360 Carb input

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rtee007

rtee007

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I have just bought a car with a MoPar 360 crate engine installed. 3K miles on it. Previous owner installed the engine and tells me it is the 380HP model. It has the M1 single plane intake. He has installed a 750 Eddie. It has an MSD ignition and headers. 4 speed and 3.32 open 8.75.
I feel this is too much carb. For this set up. It bogs on instant acceleration.
I have a 650 Holley sitting on the shelf, still in the box.
Input please?
 
Use the search button. No offense but there has been too many carb and intake questions recently. If you can't find a good answer using the search tool then pull the carb off the shelf and see what it does. Doesn't take 15 minutes to swap carbs.
 
Just varifying, but you typed 780 dp Eddie. I am sure you meant holley, but want to make sure all Info correct before giving suggestions.
 
rtee007 said:
I have just bought a car with a MoPar 360 crate engine installed. 3K miles on it. Previous owner installed the engine and tells me it is the 380HP model. It has the M1 single plane intake. He has installed a 780 DP Eddie. It has an MSD ignition and headers.
I feel this is too much carb. For this set up. It bogs on instant acceleration.
I have a 650 Holley sitting on the shelf, still in the box.
Input please?
Click to expand...
What gears and either converter or trans you have ? I have a 750 holley street avenger on my 340 and it runs great . Air gapp , 3:55 .
Try the 650 should work off the line , top end might be lacking , might .
 
Its a matter of CFM....required for Maximum Air Consumption.

360 c i...... X MAX RPM........ / by 3456 = CFM

360 x 5000 / 3456 = 520.83 CFM

360 x 5500 / 3456 = 572.91 CFM

360 x 6000 / 3456 = 625.00 CFM

360 x 6500 / 3456 = 677.08 CFM

360 x 7000 / 3456 = 729.16 CFM

360 x 7500 / 3456 = 781.25 CFM

These numbers are pretty close to the Air a given Cubic Inch Displacement engine will move......

A 650 cfm carb would probably be best suited to your engine....because the smaller venturi's...the engines' Vacuum Signal to each cylinder would be improved.

I usually like to lean to the performance side and use a 750 on a 360 because it has larger venturi's and hence less air restriction......and a 650 or less on a 318.
 
rtee007 said:
I have just bought a car with a MoPar 360 crate engine installed. 3K miles on it. Previous owner installed the engine and tells me it is the 380HP model. It has the M1 single plane intake. He has installed a 780 DP Eddie. It has an MSD ignition and headers.
I feel this is too much carb. For this set up. It bogs on instant acceleration.
I have a 650 Holley sitting on the shelf, still in the box.
Input please?
Click to expand...

The carb bogging on instant acceleration is not due to the carb size, its a tuning issue. With that said, carb size is really dependent on what you want out of your motor. If you are just going to be putting around town, and don't really care if you get maximum horsepower out of your combo, then the 650 would be great. If you race on occasion and want max power, I would go with a Holley 750dp with a HP main body (or Proform).

The carb sizing calculators work ok for general sizing of carb for a street only car, but if you are a street/strip or race car and want max power you should toss those numbers out the window. For what its worth, on my previous mild 360 combo (eddy heads, MP 509 cam, RPM intake), my car picked up 3 tenths of a second and 3 MPH in the 1/4 mile when I switched from a 650dp to a 750dp.
 
650 for a mostly street driven application, for the track, A 750 for the max power out put. The differance will be approx. 10-15 HP.

The 360/380 create engines routinely dyno'd 410-415 HP with a 750 & 1-3/4 headers.
If your running the track mostly, with parts like 4.10'or numerically high ratios and high stall converters, then the 750 would be very good to use.
Less than 4.10's and on the street more often I would suggest a 650 for a ran crisp throttle response. FYI, The 750 on the street is doable.
 
It's difficult to get a mechanical secondary carb not to bog with an auto trans.

Why not go with a vacuum secondary? Like a Holley 3310.


With the cam and single plane intake on the 380 HP crate 360, it's not going to have very much low end torque and power.

