Straight 6 to small block swap??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1972CST · 03-15-2009, 09:31 PM

I am getting ready to swap the worn out I6 for a small block in my 79' auto 2-WD truck and was wondering if there are any major mods needed? What will I need from a v8 truck? I did a search for v8 swap but didnt come up w/ much. I know this has to be a common swap.Thanks in advance!

sierra4x4 · 03-15-2009, 09:59 PM

This is a simple swap all you need is a V8 with all the v8 accessory brackets and it will drop right in. The engine mounts(frame ones) are the same for both engines and the tranny will bolt right up. The wiring will be a little different but still simple to change. A 6cyl rad will work fine but the hoses will be different. Throttle cable will be the same also. The exhaust will be different but a v8 Y-pipe should hook up to the original 6cyl exhaust. It would be simplest to use a v8 power steering pump but the 6cyl one will work with the right brackets.

**old Rusty C10** · 03-15-2009, 10:40 PM

I beg to disagree id upgrade the radiator..

fast75 · 03-16-2009, 06:36 AM

Quote:

Originally Posted by old Rusty C10

I beg to disagree id upgrade the radiator..

i did this swap with mine. it had a I6 (yeah till about 3 hours after i got it home.) i'd listen to old Rusty C10. i would definately put a V-8 radiator in. they're plentiful, around here anyway. everything else will bolt up fine. i even have the original (for now) 3 speed tranny that was behind the 6 cyl. new zoom clutch and she was ready to go.

**Captkaos** · 03-16-2009, 06:12 PM

The mounts on the V8 are different, but the mounts on the frame are the same, you just have to move them up.

1972CST · 03-16-2009, 06:42 PM

Thanks for all the help guys. I have all the stuff off the v8 truck like pulleys,brackets, manifolds, y-pipe, radiator ect. The ac might be a little fun but we shall see. Does anyone know what the 6 bangers were geared from the factory?

dubb492 · 02-01-2011, 12:38 PM

i have a stright 6 250, and want to do the same thing! so the engine mounts i have now will work perfect with small block 350??

bigblock73 · 02-01-2011, 12:47 PM

The engine MOUNTS are different, but the STANDS are the same (as Chris said). The stands have to sets of holes, labeled "6" and "8", pretty self explainatory right?

motornut · 02-01-2011, 01:08 PM

I changed the tranny,rad,mounts all from donors
the smaller rad might be ok to test fire but not worth the risk
maybe you can sell some parts...

stepside83 · 02-01-2011, 06:34 PM

im doing the same mod, switching from a 250 I6 to a 1987 chevy 350, makin around 350 horse, i know nuttin to brag about, i was wondering tho where i could find a power steering pump bracket that bolts to the block, either oem or after market dosent reallly matter, ive looked at all salvage yards round my house and they got nothing, so was wondering if i could order one online some where, i need one because who i bought the motor from kept it for his crate motor thanks with any help

manimal · 02-01-2011, 11:10 PM

Is it a 250 or 292? The 292 uses a different passenger side mount and frame stand.

jaxncurtis · 02-12-2019, 11:22 AM

Im interested in doing the swap from 250 to a 350. I recently had my manual transmission upgraded to a Automatic Transmission. He did a great job and seems to be well educated mechanic.

I spoke to him last week and he is certain I can not swap to a 350 with my setup... easily? But everything that i have read in books and on the forums this should not be too difficult of a job.

Can anyone think of why myset up would be different from everyone else? I have a 1970 Blazer 4x4.

WarBeard · 02-12-2019, 08:05 PM

I must be the only guy willing to swap his 350 for a straight 6. I think inline 6's are cool as hell.

D13 · 02-13-2019, 07:02 AM

You do realize this is a 10 year old thread...
But I love my L6's too.

jaxncurtis · 02-13-2019, 11:51 AM

Quote:

Originally Posted by D13

You do realize this is a 10 year old thread...
But I love my L6's too.

"You do realize" if I would have started a new thread someone would have trolled me saying I should search the older threads... Now you troll me for posting on a old thread... seems I cant win here...

D13 · 02-13-2019, 12:46 PM

Quote:

Originally Posted by jaxncurtis

"You do realize" if I would have started a new thread someone would have trolled me saying I should search the older threads... Now you troll me for posting on a old thread... seems I cant win here...

Not meaning to troll. If i came across that way I apologize.

I thank you for doing the search and finding the thread, and I'm glad someone else likes the L6 chimed in too. I was just surprised to see the original thread date, I guess I was expecting a new thread with 'I found this old thread, any newer info?'. Although in this case I suspect nothing new has been found... not exactly a hot topic it seems.

Again, sorry if I came across as trolling, not my intention.

03-15-2009, 09:31 PM	#1
1972CST Registered User Join Date: Mar 2008 Location: Concord NC Posts: 511	Straight 6 to small block swap??? I am getting ready to swap the worn out I6 for a small block in my 79' auto 2-WD truck and was wondering if there are any major mods needed? What will I need from a v8 truck? I did a search for v8 swap but didnt come up w/ much. I know this has to be a common swap.Thanks in advance! Last edited by 1972CST; 03-15-2009 at 09:34 PM.

