swissarmychainsaw

1976 Suburban 4x4
TH350
NP203 transfer case
2008 LS2, with cam and headers
MSD Ignition
Holley 670 Carb (vacuum secondaries)

This truck came with the LS2 set up for a carb & msd (I put the 670 on it).

I'm having some issues that I'd like to clear up, and I'm partly thinking of just moving to EFI.

1. Mild throttle stumble when you give it quick 1/4 throttle
(I think this means I need a bigger squirter)

2. Does not like to run when stuck on a hill (it's a 4x4! this happens!)
(I think this is just a carb thing, not running at an "extreme angle")

3. In the mountains ( ~8,000 ) feet It feels like it's starved for fuel when climbing on the highway in 3rd gear; feel like the secondaries are not producing enough fuel. Eventually I lose enough power and slow down, then it will downshift into second. At higher RPMs (in second gear) it runs fine with the pedal down.
(not sure if this is angle or elevation, or throttle, or vacuum!)

I'm a weekend warrior and not a carb guy. I'll tackle it with the right advice, but right now I have more money than time and am considering "fixing" this by bolting up some Holley Sniper EFI and driving it!

If you recommend tuning the carb, what "kit" should I get for this?

So... Learn to tune the carb, or move to EFI?
thanks,
Nick

Doug G

Any time you use a carb on a 4x4, I would highly recommend an off road float kit

http://www.allcarbs.com/detail.php?p...&ctgn=45&stt=5

As for the starving at higher elevations....I would say it needs more tuning.

BUT, yes, FI would maybe be easier in this case ?

TXsilverado

iTrader: (18)

get a wideband and give us real data. throttle percentages vs AFR and RPM if you can log it.

swissarmychainsaw

Good tip! Found a good article on making your carb more off road worthy.
http://www.fourwheeler.com/how-to/en...ad-carburetor/

Doug G

Been there, done that....back in my muddin' days, truck get a bad bounce, floods, shuts down, friends laugh because you look stuck, ETC.....fix it

Pop N Wood

iTrader: (1)

Yep, need a wideband to tune effectively. It will be some simple adjustments that will take some time to get right, but no question you can fix what it if you are motivated.

Carb or EFI is a question only you can answer.

Holley sniper kits are pretty pricey. Maybe better to source a stock pull off and put that on.

swissarmychainsaw

I'm a bit concerned that by the time I get this carb running right, I'll have close money to the sniper kit.

Hot Rod did an article on this and they spent $1000 on stuff.

http://www.hotrod.com/articles/ccrp-...g-tips-tricks/

+ a $400 carb and Suddenly that Sniper is not expensive at all!

I'm new to the wideband thing. Seems that not all of them actually log data (is that a separate box?).
Please point me in the right direction at a Wideband with logging capabilities. Also seems like sample rates/averages are important.

Thanks!

TXsilverado

iTrader: (18)

log it the cheap way. go pro or cell phone on the tach and wideband.

swissarmychainsaw

Ok Wideband is on the way.

Still not sure if I should buy some kind of Holley Jet kit, "tuning kit", squirters or what.
First will install the Wideband and go from there.