# New Engine-305 vs 350



## Dobber (Dec 8, 2009)

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.

~Joe

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


----------



## cubicinches (Oct 19, 2008)

See my screen name?

End of story.


----------



## 2COR517 (Oct 23, 2008)

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.


----------



## Mark13 (Dec 3, 2006)

Dobber;1007972 said:


> 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...
> ...


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.


----------



## lawnmedic (Jan 9, 2004)

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 (Sep 15, 2007)

lawnmedic;1008021 said:


> 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.....


Bored and stroked to a 350 but not all bore.


----------



## derekbroerse (Mar 6, 2004)

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.


----------



## augerandblade (Jan 17, 2009)

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.


----------



## chcav1218 (Jul 31, 2008)

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


----------



## andcon83 (Dec 10, 2005)

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


----------



## mnglocker (Dec 24, 2008)

2COR517;1007983 said:


> 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.


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.



lawnmedic;1008021 said:


> 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..*...


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.


----------



## 2COR517 (Oct 23, 2008)

mnglocker;1008241 said:


> 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.


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.


----------



## cubicinches (Oct 19, 2008)

mnglocker;1008241 said:


> 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.





2COR517;1008250 said:


> 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.


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!


----------



## cubicinches (Oct 19, 2008)

derekbroerse;1008132 said:


> 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.
> 
> ...


That is all accurate info. You've obviously done some engine work.


----------



## Dobber (Dec 8, 2009)

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??

~Joe
PS: thanks, i wasnt expecting all these replys.


----------



## derekbroerse (Mar 6, 2004)

cubicinches;1008293 said:


> That is all accurate info. You've obviously done some engine work.


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...


----------



## derekbroerse (Mar 6, 2004)

Dobber;1008300 said:


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


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.


----------



## cubicinches (Oct 19, 2008)

derekbroerse;1008527 said:


> 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...


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


----------



## NICHOLS LANDSCA (Sep 15, 2007)

derekbroerse;1008132 said:


> 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.
> 
> ...


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


----------



## Dobber (Dec 8, 2009)

OK,
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. 

~Joe


----------



## B&B (Nov 4, 2006)

Dobber;1009124 said:


> OK,
> 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.
> 
> ~Joe


It's an '83 305 with the old style (pre-'86) perimeter bolt heads. If you look closely you'll find the four center intake bolt holes are hogged out in the intake and the bolt heads don't quite set right with the bolt flange on the intake as Derek was referring to. Because thats the only way to get a TBI intake onto pre-86 heads.


----------



## cubicinches (Oct 19, 2008)

Dobber;1009124 said:


> OK,
> 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.
> 
> ~Joe


That's a 305. The heads are non-TBI. Dipstick is on the passenger side, correct?


----------



## 2COR517 (Oct 23, 2008)

B&B;1009141 said:


> ..... bolt holes are* hogged out *in the intake .....


Nice usage of that expression  :salute:


----------



## Dobber (Dec 8, 2009)

yes, the dipstick is on the passenger side, right under the air tube for the tbi. 
ok, so two more questions,
first, will this non tbi engine with tbi hackjobed onto it cause me alot of problems,
and second, i tried timing it. i got it zeroed but it runs worse than ever now. kinda sounds like it has a mild cam in it, i press the gas very lightly and it goes just fine, but the more i get on it, the slower it gets. another friend of mine said something along the lines of the engine might be set up for 2 barrel carb with a 2 barrel cam and heads and isnt getting enough air, but he says he knows more about diesels and dont take his word for it. any ideas?

thanks in advance

~Joe


----------



## B&B (Nov 4, 2006)

Dobber;1010224 said:


> yes, the dipstick is on the passenger side, right under the air tube for the tbi.
> ok, so two more questions,
> first, will this non tbi engine with tbi hackjobed onto it cause me alot of problems,
> and second, i tried timing it. i got it zeroed but it runs worse than ever now. kinda sounds like it has a mild cam in it, i press the gas very lightly and it goes just fine, but the more i get on it, the slower it gets.


 Did you disconnect the timing connector before you adjusted the timing? If not it will be way ********...and will cause the exact problem you have. It'll be a tan wire with a black tracer. There's usually hidden under the plastic cover on the pass side of the firewall but sometimes also can be found snaked out of the main harness over near the brake booster. Once you locate it, disconnect it (engine off), start the engine, set the timing with your light, turn engine off and reconnect the wire. Then clear the DTC code it sets (from having it running with the connector apart) and you should be good to go.



Dobber;1010224 said:


> another friend of mine said something along the lines of the engine might be set up for 2 barrel carb with a 2 barrel cam and heads and isnt getting enough air, but he says he knows more about diesels and dont take his word for it. any ideas?
> thanks in advance~Joe


I hope Diesels really are his specialty Joe because he has no clue what he's talking about. This is a GM not a Ford, there is no 2bbl/4bbl specific cylinder heads or cams.


----------



## got-h2o (Sep 26, 2008)

I'm selling a 350 out of a 95 with 90k miles for $500 complete with all accessories. Great runner, no leaks.


----------



## Dobber (Dec 8, 2009)

got-h20,
do you know if the computer in my truck, being an 88 with a 305 originally so it has that computer, will work with the 350? 

and also i finially got the timing down. and by me i mean my buddy. he tossed the timing light and timed it by ear and it runs like a raped ape now! that damn thing is QUICK!! 

B&B, was sir i did disconnect the timing connector. took me about 15 minutes to find it because whoever put this engine in but it BEHIND a hose. and yea, Diesels are his specialty, and i dont think he has owned anything other than a ford and the company that we worked for only had fords too so i guess he just didnt know. 

~Joe


----------



## B&B (Nov 4, 2006)

Good you got the timing squared away. 

To run a 350 in place of a 305 you have to change the chip in the ECM and the injectors in the TBI to be correctly compatible with the larger displacement, otherwise they run very lean. Not that the TBI's don't already. But in all honestly if the engine runs good and has good power I wouldn't bother swapping it out to a 350. If it isn't broke why fix it?

Unless Bill needs the cash of course.


----------



## Dobber (Dec 8, 2009)

Well, judging from his signature, he may need to fill up half a tank in one of those Duralaxes. well then again they are short beds so they got the smaller tanks so maybie one ran out of fuel in the middle of a push, lol. shoulda stuck to the good old detroit not that isuzu scrap!

im just kidding man i could only dream of owning a fleet as nice as got-h20's is. im just jealous cause i bought fords and they are all rusting away and have no power!!!!!!!!!

as for the engine, i think that i will drive the truck for a week and take it from there, and find out how much it would be to do the swap in the meantime. thank you very much for the offer but dont wait on me to sell it. i will send you a mesage one way or the other and thank you again for the offer.

~Joe


----------



## got-h2o (Sep 26, 2008)

Thanks B&B..........and Dobber!!!!

I actually have the computer too, so that would go with. As for selling it, I'd like it gone, but not trying to press a sale by any means. 

And listen here Ford boy..............that's why I have 100 gallon transfer tanks in the trucks!!! Lol. 

Really though, milage is great in a Dmax


----------

