 3990918.

Paul
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69Z28-RS
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« Reply #7 on: February 14, 2013, 01:29:22 PM »

Anyone got a suggestion for the *best* source for a compatible motor mount (for the 3990918 chevy pn)?   I don't really feel like paying several hundred $$ for NOS gm versions.. Smiley
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
Ed Bertrand
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« Reply #8 on: February 14, 2013, 01:43:33 PM »

This is really strange. 3990918 superceeded 3962748 in 1971, but 3990918 was then superceeded BY 3962748 again in 1990! And 3962748 is still available from your local GM dealer (gmpartsdirect.com shows them for $51.51 each). What the differences are, I don't know, but I found it interesting that 3962748 was superceeded by 3990918, and then 3990918 was superceeded by 3962748 later on! A big circle here!

Ed
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crobjones2
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« Reply #9 on: February 14, 2013, 07:56:23 PM »

Is 3990918 the part number of the recalled motor mounts? or was the leash the only change as part of the recall?
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Chris
69 SS 350
69Z28-RS
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« Reply #10 on: February 14, 2013, 10:42:49 PM »

The 3962748 seems to be a bit thicker (as much as 1/2") than the 3990918 part... which raises the motor a little, enough to cause my headers to hit my floorboard of my car.   I put 'parts store' mounts in and they are shorter than the 3962748 parts.   I don't have 'new' 3990918 parts to directly compare.
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
tmodel66
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« Reply #11 on: February 15, 2013, 09:50:12 AM »

Gary I had the same problem when we built my car. The parts store mount too high. I was lucky and found an old set of Anchor brand name mounts. You can still get these from Anchor online. If you buy from them be sure and buy the 396 mounts to fit your application. They don't list the 302 and the 350 mounts are the regular passenger car mounts. Here's the link Anchor
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Daniel  
'69 SS 350/4 speed  Fathom Green--POP
lynnbilodeau
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« Reply #12 on: February 15, 2013, 12:54:50 PM »

Lots of misinformation out there on motor mounts.

Ed, are you saying the 918 mount didn't exist in 1969?  I was under the impression that all the 67 and 68 Camaros received non locking mounts.  Early 69 cars received non locking mounts, and later (not sure when the change took place) cars received the locking 918 mount.

I had a set of the 918 mounts that I sold to a guy up in Canada, eh.  There were three part numbers embossed on the side with a written color code after each number.  IIRC, the 918 number was followed by the word "GREEN"  and there was green paint swabbed on the side over all three part numbers.  I believe the rubber mold was the same for all three (hence three part numbers) with slight differences in the metal part that it was molded to.

Only way to tell which part number you had visually was to see what color paint was swabbed on the side.

Kind of like the early alloy valve covers.  They have two part numbers embossed on the inside followed by the words "Aluminum" and "Magnesium" (may be abbreviated) so that you have to figure out which metal you have to know which part number applies.  That way they could use the same mold for both.

So.... anyone know for sure:

1.  What part number mount was used early 69
2.  What part number mount was useed late 69
3.  When did they change over (if they did).
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Ed Bertrand
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« Reply #13 on: February 15, 2013, 02:38:39 PM »

Here's the deal.

If you look in the 1969 AIM (UPC Z28, sheet A4), the motor mount (item #4) states that it's a "PRODUCTION PART". This means it's the same as the base V8 shown on UPC 6, sheet B4, item #2, P/N 3964895, which is a non-locking mount).

The September, 1968 P&A 34 shows TWO service part numbers for the 1969 302! The first is 3886466, which I believe to be the non-locking mount, and the second is 3939728, which I believe to be the locking mount (see attached). No dates given for any changeover, so that's of no use at all. Another kicker is the September, 1968 P&A X691A shows P/N 3939728 as being used on the 302, the 350 AND the 327!

The 3990918 part number doesn't show up until the 1970 P&A, so to be "factory correct", you have to have the 3964895 mounts.

The problem is, it's not longer available. It was superceeded in January of 1971 by P/N 3989488, which was then superceeded in January of 1973 by P/N 3990914.

3990914 is shown in the 1972 P&A as being used in the 69 Camaro with 307 or 327, and P/N 3990918 as being used on the 69 Camaro with the 350, 396 and 302 engines, so somewhere along the line, things got really cobbled up.

Ed
« Last Edit: February 15, 2013, 02:58:58 PM by Ed Bertrand » Logged
69Z28-RS
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« Reply #14 on: February 15, 2013, 02:56:44 PM »

Thanks for the digging Ed..   It's at least good that someone agrees with me that it's a screwed up mess..  Smiley
My main concern was the 'height' of the mount.  Today, I retreived another part number from my 'old garage', and did some photographs showing 3 different motor mounts.   The ones the parts store sold me for the 302 actually don't even fit the engine stand (on the frame).    The frame stand has a width of ~ 2.5".   The mount the parts store sold me has a 3" wide saddle to fit over that 2.5" stand, so there's a lot of slop and I'm inclined to believe that would be a problem.    Another difference I noted was the thru hole for the bolts that hold the motor mount to the frame stand.   Two of the engine mounts I looked at had an 'oblong' thru hole, which would allow a little alignment wiggle, while the 3962748 motor mount has a round hole sized to the bolt (no wiggle at all).   I think my memory tells me that the original mounts had an oblong thru hole... but I've got no data for that.
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
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