Thoughts on EFI upgrade

[zieg85]

OK here is the deal...  My 1985 C-20 has a 454 and has a little over 130K miles on it.  As far as I know the carb has never been touched and is in need of a rebuild.  It still has the plugs for the air/fuel adjustments and when it is idling there is a strong fuel smell even when warmed up and it does not have a smooth sounding idle from the still factory dual exhaust that is original.  It also is the 8600 GVW that does not have catalytic convertors.  For starters it has needed a choke pull off ever since I got it and I have to keep it going until it warms up enough for the electric choke to take over.  It also will not pass our emission testing but I went to a larger weight rated plate for an additional $50 a year to be exempt from testing. 

1) What years for donors should I be looking for?

2) Would the conversion be worth the effort well knowing a proper operating quadrajet has gotten me 15-16 mpg in the past.

3) In the long term I would like to use this power train to pull a 5th wheel doing mission work and will really be looking for long term durability and simplicity.  When I open the hood now it retains everything it did when it rolled off the line including every vacuum line, and dual smog pumps.

$300 is what I have been quoted to make my carb brand new and adjustable.

 

[VileZambonie]

No matter what you do, a carburetor has to essentially be torn down to calibrate it. Idle mixture screws will have very little effect at all other than idle quality. So as far as adjustable goes your qjet is already as adjustable as possible. You can knock the plugs out and play with the idle mixture screws. EFI is a great upgrade but you will have to do some work. I am putting TBI from a 93 Suburban on the bb I'm putting in my 74. Is it a lot more work? Yes but I prefer EFI. Any 87 - 95 tbi system will work. The earlier models are easier to implement.

[Stewart G Griffin]

Question #2 is the key...

i've debated this alot.  And i've decided that given the amt of time it will take to get an efi system running, in addition to the savings amount, i think i will be better off sticking with carbs both money and time-wise.


It all boils down to numbers---how much driving will you do?   Based on the miles that i do, and efi conversion for me does not add up.


Now, having said all that, how plug-and-play is the ramjet system from GMPP?   What about the accel super ram?
Part of what makes an efi conversion make sense, to me, is how fast/easy you can get the system up and running.   This is mostly if you just enjoy efi and would like it, not really doing it for the financial gains......


P.S.  i dont know---maybe you should check out one of the more hardcore efi forum on the web if you're really interersted in it:
http://coloradok5.com/forums/forumdisplay.php?f=81

[VileZambonie]

What makes the most sense to me is that you can grab a donor factory system from an equipped vehicle for free in many cases or dirt cheap. With very little $ you can make the system work very well and have all of the luxuries of fuel injection. Sooner or later you should graduate to some newer technology anyway before it passes you by...(not that tbi is new technology) but I think you know what I'm saying. The guys that are doing LS swaps more and more frequently are doing so because it's a relatively inexpensive upgrade with newer technology. Better power and fuel efficiency at the same time is nothing to turn down because it would take a few more hours to set up in my opinion.

[Stewart G Griffin]

More, deeper, comments concerning EFI later.

i have to finish shopping, but i'm afraid of the mall traffic.

[zieg85]

No matter what you do, a carburetor has to essentially be torn down to calibrate it. Idle mixture screws will have very little effect at all other than idle quality. So as far as adjustable goes your qjet is already as adjustable as possible. You can knock the plugs out and play with the idle mixture screws. EFI is a great upgrade but you will have to do some work. I am putting TBI from a 93 Suburban on the bb I'm putting in my 74. Is it a lot more work? Yes but I prefer EFI. Any 87 - 95 tbi system will work. The earlier models are easier to implement.

When did TBI become available for the 7.4L?  I looked at a 1987 and it still had the carb.  Did GM get fancy with vortec heads on the big block needing a special intake or were they all the same?  I would go the donor route, obviously a 7.4 TBI in a Crew cab stick would be perfect canditate, especially for the in-tank fuel pumps.  

