V6 to SBC Swap

clean8485

Comic Book Super Hero
Dec 18, 2005
2,709
113
Ontario, Canada
There are several small block Chev engines that are less than 305 cubic inches. There are 2 4.3lt V8s-a 262 LV8, that was built around 1975-76, then a 262 L99 that was built around 1995-96. There was also a 4.4lt V8 that was built from around 1979-81. There was also the 283 V8 which was built from 1957-67, and the 302, that was built for the Z28 Camaros from 1967-69.
 

86montedude

Not-quite-so-new-guy
Oct 16, 2010
19
0
iv searched and read about everything on here and i cant find a real awnser im putting a vortec 350 from a 99 van in my 85 monte that has a 4.3 can i use the 4.3 flex plate on the 350 so i can use the starter off the 4.3 also
 

jrm81bu

Comic Book Super Hero
Jul 9, 2008
3,000
48
Antwerp, OH
86montedude said:
iv searched and read about everything on here and i cant find a real awnser im putting a vortec 350 from a 99 van in my 85 monte that has a 4.3 can i use the 4.3 flex plate on the 350 so i can use the starter off the 4.3 also

The best I can tell the older 4.3 uses an internally balanced flexplate, just like it's small block counterparts. I know the newer small blocks use a weighted flexplate. So i'm gonna say the answer is no.
But if the flexplates are the same diameter, then you should be able to use the 4.3's starter any way.
 

86montedude

Not-quite-so-new-guy
Oct 16, 2010
19
0
i wish someone could tell me for sure i dnt have the old vortec 350 flex plate i think the vortec flex plate has more teeth on it so i wouldnt beable to use the 4.3 starter on the 350 witch i would like to use so i wouldnt have to buy a new sbc starter someone said it would work but it would be unbalenced and put more wear on in the bearings so if anyone could plz tell me if it for sure will work or deff wont work before i put the 350 in the car and it nt work thanks
 

jrm81bu

Comic Book Super Hero
Jul 9, 2008
3,000
48
Antwerp, OH
86montedude said:
i wish someone could tell me for sure i dnt have the old vortec 350 flex plate i think the vortec flex plate has more teeth on it so i wouldnt beable to use the 4.3 starter on the 350 witch i would like to use so i wouldnt have to buy a new sbc starter someone said it would work but it would be unbalenced and put more wear on in the bearings so if anyone could plz tell me if it for sure will work or deff wont work before i put the 350 in the car and it nt work thanks

Looks like the 4.3 uses a 153 tooth flexplate and the vortec uses the 168 tooth flexplate. So it's not gonna work. And even if they were the same diameter but the 4.3 didn't have the weight on it you wouldn't want to use it anyway.
 

86montedude

Not-quite-so-new-guy
Oct 16, 2010
19
0
is there a flex plate that i can buy for the vortec that has 153 teeth on it instead of 168 that would work with the 4.3 starter
 

86montedude

Not-quite-so-new-guy
Oct 16, 2010
19
0
i found a flex plate from a 89 4.3 that came out of a s10 and it is the exact same one as the stock vortec 350 was, could i put that on the 350 and use the 85 4.3 starter sence the flex plate came from a 4.3?
 

jrm81bu

Comic Book Super Hero
Jul 9, 2008
3,000
48
Antwerp, OH
86montedude said:
i found a flex plate from a 89 4.3 that came out of a s10 and it is the exact same one as the stock vortec 350 was, could i put that on the 350 and use the 85 4.3 starter sence the flex plate came from a 4.3?

Nope, the one for the 89 is still 168 tooth flexplate. To put the starter from the 4.3 on the 350 you will need an externally balanced(weight welded on) flexplate that is the smaller 153 tooth. Something like this. http://www.summitracing.com/parts/PIO-FRA160/ But then you will still need to make sure of the torque convertor bolt pattern to make sure it will bolt to it, or find one with a dual pattern.

I'm guessing here but are you trying to do this to avoid buying the somewhat expensive starter for the 350? After spending the money on the new flexplate your not really saving a whole lot. And the starter for the 350 is gonna be better and lighter.
 

Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
3,309
113
Galaxy far far away
I don't know about the Chevy V6s, but the Chevy V8s still had 2 piece rear seals in 85 which used a different flange and flexplate than the newer 86 and up SBC blocks which had 1 piece rear seals with a redesigned crank flange and flexplate. A vortec block is going to be a 1 piece seal block and crank that needs the 1 piece rear seal style flexplate.
 

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