More 440 questions

[66HOTROD]

I have a rebuilt 440 with mild cam, 440 Source heads, Edelbrock Performer intake, 850 cfm carb, mild cam, headers. It has great power running on 2 barrels, but instantly bogs out when I try to kick in all four barrels. Too much carb, or what else may be wrong?

 

[wyrmrider]

What carb and how is it jetted now, power valve if it has one, squirtters and accelerator pump cam and linkage settings?

 

[Lefty71]

With the mild cam, i'd bet you would absolutely love a properly prepped 750 double pumper from a performance standpoint. It takes a good bit of signal to give an 850 a workout.

Anything stuck on that carb by any chance?

 

[66Satellite47]

Which carb, many 850's out there? A smaller carb would likely be better for a smallish cam, but still depends on what you got.

 

[Demonic]

What is you initial and total timing, and where does it come in?

 

[PurpleBeeper]

I have a rebuilt 440 with mild cam, 440 Source heads, Edelbrock Performer intake, 850 cfm carb, mild cam, headers. It has great power running on 2 barrels, but instantly bogs out when I try to kick in all four barrels. Too much carb, or what else may be wrong?

All good questions above. A 850 cfm is a little big, but it should work. If it's a double pumper holley, your secondary accelerator pump isn't working.

 

[66HOTROD]

All good questions above. A 850 cfm is a little big, but it should work. If it's a double pumper holley, your secondary accelerator pump isn't working.

Carb is an Edelbrock, bought used from a guy that went to EFI. Initial timing is 8 degrees. I'll admit I am just a novice at this stuff. There just doesn't seem to be anyone around here I can hire that really knows tuning a Mopar engine for maximum performance, so I need to learn an awful lot more than I know now.

 

[khryslerkid]

I'd try a little more timing, like 15*.

Make sure you're getting a good squirt out of your accelerator pump. Orange = good. Blue = bad (color of the accelerator pump inside the carb)

If you're useing vacuum advance, make sure it's working properly.

 

[beanhead]

Just need to dial that carb in..start by getting your timing right, otherwise you'll be going in circles. That engine should have more than 8° initial, and mopars typically like somewhere around 34-38 degrees of total mechanical advance(If you don't have a vacuum gauge, get one! They're not expensive and are a must for tuning and troubleshooting.) With your higher-than-stock flowing heads and headers 850 cfm will work fine, just needs the fuel delivery set properly to keep the mix happy when you crack the secondaries and introduce that instant gulp of air. There's some much sharper folks than me around here with the edelbrock carbs, with some tuning you'll get it dialed in..do a search here for 'Edelbrock carb' that will get you started on your journey..

 

[Cranky]

When does the engine bog? Does it hiccup when you are running 50 and floor it? Last months Hot Rod Rag had a fairly large article on tuning tips using a 'wacuum' gauge......plus there's plenty on the net about it too. And there's no reason why that 440 can't handle the 850, however a smaller carb will generally make any engine more crisp for in town stop and go traffic but on the other hand, my ancient build with a 383 in a 3600 lb car did fine with a 750 DP on it. That engine had stock heads, very mild cam, an Offy 360* intake and headers. It also had a 3.91 gear in the rear.

 

[threewood]

Be advised that raising the initial timing (I agree it needs more timing) will also raise your total timing advance without modification. BB Mopar should be around 36-37° total. Any more and you risk pre ignition or detonation on pump gas.

 

[Cranky]

Be advised that raising the initial timing (I agree it needs more timing) will also raise your total timing advance without modification. BB Mopar should be around 36-37° total. Any more and you risk pre ignition or detonation on pump gas.

That also depends on what the CR is.....also cranking PSI will tell ya what it might like. We don't know what pistons were used in the rebuild or what his cranking PSI is. If it's low, it'll most likely like more initial and total.

 

[wyrmrider]

ok lots of good techso far
do a compression test
learn how to limit your total advance so when you bump the initial you do not overadvance at higher rpm
do some basic carb checks
report back
Rome was not built in a day and neither is tuning

 

[Curiousyellow71]

Depending on how much its bogging...I think there may be a passage or jet plugged on the secondary side of the carburetor. Something may have crawled in there when it was off the car. Edelbrocks are pretty simple.

 

[66Satellite47]

I agree with checking "total timing" (need a timing tape on the damper), lower CR or cranking PSI will like more total & initial timing(35-36 higher CR, 38 for lower). Most stock distrib's may have too much mechanical advance built in to advance initial timing much without getting the total too high. So, as Cranky said you may need to limit the "slot" travel on the mechanical plate in the distrib. Still most likely problem is in the accelerator pump. Good luck.

 

[Turboomni]

If you haven't done so already pull the carb and rebuild it,and see what jets and metering rods are in it. If needed get a carb tuning kit and modify it.

 

[451Mopar]

Carb is an Edelbrock, bought used from a guy that went to EFI. Initial timing is 8 degrees. I'll admit I am just a novice at this stuff. There just doesn't seem to be anyone around here I can hire that really knows tuning a Mopar engine for maximum performance, so I need to learn an awful lot more than I know now.

Need to get it to someone who knows how to re-curve the ignition (then advance timing), and tune/adjust the carb if the previous owner didn't screw it up too bad.
If it is a AVS type carb, you should be able to tighten the spring tension on the secondary air valve. If it is an AFB, check that the other owner did not cut the counter weights on the air valve.