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Alcohol carb

28K views 33 replies 13 participants last post by  Sbc406vega 
#1 ·
I just switched my braket car over to alcohol carb , with a new hp 950 holley carb, i blocked the rear power valve and added jet ext, and increased the jet size up 10 to start with.The car was way rich, i started lowering the jets down 2 sizes at a time untill the mile per hour started to drop off, 144 [square] now my egts are 1300 deg going throug the lights, [1/8] the coolant temp. still will not increase on the pass and off idle it is still rich [blubbers] driveing it around the pits. it seams to run good the spark plugs look good , the car is a 3400 lps nova with a 11/1 406 sbc mild mech roller iron eagle 215 heads with a glide also i never pick up any et or mph from the gas to alch switch, car still runs the same as it did last year when it was on gas. any help would be greatly app,
 
#2 ·
Try going up .005 to .060 on the idle air bleeds, it should help around the pits. Go up to .065 if it needs more, if it is still to much you need to go down on the idle jets, try .002 at a time. Also if the bleed cause a stumble on light throttle, go down on the idle jets instead. You can make your own with a drill index and brass set screws, stainless will work if you cant find brass locally. DO NOT use regular steel set screws. When you get it better you may be able to go back up a little with the main jets. What gear, converter stall, and ET is the car running?
 
#3 ·
THE CAR HAS 4.56 GEARS CONVERTER IS 5800 RPM STALL SPEED CAR IS CURANTLY RUNNING 6.85 IN THE 1/8 AT 99.50 , BE FOR I STARTED JETTING IT DOWN IT WAS RUNNING PRETTY CLOST TO THE SAME ET,S BUT AT 100.50 MPH , STOCK JETTING WAS 157 CURANTLY ITS GOT 144,S SQUARE THE AIR BLEEDS [IDLE & HIGH SPEED]ARE AS IT CAME FROM HOLLEY.
 
#4 ·
Your gear and converter are probably real close to optimum, since alcohol gains most around peak torque is probably why you are not seeing gains you may be expecting. I think alcohol shows more improvement when the gearing and converter are less than optimum, 11 to 1 doesn't help as well. And the reason for the switch to alcohol was hope for better ET or reduced fuel cost? If you were looking primarily for better ET you may have been better off with a well built Dominator.
 
#5 ·
THE MAIN REASON FOR THE SWITCH WAS FUEL COST AND consistency I WANTED TO DABBLE IN SUPER PRO AND THE 2 CLASSES RUN BACK TO BACK , SO NO COOL DOWN TIME WAS NEEDED AND THERE ARE ABOUT 30 PIPE RACKS [DRAGSTER] AND 2 DOOR CARS , REALY DOSENT MATTER IT IS NOT ANY QUICKER BUT I KNOW THE CARB IS NOT CORRECT AND I DONT WNAT TO HURT ANY THING,
 
#6 ·
Try the changes I suggested, and go back to the jetting that puts the MPH back up. You can lean idle and transition as much as you can as long as it doesn't cause a lean stumble, as long as you have sufficient fuel at WOT you will be fine.
 
#7 ·
That 11-1 Comp is killing you most of the fuel is going out the pipes at the Comp. Alky is very hard to light and it really needs to be smashed to make power. You need at least 12.5-1 or more Comp. I would say you are not going to gain any power but it we be more consistent and it will run cooler.

All the Alky carbs I have used have a flubery mid range that is how they are. Really I think you may be fighting an engine that is not set up to run on Alky.
 
#8 ·
Compression is a taste low but will still work. Temp wise (egt) you are there. The coolant temp should increase 10-15 degrees at the end of the run from the starting line temp. What temp are you leaving the starting line at ? Are you able to put any heat at all into the engine when started cold ?
Do you have a ball valve connected to a hose in the intake plenum to lean it out when warming it up ?

Are you running your water pump all the time ?

What fuel pump are you running and what is the fuel line size from the cell to the pump, to the reg, to the carb ?

I've raced an alky injected 406 for years and left the line at 170-175 degrees. Water pump running all the time the engine was.
 
#9 ·
thanks horndog i have a magnaflow 500 with a #12 feeding it from the cell , a #10 to a mangaflow reg and from there 2 #8s to the carb , i have a lean out valve [ball valve] but dont use it as it will heat up , i leave the line at 160 deg [ i also use a 160 thermostate] if i keep the fan and water pump on it crosses the finish line at 160 , if i keep the fan and water pump off during the run it crosses the stripe at 190 deg i keep the fuel pressure at 7 psi and it stays there all the way through the run, the egts ar around 750 to 800 at the starting line on the 2 step car leaves just as it all ways has and was blurbring with the stock jetting [157] i just kept jetting it down untill it made a clean pass now its down to 144 square , i click it off in the lights and pulled a plug the ground strap is showing heat all most to the bend the porslin is white with a nice black ring at the base of it. the timing is set at 36 deg and is locked there, as i stated it is very rich when just off idle , when driveing it back to the pits, when it just idling it fine and seams to be at wot, once in a wile it will shut off when i lift in the lights but starts right back up and idles fine ???
 
#14 ·
1300 is TOO hot! 1150 max on the egt in the 1/4
your compression is fine..don't listen to that crap...alky will pick up a low comp engine more than a high comp engine. St Louis area has been running alky in holley carbs since early 80s...yes early 80s thanks to 1 of our local racers. I personally have run it since 86 and ran a lot of 11:1 cr engines (jn 3600 lb car)that picked up 6 tenths in the 1/4 compared to box stock 750s and 850 gas carbs.
The off idle will always blubber...that comes from when the boosters start dumping fuel...don't worry about that.
Not to say out of the box holley alky carbs are good or bad...but you should have spent your $$ wiser and gone with BLP, APD (I only have used these 2, others Im sure make good product as well) or some of the others that are true carb gurus, not a bulk supplier.

