Greetings,

I'm running a 22 tall block punched .020 over with some Pistons and a 20r head. From what I can tell there has been a bit of polish work done to the intake runners. TRD stage 2 cam, not sure on valves. 2.25 header to magnaflow exhaust. Weber 32/36 for fuel fed by a Holley FPR, set at a whopping 6 psi by the previous owner. The 32/36 is showing it's wear, and from what I can tell, is not running factory jets. Motor runs great in the low to mid rpm but does not want to rev too far borth of 4k rpm. Any suggestions on what to do carb wise? Try a stock 32/36 or maybe a 38? Throw richer jets in the 32/36? I know I need to get fuel pressure down to 2-3psi, but I'm at a loss on how to do it. Any of you hybrid guys mind sharing your jetting? I'm in vegas so not very high elevation. Thanks

 

Swap to a lower pressure fuel regulator

 

Holley FPR I'm running is adjustable. When I dial down to 2.5-3psi truck seems like it's screaminf at 3k rpm. My guess is no fuel. Tried richer jets today. Something along the lines of

Idle- 60/50
Mains-150/160
Air corrector- 170/180
Pump- double pump 55

Truck runs better, mix screw about 1.75 turns out. But idle screw has to come in 2-3 turns. Idle too lean? Also, seems to stukble pretty bad off idle. If you ease into throttle no problem but if you mash te gas she bogs down bad. Truck revs out to 4-4.2 k now. Still not what Im shooting for but better. Any ideas?

 

Sounds like the typical problem you get when running a 32/36 on a moderately built engine that demands more fuel. Same thing was happening to me when I had a 32/36 on my engine (completely rebuilt, bore .020 over, desmogged, Rock Ripper headers, 2.25" exhaust) and no matter how much I re-jetted the carb, I couldn't fully alleviate the hesitation when mashing into the secondary barrel. I ended up bumping up to a 38 and I haven't had any problems since. Performance is great - more HP, more torque and only a 1-2 MPG loss in fuel economy.

 

Sounds like my build is very similar. 2 quick questions.

Is stock jetting in the 38 working for you?

When you say 1-2mpg worse, ballpark where are you at? I can't seem to get more than 12mpg at the moment.

Also does the 38 do okay at weird angles?

 

The stock jetting was damn near perfect - I hardly had to adjust the mixture from baseline settings. I've been getting anywhere from 18-21 MPG with the 38, but typically my lower MPG comes during times like now when I don't drive it often. Lately I've been driving it two to three times per month because of the weather (I don't drive it in rain and snow after the restoration). I imagine that the lower fuel economy lately has something to do with evaporation; however, the fuel economy is certainly better when I am regularly driving it during the warmer months. I can't speak for the driving angles because I do not wheel my pickup, but I imagine that it operates pretty much the same as the 32/36 does at certain angles.

 

I really appreciate your time. Sounds like it might be about time just by a 38 kit and throw that on. 18-21 is pretty stellar. Even with some loss for the big tires I will be happy if I can clear 15. Thanks again, seems like this is the way I need to go.

 

You'd be surprised at how bad old carbs can be. I'm well versed in rebuilding and tuning carbs; however, when I first bought my truck I couldn't get the original Aisin carb tuned right to save my life. I rebuilt it twice, replaced the jets and still couldn't get it tuned properly! The previous owner was an absolute idiot plus I still maintain that the Aisin carb has got to be one of the hardest carbs to tune...EVER! I was getting 8mpg, MAX. I ended up switching over to a 32/36 and I was able to get 17-19 mpg on an old worn out engine. After I completed the restoration, that same 32/36 would get me around 21-23 mpg (sometimes a lot higher) but it simply didn't have enough volume to feed the engine. That's when I went with the 38 and never looked back.

 

Lol my aisin carb is a complete mess. I'm getting 21.8 mpg but it won't stop running rich. I think I can get about 24-25 with the 32/36. It also bucks in first gear. Just chiming in on the carb problem life. : )