Carb suggestions for 360

-

392Mopar

Well-Known Member
Joined
Sep 12, 2008
Messages
421
Reaction score
1
Location
Hazlet NJ
Hey guys, looking for suggestions on a new carb for my motor heres the story...

Bought a complete worked 360 off a guy tore it down to inspect( looked almost new), put it back together and dropped itin my 72 Duster. It came with what I'm told is a 750 Holley DP that was rebuilt a year ago but the choke was milled off so I have no #'s to confirm, first is there any way to tell what it is without #'s?

Anyway the motor is a 74 360 bored .030 with what look like slight domed and milled hyper pistons( was told they were forged but look like hypers). J heads with 2.02/1.60 valves with a fresh valve job that have a nice porting on the runners but not much bowl work. I cc'ed the heads at 68cc's which brings the compression at 10.07:1 . It has a Racer Brown SSH-25 Hydraulic cam (238 duration @ .050 and .485 lift on intake/exhaust with a 108 Lobe separation),1.5 rockers, Holley stip dominator intake with a 1" 4 hole spacer and the Holley 750 DP, it also has a Miloden deep pan and windage tray. It has an MP distributor with a Crane High 6 Digital box.

This is all now in a 72 Duster with a close ratio A833 with an 8 3/4 with 3.91's and a 325/50-15 tire (28" tall 13" wide).

So I'm still breaking in the clutch(Centerforce Dual Friction) so I haved stomped on it yet, but it seems like a beast of a motor for the street. The carb seems ok, but there a slight stumble when you hit it, and I dont like not having a chock for a street car, take too long to warm up and have to hold it at 2K for a min. or 2 before it will idle on its own. So I'm looking into a different carb seeing as its a modified carb thats been rebuilt and had the butterflies drilled.

So what would be a goot carb for this setup, I was thinking something like the new Holley Ultra 750 DP with electric chock, goes for about $500 which is steep but I'd rather have a quality carb but not much more $ than that. I ran a 750 Speed Demon on my 68 Satallite wit a 440 and loved it, should I go Holley Ultra, 650-750 Speed Demon( I know they flow more than advertized) or something like a Quick Fuel? What do you think?

Last owner thought the motor was pushing over 400HP and with a more radical cam put a 68 Coronet in the mid 12's.

Butch
 

Attachments

  • DSC01485 (Medium).jpg
    107.9 KB · Views: 544
  • DSC01486 (Medium).jpg
    117.8 KB · Views: 533
Nuthin wrong with that carb if it's what you suspect it is and it's in good shape. Run it and see what happens.
 
Rub the idle curcuits to best vacuum,drop the idle speed to 850-950.After that,you might need more pump squirter.tune what you have,nice combo.
 
So a 750 DP sounds about right for this setup? The carb seems to work really well except for the off idle hesitation, and has no leaks, but takes so long before it will run without holding the gas on startup when cold. I could probably deal with it. I cant seem to get the idle too much lower than 1K, I think due to the butterflies being drilled, I'm guessing it was done because there was a more radical cam in it at one time.

I quess I'll play with it and see what I can do before dishing out $ on a new one. Still need to play with timing a little too, have it set at 14 initial, and have vacume advance hooked up.

But if I do decied that a new carb is in order and want a choke, what would be a good choice?
 
Thats a good carb you have if everything is in working order. I had to educate myself about how these carbs work and how to properly tune one. There is all kinds of ways to tune the carb to engine but you have know what you're doing. It didn't come fast to me and still not the best at it but I'm better than I was. lol After I learned the fundamentals and some trial and error situations I've come to like Holley carbs.
 
Yeah carb tunning was never my strong point!!! I quess its time to dig out the Holley book and do some reading. Dont even know whats in the carb as far as jetting or anything. Any thoughts on a good starting point to work from. Also should I think about swapping out the throttle plates so there not drilled, only primarys are drilled. Think that could cause tunning issues?
 
After one of your drives, without too much idling shut it down and check a plug on each bank. They should be a sandy tan color, if they lean towards dark brown to black you are too rich, step down on the jets. If they are light tan, to white you are too lean, step up on the jets. I usually do this in one to two step increments and try to drive the same course each time. Just my .02.

Bill S.
 
Thanks, I'll do that this weekend and spend some time trying to fine tune and see what happens. I remember my 68 Satellite 440 with a 750 Speed Demon didnt take as long before it would idle on its own on startup and that didnt have a choke.
 
Thanks, I'll do that this weekend and spend some time trying to fine tune and see what happens. I remember my 68 Satellite 440 with a 750 Speed Demon didnt take as long before it would idle on its own on startup and that didnt have a choke.
Other than the carb my set up is like yours, Im running the new holley 770 streetavenger it was very easy to tune it has vacume secondaries but they give you all the springs so you can tune to open right away or delay it for fuel milage. They say run it right out of the box and it does well just neededa little tweaking. You may want your initial up to about 19 and total around 35 thats what took the stumble out of mine. Good luck
 
Good carb for that combo.

