Engine Swap

jefferias · September 22, 2007

hello everyone! Just lookin for a lil insight. i own a 1984 gmc sierra 1500 2wd. it has a tired 305 in it. i bought a targetmaster350 with 60000 miles on it out of a 93 2500 i believe. i have full intentions of switching the tbi to carbeurator and utilize an hei ignition. ( istill have to pull the motor out -but its mated to a turbo 350 tranny which is what i got.) so was just wondering bout the flywheel/flexplate, if there the same? i believe it has a 2 pc rear seal which is what i have right now as well. also, prolly dumb question, but uh, there are manifolds i can buy to switch over the tbi to a carb-hei ign setup right? anything else would be much appreciated. thanks

nhproxr · September 22, 2007

hello everyone! Just lookin for a lil insight. i own a 1984 gmc sierra 1500 2wd. it has a tired 305 in it. i bought a targetmaster350 with 60000 miles on it out of a 93 2500 i believe. i have full intentions of switching the tbi to carbeurator and utilize an hei ignition. ( istill have to pull the motor out -but its mated to a turbo 350 tranny which is what i got.) so was just wondering bout the flywheel/flexplate, if there the same? i believe it has a 2 pc rear seal which is what i have right now as well. also, prolly dumb question, but uh, there are manifolds i can buy to switch over the tbi to a carb-hei ign setup right? anything else would be much appreciated. thanks

'93 motor is a 1 piece seal motor. Went to 1 piece in '86. I believe it'll use a different flexplate. Don't think a '93 2500 is gonna have a th350 in it. I think at that point it would be a 4-spd with overdrive. Believe 93 is the year they went electronic with the trannys, so its a 4l60e in a light duty 2500 (6 lug wheels) or a 4l80e in a HD. If it is a 3-spd its a th400. Google the pan shapes for all these trannys and compare to what you have. Also the electronic trannys have a wire harness going into the side of it.

Also yes you can put any small block intake on there to convert to a carb. Only a problem for '96-up 350s with vortec heads.....can still run a carb just need a intake to run a carb w/vortec heads.

Genuinefine409 · September 22, 2007

Also yes you can put any small block intake on there to convert to a carb. Only a problem for '96-up 350s with vortec heads.....can still run a carb just need a intake to run a carb w/vortec heads.

in 1987 they changed the angle of the middle bolts, the four middle bolts are on a 72 degree angle. several companies make intakes for the 72 degree center bolt heads. some companies like professional products have bushings you use for the middle bolts which is nice if you'd ever switch to standard heads you could just remove the bushings.

jefferias · September 22, 2007

thanks alot guys. it is much appreciated. i still think its a 2 pc rear main because my boss put it in his work truck, he bought the crate motor straight from mehico lol. very well prolly is a th400 for the tranny i was just hoping the flexplate would be the same. i know its a 3 spd for sure. with the intake thankyou much for the info. one more question - the 350 motor uses a ugly and beefy serpentine belt setup, and i have the nice clean 2 v belt set0up (in my opinion) is there really any benefits to a serpentine because i want to use my v belt setup. again i thank you all in advance. opinions on headers as well would be nice-what kind, brand ,size ???

nhproxr · September 22, 2007

Forgot about the center bolt heads, you are correct about the middle bolts.

As far as sepertine vs. v-belts, serpertine belts are nice cause there's only one, they seem to slip less too. But of course the belt tensioner adds one more thing that can fail in this system, so there is some trade off. If it were me I'd go with the stock (to the '84) v-belts, this way you still can go to any auto parts store and get belts for the '84 without having to think about what the engine came out of.

Oh yeah for headers, I have cerma coated dynomax headers in my '77 and I like them. Whatever you get just make sure they have the thickest gauge tubing and especially mounting flange possible. Spend the money on quality gaskets too for the both the mounting flange and the exhaust flange. Sucks when your header to exhaust flange leaks constantly.

jefferias · October 8, 2007

K here's what i found out. block is 10243880. heads are 14102193 it has one pc rear main seal. Measured the pushrod length and it is 7.8 inches so i believe it has flat tappet cam,from what ive read. non vortec heads. mechanical fuel pump plate bolted up. my questions:

1) will this cam have a lobe for the fuel pump?

2) will bellhousing bolts line up-i have a rebuilt turbo350 mated to a 84 305 right now

3) my guess is i have to use the flexplate on the new motor?(cause its 1 pc now)

4) oil pressure sending unit-iwanna use my 84 design to direct plug in-will it fit/work?

5) i think theres a knock sensor - can i just leave it plugged in hooked up to nothing?

any suggestions or thoughts would be greatly appreciated