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Discussion Starter · #1 ·
I was wondering how hard it would be to drop a 305 or 350 into my '92 4.3L V-6 S10. I have a buddy who has all the mounts he'll give me and I can pick up a motor cheap but I wasn't sure if I'd need to pick up a new trans or not. I can find 305's for a few hundred and the 350s are just a bit more around here. Also would I really see THAT much of a power increase with a 350 over a 305, would it be worth the sacrifice of fuel? Trying to finish a project without dad's help for once so thanks for any help you can provide lol. :thumbup:
 

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There is too much involved with any engine swap to address it here. I suggest you get this publication, written by those who have "been there, done that" and read it through several times before beginning.....
http://www.jagsthatrun.com/Pages/Chevrolet_S-10_V-8.html

As far as a 305 vs 350, consider that the 305 has a tiny little 3.736" bore compared to a 4.000" bore on the 350. This alone would be reason enough for me to begin with a 350 block. There needs to be enough room between the edge of the intake valve and the cylinder bore to allow a nicely-formed kernel of mixture to pass into the cylinder without it being deformed by the proximity of the valve to the bore. This is tough to accomplish with the small bore, unless you use really small valves and really small valves defeat the purpose of doing an engine swap in the first place.

Now, having said that, realize that there are probably millions of 305's out there running every day and serving their owners admirably. You just need to pull your horns in concerning power expectations between a 305 and a 350. Anyway, that's my opinion.
 

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Cruzin w/Elvis in Bigfoots UFO
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You might want to look into warming over your 4.3L over the 305 swap. Later model Vortec heads, mild camshaft and exhaust improvements should buy you considerably better breathing and the shortblock will never have to come out. It's got a lot going for it compared to a 305 swap.
 

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many issues including exhaust engine mounts and more.

ECM/chip change, bigger injectors,

radiator and fan issues

etc.

4.3L dont seem to be any better fuel mileage than a v-8

none that ive ever owned have been anyways

i the 4.3L runs fine then id probably leave it be

these 4.3L run great and strong when in good condition

my 197k miles 92 one is staying put because it runs so strong it will roast the tire off the rim for as long as i want to

only mods are that i modified the uel pressure regulator to increase fuel and it has full custom y pipe and dual split exhausts and no converter


very easily and will outrun pretty much anything i want

much fun

no need for a v8 in mine
 

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motorhead09 said:
I was wondering how hard it would be to drop a 305 or 350 into my '92 4.3L V-6 S10. I have a buddy who has all the mounts he'll give me and I can pick up a motor cheap but I wasn't sure if I'd need to pick up a new trans or not. I can find 305's for a few hundred and the 350s are just a bit more around here. Also would I really see THAT much of a power increase with a 350 over a 305, would it be worth the sacrifice of fuel? Trying to finish a project without dad's help for once so thanks for any help you can provide lol. :thumbup:
you will see a difference in a 350 from a 305 and a difference in a 305 from a lazy arse 4.3 gas addict. you will get better fuel mileage from a v8, if not the same as a 4.3. i never could understand the 4.3 over a 305 decision.
 

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not all 4.3 are lazy

you should drive mine some time


vehicle weight, exhaust system, and axle ratio make a huge difference


mine screams

evne some 305 i have had have been really super strong, more so than many bigger engines, especially the L69 305 engines in the 80s, 190hp ones which are common in the 83 84 85 86 years of F bodies and G bodies

just because its not big doesnt mean it doesnt run good

just look at the old 327 and 283 engines. they would scream. deeper axle ratio helps alot though
 

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techinspector1 said:
There is too much involved with any engine swap to address it here. I suggest you get this publication, written by those who have "been there, done that" and read it through several times before beginning.....
http://www.jagsthatrun.com/Pages/Chevrolet_S-10_V-8.html

As far as a 305 vs 350, consider that the 305 has a tiny little 3.736" bore compared to a 4.000" bore on the 350. This alone would be reason enough for me to begin with a 350 block. There needs to be enough room between the edge of the intake valve and the cylinder bore to allow a nicely-formed kernel of mixture to pass into the cylinder without it being deformed by the proximity of the valve to the bore. This is tough to accomplish with the small bore, unless you use really small valves and really small valves defeat the purpose of doing an engine swap in the first place.

Now, having said that, realize that there are probably millions of 305's out there running every day and serving their owners admirably. You just need to pull your horns in concerning power expectations between a 305 and a 350. Anyway, that's my opinion.
most late model 305's have the #416 casting head which are 1.84/1.50 valve, and have an intake runner size of the 350. probably wont breathe past 6,000 rpm, but at 6,000 rpm a smallblock in an s10 with a 3.42 gear is close to 140 mph. you cant beat the power to weight ratio.
 

