What problems with I6 to V8 Swap? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72c10step · 07-31-2003, 02:50 PM

I am asking this for a friend of mine, because he's not good with computers. Besides driveshaft, motor mount, and wiring harness issues, what other problems might he (and his helpers me and another friend) experience when converting his truck over to a V8? He's going from an I6/3-on-tree combo to a 350 V8/TH350 combo. Any input would be appreciated. Thanks,

-Jay

dubie · 07-31-2003, 02:59 PM

He will need an automatic crossmember, the front driveshaft from an auto truck and V8 motor mounts. He will also need the throttle linkage setup from a V8 truck, other than that, you should be ready to go. I am doing the same swap only my 350 is going in the I6 position and I am sticking with the 3 speed. Oh, and you might wanna switch to a 4 core rad if you haven't done so already. Then both ends of the rad hoses will be the same size

72c10step · 07-31-2003, 03:05 PM

Thanks Dubie! I forgot to mention his is a 2wd, so he won't need the front driveshaft

, but everything else is pretty helpful. He's also planning on converting to a front disc/5 lug setup from a wrecked donor truck (rear axle is good, front suspension is iffy though), anybody see any large problems there (other than the fact that the front suspension might be tweaked and therefore junk)?

**CPNE** · 07-31-2003, 03:37 PM

Jay, give me a few more details and i may be able to give you specifics and/or options:

1. What year is truck? LWB or SWB?
2. Is the I6/3 speed the original drivetrain?
3. What year is donor truck?
4. Does he care about originality (shift linkage, engine placement, etc)

Plus if he's in need of some parts, I may have it.

bigvinnie · 07-31-2003, 03:46 PM

I did the same swap and as I recall, I needed the speedo cable out of an original auto truck, the 3 speed cable was too short... you'll also need a radiator with a trans cooler, or a stand-alone cooler.

bpmcgee · 07-31-2003, 03:49 PM

I don't see any mention of how he'll solve the shift linkage problem. Won't he either need an aftermarket floor shifter or an auto column?

Brian

**COBALT** · 07-31-2003, 04:02 PM

You will need another driveshaft swapping transmissions, both because the auto trans will take a slip yoke, and the transmission won't be in the same place. If it's LWB then the front piece will have to be swapped. I don't think dubie was talking about 4x4 trucks.

You'll need a new steering column, and new steering rigging up to the rag joint. You'll also need the shift linkage that rivets to the frame, and connects the shift lever from the steering column to the transmission.

Finally, you'll need to set up cooling lines for the transmission, which may mean a new radiator, or at least a secondary cooler.

72c10step · 07-31-2003, 04:15 PM

CPNE:

1. Truck is a 1969 2wd swb fleetside
2. Yes, I6/3spd is original to best of his knowledge (I gotta get his VIN to look it up)
3. Donor truck is a 72 lwb fleetside (also has a 69 or 70 CST for parts too)
4. Would probably want it to look original, but will probably go easiest/cheapest way.

Don't know yet if he needs parts. Maybe as he gets farther along. He's got the donor drivetrain together, and will hopefully pull out his current setup soon.

bpmcgee:

The donor truck has an auto column, but we have to inspect it for damage. The donor truck is pretty messed up.

Not sure what he's doing for the radiator and tranny cooler, but could probably stand to get a new one. BTW, the motor originally came out of a 72 Chevelle, and was hotrodded back when his dad owned it. Can't wait to see how it runs!

dubie · 07-31-2003, 04:19 PM

Yeah, the front driveshaft I was talking about is the front half of the 2 piece. He will need one from a V8 truck. PLease keep us updated as he gets further along

72c10step · 07-31-2003, 04:26 PM

I'll keep you updated, I just hope that he gets it done soon. He and his dad are very busy (they own and run an apple orchard), and have a habit of not finishing projects. Currently they are working on (or not working on, as the case may be) fixing up an old Subaru Brat, restoring a '34 Chevy Truck (his dad started 30 years ago, and it just needs to be put back together), an early '40s Willys Jeep, an '84? CJ7, and his '69 C-10.

**CPNE** · 07-31-2003, 04:30 PM

Well based on that info, you have a decision to make.

1. Mount V8 in I6 position and use existing driveshaft. The overall length of the 69-72 3 speed manuals with bell housing and the short shaft th350 are the same. Plus both are slip yolks and are spined identically. This means the driveshaft shoud work without modifications. This also means that the V8 column shift linkage for the auto may not work.

2. Mount the V8 in the factory forward position. This will ensure stock linkage for tranny will "bolt" in and work. The driveshaft will need to be lengthened however.

