HEI in a 72 GMC Jimmy? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Kiss My SS · 11-13-2002, 04:27 PM

Does anyone know if you can put an HEI distributor into a 72 4x4 without modification to the firewall? I was told that it wouldn't fit but I wanted some other opinions. I am tired of dealing with points style distributors. thanks for any input you might have. By the way, I am new. Good to be here.

GMC71k20 · 11-13-2002, 05:30 PM

mine fits but its close and im pretty sure the motor is in the 6cyl position because its way back in there. if your really worried you should get an aftermarket HEI dizzy because theyre much smaller.

Kiss My SS · 11-13-2002, 06:31 PM

I would go with a new one but I am a poor college student. I figured that there were plenty of vacuum advance HEI's laying around at junkyards and I could get several and make one good one to use. I think it will fit. My engine is way back there too. Does anyone else have experience with this?

Mike C · 11-13-2002, 11:15 PM

The 4 wheel drives all have the motor mounted back in the firewall recess. This is done in order to make the front driveshaft as long as possible. I just barely got my points distributor in and out on my Jimmy. I went with an MSD ready to run electronic distributor that uses the window style cap. Let me keep my new wires I had bought as well.

Blazer1970 · 11-14-2002, 08:58 AM

Mine had an HEI in it when I got it. It fit, and you could get the distributor in and out as long as the cap was off. It was very close to the firewall though. The closest thing to it was the end of a screw that sticks through the firewall in that location that holds on part of the heater box on the inside of the cab. My truck has A/C, and that screw might not be there in a non A/C cab. The HEI will normally fit like this in 4X4 trucks, but you better have good motor mounts. I would also have someone brake torque the engine while you watch for clearance between the distributor and firewall as the engine rocks on the mounts. I swapped my factory HEI out for an MSD small body HEI.

Also, GMC71K20, all '67 - '72 four wheel drive V-8 trucks have the engine mounted in the "back" (6 cyl.) location.

**MJN** · 11-14-2002, 11:43 PM

The HEI in our Blazer is really close, my dad massaged the firewall a little (without me there) so it isn't as bad as a stock firewall. The wires farthest back against the cap may rub through from rubbing on the firewall, this happened to two of mine and I rerouted and no rubbing anymore. The only way to get it out is without the cap on and then it is still close.

Beast388 · 11-17-2002, 05:12 PM

I have a Summit HEI in my 4X4 Suburban. As previously stated, it is close and the only way to remove the distributor is with the cap and rotor removed. There is about a 1/4 to 3/8 room between the cap and firewall. I would recommend leaving the stock HEI wire retainer off. I would say do the swap....it's close but will fit.

72C10chevy4x4 · 11-17-2002, 05:53 PM

I didn't know what an HEI was in my truck-especially when walking in to the auto parts stores and looking for a 'stock' vacuum advance unit :-)

anyhow, my truck came w/ an HEI unit, possibly from mid 70's vehicle. It fits-but is tight-only problem I had was with the wires (1) not being long enough. I've got the 4 speed engine-not sure if there in how far a manual versus an automatic pushes the engine back.

Paul

Kiss My SS · 11-17-2002, 11:58 PM

Well, guys, I got an HEI out of a mid seventies 3/4 ton 4x4. I took it apart and it all looks good, I am planning on putting it in middle of next week. I am having my dad mail me several new HEI parts that I had at home for my Monte Carlo SS as well as 2 sets of plug wires so I can pick the best wire from each set. It should be all good and not a moment too soon. My points distributor is starting to screw up. I was towing my friends car on a trailer and anytime I got at or above 3000rpm it started missing really bad so I had to tow it at 30mph or less. I assume that it has something to do with the weights or vacuum advance but I dont want to mess with it. I'll let you know how it turns out. Thanks for the advice.

72C10chevy4x4 · 11-18-2002, 08:46 AM

I found a weight kit for the advance portion at Pepboys for ~$7.