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fast68 said:
not all 4.3 are lazy

you should drive mine some time


vehicle weight, exhaust system, and axle ratio make a huge difference


mine screams

evne some 305 i have had have been really super strong, more so than many bigger engines, especially the L69 305 engines in the 80s, 190hp ones which are common in the 83 84 85 86 years of F bodies and G bodies

just because its not big doesnt mean it doesnt run good

just look at the old 327 and 283 engines. they would scream. deeper axle ratio helps alot though
their power isnt worth the fuel mileage i get out of them. i vote 305 over a 4.3 any day. im sure yours screams but think if you had those 2 extra cylinders.
 

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Discussion Starter · #9 ·
Thanks for the quick replies everyone!

I don't really have any problems with the 4.3L other than the fuel consumption seems a little high for being a V6. Figured if I'm only gonna get around 18-20mpg I might as well upgrade to something with a little more balls to it... know what I mean?

I'm seeing most people are leaning towards the 305 which is nice cause those are plentiful here in Dayton, Ohio.

Still didn't see anyone mention the transmission. I've been told it will bolt right up while others have said I'll need to swap.

Thanks again for all the help :D I knew this was the place to go for help
 

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motorhead09 said:
Thanks for the quick replies everyone!

I don't really have any problems with the 4.3L other than the fuel consumption seems a little high for being a V6. Figured if I'm only gonna get around 18-20mpg I might as well upgrade to something with a little more balls to it... know what I mean?

I'm seeing most people are leaning towards the 305 which is nice cause those are plentiful here in Dayton, Ohio.

Still didn't see anyone mention the transmission. I've been told it will bolt right up while others have said I'll need to swap.

Thanks again for all the help :D I knew this was the place to go for help
if your v8 is gonna be stock to mild cam. i say a 350 turbo trans with a 400 turbo 13 inch torque converter. great down the highway with a 3.42 gear or higher. ive never got any worse than 15mpg with v8 s10s. ive got a 94 ss with a 4.3 right now that gets 14 mpg.
 

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my v-8 s 10 was a direct swap, from a 98 4.3 to a 98 5.7, trans mounts up, fuel pumps are the same, some relocating moter mounts from summit, v-8 s10 headers (wrap around the steering shaft), small modification to the firewall (dent it) bend up the pinch weld, some low profile electric fans, propor fuel/ecm setup and your driving, mods down the road (get it in and running right first) are mild camshaft, trans freshen up, rear end/gears, suspension upgrade (to get that light rear end to hook up)
 

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I did a 350 swap to my '95 S10 in about a week, including painting the frame, modifing the crossmember and getting it running. I scrapped the stock gas tank for a fuel cell and an Aeromotive fuel pump with -10 feed and -8 return lines. The work wasn't bad if you have all the tools. I did this in my driveway. The first time around the truck made 323hp and 322ft/lbs to the wheels pushing 5.5lbs of boost with a weiand 177 blower
 

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jkrestoration
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i put a small block in my s-10...hammered the lip on the firewall flush with it...set the motor as far back as it would go....had to put a small starter on it..used a TPT flex fan....a radiator out of a 89 corvette and used a 700 R4 tranny...gets 19 miles to the gallon....
 

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cobalt327 said:
Just curious- ever done any testing to see if leaving the rear gate on helps the aero? I heard it did...
Nope, it didn't come with one when I got it so I shaved everything. It seems to hook pretty good though since I twisted the splines on both 31 spline axles. :mwink:
 

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S10 Racer said:
Nope, it didn't come with one when I got it so I shaved everything. It seems to hook pretty good though since I twisted the splines on both 31 spline axles. :mwink:
Yeah, what I was talking about was the aerodynamic help (or not) it gave at the other end.

When the gates started to be replaced by aftermarket nylon webbing, the car rags commented on the OEM gates-if left in place- actually helped (or at worst, didn't hurt) mileage due to less aero drag and/or downforce.

Likely it doesn't make enough difference to be concerned with, anyway.
 

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My 88' with a 305/200R4 and 3.73's gets 23 miles out of a gallon during my normal commute back and forth to work. Sub 2 sec 60' times and mid 8's in the eighth. It makes about 100 passes a year, and I drive 43 miles one way to work. The tail gate being up or down makes not a bit of difference what so ever. Fuel mileage, ET, MPH............Nada..........Dan
 
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