What do I need to convert from 6 cyl to 8? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**ScottH** · 05-23-2013, 11:32 PM

Will be getting a 83 swb in the near future that was originally a 250 6 cyl engine.
I plan to put a sbc in and was wondering what is needed to make the change?
Can I use the engine mounts from the 6? Do they need to be relocated?
I am thinking about using the original sm465 trans & would like to keep in the 6 position (trans, cross member, etc.).

Any info is appreciated.

Thanks guys!
Scott

izzy_Britton · 05-23-2013, 11:40 PM

It has been forever since I done a conversion, so dont quote me on it.

But i believe you NEED the SBC motor mounts and they bolt to the same spot as the 6ers do. I think all the rest of the hard parts bolt up. you will need some fuel lines and radiator and heater lines and what not but otherwise you should be good to go.

-Izzy

**ScottH** · 05-24-2013, 10:55 AM

Thanks Izzy

Any other input, suggestions, etc??

chrismoore701 · 05-24-2013, 11:45 AM

I recall the same for my swap

Tx Firefighter · 05-24-2013, 01:25 PM

My truck (78 model half ton) was different. The engine mounts were dual drilled from the factory for inline 6 or V8 options. GM even labeled them for knuckledraggers like myself so we wouldn't be confused.

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SamsAutoParts73-87 · 05-24-2013, 04:04 PM

I agree you should be able to use the same engine mounts, you should be buying new clam shells anyway. Your trans & bell housing should bolt right up. But if I remember correctly you will need a V8 flywheel and clutch. you will need a V8 radiator and wire harness though.

Tx Firefighter · 05-24-2013, 04:33 PM

If the current six cylinder is a 4.1L (250 cu/in), the flywheel and clutch and starter will bolt directly to any non 400cid small block engine that uses a 2 piece rear main seal.
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**ScottH** · 05-24-2013, 10:41 PM

thanks guys, appreciate the info

05-23-2013, 11:32 PM	#1
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,190	What do I need to convert from 6 cyl to 8? Will be getting a 83 swb in the near future that was originally a 250 6 cyl engine. I plan to put a sbc in and was wondering what is needed to make the change? Can I use the engine mounts from the 6? Do they need to be relocated? I am thinking about using the original sm465 trans & would like to keep in the 6 position (trans, cross member, etc.). Any info is appreciated. Thanks guys! Scott __________________ 1963 C10 swb fleetside 1966 GMC G1000 Handi-bus (future project) 1955 Chevy 2 dr. wagon

05-23-2013, 11:40 PM	#2
izzy_Britton Registered User Join Date: Apr 2013 Location: Nor-Cal Posts: 632	Re: What do I need to convert from 6 cyl to 8? It has been forever since I done a conversion, so dont quote me on it. But i believe you NEED the SBC motor mounts and they bolt to the same spot as the 6ers do. I think all the rest of the hard parts bolt up. you will need some fuel lines and radiator and heater lines and what not but otherwise you should be good to go. -Izzy __________________ WHO_DCTC - Wifes 05 Z-71 Build - Now defunct as she decided she wants an Escalade too Cream Puff - LS'd Square - Slow going on the back burner Tripple Threat - 3 Wrecks for the price of one build thread Project Delongdium - Step-Sons Plastic Clad 2003 Avalanche - DONE and Delivered.

05-24-2013, 10:55 AM	#3
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,190	Re: What do I need to convert from 6 cyl to 8? Thanks Izzy Any other input, suggestions, etc?? __________________ 1963 C10 swb fleetside 1966 GMC G1000 Handi-bus (future project) 1955 Chevy 2 dr. wagon

05-24-2013, 11:45 AM	#4
chrismoore701 Registered User Join Date: Dec 2004 Location: Highland, IN Posts: 2,326	Re: What do I need to convert from 6 cyl to 8? I recall the same for my swap __________________ Chris _______________________________ 1979 Chevy Stepside SPORT 2018 Chevy Silverado, 39 years apart My build 2008-2016. http://m.imgur.com/a/bURrE

05-24-2013, 01:25 PM	#5
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: What do I need to convert from 6 cyl to 8? My truck (78 model half ton) was different. The engine mounts were dual drilled from the factory for inline 6 or V8 options. GM even labeled them for knuckledraggers like myself so we wouldn't be confused. Posted via Mobile Device

05-24-2013, 04:04 PM	#6
SamsAutoParts73-87 Registered User Join Date: Feb 2013 Location: Rome PA Posts: 340	Re: What do I need to convert from 6 cyl to 8? I agree you should be able to use the same engine mounts, you should be buying new clam shells anyway. Your trans & bell housing should bolt right up. But if I remember correctly you will need a V8 flywheel and clutch. you will need a V8 radiator and wire harness though. __________________ 1987 Chevy R30 CC 454/4spd Work Truck 1979 Chevy K10 SWB 350/4spd/NP205, 1979 Chevy C10 LWB 350/TH350 Project 1981 Chevy K30 350/Th400/NP205 1986 Chevy K30 CUCV 6.2L/TH400/NP208

05-24-2013, 04:33 PM	#7
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: What do I need to convert from 6 cyl to 8? If the current six cylinder is a 4.1L (250 cu/in), the flywheel and clutch and starter will bolt directly to any non 400cid small block engine that uses a 2 piece rear main seal. Posted via Mobile Device

05-24-2013, 10:41 PM	#8
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,190	Re: What do I need to convert from 6 cyl to 8? thanks guys, appreciate the info __________________ 1963 C10 swb fleetside 1966 GMC G1000 Handi-bus (future project) 1955 Chevy 2 dr. wagon



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