You should have around a 750 CFM carb, a stall, and a gear to work with it.
 

The car has a 3.23 open 489 case. It also has a standard transmission 4 speed. The previous owner told me the carb was 780 Eddie (i see now it should be 750) it has dual fuel inlets to the carb like a DP Holley.
My plans are to put a 3.90 rear axle ratio in there with a sure grip but right now I want to concentrate on the engine. Yes I go to the drag strip every once in awhile but the street will be the place this car is driven most of the time.
The car is actually fairly fuel efficient on the highway at 15.38 miles per gallon on a weekend trip. Average 3000 rpm at 70 miles per hour.
I am all for keeping the current carburetor but I must eliminate this bogging issue.
Yes I did look through several years of previous posting before asking for some more direct help with my post.
 
krazykuda said:
It's difficult to get a mechanical secondary carb not to bog with an auto trans.

Why not go with a vacuum secondary? Like a Holley 3310.


With the cam and single plane intake on the 380 HP crate 360, it's not going to have very much low end torque and power.

You should have around a 750 CFM carb, a stall, and a gear to work with it.
Click to expand...

Because all these other people are tellin him double pumper and they're experts.

<insert eyeroll here>
 
My auto cars with DP carbs don't bog... They are also .2-.3 faster in the 1/4 than the best vacuum secondary carb.

Some even have what I consider tighter converters.

Pick something and learn to tune it would be my suggestion. An A/F meter can be your friend.
 
crackedback said:
My auto cars with DP carbs don't bog... They are also .2-.3 faster in the 1/4 than the best vacuum secondary carb.

Some even have what I consider tighter converters.

Pick something and learn to tune it would be my suggestion. An A/F meter can be your friend.
Click to expand...

This post,makes the most sense.... What do you expect of it,what do you want it to accomplish? Have you checked the timing curve,initial at idle ,and around 2500- 3000 total?. We don't know your tune ,guy....
 
krazykuda said:
Ok then. Walk him through tuning it....
Click to expand...

Steps and in this order only....

1) Ignition timing first
2) Ignition timing first
3) Igniting timing first
4) Ignition timing first
5) Ignition timing first
6) Igniting timing first
7) Ignition timing first
8 ) Ignition timing first
9) Igniting timing first
10) Ignition timing first

Once that is all figured out. Initial, mechanical advance , all in / Total timing
11) THEN GO AFTER THE CARB
 
Mad Dart said:
Steps and in this order only....

1) Ignition timing first
2) Ignition timing first
3) Igniting timing first
4) Ignition timing first
5) Ignition timing first
6) Igniting timing first
7) Ignition timing first
8 ) Ignition timing first
9) Igniting timing first
10) Ignition timing first

Once that is all figured out. Initial, mechanical advance , all in / Total timing
11) THEN GO AFTER THE CARB
Click to expand...

I think I got this, but could you explain steps 1-10 again :D
 
Almost all hesitation / bogging etc. is ignition related. If the ignition timing is wrong you will never be able to set the carb up correctly

Getting the ignition timing set correctly makes it easy to tune the carb!
 
Walker434 said:
I've got 750 DP on an auto car with no bogg. Hauls ***! A body's are light. Just have to tune it correctly.
Click to expand...

Thanks for you assistance. I will look into having the timing checked and the carb tuned. I have no tools to attempt this at the moment. The car is indeed very fast. With the correct adjustment it could get scary:glasses7:
 
I'm running a mechanical 6 pack, a true 1,100 cfm setup with three accelerator pumps dumping at once without a bog on my 400 hp 360 !! 4 speeds are less forgiving with a big carb than a auto especially a auto with even a mild stall converter. That said with the 4 speed I would go with a 650dp, you may loose a few up top but idle to 4,500 should make the car rev quicker.
 
750 Edelbrocks are notorious for off idle bogs, yet the 600's seem to be less effected. I would throw that Holley on it and try it out. I think a good old (new) 3310 Holley 750 would work great. Is your pump linkage in the closest hole, try that. You will get more pump volume with the close hole.
 
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