Fkin motor mount bolts!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

dubie · 03-27-2004, 07:40 PM

Alright guys I need some help here. I am at the shop and replacing the motor moutn bolts. I have brand new polyurathane mounts for this 350. I was told that the bolts are 7/16" dia x 1 " long. But the bolts I just picked up, which are that size, don't fit, they're to big in diameter. Are the holes on the new mounts metric??

jamis · 03-27-2004, 09:04 PM

the bolts that go into the block are 3/8-18, the length will depend on how thick the mount is. And if you use the factory P/S bracket, one of the bolts will need to be a little longer, so as to hold the bracket and mount in.

cableguy0 · 03-27-2004, 09:34 PM

they are a 3/8 bolt not 7/16

Scrub · 03-27-2004, 11:24 PM

I just went through that last week. I bought two new motor mounts and one was 7/16 and the other was metric. They all seem to be made In India. Try a metic bolt that is very close to 7/16. I pulled the on that was metric (Thinking the bolt had screwed up the threads) and drilled it to 7/16 tap size. The size was very close, but I almost broke a tap before I quit. the Steel is hard!.

Good luck

69ride · 03-28-2004, 12:38 AM

get an impact gun and run those suckers in. cross-thread is better than no thread

. Tim you love my cab don't you.:p

*Slams_58* · 03-28-2004, 12:48 AM

Your cab corners look awesome!

FRENCHBLUE72 · 03-28-2004, 02:25 AM

I just bought 2 new motor mount's and one take's a metric bolt and the other a standard....

Zeke · 03-28-2004, 07:30 AM

I had the same problem, drilled and tapped just so I could use the same size socket. Since I have to work on the grass the fewer tools I need the better. Hate finding lost tools with the lawn mower.

Bowtie67 · 03-28-2004, 09:44 AM

Are you talking the ones to the block of the ones that bolt into the mount it's self? The block bolts are 3/8 coarse and the old original where 7/16 coarse going into the mount. I just replaced my motor mounts with some poly ones but they came with bolts, never bothered to check to what what the bolt pattern was. And I will fess up that I was the one that told you they where 7/16 bolts.

dubie · 03-28-2004, 11:22 AM

No biggie there Bowtie. I was just a bit confused when one of the bolts I had snugged up perfect in one side and not the other. I'll take another shot at that mount today

Thanks for the info guys

cdowns · 03-28-2004, 12:51 PM

i'm just curious how those poly engine mounts workout considering how bad the poly tranny mounts are with the excessive noise,vibration and causing tranny tailshafts to break etc

dubie · 03-28-2004, 11:42 PM

Just to update you guys.

We took the motor mount out and tapped a new 7/16" hole in it. I couldn't have done it without fellow member 69ride and my little wifey. Big thanks to you guys!!

03-27-2004, 07:40 PM	#1
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,853	Fkin motor mount bolts!! Alright guys I need some help here. I am at the shop and replacing the motor moutn bolts. I have brand new polyurathane mounts for this 350. I was told that the bolts are 7/16" dia x 1 " long. But the bolts I just picked up, which are that size, don't fit, they're to big in diameter. Are the holes on the new mounts metric?? __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

03-27-2004, 09:34 PM	#3
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	they are a 3/8 bolt not 7/16 __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

03-27-2004, 11:24 PM	#4
Scrub Collector of rusty Items Join Date: Dec 2001 Location: Sisters,Oregon USA Posts: 731	I just went through that last week. I bought two new motor mounts and one was 7/16 and the other was metric. They all seem to be made In India. Try a metic bolt that is very close to 7/16. I pulled the on that was metric (Thinking the bolt had screwed up the threads) and drilled it to 7/16 tap size. The size was very close, but I almost broke a tap before I quit. the Steel is hard!. Good luck __________________ Scrub Sisters, Oregon - Home of the Sisters Rodeo. 70 GMC 1,000,000 + miles 72 K-20 project, 456 Dana60 front, Corp14 rear w/locker, 265R19.5 tires 20-ply. Warn 12k winches both ends, Cross-over steering with raised tie-rod, Powerbox steering, 4500 watt 120-AC power, Air, Hydraulic aux power, 4 inch lift, 5000 lb air-bags both ends.

03-28-2004, 02:25 AM	#7
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,606	I just bought 2 new motor mount's and one take's a metric bolt and the other a standard.... __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

03-28-2004, 07:30 AM	#8
Zeke Active Member Join Date: Jun 2002 Location: L.A. Lower Alabama Posts: 453	I had the same problem, drilled and tapped just so I could use the same size socket. Since I have to work on the grass the fewer tools I need the better. Hate finding lost tools with the lawn mower. __________________ 1969 C10 350 3spd 1995 GMC 3500 XC 350 dually When Thomas Edison worked late into the night on the electric light, he had to do it by gas lamp or candle. I'm sure it made the work seem that much more urgent. George Carlin

03-27-2004, 09:04 PM	#2
jamis F.A.S.T. president Join Date: Sep 2003 Location: Florida Posts: 1,883	the bolts that go into the block are 3/8-18, the length will depend on how thick the mount is. And if you use the factory P/S bracket, one of the bolts will need to be a little longer, so as to hold the bracket and mount in.

03-28-2004, 12:38 AM	#5
69ride All Go, No Show Join Date: Jul 2003 Location: Creighton SK Posts: 286	get an impact gun and run those suckers in. cross-thread is better than no thread . Tim you love my cab don't you.:p

03-28-2004, 12:48 AM	#6
Slams_58 Account Suspended Join Date: May 2002 Location: I let ya know as soon as I know Posts: 3,593	Your cab corners look awesome!

03-28-2004, 09:44 AM	#9
Bowtie67 Registered User Join Date: Jan 2004 Location: NH Posts: 2,266	Are you talking the ones to the block of the ones that bolt into the mount it's self? The block bolts are 3/8 coarse and the old original where 7/16 coarse going into the mount. I just replaced my motor mounts with some poly ones but they came with bolts, never bothered to check to what what the bolt pattern was. And I will fess up that I was the one that told you they where 7/16 bolts.

03-28-2004, 11:22 AM	#10
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,853	No biggie there Bowtie. I was just a bit confused when one of the bolts I had snugged up perfect in one side and not the other. I'll take another shot at that mount today Thanks for the info guys __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

03-28-2004, 12:51 PM	#11
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	i'm just curious how those poly engine mounts workout considering how bad the poly tranny mounts are with the excessive noise,vibration and causing tranny tailshafts to break etc __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

03-28-2004, 11:42 PM	#12
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,853	Just to update you guys. We took the motor mount out and tapped a new 7/16" hole in it. I couldn't have done it without fellow member 69ride and my little wifey. Big thanks to you guys!! __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795



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