engine towers question? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Ricks1971** · 05-06-2007, 12:03 AM

Hey guys I have a question about big block and small block engine towers? I took a set of these towers out of a 1971 3/4 ton big block truck and a set out of a 1972 3/4 ton with a small block and the towers are exactly the same. Should they of been different? Thanks Rick

**Ricks1971** · 05-06-2007, 11:04 AM

Bump?

Americanrider · 05-06-2007, 11:22 AM

Posted pics of what you have would be helpful. The black set is 69-71, the others (slighty rusted) are 72 only BB mounts. Small block tower have small holes in the center. About 5/8th's I think.

**Ricks1971** · 05-06-2007, 11:57 PM

both sets look the set on the left. I thought that there was a difference between big block and small block towers. Oh well!

gus · 05-07-2007, 04:20 AM

rick towers are different on angle, I just finished installing a 90'454 on my 71 2wd had a 350 on it and I tried to use same towers but oil pan on big block was sitting on top of the cross member, some one had told me to use any BB towers from 73's87's I tried it and they were to high off by 3", so my only option was early classic or truck shop in Orange CA both same arm and a leg but it did work ! original GM towers with motor mounts $360 very expensive for conversions from 350 to 396-502s

**Ricks1971** · 05-12-2007, 12:09 AM

Gus, the set of towers I took off the 71 with a big block in it are exactly like the set I took off a 72 with a small block? I just wonder if its the motor mounts that might be different from a big block to a small block. I'll clean them up a take a pic and post them tomorrow

**Ricks1971** · 05-12-2007, 03:48 PM

as you can see these towers look the same? one set off a 72 with a small block and the other set off a 71 with a big block?

71 super · 05-12-2007, 04:50 PM

Congrats it looks like you have two sets of 68-71 big block mounts. Stands are not worth as much as 72 only but with the rubber inserts can still bring good money. Looks like someone switched original set in the 72 out at some point.

**special-K** · 06-17-2007, 11:50 PM

So,what do we have here?Are these mounts exactly as stated or were some switched at some point.If totally original,than 68-71 SBC towers will work for a BBC,right?

stude283 · 06-18-2007, 10:21 AM

ok,so what actually is the difference in the mounting position of the motor?
Does the bb sit higher and why is this necessary? Is the motor offset in the frame and why?I know bb and sb normally bolt in place of each other so why not in our trucks?Thanks to all for your valuable help and information!

**Classic Heartbeat** · 06-18-2007, 12:07 PM

First off those in the picture look to be 68-71 Big Block towers. If you for found a set in a 72 then someone changed them. The reason for the different mounts is location of the engine, strength of the motor mounts, and less stress on the chassis. Big Blocks tend to break the weaker, less flexible small block mounts quite regularly and the design does not absorb the extra torque of the Big Block. Causing extra stress on the chassis. The Big Block towers have a larger hole in the center for the 3 piece motor mounts. The 3 piece motor mounts put rubber on top and bottom of the big block towers, with a metal tube that slips through the entire works. When the engine is bolted down with this, it alows for the extra torque of the big block. WES

**special-K** · 06-19-2007, 09:04 AM

Thanks,I appreciate that explaination.That was my question,if we knew if those towers are original to the truck.

05-06-2007, 12:03 AM	#1
Ricks1971 Senior Member Join Date: Mar 2006 Location: Clarkrange Tennessee Posts: 1,787	engine towers question? Hey guys I have a question about big block and small block engine towers? I took a set of these towers out of a 1971 3/4 ton big block truck and a set out of a 1972 3/4 ton with a small block and the towers are exactly the same. Should they of been different? Thanks Rick

05-06-2007, 11:04 AM	#2
Ricks1971 Senior Member Join Date: Mar 2006 Location: Clarkrange Tennessee Posts: 1,787	Re: engine towers question? Bump?

