Holley 650 DP Question

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MOPARJ

MOPARJ

What can I upgrade now?
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Now that I posted on the correct section, I have acquired a holley 650 double pumper with electric choke. I have just installed it on my 318 in my duster with a Comp XE268 cam, stock heads with 3 angle valve job, TRW 8:5:1 compression pistons, hooker headers and edelbrock performer intake. The gearing is 3.21.

My question where and how is the best way for hooking up the electric choke, or should I even bother with this large of a cam and just wire it open? Are these well calibrated directly out of the box?

BTW, it is a vacuum secondary carb.
 
If its a vacuum secondary its not a double pumper. What you have 600cfm 4150 dual feed carb.

For the choke it just needs to be wired to any switched hot. get the test light out.
 
You are completely correct, Adam. It is a Dual feed 650 cfm, not a "double Pumper". I always get the two confused, but this time in writing.
 
I use no choke. Its not very warm here in Michigan most of the year too. Now I do keep my exhaust heat open on the intake manifold and have a hot MSD 7 spark box. I can start it ice cold with 2-3 pumps of the gas and after 30 seconds its good to go. Idles rough but strong for the first 5 mins, then is good the rest of the day. Even without driving it for a few hours.
 
Well, I got the choke hooked up and fired the car up. Runs and revs ok and the choke door opens as it should. When out on the road, it will run fine when shifted manually and hard on the gas, but it seems to bog and surge somewhat when just cruising below 2,000 rpm. If in second gear and cruising and you decide to easily accelerate, it will bog down and fall on its face somewhat if you gently ease into the throttle, but will break out of the surging if you give it more throttle.

I checked the choke and when revving, its ok, but that isnt to say that it is acting differently when under a load driving. All of the plugs were a light tan, a few with taninsh white hue on the tips. No signs of being rich, if anything a little lean. Is it possible that it needs to be jetted a little richer or am I just chasing my tail and the electric choke is not functioning properly?

Does anyone know what jets usually come in the carb from the factory and what size I should go to next, if its the issue? Again, this is a holley 650 dual feed vacuum secondary with electric choke on a rebuilt 318 with TRW 8:5:1 pistons, slightly reworked stock heads, XE268 cam, and hooker headers.
 
Two thigns, make sure you wired the choke to the key "on" position, but NOT to the ballast resistor or the feed for it. I acutally use the accessory spot on the fuse block for it. It draws too much and it can really limimt the output of the ignition. Second, you will want to make sure the spring in the secondary vacuum pod is stiffer than purple... (they are color coded) I think the natural one would be fine for that setup. Also verify the power valve used is about 1-2 numbers lower than your engine idle vacuum in gear at running temperature. A power valve that is too low a number will cause a studder, especially if the secondary spring is too light.
 
Disconnect the choke,and rig it wide open.Drive it and see if it runs better.Make sure the car is completely warm before flogging it.

Not sure what # the jets are in a 650,but usually you change jets in numbers of 2.
 
moper said:
A power valve that is too low a number will cause a studder, especially if the secondary spring is too light.
Click to expand...

I agree with the above statement but usually a low rpm surge and bog is caused by the jetting being too low and causing a lean condition. If you can get me the list # stamped on the air horn, I can tell what it came with stock, assuming the carb is new and hasn't been fudged with.
 
ramcharger said:
I agree with the above statement but usually a low rpm surge and bog is caused by the jetting being too low and causing a lean condition. If you can get me the list # stamped on the air horn, I can tell what it came with stock, assuming the carb is new and hasn't been fudged with.
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650 cfm vacuum secondary, electric choke

P/N 0-80508S , 0-80783C
 
MOPARJ said:
650 cfm vacuum secondary, electric choke

P/N 0-80508S , 0-80783C
Click to expand...


I have the same carb, 0-80783.

Holleys are wet flow tested before they are boxed. The jets that come with them are more than likely the most optimun size for that carb...usually on the lean side for fuel economy.

I would try changing the squiter from the 28 that the carb would have come with, which I think is lean, to a 35. Then more fine tune it by playing with the accelerator cam.

If you need to go into jetting, then the carb might not be the right size for your application.

I set my choke 2 notches rich to fully open the plate.

Hope this helps.
 
MoparJ, these carbs came stock with 67's on the primary side. I would bump them up to a pair of 72's and work from there. 67's are pretty lean for even a mild build.
 
ramcharger said:
MoparJ, these carbs came stock with 67's on the primary side. I would bump them up to a pair of 72's and work from there. 67's are pretty lean for even a mild build.
Click to expand...

I agree. The mannor of the stumble and how it falls on its face at certain acceleration points, it does seem lean.

Drove the car to work today (25 miles one way, 50% highway) and just went out during my lunch break to check it out. Got nice and warm and made a few hot laps down the street then checked the choke: it is wide open. I cannot see this being a choke issue during load, as I do not think there is that much of a variance in power output from my fuse box's accessory port.

