pully line up? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

RAT-AT-TACH · 08-15-2003, 12:19 AM

hi guys,sorry i havent been around lately but i got my burb a month ago and i havent stoped driving,besides i cant really give any advice on these trucks yet as i am still learning about them,anyway i noticed on my burb and other 71 gmc,s that if you look down the fan belt from the drivers side the pullys(main and alt)do not line up they are off set by about 1/2 inch,can anyone tell me why and will it hurt the belt in any way,its a 402 bb.

thanks

JimKshortstep4x4 · 08-15-2003, 07:13 AM

Misaligned pulleys will cause problems with increased wear and
the possibility of the belt coming off under hard acceleration.

My guess would be that one or more pulleys are wrong. It is possible that you have a mixture of short and long water pump pulleys as they will fit but will not necessarily line up.

Jim

oldsub86 · 08-15-2003, 11:35 AM

If it is only the alternator that is out of alignment, you can probably shim it out or in to match. I did it years ago on my truck by cutting a bit out of the alternator itself and then shimming the other end of it with washers. Not a proper fix I will admit but it has now served me as is for about 17 years. Someday I should see if I can figure out why or swap to a 350 and then I won't need to worry about it.

**CPNE** · 08-15-2003, 11:46 AM

This is what the factory setup should look like on a 72 402 BB.

**CPNE** · 08-15-2003, 11:47 AM

another

**CPNE** · 08-15-2003, 11:48 AM

and another

RAT-AT-TACH · 08-16-2003, 07:13 PM

hi guys,thanks for the replys ,i guess i will have to shim it a bit heres a pic ,its not the best angle but it should be the right set up.

ddsmith · 08-16-2003, 08:14 PM

Your upper bracket looks different than CNPE does. I couldn't see the lower bracket on your setup. It also looks like you running a different alternator and I know they sometimes don't measure the same distance from the mounting points to the pulley. Have fun shimming!

Rod · 08-16-2003, 08:50 PM

CPNE shows the 72 only upper alt bracket.

**CPNE** · 08-17-2003, 08:34 PM

I know exactly what your problem is. Notice the belt tension bolt location on mine. It bolts thru the back with the alt setting on the outside of the bracket. Yours is bolted thru front with the alt behind the bracket. Your setup makes logical sense but the factory bolted it thru from behind like mine. Set it up like mine and it'll line up without shims. FYI, I made same mistake too.

08-15-2003, 12:19 AM	#1
RAT-AT-TACH Registered User Join Date: May 2003 Location: shawnigan lake b.c. canada Posts: 287	pully line up? hi guys,sorry i havent been around lately but i got my burb a month ago and i havent stoped driving,besides i cant really give any advice on these trucks yet as i am still learning about them,anyway i noticed on my burb and other 71 gmc,s that if you look down the fan belt from the drivers side the pullys(main and alt)do not line up they are off set by about 1/2 inch,can anyone tell me why and will it hurt the belt in any way,its a 402 bb. thanks

08-15-2003, 11:35 AM	#3
oldsub86 Registered User Join Date: Dec 2002 Location: Canada Posts: 695	If it is only the alternator that is out of alignment, you can probably shim it out or in to match. I did it years ago on my truck by cutting a bit out of the alternator itself and then shimming the other end of it with washers. Not a proper fix I will admit but it has now served me as is for about 17 years. Someday I should see if I can figure out why or swap to a 350 and then I won't need to worry about it. __________________ 1968 Chevy - 292 with a powerglide

08-15-2003, 11:46 AM	#4
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,662	This is what the factory setup should look like on a 72 402 BB. Attached Images __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

08-15-2003, 11:47 AM	#5
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,662	another Attached Images __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

08-15-2003, 11:48 AM	#6
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,662	and another Attached Images __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

08-15-2003, 07:13 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Misaligned pulleys will cause problems with increased wear and the possibility of the belt coming off under hard acceleration. My guess would be that one or more pulleys are wrong. It is possible that you have a mixture of short and long water pump pulleys as they will fit but will not necessarily line up. Jim

08-16-2003, 07:13 PM	#7
RAT-AT-TACH Registered User Join Date: May 2003 Location: shawnigan lake b.c. canada Posts: 287	hi guys,thanks for the replys ,i guess i will have to shim it a bit heres a pic ,its not the best angle but it should be the right set up. Attached Images

08-16-2003, 08:14 PM	#8
ddsmith Glowing since 1978 Join Date: Mar 2001 Location: Lusby,MD,USA Posts: 532	Your upper bracket looks different than CNPE does. I couldn't see the lower bracket on your setup. It also looks like you running a different alternator and I know they sometimes don't measure the same distance from the mounting points to the pulley. Have fun shimming! __________________ 66 Chevy C30 Stakebody Dump, PS,PB, 327cu in 71 Corvette Coupe 454 4 speed 69 Chevy C20 Custom Camper

08-16-2003, 08:50 PM	#9
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	CPNE shows the 72 only upper alt bracket. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

08-17-2003, 08:34 PM	#10
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,662	I know exactly what your problem is. Notice the belt tension bolt location on mine. It bolts thru the back with the alt setting on the outside of the bracket. Yours is bolted thru front with the alt behind the bracket. Your setup makes logical sense but the factory bolted it thru from behind like mine. Set it up like mine and it'll line up without shims. FYI, I made same mistake too. __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all



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