Shoot me a pm with your phone # and I will give you the true poop on running alky without all the hype or mystery....it is EASY,.....too many over complicate it
 
#20 ·
1300 is TOO hot! 1150 max on the egt in the 1/4
Not true every combo responds different, you can change your egt by 200 degrees just by changing header size,,, there is no set temp for every engine also the placement of the temp probe has a lot to do with it,,, you should not use EGT to tune --There is no sub. for reading plugs
 
#16 ·
I RUN NGK #8S AND 9S THE GAP IS .035 MSD DISTB. WITH A DIGITAL 6 PLUS AND MSD COIL [ROUND ONE] I DONT REMEMBER THE NAME IM OPEN TO SUGGESTIONS , MY METERING BLOCKS IS THE STOCK HOLLEY BLOCK NOT THE BULLIT ONES, SO I WOULD HAVE TO PULL THE RESTRICTORS OUT AND TAPE THEM AND INSTALL REMOVABLE ONES 607 427 4368 TONY
 
#17 ·
I RUN NGK #8S AND 9S THE GAP IS .035 MSD DISTB. WITH A DIGITAL 6 PLUS AND MSD COIL [ROUND ONE] I DONT REMEMBER THE NAME IM OPEN TO SUGGESTIONS , MY METERING BLOCKS IS THE STOCK HOLLEY BLOCK NOT THE BULLIT ONES, SO I WOULD HAVE TO PULL THE RESTRICTORS OUT AND TAPE THEM AND INSTALL REMOVABLE ONES 607 427 4368 TONY
Drop that plug gap to 0.025.
Remember your running alky which means your trying to lite 2 times more fuel that when you were running gas.
 
#18 ·
Uncle with posting rediculous suggestions as .025 plug gap....you should have went with your 1st thoughts and NOT posted. AN MSD will fire .035 gap NO problem and that is NOT his problem!

You need to modify your signature line...it isn't correct any longer (if it ever was)

this is the EXACT BS I was trying to help the OP avoid....when having a situation...a bunch of BOGUS help does nothing!
 
#22 ·
Uncle with posting rediculous suggestions as .025 plug gap....you should have went with your 1st thoughts and NOT posted. AN MSD will fire .035 gap NO problem and that is NOT his problem!

You need to modify your signature line...it isn't correct any longer (if it ever was)

this is the EXACT BS I was trying to help the OP avoid....when having a situation...a bunch of BOGUS help does nothing!
i have been running alky systems inj and carb for over 20 years and i still learn something everytime Uncle Paul has a post, this guy has years of tuning exp on alky and has helped countless people set up there stuff on here he is just trying to help the guy set up a base line,, give him some credit man
 
#19 ·
Anytime someone is having a problem I always suggest they go back to basics.
1. Ignition: good wires, cap, rotor and if methanol drop the gap to start. A 6 box with the round coil isn't the hottest kid on the block.
2. Fuel pressure and more importantly volume. What pump and line size.
3. Where in the header is your EGT probe(s)? How far from the header flange? Have you ever tried a new one or has it ever been calibrated?
 
#24 ·
my .02

Have run an alky carb on a SBC with 1300 - 1325 EGT. Same motor with Toilet runs a bit cooler than carb did with nearly the same ET@MPH

A Vac reference port regulator can lower your fuel pressure at idel and give you max at WOT. Works well for me.
 
#29 ·
i was able to get to the track for some testing , i closed up the plug gap to .025 made 2 passes , no change, up the bleeds to .65 and it cleaned the idle up a little. made 2 passes no change, droped the front jets [main] from 144 to 140,s car pick up 2 miles per hour, gained 5 deg, of coolant temp & egts droped from 1300 to 1000 deg in the 1/8 , resst the plugs to .035 no change, put the air bleeds back to stock no change but the idle was a little blubbery , ran out of time to drop the rear jetting but i will try it this fri, night id it is not raining , car ran deadly cosnisent after the dropping the front jets 60 foots also pick up 2 and all the runs after the jet change were with in .0001 to .0003 all the way down the track. 60s 330, 594, 660 thanks for all your guys i think im on the right track. just not sure why it had high egts when it was rich and after i leaned it out some more they came down ????
 
#34 ·
i was able to get to the track for some testing , i closed up the plug gap to .025 made 2 passes , no change, up the bleeds to .65 and it cleaned the idle up a little. made 2 passes no change, droped the front jets [main] from 144 to 140,s car pick up 2 miles per hour, gained 5 deg, of coolant temp & egts droped from 1300 to 1000 deg in the 1/8 , resst the plugs to .035 no change, put the air bleeds back to stock no change but the idle was a little blubbery , ran out of time to drop the rear jetting but i will try it this fri, night id it is not raining , car ran deadly cosnisent after the dropping the front jets 60 foots also pick up 2 and all the runs after the jet change were with in .0001 to .0003 all the way down the track. 60s 330, 594, 660 thanks for all your guys i think im on the right track. just not sure why it had high egts when it was rich and after i leaned it out some more they came down ????
If your running 140's and im at 180 jets, no wonder my car shits out hitting 3rd gear. Too much fuel for my lil 406 sbc. What ever came of this TONY???
 
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