what year? tbi, mpi (vortech)??

 

We swaped out a 305 for a 355 in a 89 1/2 ton in Ag Mechanics eariler in the semester, it was easy, although we just pulled the new motor and out in the reman one. i think all we ended up doing was getting new manifolds, and belts.

 

non-computer controlled is simple.....pull one...drop in another...very easy to do. if its computer controlled, i dont know...i think that'd be a can of worms

 

Its an 86 chevy with a 5.0 v8 in it, i'm not sure i want to do this yet because it drinks gas like it was margaritas already but i'd like the extra power.

 

actully you'll prolly find that the milage will be about the same overall. the 350 will pull weight a lot beter than that 305...and the added power is good too. do you know what gearing you have? low gears and a 305 are rough, but low gears and a 350 arent all that bad.

 

yeah, what mr u4ia4 said....the 350 would probably ease your gas woes....running around un a full siuze truck with a full size motor is more efficient than a full size truck and a small motor.

 

Thanks for the input, my gear ratio is stock so i think its around 3.73 (i'm no expert)..I have a 3.5'' suspension lift on it and i'm just running 31x10.50's. I plan on giving it a 3" body lift and running 33's and then switching the ratio to 4.10 so i was hoping to have the engine in first.

 

weeeel. for one...with 6.5" of lift you can fit 35s...33s will liekly fit how you have it. if your'e regearing there is no real point in spending the cash for it to only go from 3.73-4.20...you should go at least to 4.56. i havea 350, 3.73 rear end, NV3500, and NP-241. and it still gets up and goes. granted i could take off a bit faster with the 4.56 or 4.10 NOW...but before i had the locker i nthe rear all i would hear was tires spinnin...not enough traction.
SOOOOOOOOOOO. 6.5" lift will clear 35s
dont just jump one step in gears
as far as ghears go...check yoyr RPO codes in the glovebox. they will tell you waht gears you have. all our codes start with G........gear choices are either GU,GA,orGT and then a number....G80 is for the limited slip rear. post your code and we can tell you what your ratio is. i can recognize them, but i cant off the top of my head oput a number to the RPO code

 

Ok, i'll look tommorrow b/c its in my dads garage b/c we we're putting in a new transmission today. I already checked and 33's fit on it right now but i didn't want to put them on yet b/c with my smaller engine and stock ratio (as far as i know it is) it would lag like crazy i imagine. But i'll get back to you tommorrow, thanks alot.

 

i have 33s with stock and it really doesnt lag
BigBlueZ71 has 3.42s with 33s and a non-vortech engine and he does alright.

 

i might consider the 35's then, i took my truck to discount tire and the put on 33 bfgoodridge all terrains and they fit just fine so with the extra 3 inches it wouldn't hurt to put on 35's as long as i change the ratio...how much does it usually run to swap gear ratio's??

 

Just a couple things that come to my mind when swapping an 80 - 86 pickup engine. The oil dipstick is on the passenger side of the engine block after 1980. The head bolt pattern for the exhaust manifolds after 1980 have 7 bolt holes. Usually pickups after 1980 have exhaust manifolds that require the 7 bolt hole pattern. Sometimes it get to be a hassle to gets an older 350 engine into a newer pickup.

If I were to upgrade to a 350 for that year truck, I'd most likely start with a newer 350 engine block, using the roller cam and one piece rear main seals and Vortec heads. This adds considerable cost to getting a good core engine, but I feel it's a better engine in the long run.
dave

 

the mileage won't be a substantial decrease, it might even be better due to the fact that you won't be using as much pedal to achieve the same acceleration, and seeing that its an 86 you can use all of the same components (except i wouldn't use the heads)

 

actually I *think* I rember hearing that their the same block

 

I've done 3 80's 305 to 350 swaps. A few things I've found: The exhaust manifolds from the 305 won't fit on the 350 because the bolt hole is further back on the passengers side rear of the manifold. When you change manifolds, you have to change the cross-over pipe to match. Dipsticks sometimes switch sides, but is no big deal. The flywheels/flexplates are different on 87 and newer v8's, and some 86's. If you put in the 350, and swap the stock Q-jet for anything else, you will see an increase in mileage and power. Other than that, you should be OK.

 

no, they are definatly not the same block, they have a different bore and stroke, they do however have the same dimensions on the outside of the block so all of the EXTERNAL parts are interchangable. this is true from a 265 ci to a 400 ci from 1955 - 1999 (except for the valve covers and oil pan from 86 - 95 (center bolt heads, 1 piece rear main, and passenger side dipstick)) also at the begining of 96 was the vortech heads, and from 91 or 92 was the begining of the lt1/lt4 (gen 2) THEN you have the ls1/ls6 (gen 3) that started in 97 in the corvette, but keep in mind that all of these engines will fit the same transmission and engine mounts (so in thieory you could take a stock 55 chevy and bolt up a ls6 motor from a z06 in it)

 

I've got a 305 with 3.73 gears, do you think i'm going to notice a big performance hit when I get my 33's on? Is it worth dropping a 350 in now or should i wait till my 305 dies?

 

what is the size of your tire now?

 

well for gthe cost and pain of an engine swap. i'd go 33 now...and tehn 350 when the time comes for it....mayeb you can get the block and be building it i nthe eman time till the 5.0 dies on you

 

I have 245/70/R16 right now. I'll be putting on 33/12.50 on 15x10 rims with a 4" lift. I'm just worried about a huge loss of power.

 

It shouldn't be too bad. A 4.10/33" combo is just about ideal with an OD tranny so a 3.73 isn't going to be too bad. Try going to 35"s with 3.42 gears! Now THAT was not fun

 

a 305 and a 350??

 

well, here it is 245/70/r16's are a 30" tire, that 1 1/2" won't make a huge difference, i think the big difference is going to be in fuel economy. like i said, it'll be a little, but not much also, just a suggestion, i've been looking at tire and wheel combo's and the 10" rim might look a little big for the tire. i like the 8" rim with a 12" tire, and a 10" rim with a 14" tire. it looks sooo much tougher (like a 285/70/16 on your current wheel)

 

I drove around with 35's and 3.73's for a while on my 350 and it wasn't that bad really. I just left it in 3rd most of the time. After switching to 4.56 the only difference was more low end and way more power in OD. With 33's it should be fine.

 

I just checked the rpo and now i'm disturbed....the code is a gu2 which is a 2.73 ratio gear and upon looking this up it says this ratio was generally used with v6's and the 200-4R transmissions which is really weird because i have a v8, with a th350c transmission....i guess this may explain why my transmission burnt up recently..even though i'm only running 31x10.50's that might be alot for something that originally had 235's.....well that sucks....now going to 4.20 will be going up a couple steps...