If my assumption on the driveshaft is correct, the path of least resistance is to mount in I6 position and find an aftermarket shifter for the tranny.

72c10step · 07-31-2003, 09:02 PM

So that's it huh? Sounds pretty simple.

Looks like he's getting more work done on it, while I was up there putting in a new radiator in mine, he was mating the tranny to the engine. Thanks for all the help!

tickets · 07-31-2003, 09:13 PM

man, that 3 spd manual crossmember is a ***** to get out. i swapped out a 3 spd manual for a th350 about 3 or 4 months ago. i got a short tail th350 and like he said, it was the same length as the manual and the driveshaft fit perfect. so far the driveshaft has held up fine, even with big meats, a locker out back, and 3 or 4 months of my "reckless" driving. i dont know about the I6 though, mine was already a V8.

GMC69 · 08-01-2003, 12:17 AM

Well since this thread is already started, I am doing something similar and just had a few ?'s too.

69 LWB
currently has a 2 speed powerglide auto tranny
I-6

converting to V-8 and probably a 350 or 400 auto tranny. I am also swapping the front suspension either out of an 83 chev pickup or I also have a V-8 crossmember out of a 78 chev pickup.

Do I need to worry about shift linkages and drivshaft length, and any other possible problems???

Sorry for asking in here, but seems to be on a rool already.

07-31-2003, 02:50 PM	#1
72c10step WHYBYNU when old will do? Join Date: Jul 2003 Location: Loudon, NH Posts: 876	What problems with I6 to V8 Swap? I am asking this for a friend of mine, because he's not good with computers. Besides driveshaft, motor mount, and wiring harness issues, what other problems might he (and his helpers me and another friend) experience when converting his truck over to a V8? He's going from an I6/3-on-tree combo to a 350 V8/TH350 combo. Any input would be appreciated. Thanks, -Jay __________________ -72 Chevy C10 Stepside -2002 Chevy Silverado 2500HD 4x4 -1984 Jeep CJ7 -1995 Polaris XCR600 Custom -2003 Honda 300ex

07-31-2003, 02:59 PM	#2
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	He will need an automatic crossmember, the front driveshaft from an auto truck and V8 motor mounts. He will also need the throttle linkage setup from a V8 truck, other than that, you should be ready to go. I am doing the same swap only my 350 is going in the I6 position and I am sticking with the 3 speed. Oh, and you might wanna switch to a 4 core rad if you haven't done so already. Then both ends of the rad hoses will be the same size __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

07-31-2003, 03:05 PM	#3
72c10step WHYBYNU when old will do? Join Date: Jul 2003 Location: Loudon, NH Posts: 876	Thanks Dubie! I forgot to mention his is a 2wd, so he won't need the front driveshaft , but everything else is pretty helpful. He's also planning on converting to a front disc/5 lug setup from a wrecked donor truck (rear axle is good, front suspension is iffy though), anybody see any large problems there (other than the fact that the front suspension might be tweaked and therefore junk)? __________________ -72 Chevy C10 Stepside -2002 Chevy Silverado 2500HD 4x4 -1984 Jeep CJ7 -1995 Polaris XCR600 Custom -2003 Honda 300ex

07-31-2003, 03:37 PM	#4
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,664	Jay, give me a few more details and i may be able to give you specifics and/or options: 1. What year is truck? LWB or SWB? 2. Is the I6/3 speed the original drivetrain? 3. What year is donor truck? 4. Does he care about originality (shift linkage, engine placement, etc) Plus if he's in need of some parts, I may have it. __________________ 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

07-31-2003, 03:46 PM	#5
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	I did the same swap and as I recall, I needed the speedo cable out of an original auto truck, the 3 speed cable was too short... you'll also need a radiator with a trans cooler, or a stand-alone cooler. __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

07-31-2003, 03:49 PM	#6
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	I don't see any mention of how he'll solve the shift linkage problem. Won't he either need an aftermarket floor shifter or an auto column? Brian

07-31-2003, 04:02 PM	#7
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	You will need another driveshaft swapping transmissions, both because the auto trans will take a slip yoke, and the transmission won't be in the same place. If it's LWB then the front piece will have to be swapped. I don't think dubie was talking about 4x4 trucks. You'll need a new steering column, and new steering rigging up to the rag joint. You'll also need the shift linkage that rivets to the frame, and connects the shift lever from the steering column to the transmission. Finally, you'll need to set up cooling lines for the transmission, which may mean a new radiator, or at least a secondary cooler. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

