4.3 liter questions

K45

K45

Active Member
Joined
Feb 21, 2007
Location
Statesville
Was curious who all here are experts on the Chevy 4.3 motors. I am familiar with them but not an expert.

Whats the best years of the 4.3?

Is the vortec that much better than the regular 4.3?

Does the computer controls have to interface with the tranny?
Some motor controls have an interface with the tranny and I want to see if a 4.3 will bolt up to an older 700r4 tranny.

What disadvantages and advantages of this engine?

Thanks
 
I used to have a YJ that I installed a 4.3 in. My research found that the strongest year was the 93 model with the CPI, central port injection. The computer does control the tranny if you are using the 4L60E. I learned this the hard way: I bought the 93 engine and computer and a 97 model 4L60E. Well, in 96 or 97, chevy changed how the computer gives a signal to the tranny slightly, so my tranny never received the proper signal to lock up the torque converter. For a trail rig or a rig you just drive around town it was absolutely not a problem. But if you are building something you want to drive on the highway, don't get a pre-97 computer and post-97 4L60E tranny.

The advantages was it was a dang strong motor. the disadvantage, besides what I mentioned already, was that the spider assembly, that is the fuel assembly in the CPI motors, has a tendency to start leaking into the cylinders. I had to replace mine.
 
I've owned a 98 S-10 LS 3rd door, 2wd 4.3, 4l60e since 02 and it has 170K mi. It gets 20-22mpg around town and runnin 75 on a 46mi. roundtrip to work on I-40 and I put my foot in it alot . It has 215 75 15s instead of factory 205 75 15s. The tranny or TC went at 155K and was rebuilt. The guy told me he fixed it to lock up sooner cause I had trouble w overheating towing a 18' boat in summer heat. It has been a good engine IMO and I did drive it sensably until 5 yrs ago when the ac quit and I did'nt want to spend 800 fixing it. Since then I've rode it hard and it just keeps runnin while the rest of the truck wears out!! It is TBI and I think 190hp.
 
I just put a 95 CPI 4.3 in my buggy mated to a TH350. The vortec's do produce more HP that the standard 4.3's. Typically every generation of 4.3 gained some HP.

The early's (up to 91 i think) are true TBI's
92-95 were both CPI or TBI
and 96 up to the block change (LS block style) is the CSPI.
Anything with a 'LS-style' block you have to either switch the flexplates or get an aftermarkert flexplate to mate to a 700R4 or TH350

I use a TH350 behind mine with a full manual valve body. The computer has no control over shifting the trans until the 4L60e was used in either 94 or 95 on. (i.e. he 7004R and 4L60 doesn't need computer control however they still require a correctly calibrated kickdown cable for downshifting) All years but the TBI's require a VSS for the computer which you have to figure out if you mix and match transmissions. I don't run one on my CPI, but it keep the engine light on and sometime dies if the pedal is released from wide open throttle which is a result of no VSS. I like mine and there solid motor with a lot of torque for their size. Plus in a pinch, most sensor, accessories, etc can be used from the common SBC 350.
 
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