Dean · 11-18-2002, 01:11 PM

I have GM HEI distributors in three of my 71 K20s. It is close but it will go in there. I'm not sure I would want to be doing any radical 4x4ing with it like that though. Wouldn't take much movement to crack the cap.

bouncytruck · 11-19-2002, 06:51 PM

HEI in my '69 and it fits but, as with everyone's, it is tight. I have heard of people doing some "Modifications" to the firewall with a big hammer.

Kiss My SS · 11-21-2002, 03:07 AM

Well, guys, Igot it in. Runs Awesome. Come to find out that the reason it was missing above 3k was one of the little hooks that holds the cap on was off so the cap would wobble and miss. Oh, well, i guess I never noticed that before. anyway, I am happywith the HEI, thanks for the help.

tai · 12-14-2002, 04:16 PM

his stock 72 fits a stock chev\gm hei on a 350
msd makes a billet one peice, raced bearing(no fing bushings) hei with vacum advance thats sick and should fit nicely

11-13-2002, 04:27 PM	#1
Kiss My SS Registered User Join Date: Nov 2002 Location: Omaha/Grand Island, NE Posts: 229	HEI in a 72 GMC Jimmy? Does anyone know if you can put an HEI distributor into a 72 4x4 without modification to the firewall? I was told that it wouldn't fit but I wanted some other opinions. I am tired of dealing with points style distributors. thanks for any input you might have. By the way, I am new. Good to be here. __________________ 1972 GMC Jimmy 4x4 1985 Chevy Monte Carlo SS 1996 Saturn SC-2 1996 Ford Explorer XLT -Wife's rig

11-13-2002, 06:31 PM	#3
Kiss My SS Registered User Join Date: Nov 2002 Location: Omaha/Grand Island, NE Posts: 229	I would go with a new one but I am a poor college student. I figured that there were plenty of vacuum advance HEI's laying around at junkyards and I could get several and make one good one to use. I think it will fit. My engine is way back there too. Does anyone else have experience with this? __________________ 1972 GMC Jimmy 4x4 1985 Chevy Monte Carlo SS 1996 Saturn SC-2 1996 Ford Explorer XLT -Wife's rig

11-13-2002, 11:15 PM	#4
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,727	The 4 wheel drives all have the motor mounted back in the firewall recess. This is done in order to make the front driveshaft as long as possible. I just barely got my points distributor in and out on my Jimmy. I went with an MSD ready to run electronic distributor that uses the window style cap. Let me keep my new wires I had bought as well. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

11-14-2002, 08:58 AM	#5
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,507	Mine had an HEI in it when I got it. It fit, and you could get the distributor in and out as long as the cap was off. It was very close to the firewall though. The closest thing to it was the end of a screw that sticks through the firewall in that location that holds on part of the heater box on the inside of the cab. My truck has A/C, and that screw might not be there in a non A/C cab. The HEI will normally fit like this in 4X4 trucks, but you better have good motor mounts. I would also have someone brake torque the engine while you watch for clearance between the distributor and firewall as the engine rocks on the mounts. I swapped my factory HEI out for an MSD small body HEI. Also, GMC71K20, all '67 - '72 four wheel drive V-8 trucks have the engine mounted in the "back" (6 cyl.) location. __________________ Tim

11-17-2002, 05:12 PM	#7
Beast388 Suburbans RULE! Join Date: Jan 2000 Location: Clinton, IA 52732 Posts: 689	I have a Summit HEI in my 4X4 Suburban. As previously stated, it is close and the only way to remove the distributor is with the cap and rotor removed. There is about a 1/4 to 3/8 room between the cap and firewall. I would recommend leaving the stock HEI wire retainer off. I would say do the swap....it's close but will fit. __________________ --Ben 71 GMC Suburban 4X4 The "Beast" 388 CID Stroker, TH350, NP205, 8-lug D44, 14BFF w/ Detroit, 4.10:1 gears, 4-Wheel Disks 4" Lift, 35" MT/R's.

