Engine Positioning Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ManNamedJed · 02-19-2019, 07:34 PM

I have a 71 suburban 4x4. It originally had a 6cyl, but now has a 350.

Since I got it last year I noticed a few odd things - the distributor and air cleaner are really tight with the firewall. I installed a Classic Air AC kit and the hose from the front of the truck to the AC compressor barely reached, whereas the one from the firewall forward to the compressor is extra long.

Then I read that 6cyl and V8 mounts in a different spot on the frame. So I go take a look and sure enough, there are other mount holes about 2" forward from where my motor mounts are.

Is there a reason they didn't reposition things when they did the engine swap? If the engine, and trans and tcase move to the forward spot, will the stock drivelines need replaced? Did Chevy have different driveline lengths for I6 vs V8 vehicles?

I am about to install an HEI dist and new intake, so I'm concerned about clearance.

If I move my engine to the forward position, other than the exhaust, and drivelines, will I run into any other issues? Looks like there is room for the fan.

Thanks!

Hubscrub · 02-19-2019, 07:49 PM

Not sure about burbs, but pickups had different 6cyl, v8 positions. If i remember correctly the 4x4 used the back mounts anyways with either engine. I know my 67 and 71 were orginal inline 6 trucks and i didn't move mine to save the extra work. The hei has room, and i just installed 4x4 fan shrouds instead of 2wd ones for the added depth.

**truckster** · 02-19-2019, 09:34 PM

My Blazer 4WD has an HEI in it. It's close to the firewall, but it can fit.

dave`12 · 02-19-2019, 10:07 PM

My 67 fleetside had the 250 engine and I replaced it with a 350. I used the 6 cylinder mounts, otherwise you have to mess with the driveline to get it to work (lengthen driveshaft, move tranny mount, etc.)

My Hei has about 1" clearance.

But mine is a 2x4, not a 4x4.

ManNamedJed · 02-20-2019, 11:47 AM

Thanks everyone. I guess I'll leave it where it is!

**kwmech** · 02-20-2019, 12:12 PM

GM stuffed the V8 back so the oil pan would not be damaged by the front axle hitting it. If you have a lift, move that thing forward. (I've done several over the years). Only thing that gets weird is the auto linkage frame bracket in relation to the leaf spring shackle and bending the linkage rod from the column

**'68OrangeSunshine** · 02-20-2019, 02:06 PM

If your sub had a 292 L6, it would've had a diagonal crossover support.
And if you still have clearance issues, you can get a low profile HEI cap w/o coil [remote coil] and just mount the coil on the block or firewall.

02-19-2019, 07:34 PM	#1
ManNamedJed Registered User Join Date: May 2018 Location: Reno, NV Posts: 232	Engine Positioning Question I have a 71 suburban 4x4. It originally had a 6cyl, but now has a 350. Since I got it last year I noticed a few odd things - the distributor and air cleaner are really tight with the firewall. I installed a Classic Air AC kit and the hose from the front of the truck to the AC compressor barely reached, whereas the one from the firewall forward to the compressor is extra long. Then I read that 6cyl and V8 mounts in a different spot on the frame. So I go take a look and sure enough, there are other mount holes about 2" forward from where my motor mounts are. Is there a reason they didn't reposition things when they did the engine swap? If the engine, and trans and tcase move to the forward spot, will the stock drivelines need replaced? Did Chevy have different driveline lengths for I6 vs V8 vehicles? I am about to install an HEI dist and new intake, so I'm concerned about clearance. If I move my engine to the forward position, other than the exhaust, and drivelines, will I run into any other issues? Looks like there is room for the fan. Thanks!

02-19-2019, 07:49 PM	#2
Hubscrub Cruzin Join Date: Dec 2009 Location: on the road Posts: 2,835	Re: Engine Positioning Question Not sure about burbs, but pickups had different 6cyl, v8 positions. If i remember correctly the 4x4 used the back mounts anyways with either engine. I know my 67 and 71 were orginal inline 6 trucks and i didn't move mine to save the extra work. The hei has room, and i just installed 4x4 fan shrouds instead of 2wd ones for the added depth. __________________ Lime Wife's 67https://www.google.com/url?sa=t&rct=...wZEMODaS2d94u8 Back to the Fifties 59 https://www.google.com/url?sa=t&rct=...NAeStpydfrcj_U Proverbs 3:5,6 "Thanks to the Interstate Highway System, it is now possible to travel across the country from coast to coast without seeing anything."Charles Kuralt In memory of our first baby daughter, daddy and mommy love you. Danica Grace 6/26/14

02-19-2019, 09:34 PM	#3
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,976	Re: Engine Positioning Question My Blazer 4WD has an HEI in it. It's close to the firewall, but it can fit. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

02-19-2019, 10:07 PM	#4
dave`12 Registered User Join Date: Sep 2015 Location: Lake Placid florida Posts: 599	Re: Engine Positioning Question My 67 fleetside had the 250 engine and I replaced it with a 350. I used the 6 cylinder mounts, otherwise you have to mess with the driveline to get it to work (lengthen driveshaft, move tranny mount, etc.) My Hei has about 1" clearance. But mine is a 2x4, not a 4x4. __________________ 1967 C-10 4-speed, 350v8

02-20-2019, 11:47 AM	#5
ManNamedJed Registered User Join Date: May 2018 Location: Reno, NV Posts: 232	Re: Engine Positioning Question Thanks everyone. I guess I'll leave it where it is!

02-20-2019, 12:12 PM	#6
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,628	Re: Engine Positioning Question GM stuffed the V8 back so the oil pan would not be damaged by the front axle hitting it. If you have a lift, move that thing forward. (I've done several over the years). Only thing that gets weird is the auto linkage frame bracket in relation to the leaf spring shackle and bending the linkage rod from the column

02-20-2019, 02:06 PM	#7
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,500	Re: Engine Positioning Question If your sub had a 292 L6, it would've had a diagonal crossover support. And if you still have clearance issues, you can get a low profile HEI cap w/o coil [remote coil] and just mount the coil on the block or firewall. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.



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