Engine swap or fix the 4.3?

[Ruger_556]

My 4.3 needs an intake gasket, has a really quiet knock at idle (No idea what it is), ticks under load, and idles rough... Fix it or drop a 305 in? What do you guys think?

 

[sewlow]

If you're going to go to the trouble of swapping in a V8, do a 5.7. Same amount of work, better pay-off!

 

[BOTTLEDZ28]

^^^^^what he said!^^^^^^

 

[SCOTTYINWV]

I say find a good running v8, and freshen it up in your spare time. Let nature take it's corse on the v6 and swap when she blows. With a v8 and 3.42s, I don't see you loosing THAT many mpgs with the power to weight ratio.

 

[cjman250]

That or you can go to the place that I bought mine, got it for $1190. Their website is Warrenengines.com

Sent from my awesome S5

 

[TylerZ281500]

350 swap, no 305 youll get better mpg with a properl built and tuned 350

 

[great white]

So, before I give you my "opinion", what is the intended use of the truck? What is the transmission in the truck? What is the rear end gearing?

You seem to daily driver it with some light towing (approx 5,000 lbs) IIRC most of your posts.

Theses are all questions that are worthwhile knowing when choosing/building an engine.

The difference between a 5.0 and a 5.7 MPG wise is relatively small. 5.7 would make towing much more comfortable. As long as you resist the urge to go crazy with cams and induction methods, it should make a fairly calm daily driver with decent power and reasonable mpg. All things equal, 15 mpg on a 350 with the 3.42's and an auto in daily driving is a reasonable expectation. If it's all in good shape that is.

You need to consider the rear gearing, since the 4.3 is probably fairly lowly geared compared to the V8. 3.73's are a pretty good compromise. 3.42's could be pulled by a 350 but make it a little less fun towing.

If you're a 5 speed, you're pretty safe to just bolt it up (I'd change the clutch and assorted bits just because). Auto you have to look at stall speeds on the convertors. I can't say for sure, but I'm willing to bet a 4.3 converter will stall higher than a 5.0/5.7 oem truck.

Then there's cooling. Is the 4.3 rad the same size as the 5.0/5.7? Transmission coolers, oil coolers, fan shrouds, etc.

Then, at the end of all that, there's the economics of the situation. can you afford to have it down for a week or so? Can you afford the swap (don't forget the nickle and dime stuff like hoses, belts, etc are also in there)? Can you support the small reduction in fuel mileage that adds up over the year? etc.....

Lots to consider.

You're a tech IIRC, right? Best advice I can offer is don't be influenced by anyone else, do your research, answer yourself those things I've mentioned honestly and you should come to the right decision for your own purposes.

 

[TylerZ281500]

4.3 converter stalls at 2200 v8 stalss at like 1200 or 1500 or something stupid low. hes got an automatic if i recall so the added stall would benefit a slightly built 350 for sure.

as great white said for towing 3.73s wll help over 3.42s but if your mainly street driving it youll be fine with 3.42s

 

[Ruger_556]

So, before I give you my "opinion", what is the intended use of the truck? What is the transmission in the truck? What is the rear end gearing?

Automatic with 3.42's

You seem to daily driver it with some light towing (approx 5,000 lbs) IIRC most of your posts.

It's my daily... I ran the numbers for getting a second rig and the fuel savings would never offset the insurance. Right now I'm just commuting to work and school but I plan on buying a house in the next two years. At that point I'll be doing everything with it (Daily, haul lumber, tow a trailer around, etc...)

Theses are all questions that are worthwhile knowing when choosing/building an engine.

The difference between a 5.0 and a 5.7 MPG wise is relatively small. 5.7 would make towing much more comfortable. As long as you resist the urge to go crazy with cams and induction methods, it should make a fairly calm daily driver with decent power and reasonable mpg. All things equal, 15 mpg on a 350 with the 3.42's and an auto in daily driving is a reasonable expectation. If it's all in good shape that is.

You need to consider the rear gearing, since the 4.3 is probably fairly lowly geared compared to the V8. 3.73's are a pretty good compromise. 3.42's could be pulled by a 350 but make it a little less fun towing.

If you're a 5 speed, you're pretty safe to just bolt it up (I'd change the clutch and assorted bits just because). Auto you have to look at stall speeds on the convertors. I can't say for sure, but I'm willing to bet a 4.3 converter will stall higher than a 5.0/5.7 oem truck.

Then there's cooling. Is the 4.3 rad the same size as the 5.0/5.7? Transmission coolers, oil coolers, fan shrouds, etc.

Then, at the end of all that, there's the economics of the situation. can you afford to have it down for a week or so? Can you afford the swap (don't forget the nickle and dime stuff like hoses, belts, etc are also in there)? Can you support the small reduction in fuel mileage that adds up over the year? etc.....

Lots to consider.

You're a tech IIRC, right? Best advice I can offer is don't be influenced by anyone else, do your research, answer yourself those things I've mentioned honestly and you should come to the right decision for your own purposes.



I believe the 305 shares a radiator IIRC... I'm a heavy diesel tech.

I think I'll just fix what I got for now. I don't really have a good place to do an engine swap at the moment. The only thing that bothers me is the knock at idle... I don't think it's mechanical because it goes away with throttle. I took a broom handle and tried to find it but it's just a present sound without a location. It's not in the valve train or coming through the pan but it's louder at the back of the motor It's really, really quiet so maybe it's not important but it bothers me just the same.

 

[twomanymontes]

I'd just spend the $75 in parts and an afternoon replacing the intake gasket. I'm doing one this weekend. They are pretty easy compared to swapping the motor.