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New Engine-305 vs 350

Discussion in 'Chevy Trucks' started by Dobber, Feb 20, 2010.

  1. Dobber

    Dobber Junior Member
    Messages: 25

    Here goes,
    i was cruising aroung the other day and i saw this very clean 88 1500 4x4. its a southern truck and it was for sale. guy told me it was a 350 and had been rebuilt. ended up haggling him down to 1500 and bought it. (along with many jokes of the 1500 symbol on the door being the price tag) being very proud of myself for snagging such a sweet deal, i brought it over my friends house who knows more about chevys than chevrolet, to show him and borrow his timing light. he whips out a peice of tin foil and gets the casting number off the block and comes back as a 1983 305 out of a van, with 170 horse with a 4 barrel. it has tbi on it now, so probbably less. then i start it and he tells me ive got a bad valve or cam, and the motor probbably had high miles. either way, it runs fine for now.

    I know i cant use it for plowing cause its a half ton, but i can use it to pull a little trailer or something, and you guys seem to know your stuff on here so i ask you the age old question...

    350 or 305 for my shiny old truck?

    ive seen everything online from 350 gets same mileage with way more power to 305 gets 26 mpg... so i dunno. my grandpas 305 gets decent mileage but its 2wd

    thanks in advance and sorry for the long post.


    PS: didnt see anything in the search bar...
  2. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    See my screen name?

    End of story. ;)
  3. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    You will never get 26 mpg with ANY motor in that truck. Put in a 350, keep the TBI.

    And you can plow with that truck, just not heavy commercial. Put a 7 1/2 or light 8 footer on and you will be fine.
  4. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,722

    You can plow with the truck, I'm on season 3 with my 98 Chevy 1/2ton and it's still goin good.

    If your looking to swap motors, I'd say 350 or 383 stroker. I've got the 350 vortec in my truck and it's a good motor, wish it had a few more ponies sometimes but it does pretty good.
  5. lawnmedic

    lawnmedic Senior Member
    Messages: 703

    Well it could be a 305 block that was bored out to a 350. They use the same casting. Hey if it runs,,,,run it.....:)

    NICHOLS LANDSCA PlowSite Veteran
    Messages: 4,286

    Bored and stroked to a 350 but not all bore.
  7. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    You guys are both wrong. A 305 bore is 3.736", stroke is 3.48". A 350 is a 4.00" bore and a 3.48" stroke. The crank is identical other than balancing weight. A 305 block cannot be bored out to 4"

    The heads are unique to a TBI setup (bolt pattern). A 305 uses a 1.84" intake valve, while a 350 uses a 1.94" intake valve. Both use 1.5" exhaust valves. TBI is much better than most carbs for easy starts, driveability, and mileage.

    Figure out what the truck had originally from the option codes in the glove box. Your computer will be set up to work with one engine size or the other, not both. For the small difference in economy, I'd build a fresh 350 short block, then if necessary freshen the TBI heads up and reinstall them regardless of what they were. (should be #187 for a 305 and #191 or 193 for 350) If you have a 305 computer, get an aftermarket performance chip for the 350.

    Also, post the casting number if you can. Your buddy could be wrong, too.

    Keep in mind other things as well--all 86+ engines have a one-piece rear main seal and different flywheel pattern. A LH 305 exhaust manifold has a slightly different bolt pattern on the front cylinder than the 350... there's a few differences but you can make it all work regardless.

    Good luck with a nice project truck.
    Last edited: Feb 21, 2010
  8. augerandblade

    augerandblade PlowSite.com Addict
    Messages: 1,054

    You should be able to plow and pull a trailer with that truck, had a 86 Chevy, and plowed with it for 12 years and hauled a landscape trailer , twenty footer with two zero turn mowers.
  9. chcav1218

    chcav1218 Senior Member
    Messages: 954

    I would also think you could plow with that truck. I've seen a lot of people do it and those old 1/2 tons are a little heavier duty than todays half tons
  10. andcon83

    andcon83 Senior Member
    Messages: 388

    86 is twice the truck the 88 is. I had an 86 1/2 ton and plowed with it for 6 years. Great truck.
  11. mnglocker

    mnglocker Senior Member
    Messages: 922

    Exactly, half tons make great little drieway rigs. Put a 7.5' poly plow on it with a hinged back drag edge and you're in business for residential driveways or for edge/detail clean up in parking lots.

    This, right here is some good advice, don't drop all your money into a $1500 truck, run that engine till it locks up, maybe you'll luck out and go for five years on it. That's less than a dollar a day for a truck. Pretty good in my book. :nod:
  12. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Yeah, I had a sweet little 89 K1500 before I bought my 97 K2500. Didn't really need the money when I sold it. Wish I had kept it and put a blade on it.
  13. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Very true. Some of the trucks that plow our biggest residential routes, anywhere from 70-80 drives in 4 hours or less(which, BTW, I was referring to in the most recent disappearing thread) are half ton short boxes with 8' or 8.5' Western Pro plows. Very maneuverable with a big blade gits 'er done! :D
  14. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    That is all accurate info. You've obviously done some engine work.
    Last edited: Feb 21, 2010
  15. Dobber

    Dobber Junior Member
    Messages: 25

    ok, I do know the truck left the factory with a 305 in it. ill get the casting number ASAP, but im pretty sure my buddy is right, cause the guy that i bought it from said that it was "an older 350 out of a van that the mexican i bought it from put in there" but it drives just like my grandpas 1995 1/2 ton with the 305 does. i also think someone turned up the torshion or timberins(???) cause the truck sits very level, if not up a little in the front.

    what would happen if the heads were older carb heads since it has tbi??

    PS: thanks, i wasnt expecting all these replys.
  16. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    I spent a few years in a local shop working on and building race engines for the dirt and asphalt ovals... a few drag racers... and of course the regular yawn class of engines for fleets, cars and trucks...
  17. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    The TBI intake manifold will not bolt up to those heads unless it has been butchered around the center mounting bolts. Older carb heads have the two center intake bolts on each side perpendicular to the machined face the intake seals against. TBI heads have the angle on them changed so they are vertical when the engine is installed. I've heard people claim they were able to slot the hel! outta the holes on the intake and make it work but have never seen it successfully done. Pretty butch if you ask me.

    The quickest and easiest way to recognize the TBI generation heads (87 and newer) is the 4 valve cover bolts being in a straight line in the center of the cover, where as the older carbed heads (86 and older) use four bolts as well, but two on top and two on bottom of the cover, around the perimeter. If you wanted to go really far back (late 50's) you would find the two upper cover bolts closer together that the lowers. Something tells me they continued that til about '62 or so.
  18. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Nice. That's my year round business for 24 years now. In addition to the plowing business in the winter.

    NICHOLS LANDSCA PlowSite Veteran
    Messages: 4,286

    Who ever said anything about a stock crank? But you still can't get 350 out of a 305. If my math is right .060 over and a 3.75 crank would get you close. Not that anyone would want to spend any money on a 305 though:D
  20. Dobber

    Dobber Junior Member
    Messages: 25

    casting number on the engine is 14010203
    also the valve cover bolts are 2 on each long site on the lip where it meets the head, not down the center.