My biggest fear is to go through all the work and not achieve the mpg I get right now.  

[VileZambonie]

87-91 R/V were available in both Qjet and TBI models. The 88 up C/K models were all tbi. Vortec heads were for small chevy. The BBC intake and heads were iron and not very geared towards performance. A simple upgrade is an aluminum intake and tbi adapter plate.

[zieg85]

Vile,  Thank you for your time today in responding.  I guess I will start my search for a donor truck.  I am not into performance as much as effenciancy.  I know what my truck does now.  It can pull my car trailer with a full size truck on it effortlessly.  I know I can be in 4th gear by 30 mph and the engine isn't working at all and if I ease on down on the go pedal I am going 60 before I know it.  I also know the sweet spot in gas mileage is 60-65.  If I travel the Indiana speed limits of 70 I loose 2 mpg.  Have a Merry Christmas

[VileZambonie]

Zeig, although I am all for efi, why not just rebuild the carb in the meantime and see what happens. $35 bucks in parts is worth a try first.

[Stewart G Griffin]

1) Here is a somewhat detailed ,and quickly becoming famous, thread on TBI swaps:
http://67-72chevytrucks.com/vboard/showthread.php?t=352321

a) Keep in mind the sheer complexity of the swap AND keep in mind the amount of time it took for him to complete the swap---3 1/2 months!  


i'm not saying no to EFI;  Don't get me wrong---i love efi/tbi;  It's what i have on my cavalier and it has worked great for 280K+ miles.  i also acknowledge that EFI is superior to carbs.

It's just that, in my situation, i bolted a 2G to my manifold and in about 15mins, i had the truck running.   In the above link, it appears that he actually had some aptitude for electronics and it still took him 3.5 months.   If i were to try that................?

In fact, what i am saying is if you really like EFI/TBI etc.  then go for it!   Just be aware of the time, complexity, and possibly aggravation it will take.

a)  If one really wants to go hard-core, i would recommend the megasquirt system and custom build and select components to make up the system.

[zieg85]

Gears are a spinning now.... Getting off the path a bit I found a 91 GMC 3500 dually, perfect candidate for the SB conversion I always wanted... and a 90 Suburban 454 that fits the donor vehicle.  Both I will look at next week and post my findings.

[Captkaos]

The TBI on all 454s EXCEPT the 454SS pickup only differed from the other TBI's by the ECM Chip and the injectors.  So you could get a donor off a 4.3L or 350 if you wanted and just get the specific injectors and a chip.

Mega Squirt is NOT hard core.

[zieg85]

Obviously I am a newbie big-time when it comes to TBI.  What underhood/ecm wiring differs?  Will it be self explainatory when/if I tackle this project.  I am looking at a 90 Suburban with a 454 so there is the intake with the throttle body and underhood wiring-ECM.  I only need to figure out the best path for a fuel pump.

[Captkaos]

If you have a Donor 454, take all of it and swap it over.  It will be pretty explanitory.  Howell has a harness if you would rather do it with a new harness.

There is no difference on TBI wiring for SBC vs BBC.

If the tank in the burb is 28 or 31, get it and the lines and rebend them for the truck, OR get inline tube or classic tube to send you new lines for a 87 TBI truck.

[malibu795]

EFI made stupid simple by FAST
http://www.fuelairspark.com/ezefi/default.asp

remove crab
install efi throttle body housing
hook up linkage
remove mech fuel pump
install efi in-line fuel pump
drill hole in exhaust collector
weld O2 bung screw in 02 sensor
connect +/- wires
set desire AFR for idle cruise and WOT
then drive..

heres the instructions for it.. PDF .
it goes in pretty basic functions... good info as well.. and a good read basic mechanac skill is all you need for this and 8th grade reading comprhension 
http://www.fuelairspark.com/Instructions/Files/FAST4-152%20-%20EZ-EFI.pdf
thats roughly all you have