Make sure you have the ignition timing dialed in, initial and total, before messing with carb settings. I'd guess it would want around 20* initial and about 34-36 total depending on fuel available.
 
Thanks guys, I'll do some testing this weekend with the timing. I'm almost botomed out on the idle adjustment though, so more intitial and I may not be able to idle lower than 1100, I'll test and see. I know I tryed conection the vacume advance to full vacume (theres a post where some recomend this so I figured I'd try)and set it at 20 initial and the idle was way too high with it all the way adjusted down.Do you think thats a product of the drilled plates or something else? Sundays soposed to be nice here and the wifes taking the kids o Great Adventure so I'll have lots of tune and test time!!!!

Thanks again for the sugestions

Butch
 
If it's got drilled plates I'd epoxy them back up. Also check the secondary opening adjustment, they may be open too far.

No reason that shouldn't idle lower like in the 900-950 range. It would propably run a better et with an Air Gap on it instead of the SD manifold.
 
Thanks crackedback, is epoxy safe, shouldnt I be worried about is coming loose and droping into the intake? If not what would be a good epoxy to use, or should I just replace the plates? I was thinking about an Air Gap down the line, but the Strip Dominator came with the motorso I figured I'd give it a shot. I'll check the secondarys too, thanks for the tip!!!
 
I'd go with a manual choke Holley or Speed Demon 750DP or an electric choke Edelbrock 800AVS carb. You live in NJ so you want a choke for a street car.

I had the same cold start issues with my old Duster 340-4spd/508 cam. It had a chokeless 850cfm TQ on it.
 
Ok, secondaries were open to far, adjusted so there almost closed and bumped timing to 19 initial, seems to run better and I can get it to idle lower now. after doing some adjustments the most I can get is about 10 in of vacume, sound right for that cam?

Now that the clutch is Brocken in a little I got on it and has slot of power but seems to bog when the secondaries open, nice and crisp on the primaries but bogs when you punch it while moving. What would cause this, to big of a carb or squirters and jets? Still some playing to do but any suggestions would help.
 
Vacuum sounds decent for that cam. Is it idling in the 900ish range (+/- 50)

Sounds like you have a handle on it. Nice work.

You'll have to fine tune the ignition curve and squirter size/pump cams on your carb. Might not be a bad idea to open the carb up to see what's in it, jets, power valve(s).
 
Yeah I have the idle around 900, but I can get it to idle lower but dont want to take the chance of stalling on the road as the cams got a good amount of chop to it due to the 108 centerline. Just have to work on the bog and I'll be good to go, then just figure out if I can live without a choke or not. Havent done a cold start since I messed with everything so I'll see if its any better. Thanks again
 
Ok, definatelly looking into a new carb, just dont like not having a choke, plus being a modified carb. So I'm thinking of either the new Holley Ultra DP or the Quick Fuel SS series DP. Got off the phone with Quick Fuel and he recomended an SS 650 DP. Most guys see running worked 340/360's are running 750's. Should I stick with the 750 or go with the 650? Also Quick Fuel has the same carb with either down leg boosters or annualr, what would be ther best to run. I can get the downleg for $487 and the annular for $523.

Quick Fuels seem like they have more features and adjustability vs the Holley, but I've heard great things about both. What do you think?

I tossed on a 625 Road Demon VS with electic choke and startup was soooo much nicer, but its been sitting and has some issues too, light throttle was great but stomp on it and it felt like the secondaries wern't getting fuel, so I'm looking at getting a carb soon or putting te Holley back on and dealing with it till spring.
 
Well, I ended up getting a Quick Fuel SS-750 AN, its a DP with electric choke and annular boosters. I was going to buy new but found a great deal on ebay for one that was only 3 months old from a guy that was swaping out to fuel injection. Put it on the other day and the cars running much better and starts like a champ!!! Still has a slight bog when secondaires open, but way better than the Holley. I'm gonna try a few things, it has an option for delaying the secondaries so I'll try that first, then moove on to larger squirters then larger 50cc accelerator pump for the rear, or mess with pump cams. It came with a bunch of extra jets, pump cams, power valves, and air bleeds. I'm sure that once I get it all dialed in it will be an awesome carb, and man does it look nice!!!
 

Attachments

  • DSC03089 (Medium).jpg
    95.6 KB · Views: 294
  • DSC03093 (Medium).jpg
    100.4 KB · Views: 276
  • DSC03094 (Medium).jpg
    92.2 KB · Views: 278
annular discharge is a very good way to go. that thing will be a monster when tuned. it sure does look good
 
Thanks guys, yeah she's purrdy!!! Went ack and fourth between annular and downleg, and seemed like annular was the way to go, ad so far I'm real happy with it. Once I get it all tuned up, it should be sweet!!!
 
-
Back
Top