Rupert carb problems..

[Birddog95]

Here's some info I can share. Rupert 1150 carb came with 172 jets, enderly belt driven pump with bypass loop and (i believe) 180 pill up to carb. The car ran awesome in Ohio (Base of 800' corrected 1900) and has now moved to Canada (base altitute 2300' corrected 4300'). I had a hard time getting heat into the car. I'd lean out till 155 and as soon as I shut the valve temp would start dropping. Dropped the jets to 164 and can now regulate temp (leave at 150 finish at 170) but I am going through an average of 2 gallons a run (towing back). Even the original owner said that is double what he used. Any suggestions would be appriciated.

[suicidebomb]

It's just a bit rich.

[hammertime]

where is the idle screws set @ ?

[Birddog95]

The air mixture screws are out 2 turns and idle is at 1400 rpms

[cepx111]

I'm going with Earl, your WAY to fat for the altitude your at, go down at least 10 more jet sizes.
Monitor your fuel consumtion and re-adjust as necessary, no way you should be using that much on one run - JMO>Cp

[hammertime]

The air mixture screws are out 2 turns and idle is at 1400 rpms

put them to 1 1/4, whats the fuel pressure ? also what size motor.

IMO your starting to get into a jet size smaller then I'd want, maybe a 1050 would be a better fit later on. Jet change will help it though.

[Birddog95]

The engine is a BBC 598. Now one thing I'm unsure of is when you say down 10 jet sizes your refering to numerical values right (currently a 164 down to a 154). I've alway been running gas and each steps down in increments of one where alky seems to step in 4's. (FYI I started at 172 jets). I'll try the idle mixture screws but with the bypass loop on the enderly pump at an idle I only have 2.5- 3 psi but as soon as I touch the throttle it jumps to 8. Should I be looking at changing the jet/ pill in the pump to limit the amount of fuel up to the carb?

[hammertime]

seems like a very small jet for that size motor, rule of thumb with a belt drive is 3@idle 8 on the transbrake.

[Birddog95]

Somethings F**ked! I went through 15 gallons of meth in 6 runs (including warm up) and we towed back! Runs were fairly clean 7.75 @ 170.3 Launching at 150 finishing at 170 degrees. I forgot to try turning the mixture screws back :roll: Air was really good here basically cause it was so cold (50F) corrected 2700 ft. Not sure what to do :?

[dparker]

You probably burned 3 gallons at warm up, your not that far off, You can save some fuel while idling with the idle mix screws. But you'll probably burn around 1 1/2 gallons a pass when its perfect. Are you milking the oil? If I don't pull my fuel cutoff back when I'm going to staging and to the line, Ill burn 2 gallons a pass also.

[Birddog95]

I just changed the oil after 20 passes and its really clean. I use Brad Penn's green oil and after letting it sit I can see a very light fog of meth contamination. I'd just like to get it set up so it's really consistant. It warms up fast with the lean out pulled, and will steadily climb once I push it back at 150 degree's (to around 165). My problem is that one pass we'll run a 7.78 and an hour later we'll run a 7:73 (with very close 60'- 1.103 to 1.106). I've heard once you get the tune up set, the car will be killer but untill then... trial and error.

[hammertime]

you have a egt ?

[shawnp]

I know there is incredible tech advice and many knowledgeable people on this board but call George direct. He built the carb and will have all the records for the carb. His phone is 931-372-9142.

If you bought the racetech I am thinking you may have bought, that car was bad ass and dead on the money. I think a little phone time with George and he has you right there.

[Birddog95]

NO EGT.....
Thanks Shawn. I've been trying to find a link on the web for George's website (I don't think he has one). I'll call him tomorrow to see what he has to say. :wink:

[shawnp]

Not a problem. Are you the one that ended up with Evan's Racetech? He said it went to Canada and a 598 with Rupert carb is what he had. If you got a buddy that loves that Racetech, I got one sitting here in Ohio that I will sell. LOL

[hammertime]

I am thinking its lean a little bit, would explain the et jump and the 20 degrees increase in temp

[Birddog95]

That's the baby!!! Sure drives like a dream. I'm sure that as soon as I can dial here in for the altitute/ weather change from Ohio, we'll be on a tear as well.

I'm thinking it's lean as well. I think I will change back to the 172 jets, turn in the idle screws a bit, and maybe lower the pump pill one size. I'm going to call George tomorrow to see what he says.

[shawnp]

Sweet. If you would be willing, would you post the results of your conversation with George and the outcome on the track? Thanks

[Birddog95]

I got to talk to George today and he gave me some interesting info. He wanted me to start with the base set up and then start leaning it out. After each run, subtract the 1/8 ET from the 1/4 ET to see if it is picking up. I think its time for another track rental....

[hammertime]

I got to talk to George today and he gave me some interesting info. He wanted me to start with the base set up and then start leaning it out. After each run, subtract the 1/8 ET from the 1/4 ET to see if it is picking up. I think its time for another track rental....

what is the base ssetup ?

[Birddog95]

I think he was refering to the 172 jets in the front and back. I stepped down to 164's right now but I'll go back and work my way down to see the difference. I'm suppost to call him once I have the info.

[Birddog95]

Ok, so I went today to a big buck bash for Top dragster to see If I could do some testing, Long story short, We enter the shoot out. Didn't want to mess with the tune up for a $8000.00 race. DA= 4400' ..88 degrees, track temp 120, Humidity 32%. The car falls off .12 from last week (DA= 3800') but the thing that blew me away is the 2.5 MPH drop. Since the beginning of the year our MPH has been dropping but the ET has been "relatively" constant. We started out at just under 171MPH and today we were 167.8 to 168.2 with a small head wind (5-7 MPH). Went 4 rounds at 7.85 only to break in the staging lanes for 5th round (sheered the teeth off the flywheel). We won $1,200.00 but now I'm wondering if I should send in the converter. The MPH we are running seems low. :?

[dparker]

I think now your a little rich. If you want the MPH back lean it back down, but then your not going to be as consistant. Your car will run more consistant rich and will run faster lean, your choice. You went up 8 sizes split the diff and try 168, maybe you can have both.JMO