4.3 to 5.7 swap (not about the install more of a what do I wanna do before I install)

Discussion in 'Chevy C/K Truck Forum' started by Mike TattooMan Burton, Oct 25, 2011.

  1. Ok so I score this 5.7 vortec out of a 98 100k miles complete motor, starter all the accys EVERYTHING.. The complete uncut harness and the ecu.... and I payed....get this.... 275 for it all... Talk about a beautifull day in central Texas... Ok so as tempting as it is to spend a few hours tomorow and put it in... I think I am going to do somethings first the thing is what to do.. I am forsure putting an oil pump and main bearings in since it is sittin in the bed of my truck and not under the hood... I am replacing the head gaskets, intake gaskets, and valve cover gaskets. I am thinking about putting a cam in. Are there any cams any one would recommend? I want it to sound good with a good lope but nothing too outrageous. The main reason I am swapping the 5.7 in place of the 4.3 is to be cool:glasses:. The 4.3 has plenty of power, but I want more. I take alot of road trips that some times have me going up 2 mile long hills with 7% or some times better grades. I dont want to downshift, my 4.3 can almost do it, well I guess it can but way out of the power band so I have nonuts (kinda like donuts). My mother has a 98 z71 with a 350 and he truck takes these hills with no problem. So I figure if I can find the right cam in this motor. I should be able to maintain speed up these hills with no problem.. (Being able to smoke the occasional rice burner would be super cool too) but what is most important is sound. I am putting a flowmaster system in so I know that will help a bit (though am open to suggestions for exhaust as well im thinkin american thunder) This is a project truck and my end result is a daily driver that I can take to a show if I so choose.

    One thing I do have a question about is my flywheel. The donor truck was an automatic, my truck is a standard. Can I take the flywheel off of my 4.3 and put it on the 5.7? I know they share alot being the 4.3 is a 5.7 minus 2 cyl. I am just unsure about balance and what not.
    Another question is clutches. I am already planning of course on replacing my clutch. I want something that grips but I am not sure I want to go with a brand like centerforce.

    Headers? I know they are not created equal. Im thinking just about any headers should bolt up to the stock exhaust right?

    I guess my last question is, the mounts... I shouldnt have to do any thing about that right? The new motor has the mounts still... it should drop in and mount right up?

    Im thinkin since I got the complete system, motor, harness, and ecm. This should be a pretty easy swap with no modifications or problems. The motor was running right before it was pulled... Nothing was disconnected or removed.

    I should be able to just drop the motor in, bolt down the ecm and plug everything up and connect the fuel line. Start her up and drive right?
  2. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    Wow that was a score!!! I got a 94 lt1 complete for $700 with 84,000 and I thought that was a steal lol!

    As far as headers go If you stay with shorties you can keep the stock exhaust, but I can tell you that on my 5.7 I have HOOKER long tube competition headers and it sounds wicked nasty!! At full throttle it sounds like your at the drag strip, which is what you would want.

    My dad had some reliability issues with centerforce clutches in the past, poor design and shoddy materials. He has been using ZOOM clutches for the last 15 years, and they are still going strong. (57 chevy, and 66 chevy c10)

    I ran into a problem on my firebird when going from a 6 to an 8 with the gauges, the sending unit sends out a certain reading to the gauges to let you know the fuel level. On mine the flow rating was close enough I kept the 6 cylinder pump, and have had no problems so far. You might have several of your gauges not working after the swap, just be prepared to possibly have to change out some sending units.

    This post might be useful or useless, either way back to the top of the list!!
  3. silverhobey

    silverhobey Rockstar 3 Years 500 Posts

    she'll rock when you are done ....good luck....I wonder how many horses a 5.7 pushes ???
  4. dunno about this exact motor, but from what I have seen somewhere around 250ish though depending on the it could be as high as 290 hp. Im thinkin I prolly got the 250 hp one. That is still one hell of a jump from 160ish that comes with the 4.3 ( Though I have read some articles that the w vin version of this motor that comes in the trucks and vans has 190 hp, which I firmly believe is what my 4.3 has due to how strong the motor is) Either way for 275 bucks 90 hp is a good hp to dollar ratio. I know I sure wouldnt get 90 hp by any bolt on or series of bolt ons that I could add for 275
  5. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    Hey like others said-even DEAD STOCK it will feel like a rocketship next to your 4.3
    My 1998 Suburban-217,000 miles-5.7 still has plenty of zip when I get on it.
    It is only rated at 250 hp- but they are stout horses- none of those phony Ford or Dodge ponies.

    I would be greatly tempted to leave it dead stock cam wise-since any peak power you add on top will have to be paid for with less torque/power at lower RPMS which is where you actually run these motors.
    Of course-I'm old-60 yo- and think like an oldster- more into mpg and reliability.

    You didn't actually mean you were going to change the head gaskets did you?? It is a little pricy to do that BUT more importantly WHENEVER you pull something apart that is working well there is a fair chance something will go wrong when you put it back together.
    If the headgaskets were good-they are still good.If they were bad there is a fair chance the motor was trashed because of the bad gaskets.

