alright.... got a couple Q's about carbs
1)I have a 670 truck avenger holley carb would I get better perf out of it or say a 750 mech. sec. double pumper holley?
2)if I use the 750 would it get better mpg than the 670 since the 670 is a vac sec carb under load it opens up to were the 750 will not unlesss you manually do it?
3)what carbs are you all using with sbc mildly built mtrs in the mud???I know most suggest using the trk avenger for off road use but will a good ol' mech sec double pumper be o.k. to?
I dont plan on hill climbing or rock crawling just goofin off in the mud! and I want throttle responce on TAP!!!!!!!
We need more info on the motor to make a better decision.....
trk avenger should do the trick,I believe they have center hung float bowls which are ideal for offroading, 670 should be fine with a mild small block.
the 750 would probably be horrible on gas!and not as friendly with the bumps, id go with the smaller carb.
I personally use edelbrocks, there simple and Ive always had great luck with them.
I use a 750 edelbrock on a 385 stroker and i have two 600 edelbrocks on a bigblock.
just my opinion, hope this helps.
383ci./400th,/205,.030 over pistons with a .100 thousandths pop up dome,mild cam .494 IN./.503 EX. lift, 224/231 degrees durration,670 cfm truck avenger carb,1/2"carb spacer/adapter,cast world products heads,1.94 I and 1.60 E.,the heads have been opened up on the intakes and exhaust ports to a felpro 1205 gasket on the I. and a gasket match for the 1 & 5/8" header,1.6 comp pro magnum roller rockers,7/16" rocker studs and guide plates,comp 1pc. hardened pushrods,double roller timing set,headers,aluminum performer intake, 3" exhaust,3"x-pipe,3" 3-chamber flo masters & turn downs
On the 670 vs. the 750 I do think it may sound like the 750 may drink more fuel but I'm thinking that the 670 being a vac sec sees just the slightest bit of load the secondaries open and then will drink the gas prolly just as much if not more? atleast with the 750 having manual secondaries I will have complete control over when they open and are not!I know the gas mpg will suffer either way but really want better throttle resonse and better performance!
Either one should work, the vac. secondaries won't open untill almost WOT so that won't be an issue. The dual accel. pumps is what kills mileage on a dbl. pumper.
Both will have great responce if tuned right. I would probably run the 670 if it is in good shape.
is this your DD.If not why are you worried about MPG?
the motor specs do not sound like a DD. motor
the motor i'm running has almost same specs,minus the
bore and i run a holley 750 vaccum secondary and it works
pretty good espescialy at top end.
not a d.d. but I got a 16 gallon cell and I really would like to see if the double pumper will do any better if just cruising? I dont really care about mpg but with gas being up around 3.68+/gallon mpg would be nice even if it got 1-2v more mpg out of it and better perf?and if I wanted to drive it a bit I might! I've already got one trailor queen already!dont really want another!
Quote from: frdboy on September 26, 2008, 01:14:10 AM
Either one should work, the vac. secondaries won't open untill almost WOT so that won't be an issue. The dual accel. pumps is what kills mileage on a dbl. pumper.
Both will have great responce if tuned right. I would probably run the 670 if it is in good shape.
X2
vac sec open only when the engine needs the extra air/fuel mix, like at wot. mech sec open even if you dont need them.
my 388 had 11.1 cr and .538 and .552 lift cam with protopline vortech heads and edelbrock rpm air gap intake with a 670 truck avenger and it made lots of power, it would carry 7000 rpm all day long
now about the vac secondarys you can change the spring in order to open the secondaries sooner or later, just buy a couple of different springs and test and tune to see what makes more power
i had it in my 98 chevy ext. cab and could only get 6-7 mpg on premium ouch!!! daily driver for a short while
thanks for all your alls help havent had time really to try nuthin out but will let you all know the outcome shortly!thanks again!
I am running a mild built sbc in my Jeep with a 650 Holley. Thing works great in the Mud and on the road. Have good power and throttel responce from it as well.
I had a 750 on it and it would flood out after a wile of it running
tried the 750 with a lil oops! guy I got it from had it on a turbo car and did a lil drilling on the front metering block he drilled out the powervalve passages a lil bit and I think its screwed up? wish I woulda known this before hand I wouldnt have tried it but I do have another 750 I think I might try?if it dont pan out I'm tired of messing with it and am gonna either buy a new one! (650-750 holley double pumper mech sec or just tune and use my 670 truck avenger)thanks!I'll keep ya'll posted I app the help!