motor mounts - The 1947 - Present Chevrolet & GMC Truck Message Board Network

obsesive23 · 12-19-2004, 12:50 AM

Ok It's kinda stupid question but none of the dumb a@# people at the auto store can help or help them selfs IMO. I need to know the size, length etc for the motor mount bolts. I bought a beater for work and I noticed that there is no bolt connecting the motor to the frame. He said he just swapped it in and couldn't get it running. All that was wrong was he didn't run a power wire to the HEI he swapped in. :p He was a little mad when I gave him $200 dollars and spent 10 min under the hood and drove it home.

Can any body just give me the correct size. Oh yea it's a 350 if that matters. Thanks in advance,
Brian

Brainchild · 12-19-2004, 01:14 AM

The ones from the stands to the frame,and the mounts to teh block are all 3/8,and the ones from the stands to the mount are 1/2 inch dia.Not sure on exact length,prolly inch and a half,use a flat washer on the stand to mount bolts.

JimKshortstep4x4 · 12-19-2004, 07:42 AM

The motor mount to block bolts are 3/8-16 x 3/4", (anything longer will possibly bottom out). The frame to motor mount bolts are 7/16-14 x 1"
long.

If you are installing new motor mounts be sure to check the threaded hole as some of the aftermarkets are tapped with a metric thread. (They can be rethreaded to 7/16-14).

JIm

obsesive23 · 12-19-2004, 12:54 PM

Thanks that helps alot. How about the long bolts? The ones that connect both mounts together?

toddtheodd · 12-19-2004, 02:20 PM

You must have clamshell mounts. I don't know the size, but I think they may be 5 to 6 inches.
Todd

Tx Firefighter · 12-19-2004, 07:08 PM

He shouldn't have clamshell mounts. I think he's talking about the bolt that goes through the frame stand and into the rubber mount.

JimKshortstep4x4 · 12-19-2004, 08:36 PM

The frame to motor mount bolts are 7/16-14 x 1" long unless he has the clamshell style.

Jim

crazy longhorn · 12-19-2004, 08:58 PM

Quote:

Originally Posted by JimKshortstep4x4

The frame to motor mount bolts are 7/16-14 x 1" long unless he has the clamshell style.

Jim

Right on

crazyL

Fenny · 12-19-2004, 10:01 PM

5/8 head. 7/16 x 5" thread.

jmanz69 · 12-19-2004, 11:44 PM

He could have the clamshell mounts. Depends on if the origianl owner swapped from a BB engine to a SB. Also, some of the SB frame mounts from the 73-87 trucks bolted in and were set up for the clamshell mounts. I had a pair that I got a while back. I compared them to the 72 BB mounts in my frame at the time and they bolted in exactly, just the mount looked a little different. When the engine has been changed, all bets are off as to what is in there now. That would explain why the Autozone boneheads couldn't help. They only know what's on the computer screen.

obsesive23 · 12-20-2004, 01:50 AM

Thanks for the info. jmanz69 is correct the po did swap out the og 396 for a 350. Thanks again you guys are great!!!!!

12-19-2004, 12:50 AM	#1
obsesive23 Who me? Join Date: Jun 2004 Location: Bothell WA Posts: 640	motor mounts Ok It's kinda stupid question but none of the dumb a@# people at the auto store can help or help them selfs IMO. I need to know the size, length etc for the motor mount bolts. I bought a beater for work and I noticed that there is no bolt connecting the motor to the frame. He said he just swapped it in and couldn't get it running. All that was wrong was he didn't run a power wire to the HEI he swapped in. :p He was a little mad when I gave him $200 dollars and spent 10 min under the hood and drove it home. Can any body just give me the correct size. Oh yea it's a 350 if that matters. Thanks in advance, Brian __________________ Living the dream 72 2WD Blazer, under going porter built surgery 67 GT Mustang fastback 67 Mustang coupe C/S clone 64 Falcon sprint hardtop

12-19-2004, 01:14 AM	#2
Brainchild Still drivin' a Rat Rod Join Date: Sep 2004 Location: Monett Missouri Posts: 4,925	The ones from the stands to the frame,and the mounts to teh block are all 3/8,and the ones from the stands to the mount are 1/2 inch dia.Not sure on exact length,prolly inch and a half,use a flat washer on the stand to mount bolts. __________________ Rusty Member #13872 Instead of saying.....you are a discomfort in the back of my front.....one should be able to say...... you are a pain in the a$# 71 GMC LWB 49 Chevy 85 Chevy G20 Check out my website

12-19-2004, 12:54 PM	#4
obsesive23 Who me? Join Date: Jun 2004 Location: Bothell WA Posts: 640	Thanks that helps alot. How about the long bolts? The ones that connect both mounts together? __________________ Living the dream 72 2WD Blazer, under going porter built surgery 67 GT Mustang fastback 67 Mustang coupe C/S clone 64 Falcon sprint hardtop

12-19-2004, 02:20 PM	#5
toddtheodd The oddest Todd around Join Date: May 2004 Location: Miami, Florida Posts: 1,418	You must have clamshell mounts. I don't know the size, but I think they may be 5 to 6 inches. Todd __________________ "The greatest pleasure is to vanquish your enemies and chase them before you, to rob them of their wealth and see those dear to them bathed in tears, to ride their horses and clasp to your bosom their wives and daughters." Ghengis Khan IIOY???

12-19-2004, 07:08 PM	#6
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	He shouldn't have clamshell mounts. I think he's talking about the bolt that goes through the frame stand and into the rubber mount. __________________ I'm on the Instagram- @Gearhead_Kevin

12-19-2004, 07:42 AM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The motor mount to block bolts are 3/8-16 x 3/4", (anything longer will possibly bottom out). The frame to motor mount bolts are 7/16-14 x 1" long. If you are installing new motor mounts be sure to check the threaded hole as some of the aftermarkets are tapped with a metric thread. (They can be rethreaded to 7/16-14). JIm

12-19-2004, 08:36 PM	#7
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The frame to motor mount bolts are 7/16-14 x 1" long unless he has the clamshell style. Jim

12-19-2004, 10:01 PM	#9
Fenny Junior Member Join Date: Dec 2004 Location: Calgary AB Posts: 41	5/8 head. 7/16 x 5" thread.

12-19-2004, 11:44 PM	#10
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	He could have the clamshell mounts. Depends on if the origianl owner swapped from a BB engine to a SB. Also, some of the SB frame mounts from the 73-87 trucks bolted in and were set up for the clamshell mounts. I had a pair that I got a while back. I compared them to the 72 BB mounts in my frame at the time and they bolted in exactly, just the mount looked a little different. When the engine has been changed, all bets are off as to what is in there now. That would explain why the Autozone boneheads couldn't help. They only know what's on the computer screen.

12-20-2004, 01:50 AM	#11
obsesive23 Who me? Join Date: Jun 2004 Location: Bothell WA Posts: 640	Thanks for the info. jmanz69 is correct the po did swap out the og 396 for a 350. Thanks again you guys are great!!!!! __________________ Living the dream 72 2WD Blazer, under going porter built surgery 67 GT Mustang fastback 67 Mustang coupe C/S clone 64 Falcon sprint hardtop



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