im looking for some help setting up/tuning my 650 dblpmpr. ive never really fiddled with carb tuning before and id like someone to possibly come lend a hand? or if someone could point me in the direction of a good shop for this kind of thing, thatd be kosher as well. its a 383, cam with ~.520 lift, 883 heads 2.02 1.60 multi angle, HEI ign any more info needed LMK
is it a demon double pumper?
no… its a holley as the title states, lol.
Hows it currently run?If it has no bogging or any current problems you may just need to start playing with the jets.Put new spark plugs in and make a pass,pull a plug and check it,if its white to lean,black to rich,tan is what it should be.
get a wide band, its the only way to tune
Is the carb new or did you buy it used?
i bought it NIB at an estate sale. in park/neutral it bogs and stumbles when i stab the throttle. if i pin it quick, it dies. if i gently bring my revs up, it runs ok. it seems to have the most issues in the 1800-2500 rpm range. i tried driving the car home from the trans shop on tues and the car was bucking and boggin the whole time like it was running low on fuel.
w/o a wide band you can do it with a vac gage. start with the idle circut adjust for most vac (in gear if auto) with the mixture screws. normally 1-1.50 turns out. dont worry about jets and pump circut to start(although that sounds like wherte the prob is)
^^^you dont need a wideband and you dont need a vac gage.
op, i know a guy in lkpt that is phenominal with tuning. he can get your timing and carb set perfect in no time. pm me for his number if you want.
also your carb is too big for that motor, itll work, but its big. and what intake it has will make a big difference as well on how this thing needs to be tuned.
for street cars and drag racing, the edlebrock/carter carbs are far easier to tune and are just as good. holleys really only outshine them in circletrack.
edit-did you check to make sure the floats were set correctly before you played with anything else yet?
i was told the carb is too small by a hand full of people. ive also heard and read that a vac gauge is the way to go. it makes sense to me. i dont know how else you would know where youre at? youre the first to say otherwise. im not saying youre wrong, just a lil more info would be nice. it has a performer RPM intake and i will also be spraying the motor.
a 650 is small for a 383. i run a 750 on my 355. w/o a vac gage is impossible. i do agree w making sure your floats are set correctly start with this:http://www.holley.com/TechService/Library.asp alot of good info on holley’s site
what list number carb are we talkin anyway(on the front of choke horn) 3310?? 4779? look and d/l instruct manual from holley. another suggestion is to set everything (pwr valve/jets/etc…) to stock and start from there
^^^i didnt know you were going to spray it…that makes a big difference. i can understand a bigger carb now. and its not impossible to tune it without a vac gage. learn to tune by ear, then drive it and see how it is, check a plug, and adjust if you have to. as i stated before, i know a guy that can tune your engine perfectly, if you want his number pm me.
how would you possibly read a plug in street driving situation. too many variables. for example the proper way to read a plug is to do a wot and shut it down immediately to read. not practical in a street sit. by the time you idle down to a stop the plug will read differently.
Dirty if you need a hand, you could swing by and i’d be willing to help
^^^umm, its actually really easy to do if you go out on a country road.
and if your plugs are getting black/wet from slower driving then you are NOT tuned correctly. my truck runs perfect. pop a header off and there isnt even black soot buildup. the inside of my heads and headers are light brown. im running a 750 on my 355, but its built up alot more and needs the carb. if your rich and you have to “clean it out” from slow driving its because youre dumping too much fuel which is pooling up in the bottom of the intake and as soon as you hit the gas youre dumping more which is causing the bog. which is why after tuning you want to take the car out on a country road around 28-3k rpm and do a pull to 6k or so, whereever you run up to to make sure it dosent bog or cutout or anything. drive it a week or so and check a plug to make sure its not too lean.
i tuned mine without a vac gauge at the begining too. but put one on later jsut to see what it was at. also the power valve should be half the total vac… i guess its the golden rule
check bowl level first, mine are 25% of the glass
wirte down everything how the carb is now ( jets, powervalve, turns per idle adj )
put new plugs in
turn the idle adj screws 1.5 turns out
start car.
turn each idle adj screw in 1/8 while jabbning the throttle once in a while and continue to until the car hesitates, wants to stall. right now all the screws should be really really close. turn each out a tiny bit so the car does stall/burp. there is a sweet spot, thats what u wanna find.
drive the car for a few miles just reg rpm and speeds.
pull over and pull some plugs, see what they look like.
dip into the throttle a lil bit see how the car feels and sounds.
if its lean or rich ( by plugs ) jet both pri and sec down or up 2 jets.
its a time consuming process but well worth it in the long run.
I spent hours driving around wny street tuning mine.
when i got it to the point of i though it was good, i put badazz’s brand new LM2 on it and the AFR was spot on. idle was mid 14s, cruise was low 14s, wot was mid 13s
i put a autometer a/f guage in my car and it mirrord the LM2. so those who say it sucks, come pull one of my plugs.
its nice to tune with the nitrous. i used my autometer to get it where i want and the LM2 told me the same reading on the bottle.
im not a pro at all, but id be willing to try to help tune it. feel free to call me 957 0377
It sounds like you need to adjust the accelerator pump to get rid of the stumbles.It should usually have a slight gap from the arm to the pump itself.Do both the front and rear pumps.Also the idle mixture screws do nothing after idle,so adjusting those will not have any effect on how it drives.They only effect idle qualty.So check float level( bottom of the hole when running)adjust idle mixture screws for best idle quality,adjust accelerator pumps and take it for a ride.If all is set correctly and you still arnt running right changes will have to be made to the carb.Jets,squiters,pump cams.