holley fuel injection???

[Steve GMC]

my dad has a 1986 k30. crate 350/400/205 with 4.10s bone stock 32s. it is his work truck (small construction company owner, the trucks a DD) and gas is killing him. right now it gets about 6 mpg. he was considering a built 700r swap but the guy we talked to said he would do everything including build the 700 and install it for 2 grand. i was thinking take the carb off and put on a holley kit like this http://www.jegs.com/i/Holley/510/502-20S/10002/-1
he said he would consider doing that. he really dosent wanna do the tranny. i also have a 4" lift ready for it (because he already wants to lift it) so with 35s i figure the 4.10s would do better too, has anyone went from Carb to TBI using that kit? how much of an improvement on mileage was it? or mileage from just a stock TBI swap?

thanks guys

Steve

 

[Hossbaby50]

I don't know about the digital systems but I know the analogs are a PITA to tune right. My best friend has one on his Truggy and he said the would never consider putting the same setup on his DD K20. Personally for that kind of $$$ you could get a TBI swap done and it should run well.

Harley

 

[shaun89]

smaller carb?...for now, im sure you have some laying around there in the barn, maybe the carb just isnt working right. what does he get around town for mpg?...or maybe he should let smokey drive

 

[Chevy305]

6 mpg? Thats terrible! I think something has got to be off it thats all he's getting...

Try adjusting timing, or do a tuneup

 

[Steve GMC]

q jets came from the factory as 750cfm IIRC. does anybody think if i went to a holley like 600cfm if mileage would be better? its all because of the small tires and non overdrive. on the highway at 65 its at 3200rpm

 

[Thunder]

O-Jets only deliver as much CFM as the engine needs. They are regulated by the air valve. If properly tuned they mostly run on the 300 cfm primaries. Even under full throttle a Q-Jet wont (or shouldn't) open fully to 750 CFM on a stock 350. So going to a smaller carb wont help. Properly tuned, a Q-Jet will give better milage than any aftermarket carb.
Going to 35" tall tires should help. They will drop the 65mph RPM down around 2600. Try to stay with as narrow of tire as possible. More width =more air resistance=less MPG
How is the tune? cap, Rotor, wires, plugs, ECT, How old is the carb? It may need rebuilt.
Does it have the orginal cat convertor? It may be clogged. In any case better free flowing exhaust will help.
As far as the Holley system you linked. I had a old projection system many years ago. It worked but needed constant adjusting, ann the fuel injectors liked to leak. I have heard the new ones are better. But you still tune them with knobs on the ECM. You may pick up a couple of MPG if you are lucky and can keep it in tune.
IMO
A stock GM TBI system would be a better cheaper conversion.

 

[Steve GMC]

the carb is original from 86 but was rebuilt, new cap rotor plugs and wires with the new engine, since its a k30 it didnt have cats from the factory and we put on headers and dual flowmasters, with instaling a GM tbi setup would all the wires behind the dash need to be changed? i know the fuse boxes are different from carb to TBI

 

[dyeager535]

Well the easy answer is to slow down.

Q-jets were 750 or 800CFM, as mentioned it doesn't really matter though.

 

[shaun89]

steve...like i said, just let smokey drive.

 

[supersize75k5]

go to a well tuned carb or factory fi..

I havealready done my share of cussing at two holley kits, through money at it..cussed, through more money at it..cussed, had 4 people over who cuss at their kits..and finally took it off.

really a nice option would be to buy a second smaller truck, like a ranger or s10.. use it on the light work days or the days he wont need a large truck. Plus its always great to have a back up.

 

[odin]

My truck is similar to your Dads 350/TH400/NP205 and its my daily driver. I was getting about 7 MPG combined city and highway with 4.10s and 33s. I converted it to tuned port fuel injection, off an 86 5.7L Z28. Mileage and horsepower have gone up noticeably. 12 MPG city and slightly better highway. Not to mention low end torque!
Its not as complicated as it sounds and all the parts cost alot less than that aftermarket setup. Look for 86-89 IROC Z28 5.7 TPI setups, a complete one should run about $400-$800.

 

[Chevy305]

swap in a standard trans like the NV4500, his mileage will be SOOO much better without the engine powering through the slush box and OD.