I do believe jetting will help, even though my exhaust smells fuelish. That could just be an idle mix adjustment, as my plugs tell the real tale of the lean condition under load. I will pick up the jet kit and switch to 72's.
 
Let us know how it turns out. Even my Ramcharger at this altitude (5280') required 70's and that was with a bone stock bottom end and heads, very mild cam and headers. It ran better with 74's, but was eating my wallet as this was a daily driver at the time.
 
ramcharger said:
Let us know how it turns out. Even my Ramcharger at this altitude (5280') required 70's and that was with a bone stock bottom end and heads, very mild cam and headers. It ran better with 74's, but was eating my wallet as this was a daily driver at the time.
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Since I may just buy the kit, I may give 74s a try, since its not a daily ride and the slightly hotter cam may like the richer shot.

And even if its lean, it seems to be sucking just as much fuel, which I guess could be a byproduct of less than ideal running conditions, engine performance wise.
 
You should go up 2 jet sizes at a time and when its very close then 1 jet size. Jumping 7 jet sizes without checking how it runs by going up 2 or 3 sizes is the wrong way to go about it.

You might be surprise how much change the carb will be by going up 2 numbers.

I have a 750 carb and 74 are right on, with a 650 I start with 70. You want the leanest size jet and still have it running smooth.
 
also check your vacuum at idle in gear. check the pv # in the carb and make sure its 2 below the vacuum reading. i bet it has the natural color spring in the secondary pot. get a spring kit so you can change it if need be.

also remember one key thing with all this info! DO ONE CHANGE AT A TIME SO YOU KNOW WHAT MADE A DIFFERENCE AND WHAT DIDN'T!
 
I agree with DF: go up two sizes at a time until you're running fat then come down one size at a time.

I also agree with red: one change at a time and it never hurts to check the power valve as he mentioned.
 
Looks like its all fine and dandy now....

I bought a jet kit and tried a few things last night. I started first by replacing the 67's with 70's. Much better and the bog was gone, but still seemed a little soft. I then experimented by bumping up to 72's. Even stronger now and is about the strongest this motor has been since I rebuilt it. I figure this would be a good balance of power and economy, if I can even say that with this lopey cam.

In experimenting out on the open road, I made a few 0-60 time records:

w/ 67s: 7.45 sec
w/ 70s: 6.76 sec
w/ 72s: 6.32 sec

I am feeling good about my hot little 318 with low compression slugs. I havent been to the track since I put the motor back in and swapped to 3.21s in the rear, but I do not think a low to mid 14 second et is out of the question. I still need to put the rest of my shift kit in and step up the converter a little more(it is stock), so there is room for more improvement.

All and all, I feel great about the "orange dustball" now, especially since I am getting it done with the Rodney Dangerfield of mopar engines.

Thanks guys for your help!!!
 
Good deal MOPARJ! Glad to see those numbers and there still may be some more in it. Keep on tunin'!
 
ramcharger said:
Good deal MOPARJ! Glad to see those numbers and there still may be some more in it. Keep on tunin'!
Click to expand...

There may very well be, as I bumped up the timing 2 more degrees in anticipation of the richer shot. Still no detonation, starter kickback, or diesiling, so I may try another degree or two.

Fuel milage is still ok. I added 5 gallons of fuel last night and drove 60 miles roundtrip to the partshouse (again for parts for Dart) and to school. It used all 5 gallons, mix of highway and city roads, so I figure 11-12 mpg average total.

Not the best, but ok for the characteristics of the cam.
 
Thats a big cam for a 318 with 3.21 gears. That vacuum secondary carb is letting it get away with it. If it had 3.91's I say get a 650 DP, then say hello to some quick times but maybe 9 mpg.
 
dodge freak said:
Thats a big cam for a 318 with 3.21 gears. That vacuum secondary carb is letting it get away with it. If it had 3.91's I say get a 650 DP, then say hello to some quick times but maybe 9 mpg.
Click to expand...

Yeah, its about as aggressive as one should go with a 318, but it still behaves well, even with the stock tc; no erratic idle, just an excellent sounding tone and mild lope.

It still has good low end torque and pulls well up to 5,800. I think it is capable of running a low to mid 14, which is quick for a teen.

Eventually, I will rebuild the 8.25 with a Sure Grip and 3.55s and should be sitting even prettier.
 
Do you have those 318 heads still on there. Must have, that helps too. With 360 heads it could hit 6500 rpms with fresh valve springs.

With the 318 heads you can run a bigger cam, with 360 heads and those larger ports, its best to stay a little on the small size.

You could always try 360 heads later on, just make sure you get them milled to around 63cc chambers to keep your compression up. I have the newer 360 high swirl heads with a 2.02 intake valve. It was a big help everywhere but I am running 3.91 with a 2.74 1st gear auto trans.
 
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