440 aspen

Heres what I have:

77 440 bored .040 over
flat top pistons
509 lift 292 duration cam
452 heads. nothing special other than new valve guides, valves, and springs
stock intake with crossover
longtube headers 2 1/2 exhaust
750 edelbrock carb. straight out of the box but adjusted
electric fuel pump
hei distributor (ill post pictures if needed)
Im guessing cr is about 8:1 give or take
727 transmission.

Heres my problem. i get surges in the 1500-2000 rpm range, when i floor it it hesitates then takes off. and on occasion itl flood if im at a stop light or taking off from one. it idles just fine once its warmed up. i know from some replies that my carb needs to be readjusted and my timing is mostlikely off. i will have to see what total and initial timing is set at. I need help

bremereric

I would just use a vacuum guage to adjust the distributer for the best vacuum reading at idle. Usually 10-15 degree initial timing and 34 to 35 degrees all in at 2500-2700 rpm.

Archer

440 A -

You're line up seems fine. I'd go with what Eric suggested, and also check the fuel pressure going into the carb.

Sorry to have to say this, but you said the carb was adjusted, but do you know it was adjusted correctly?

BTW - the purple (cam) shaft you are running, may not create a lot of vacuum and is kinda old technology (and wasn't that great in the day either).

The other things you didn't mention that can factor in are the stall on the torque converter and rear gear ratio.

Archer

78D200

Welcome!

rickyr

welcome to the forum

MReeves

Welcome ot the forum.... Be sure to check out the Mopar of the Month contest....

Coronet 500

I miss spoke in your rear end thread about the carb spring, got it backwards. Anyhoo, those 2nd and 3rd gear vacum readings seemed odd to me which takes us back to basics. Your described problem could be float level or choke. I believe the guessing and your frustration should end with a real good carb and timing set-up. Time to set the float level, note your spring and rod colour and numbers. Check the accelerator pump shaft height and actuator lever hole used. Fuel pressure for sure then move on to timing, initial and full at what RPM.
Don't think of this as work as this is the fun stuff for most of us, and the benefits could be great for no money spent. Lots of You Tube Edelbrock and timing stuff to help you along. Post up your findings and then together we'll turn this thing into a beast. You'll get this thing working, no problem.

440 aspen

i have a fuel pressure gauge right before the carb and i get about 5-6 psi. the accelorator pump is set to the hole with minimal travel. we had it in the middle but it flooded on takeoffs. im not 100% sure the carb was adjusted correctly. I built this car with my grandfather whos been hotrodding since the early 70's. hes been showing me how to do things and hes the one that adjusted my carb. Ill spend a lot of time learning how to adjust it. And with that cam, i know its low vacuum but i have manual brakes so i really dont need a whole lot of vacuum. Being 17 and wanting a muscle car as my first car, i just wanted that thing to lope like crazy. And choke is electronic but ive checked it multiple times and after its warmed up its always open all the way. Im not sure what the stall is. I know its low because right off idle (800-900rpm) she moves. rear gear i think is around 4.10. If i could work on old cars/ restore them for a living id drop everything and go so working this stuff out isnt a problem for me. Thanks for the support and the advice guys. i really appreciate it.

Archer

440

Well, that's not going to make a lot of us feel any younger...

About the vacuum, you probably should be running a PCV valve and that need a vacuum as well.

With that cam, and a low stall converter, I think stock was around 1200 rpm, you have a power band to stall mismatch, meaning the engine might be fighting the drive train.

Figure out what your rear gears are. Jack the rear of the car up (Chock the front wheels and leave the tranny in neutral). Spin a tire and see how many time the drive shaft turn relative to the number of times the wheel turns. That will also tell you if you have a posi or not. (I call it a posi, regardless of the manufacturer...) If both wheels turn in the same direction, it's a posi, if in opposite directions, it's not.

Archer

Coronet 500

Try with it hot with a rolling 5-10 mph tromp. Then a 10-15 all in 1st gear, this can give you an indication if your torque convertor is making the bog at 0 mph breakaway. If it likes the higher rpm with no bog then a higher stall T.C. could be part of the answer for that healthy cam.

440 aspen

i run around 3500rpm at 65 last time i checked and i used a mopar differential calculator and it showed i most likely have 4.10 rear. the speedometer is painted yellow at 55 so im guessing it was never intended to go much faster. and i know for a fact that its an open carrier. I have my pcv valve hooked up to where its supposed to be. And where my trans modulator valve hose would normally be attached to the carb is where im running my vacuum gauge. Now that you guys mention it i think the stall in the converter is a big part of it.

TVLynn

509 cam needs at least a2200-2500stall and a bigger carb

440 aspen

Thats what i was thinking. ive heard 440s came stock with an 850 carb

Archer

440 -

Slow down there. The Carter thermoquads where in the 800 - 850 range, IIRC the Holleys were about 600 - 650. That's all irrelevant, since you don't have a stock engine. In your case an 850 Holley DP, should be appropriate.

Here's the slow down part. Using a slightly small carb will usually increase low end throttle response and drive-ability with a possible loss of a little top end (which will only be seen at a race track). Most people are over-carbed than under.

If you want to test for stall speed, power brake the car while watching the tach. See at what rpm the wheels break free or the engine dies.

Archer

440 aspen

[QUOTE=Archer;103479]440 -
If you want to test for stall speed, power brake the car while watching the tach. See at what rpm the wheels break free or the engine dies.

Thats another problem i have. for some reason my front brakes arent doing much and im mostly relying on my back drum brakes. ill have to fix that before i do any testing

Archer

440 -

Ah, that would be a good idea...

Archer

440 aspen

any ideas on how to change that so my front brakes are applied before my rears are?

Archer

440 -

Doubt you have an adjustable proportioning valve.

It might be as simple as relaxing the rear brake adjustment and tightening up the front, but can't say that's a good fix from here.

Archer