    The 5.7'S AREN'T KNOWN for having head gasket problems- I would let them alone.
    The 5.7's are know for having bad intake manifold gaskets-100% change those suckers out- it is a 8-10 hour shade tree mechanic job when it is in the engie bay-and it costs you $25 worth of coolant.
    I think I used FEL PRO gaskets-there best ones- #98000 I think?? Cost about $70 set- supposed to be better-some fancy synthetic rubber-silicone+ stainless steel in gaskets.Supposed to be the final fix for intake manifold dexcool problem

    Did mine 1.5 years ago- no problem since-fingers crossed.

    PS-MIGHT LEAVE THE BEARINGS ALONE ALSO-100,000 miles isn't many miles on oem bearings-5.7 not known for wearing out bearings
    PPS I always have a learing curve when doing new things or things I do once every 10 years- so I screw things up-especially when I fix something that isn't broken.-MIGHT BE IT IS JUST ME, but I can screw things up that I don't do on a regular basis.
    Last edited: Oct 29, 2011
  6. Pedro

    Pedro New Member

    In all due respect to the above post, I believe a mild cam could be justified in your application. Something like a 214 int 224 exh would give you good low end and mid range torque, and a noticable change in idle. However I've always worked on the carbuerated small blocks, so I'm not exactly sure how the computer would handle it. I'm thinking you'd lose fuel economy with a cam such as this, but it should run nice seeing as the computer adjusts to the engine. Nonetheless, you should talk to an someone experienced with building these engines and see what kind of cams he thinks would be best. I've got a 212 220 @ .50 in my 383 stroker and it pulls a load nice, gets decent fuel economy, and doesn't lope. As soon as you put in a cam that starts to shake the truck you are looking at decreased engine life, and if you're going on road trips that would be undesirable, no? I may be contradicting myself seeing as I suggested to you a cam that would lope, but it's up to you. You can put in a cam that would give you better low end without having a greasy idle. Something along the lines of 204-210 int and around 212-214 exh duration @ .50 I think. Cams can be very confusing which is why I suggest you speak to a professional about it. I still have troubles wrapping my head around them at times and I'm confident in my knowledge. Putting the wrong cam in can rob you of your power and fuel economy and trash the engine very quickly. Been there done that. If this is too much for you to put into consideration just stick with the stock cam. That way you know you're safe. Best of luck.
  7. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    I'm pretty sure you are right- the electronics will easily adjust to any mild cam.

    The electronic controls make it MUCH easier to put bolt on parts on- not more seat of pants fooling with carb jetting or ignition timing-the ECM does all that heavy lifting-within reason-fuel injection systems have upper limits-a system built for 250 hp probably can't keep up with a 500 hp motor-injectors will be too small.

    Still the OEM engineers are pretty smart-they chose a cam that would max FE, throttle response,and low rpm TORQUE/POWER. A higher hp cam will give up a bit of one of these qualities.
    The cam manufacturers used to offer "tow cams" which were supposed to minimize the loss of low RPM power/torque. Guess they still do.
    I'm old,so I've kinda lost my need for speed-I like mpg and reliability now-typical oldster.
    PS NOW GOING TO A STROKER MOTOR- more displacement-will allow more cam without giving up low RPM torque- fun but expensive . I would love to put GM's 383E drop in motor in my old Suburban-lotta bang for the $$-$5000 for 90 reliable warantteed hp is really cheap, but since I don't have a spare $5000 it won't happen.
  8. silverhobey

    silverhobey Rockstar 3 Years 500 Posts

    wow, Mike ....looks like you are getting lots of input / technical info...hope all goes the way you want it ....Will you post pics before/after the project, or during the project !!! thanks for a good read on my part !!!!...I don't know much about this stuff, but it is interesting learning for me !!!:great:
  9. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    Hey $275 for the entire motor ecu and "not fouled up wiring harness" is a HUGE bargain. It is one of the main reason used GM trucks are such good bets for DIY folks with not too much $$$. You generally can keep them going for 10-20 years much more easily than you can say a Toyota(good reliable vehicles, but generally more expensive to get parts for).

    Heck I'm just "next door" New Orleans maybe 700 miles from Central TX- I would make that trip for a 100,000 motor.
    Yeah, that is a great deal-it will make you truck much quicker much better tow vehicle AND it won't hurt your mpg at all!!

    Maybe someone here will know just how tricky it will be to install it-and AT motor- in a standard trans truck?? Worse comes to worse you could probably get a AT-4L60E for not too much $$.I'm guessing the MT is strong enough for the 5.7 but better check on that also.

    Better find out if that ECU will have any problems with the MT?? and like you said- bolting AT motor to a MT.

    Have you done A gOOGLE SEARCH " installing AT 5.7 in MT 4.3"- ??? SPECIFICALLY LOOKING FOR
    1)ECU INFO- using AT ECU with MT
    2)Changes required to bolt AT motor to MT.
    3) Wiring harness AT harness ECU to MT
    4) MT strong/stout enough for 5.7 ??

    Many folks do this switch-so there should be plenty of info out there on them.
    Might try searching Ebay- 4.3 to 5.7 adapter kit-specifically looking for the AT to MT match up.
    There are all sorts of kits out there-check ebay just to get info on what is in such a kit- not to actually buy the kit(unless it is a good price)

    Yeah that is a great price- I'm jealous-
    take your time- don't buy any other parts until you are dead sure just how you are going to do it.
    You can probably get a decent enough price for your 4.3 once you have the 5.7 up and running(don't sell it until you have the bugs out of the 5.7 install-maybe 2 months after it is running well-just in case)

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