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New to forum. Was wanting to know of any major difficulties in swapping out the tired 4.3 to a carbed 350 sbc. The truck has the 700r4 which I think will bolt right up. Will guages switch over? Getting rid of the trucks wiring as far as the motor goes and going to wiring before trucks had computers. Make sense? Any advise would be greatly appreciated. Thanks, Raceinmud
That's a pretty easy swap. Use the 700r4 like you said and there's not much as far as wiring goes. Just don't rip your harness out. Get you a schematic and take things out you know you won't use like fuel injection, wires that have voltage for the pcm etc...,EGR, purge canister etc... I can't think of any out of the ordinary advice like an LS1 swap to give you. Good Luck!
Wow, that sounds like a very easy swap. You'll need the V8 motor mount for the frame and the mount mount receiver cups that mount to the V8 engine. Other than that it's going to be a simple swap. One issue you will have is fuel pressure, too much of it. Get a regulator and set it for 4 lbs of fuel delivery for the carb. You can raise the pressue later if it ever starves for fuel. Be sure it's a return style regulator so you don't overheat the fuel pump. I've read that the V8 and V6 both used the same wiring harness. If you got a 1992 V8 to swap into it you may be able to simplify things even more. Considering the fact that you're really not gaining any HP by switching to the older V8, I personally wouldn't waste my time swapping in a stock V8 from that generation truck. Hopefully you're considering some sort of crate engine with at least 250 HP. My 93 V8 engine was 100% dog!
You will also need the v8 fan shroud and you will be able to benefit from the v8 as far as torque is concerned. Get yourself a nice 350horse 350 and you will be pleased with the results. you will need the pcm in working condition if you want your guages to work and also you will want to pull the light bulb out of the guage cluster for the check engine light. the sensor that your computer reads for the temp guage is in the head not next to the thermostat housing. You wont need the check engine light for the obvious reason that you wont be using any sensors other than to read information for your guages to use.
dont be afraid to ask anymore questions everybody on here has thousands of ideas and ways of making things work
Thanks for the help! The v6 in the truck has 190k on it. We have two options as far as the V8 goes. I have a 307 shortblock and some fresh 305 heads I could put in with a performer manifold and holley 600 and some headers. I was looking at the Lunati cam # 638-60100lk for the cam (idle to 5000rpm). I think that V8 would move the truck a little better that the v6. Or, I'm kicking around building a 400 I have apart but will cost more to get going. Also, Do we need the cable & stuff for the 700r4 from "Bowtie Overdrives" to make the trans work properly? I plan on hitting the junk yard to find the shroud and mounts and whatever else I see that will help in the swap. Once again, Thanks, And I'll post how it's going and probably have a few more questions. Leon
I know a bad ass tranny builder if you ever need your 700 rebuilt but as far as the kick down im not sure
a buddy of mine has a 6.0l and 85e for sale if you want that
Another question, will the brackets off the 4.3 work/mount on the V8 for the p/s and alt or will I need a different setup. Thanks, Leon
ll the brackets from the 4.3 should work on the V8 Gen1 engine. You may have to tap a couple of holes or do without them.
Me again. On the fuel system. With the electric fuel pump, Do I have to run a return line if I go with a 4bbl Holley and a regulator. Thanks, Leon
I would say yes. The 4.3 pump put out about 15 lbs of pressure. The carb only needs about 5 lbs. To prevent overworking the pump it really needs to just bypass the fuel from the regulator back to the tank rather than have it dead-headed.
Wow, what a winter! Finally getting back to this project. Getting close to dropping in the V8. Couple more questions. Will the flexplate,TQ, and starter off the 4.3 work on the swap to the V8? Also, went with a set of 461 double humps (not drilled) with a short waterpump setup and man, I'm having a terrible time figuring out how to setup the Alt. I've bought two seperate mounting brackets and still no luck. I have the lower setup off the headers ok, but cannot figure out the top mounting. Trying to mount the alt. on the drivers side up high. Any ideas? If anyone has pics of their setup that would help a ton. Thanks for all the help! Leon
Transmission should bolt right up. As for brackets for the alt, contact the guys at Street and Performance( hotrodlane.cc ). They make brackets to fit most anything!
Thanks for the help. One more, one the Alt., can I take off the serp. pulley and replace with a v pulley and just run the current wiring? I do not plan on using the computer sys. in the truck. Problem? Going with early Hei system. Also, on the wiring, can I use a 12V wire currently running to the dist. to run to the hei or what will I need todo? Thanks, Leon
i did tha exact same swap on my 94 s10 on the trailer, at first all i did was throw a v8 in it without doing any wiring. hook athe sensors in the same respective spot on the 350, all your gauges will work. all the front accesories will bolt on including the water pump. trany is also a direct bolt on. only serious thing you have to replace is the exaust and motor mounts. now the wiring, the easiest thing to do is run a throttle body like it came with from the factory. get an intake, tb and computer for a 350 and it will work. only thing you have to do is extend the factory engine harness. if you wanna run a carbed motor, i agree with the first guy, because thats what i did, i went through every wire one by one till i was left with only what was needed. get a good fuel regulator that can be adjusted down to around 6-7 psi, i believe the factory fuel pump's press is low enough to regulate down. get a factory v8 radiator. after that you should be good. prepair youself for a lot of wire removal if you want to go back to the 60's technology, i spent 2 weeks working on mine, but its worth it. have fun
the easiest thing to do is buy a powermaster 100 amp 1 wire alternator, i had that same prob, for some reason i pulled the comp and the alt didnt charge anymore. so i put a one wire on. and yes that power wire going to your dist will work. your 6 cyl dist is just the next generation hei distQuote:
Originally Posted by RACEINMUD