350 to 454 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

griesel72 · 11-25-2003, 01:03 PM

I'm tring to decide how hard it is to swap a 454 into a 71 3/4 ton that used to have a 350. It is a 4X4 and has a 4 speed. Do i have to do anything to the frame (cutting, grinding etc) I've heard that some guys have trouble with the valve covers hitting the ac components on the firewall? Do i use the stock 350 motor mount towers? Do i have to dent the firewall to get the dist to fit?

Sorry for all the questions, just tring to decide if all the work will be worth it.

Thanks
David

**CPNE** · 11-25-2003, 01:17 PM

I think it comes down to:

Do you want to do a body lift or reposition the tranny/xfercase.

If mounting in small block position, you have cab clearance issues, if moving xfer case, you have driveshaft tranny linkage issues.

Yukon Jack is installing a BB. I think he opted for the body lift.

**breeh** · 11-25-2003, 02:11 PM

The other stumbling block in your case will be the clutch linkage. I mocked a big block setup in a 71 4spd 4x4 and even after moving the mount on the frame so that everything would line up I had interference problems with the exhaust manifolds. I think that Yukon Jack is using a hydraulic clutch setup to work around this.

griesel72 · 11-25-2003, 02:14 PM

So, would it be a whole lot easier if i went with an automatic?? Or would i still have problems with clearances?

Thanks for the help

DAvid

**breeh** · 11-25-2003, 02:17 PM

Automatic is much easier. That, I have successfully done.

11-25-2003, 01:03 PM	#1
griesel72 Senior Member Join Date: Apr 2003 Location: Howard, Kansas USA Posts: 1,997	350 to 454 I'm tring to decide how hard it is to swap a 454 into a 71 3/4 ton that used to have a 350. It is a 4X4 and has a 4 speed. Do i have to do anything to the frame (cutting, grinding etc) I've heard that some guys have trouble with the valve covers hitting the ac components on the firewall? Do i use the stock 350 motor mount towers? Do i have to dent the firewall to get the dist to fit? Sorry for all the questions, just tring to decide if all the work will be worth it. Thanks David __________________ 1969 K10 Custom 10 1997 Z71 2006 Volkswagen Jetta TDI 2006 King Ranch 1980 Wife

11-25-2003, 01:17 PM	#2
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,664	I think it comes down to: Do you want to do a body lift or reposition the tranny/xfercase. If mounting in small block position, you have cab clearance issues, if moving xfer case, you have driveshaft tranny linkage issues. Yukon Jack is installing a BB. I think he opted for the body lift. __________________ 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

11-25-2003, 02:11 PM	#3
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	The other stumbling block in your case will be the clutch linkage. I mocked a big block setup in a 71 4spd 4x4 and even after moving the mount on the frame so that everything would line up I had interference problems with the exhaust manifolds. I think that Yukon Jack is using a hydraulic clutch setup to work around this. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

11-25-2003, 02:14 PM	#4
griesel72 Senior Member Join Date: Apr 2003 Location: Howard, Kansas USA Posts: 1,997	So, would it be a whole lot easier if i went with an automatic?? Or would i still have problems with clearances? Thanks for the help DAvid __________________ 1969 K10 Custom 10 1997 Z71 2006 Volkswagen Jetta TDI 2006 King Ranch 1980 Wife

11-25-2003, 02:17 PM	#5
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	Automatic is much easier. That, I have successfully done. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"



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