03-15-2009, 09:59 PM	#2
sierra4x4 Registered User Join Date: Jan 2009 Location: Canada Posts: 308	Re: Straight 6 to small block swap??? This is a simple swap all you need is a V8 with all the v8 accessory brackets and it will drop right in. The engine mounts(frame ones) are the same for both engines and the tranny will bolt right up. The wiring will be a little different but still simple to change. A 6cyl rad will work fine but the hoses will be different. Throttle cable will be the same also. The exhaust will be different but a v8 Y-pipe should hook up to the original 6cyl exhaust. It would be simplest to use a v8 power steering pump but the 6cyl one will work with the right brackets.

03-15-2009, 10:40 PM	#3
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,310	Re: Straight 6 to small block swap??? I beg to disagree id upgrade the radiator.. __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

03-16-2009, 06:12 PM	#5
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Re: Straight 6 to small block swap??? The mounts on the V8 are different, but the mounts on the frame are the same, you just have to move them up. __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

03-16-2009, 06:42 PM	#6
1972CST Registered User Join Date: Mar 2008 Location: Concord NC Posts: 511	Re: Straight 6 to small block swap??? Thanks for all the help guys. I have all the stuff off the v8 truck like pulleys,brackets, manifolds, y-pipe, radiator ect. The ac might be a little fun but we shall see. Does anyone know what the 6 bangers were geared from the factory?

02-01-2011, 12:38 PM	#7
dubb492 Registered User Join Date: Jan 2011 Location: trinity, nc Posts: 9	Re: Straight 6 to small block swap??? i have a stright 6 250, and want to do the same thing! so the engine mounts i have now will work perfect with small block 350?? __________________ 84 c-10 stright 6

02-01-2011, 12:47 PM	#8
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,824	Re: Straight 6 to small block swap??? The engine MOUNTS are different, but the STANDS are the same (as Chris said). The stands have to sets of holes, labeled "6" and "8", pretty self explainatory right? __________________ Jeff 73-87.com 73-87.com Facebook page 73-87 cab corner 6x9 speaker brackets for sale 67-72 cab corner speaker brackets for sale 47-54 cab corner speaker brackets for sale

02-01-2011, 01:08 PM	#9
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: Straight 6 to small block swap??? I changed the tranny,rad,mounts all from donors the smaller rad might be ok to test fire but not worth the risk maybe you can sell some parts... __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

02-01-2011, 06:34 PM	#10
stepside83 Registered User Join Date: Jan 2010 Location: butler pa Posts: 328	Re: Straight 6 to small block swap??? im doing the same mod, switching from a 250 I6 to a 1987 chevy 350, makin around 350 horse, i know nuttin to brag about, i was wondering tho where i could find a power steering pump bracket that bolts to the block, either oem or after market dosent reallly matter, ive looked at all salvage yards round my house and they got nothing, so was wondering if i could order one online some where, i need one because who i bought the motor from kept it for his crate motor thanks with any help

02-01-2011, 11:10 PM	#11
manimal Registered User Join Date: Oct 2006 Location: Southern Kalifornia Posts: 3,066	Re: Straight 6 to small block swap??? Is it a 250 or 292? The 292 uses a different passenger side mount and frame stand. __________________ ------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT

02-12-2019, 11:22 AM	#12
jaxncurtis Registered User Join Date: May 2017 Location: Gilbert, AZ Posts: 33	Re: Straight 6 to small block swap??? Im interested in doing the swap from 250 to a 350. I recently had my manual transmission upgraded to a Automatic Transmission. He did a great job and seems to be well educated mechanic. I spoke to him last week and he is certain I can not swap to a 350 with my setup... easily? But everything that i have read in books and on the forums this should not be too difficult of a job. Can anyone think of why myset up would be different from everyone else? I have a 1970 Blazer 4x4.

02-12-2019, 08:05 PM	#13
WarBeard Registered User Join Date: Jul 2008 Location: Show low,az Posts: 808	Re: Straight 6 to small block swap??? I must be the only guy willing to swap his 350 for a straight 6. I think inline 6's are cool as hell. __________________ 1978 C10 Silverado Big 10 350/350.. play toy 1990 V1500 Suburban 350/700r4..Daily driver 1987 K10 Silverado 383/400.. Wife's rig WRECKED! 1989 V2500 Suburban 350/400.. SOLD! 1974 C10 Custom10 LWB 350/350.. SOLD! 1974 C10 Custom10 SWB 350/400.. SOLD! 1999 Silverado Z71 LS1.. Wife's rig WRECKED! On the hunt for a new project....... I'm a Chevy guy.....I'm just not a "NEW" Chevy guy.

02-13-2019, 07:02 AM	#14
D13 Registered User Join Date: Feb 2007 Location: Memphis MI Posts: 1,851	Re: Straight 6 to small block swap??? You do realize this is a 10 year old thread... But I love my L6's too. __________________ 1987 2 ton 1982 250/TH350 beater in progress Dad's 1981 3/4 L6 3 on tree posi and no options, awaiting restoration or scrapping Plus a mess o' tractors

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