05-06-2007, 11:22 AM	#3
Americanrider Registered User Join Date: Dec 2004 Location: NW, WA. Posts: 1,421	Re: engine towers question? Posted pics of what you have would be helpful. The black set is 69-71, the others (slighty rusted) are 72 only BB mounts. Small block tower have small holes in the center. About 5/8th's I think. Attached Images

05-06-2007, 11:57 PM	#4
Ricks1971 Senior Member Join Date: Mar 2006 Location: Clarkrange Tennessee Posts: 1,787	Re: engine towers question? both sets look the set on the left. I thought that there was a difference between big block and small block towers. Oh well!

05-07-2007, 04:20 AM	#5
gus Registered User Join Date: Dec 2006 Location: Orange County Posts: 163	Re: engine towers question? rick towers are different on angle, I just finished installing a 90'454 on my 71 2wd had a 350 on it and I tried to use same towers but oil pan on big block was sitting on top of the cross member, some one had told me to use any BB towers from 73's87's I tried it and they were to high off by 3", so my only option was early classic or truck shop in Orange CA both same arm and a leg but it did work ! original GM towers with motor mounts $360 very expensive for conversions from 350 to 396-502s

05-12-2007, 12:09 AM	#6
Ricks1971 Senior Member Join Date: Mar 2006 Location: Clarkrange Tennessee Posts: 1,787	Re: engine towers question? Gus, the set of towers I took off the 71 with a big block in it are exactly like the set I took off a 72 with a small block? I just wonder if its the motor mounts that might be different from a big block to a small block. I'll clean them up a take a pic and post them tomorrow

05-12-2007, 03:48 PM	#7
Ricks1971 Senior Member Join Date: Mar 2006 Location: Clarkrange Tennessee Posts: 1,787	Re: engine towers question? as you can see these towers look the same? one set off a 72 with a small block and the other set off a 71 with a big block?

05-12-2007, 04:50 PM	#8
71 super Registered User Join Date: Sep 2005 Location: Canton North carolina Posts: 3,080	Re: engine towers question? Congrats it looks like you have two sets of 68-71 big block mounts. Stands are not worth as much as 72 only but with the rubber inserts can still bring good money. Looks like someone switched original set in the 72 out at some point. Last edited by 71 super; 05-12-2007 at 04:51 PM.

06-17-2007, 11:50 PM	#9
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: engine towers question? So,what do we have here?Are these mounts exactly as stated or were some switched at some point.If totally original,than 68-71 SBC towers will work for a BBC,right? __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

06-18-2007, 10:21 AM	#10
stude283 Registered User Join Date: Apr 2007 Location: midstate upstate N.Y. Posts: 10	Re: engine towers question? ok,so what actually is the difference in the mounting position of the motor? Does the bb sit higher and why is this necessary? Is the motor offset in the frame and why?I know bb and sb normally bolt in place of each other so why not in our trucks?Thanks to all for your valuable help and information!

06-18-2007, 12:07 PM	#11
Classic Heartbeat Project Junkie! Fishing Poor!! Join Date: Dec 1999 Location: Olympia,Wa. 98512 Posts: 10,766	Re: engine towers question? First off those in the picture look to be 68-71 Big Block towers. If you for found a set in a 72 then someone changed them. The reason for the different mounts is location of the engine, strength of the motor mounts, and less stress on the chassis. Big Blocks tend to break the weaker, less flexible small block mounts quite regularly and the design does not absorb the extra torque of the Big Block. Causing extra stress on the chassis. The Big Block towers have a larger hole in the center for the 3 piece motor mounts. The 3 piece motor mounts put rubber on top and bottom of the big block towers, with a metal tube that slips through the entire works. When the engine is bolted down with this, it alows for the extra torque of the big block. WES __________________ On-line catolog Classic Heartbeat Pickup Parts WEHEPP@comcast.net Call us Toll Free (888) 338-2502 Like Us on Facebook No appointment necessary. 72 BB Chevy Custom Deluxe / Custom Camper 67 I-6 (Soon to be 5.7 LS1) Panel 68 BB Chevy Short Bed 72 6.0 LQ9 Short Bed Chevy 4X4 Olympia's fastest growing truck parts supplier. Olympia's home for Wayward Chevys

06-19-2007, 09:04 AM	#12
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: engine towers question? Thanks,I appreciate that explaination.That was my question,if we knew if those towers are original to the truck. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~



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