07-31-2003, 04:15 PM	#8
72c10step WHYBYNU when old will do? Join Date: Jul 2003 Location: Loudon, NH Posts: 876	CPNE: 1. Truck is a 1969 2wd swb fleetside 2. Yes, I6/3spd is original to best of his knowledge (I gotta get his VIN to look it up) 3. Donor truck is a 72 lwb fleetside (also has a 69 or 70 CST for parts too) 4. Would probably want it to look original, but will probably go easiest/cheapest way. Don't know yet if he needs parts. Maybe as he gets farther along. He's got the donor drivetrain together, and will hopefully pull out his current setup soon. bpmcgee: The donor truck has an auto column, but we have to inspect it for damage. The donor truck is pretty messed up. Not sure what he's doing for the radiator and tranny cooler, but could probably stand to get a new one. BTW, the motor originally came out of a 72 Chevelle, and was hotrodded back when his dad owned it. Can't wait to see how it runs! __________________ -72 Chevy C10 Stepside -2002 Chevy Silverado 2500HD 4x4 -1984 Jeep CJ7 -1995 Polaris XCR600 Custom -2003 Honda 300ex

07-31-2003, 04:19 PM	#9
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	Yeah, the front driveshaft I was talking about is the front half of the 2 piece. He will need one from a V8 truck. PLease keep us updated as he gets further along __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

07-31-2003, 04:26 PM	#10
72c10step WHYBYNU when old will do? Join Date: Jul 2003 Location: Loudon, NH Posts: 876	I'll keep you updated, I just hope that he gets it done soon. He and his dad are very busy (they own and run an apple orchard), and have a habit of not finishing projects. Currently they are working on (or not working on, as the case may be) fixing up an old Subaru Brat, restoring a '34 Chevy Truck (his dad started 30 years ago, and it just needs to be put back together), an early '40s Willys Jeep, an '84? CJ7, and his '69 C-10. __________________ -72 Chevy C10 Stepside -2002 Chevy Silverado 2500HD 4x4 -1984 Jeep CJ7 -1995 Polaris XCR600 Custom -2003 Honda 300ex

07-31-2003, 04:30 PM	#11
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,664	Well based on that info, you have a decision to make. 1. Mount V8 in I6 position and use existing driveshaft. The overall length of the 69-72 3 speed manuals with bell housing and the short shaft th350 are the same. Plus both are slip yolks and are spined identically. This means the driveshaft shoud work without modifications. This also means that the V8 column shift linkage for the auto may not work. 2. Mount the V8 in the factory forward position. This will ensure stock linkage for tranny will "bolt" in and work. The driveshaft will need to be lengthened however. If my assumption on the driveshaft is correct, the path of least resistance is to mount in I6 position and find an aftermarket shifter for the tranny. __________________ 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

07-31-2003, 09:02 PM	#12
72c10step WHYBYNU when old will do? Join Date: Jul 2003 Location: Loudon, NH Posts: 876	So that's it huh? Sounds pretty simple. Looks like he's getting more work done on it, while I was up there putting in a new radiator in mine, he was mating the tranny to the engine. Thanks for all the help! __________________ -72 Chevy C10 Stepside -2002 Chevy Silverado 2500HD 4x4 -1984 Jeep CJ7 -1995 Polaris XCR600 Custom -2003 Honda 300ex

07-31-2003, 09:13 PM	#13
tickets Registered User Join Date: Jun 2003 Location: FL Posts: 19	man, that 3 spd manual crossmember is a ***** to get out. i swapped out a 3 spd manual for a th350 about 3 or 4 months ago. i got a short tail th350 and like he said, it was the same length as the manual and the driveshaft fit perfect. so far the driveshaft has held up fine, even with big meats, a locker out back, and 3 or 4 months of my "reckless" driving. i dont know about the I6 though, mine was already a V8.

08-01-2003, 12:17 AM	#14
GMC69 Registered User Join Date: Jul 2003 Location: Sudbury, Ontario, Canada Posts: 734	Well since this thread is already started, I am doing something similar and just had a few ?'s too. 69 LWB currently has a 2 speed powerglide auto tranny I-6 converting to V-8 and probably a 350 or 400 auto tranny. I am also swapping the front suspension either out of an 83 chev pickup or I also have a V-8 crossmember out of a 78 chev pickup. Do I need to worry about shift linkages and drivshaft length, and any other possible problems??? Sorry for asking in here, but seems to be on a rool already. __________________ Mike Email: Click here to email me -- 2019 Silvedrado 4x4 1970 Chevy 3/4 ton, 396BB, on air bags



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.