11-13-2002, 05:30 PM	#2
GMC71k20 Registered User Join Date: Aug 2002 Location: mass Posts: 1,277	mine fits but its close and im pretty sure the motor is in the 6cyl position because its way back in there. if your really worried you should get an aftermarket HEI dizzy because theyre much smaller.

11-14-2002, 11:43 PM	#6
MJN Registered User Join Date: Feb 2000 Location: Maquoketa, Ia/ Orr, Mn Posts: 3,051	The HEI in our Blazer is really close, my dad massaged the firewall a little (without me there) so it isn't as bad as a stock firewall. The wires farthest back against the cap may rub through from rubbing on the firewall, this happened to two of mine and I rerouted and no rubbing anymore. The only way to get it out is without the cap on and then it is still close.

11-17-2002, 05:53 PM	#8
72C10chevy4x4 UK Wildcat Fan! Join Date: Oct 2002 Location: Dover, DE Posts: 515	I didn't know what an HEI was in my truck-especially when walking in to the auto parts stores and looking for a 'stock' vacuum advance unit :-) anyhow, my truck came w/ an HEI unit, possibly from mid 70's vehicle. It fits-but is tight-only problem I had was with the wires (1) not being long enough. I've got the 4 speed engine-not sure if there in how far a manual versus an automatic pushes the engine back. Paul

11-17-2002, 11:58 PM	#9
Kiss My SS Registered User Join Date: Nov 2002 Location: Omaha/Grand Island, NE Posts: 229	Well, guys, I got an HEI out of a mid seventies 3/4 ton 4x4. I took it apart and it all looks good, I am planning on putting it in middle of next week. I am having my dad mail me several new HEI parts that I had at home for my Monte Carlo SS as well as 2 sets of plug wires so I can pick the best wire from each set. It should be all good and not a moment too soon. My points distributor is starting to screw up. I was towing my friends car on a trailer and anytime I got at or above 3000rpm it started missing really bad so I had to tow it at 30mph or less. I assume that it has something to do with the weights or vacuum advance but I dont want to mess with it. I'll let you know how it turns out. Thanks for the advice. __________________ 1972 GMC Jimmy 4x4 1985 Chevy Monte Carlo SS 1996 Saturn SC-2 1996 Ford Explorer XLT -Wife's rig

11-18-2002, 08:46 AM	#10
72C10chevy4x4 UK Wildcat Fan! Join Date: Oct 2002 Location: Dover, DE Posts: 515	I found a weight kit for the advance portion at Pepboys for ~$7.

11-18-2002, 01:11 PM	#11
Dean Senior Member Join Date: Jan 2000 Location: Cincinnati, Ohio Posts: 1,492	I have GM HEI distributors in three of my 71 K20s. It is close but it will go in there. I'm not sure I would want to be doing any radical 4x4ing with it like that though. Wouldn't take much movement to crack the cap.

11-19-2002, 06:51 PM	#12
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,038	HEI in my '69 and it fits but, as with everyone's, it is tight. I have heard of people doing some "Modifications" to the firewall with a big hammer. __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

11-21-2002, 03:07 AM	#13
Kiss My SS Registered User Join Date: Nov 2002 Location: Omaha/Grand Island, NE Posts: 229	Well, guys, Igot it in. Runs Awesome. Come to find out that the reason it was missing above 3k was one of the little hooks that holds the cap on was off so the cap would wobble and miss. Oh, well, i guess I never noticed that before. anyway, I am happywith the HEI, thanks for the help. __________________ 1972 GMC Jimmy 4x4 1985 Chevy Monte Carlo SS 1996 Saturn SC-2 1996 Ford Explorer XLT -Wife's rig

12-14-2002, 04:16 PM	#14
tai Registered User Join Date: Dec 2002 Location: bend oregon Posts: 32	buddys k5 his stock 72 fits a stock chev\gm hei on a 350 msd makes a billet one peice, raced bearing(no fing bushings) hei with vacum advance thats sick and should fit nicely



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