Ok here goes, Anyone run a race demon 750? Have had odd deals with this certain carb. We have now installed new HOLLEY metering blocks and it seems to run better at low speeds, -off idle to around 1800-2800- it used to surge,buck run rich and just really run like crap. Well now it runs so lean,-by looking at the plugs- I'm afraid it's too lean. 68 in the front 78 in the rear. This motor has had a out of the box Holley 750dp and it ran awsome, well it was my father in-laws and he wanted back. This demon carb was on a dirt car,did'nt seem to have any problems. They do run WOT. Maybe should back to HOLLEY, I cant finger it out. The motor is a 83 hr 30 over sbc with mild head porting, RPM Performer,flat tops and a LUNATI hyd cam, around 510 lift. Boat runs great for what it is, it just does not run as good with this carb. On a budget. Any ideas?
I have a speed demon 750 on my 383. Its working pretty good, its got a little flat spot coming out of hole. I have 78 in the primery and 84 secondary didn't have any 86. here a chart of the specs on the 750 carb
http://www.barrygrant.com/demon/default.aspx?page=29
I have a speed demon 750 on my 383. Its working pretty good, its got a little flat spot coming out of hole. I have 78 in the primery and 84 secondary didn't have any 86. here a chart of the specs on the 750 carb
http://www.barrygrant.com/demon/default.aspx?page=29
Whats your motor build?
my 383 (388 actually) has dart iron eagle platinum 200cc heads, crane 284H (228 @050, 512 lift (w1.6 rockers), 112LSA)Rhodes lifters, brodix dual plane intake, revolution exhaust.
I am running 80's up front and 84's in back with a 6.5 powervalve. Its a Holley 4150, but they are close enough to compare.
It seems demon carb jet size is greater than holley jet size, is this correct? With the holley metering plates, do I need to jet it closer to what a holley is jetted or do I go off the BG chart?
Here is what i have in my 383 with dart iron eagle heads with a dual plane eldebrock performer intake. I dont know what the cam is , it think it small cam. motor build (http://shop.enginekits.com/osb/itemdetails.cfm?ID=81)
Kraig
I would go with the stock specs. I talked to someone their at demon and they said that i should have went to a 650. They say that their carbs will flow motor than holley same size to even to size up.
low manifold vacuume?
I had a Demon on my street car and I couldnt get it to run worth a shat,finally I talked to B.G. and they set me up with the right one ....same size different metering blocks...made it a totaly different car ..the throttle is ridiculous it runs fantastic.
Running a Demon takes a little bit of work but believe me it's truly worth it.
These carbs like alot of initial advance,I re curved my dist. it runs 16* initial
34* total.I thought they were crazy but they were right.
Well I rejetted to 78 primary and 80 secondary reset timing, installed a tiny little Fluidampner balancer and a set of Bassett headers(had logs on it)and holy smokes this thing woke up like right now! I used to be able to mat it right off idle and it would just take off, now if you do that it will spin the pump and you gotta pedal it a little, if you get it just past idle and then wack it, the ol boat jumps right up and takes off...I LIKE IT :220v:!!! Can't wait to get that diverter on, it just was dropped off by the big brown truck....stay tuned
Posting Permissions
Reply With Quote