How Is ignition timing and other tuning options,,,point gap etc. Is carb fully opening when gas pedal on the floor. Are secondary's opening when they should. Are all 8 cylinders pulling their share,,,,no bad plugs or wires, or valves etc. what is a vacuum gauge reading. 3:55's are not really tire shredders if you have a good biting tire. No lead weights in trunk.

Will engine pull rpm above say 5000 rpm.

So let's see - the LAST thing you did was change the converter and now it won't pull a greased string out of a cat's ass. How about you check and see how high you can get the engine against the converter ? Warm it up thoroughly then mash the brakes and then see how high the engine will go in first gear. A real 340 converter in your package should get you around 2600 to 2800 stall. If not then likely your stator overrunning clutch is failed in the converter. Or it's not a real 340 converter. A failed stator ORC will run down the road fine but make the car lazy off the line. The 284/484 purple shafts hated low compression and tight converters.

timing is ~18/34 degrees with electronic ignition. Carb opens all the way and all cylinders are contributing. No tach (electronic ignition) but I think I'll need to get mine going.

I'll need to see if I can check the brake stall once I get a tach in it. I can throw a spare tach in it and try it out.

The 284/484 is a decent cam if "everything" is built around it,if not,don't expect miracles.

And what carb was on it then?

He said it had a double pumper on it, changed the converter, the problem developed, and was told to take off the double pumper as that was the problem. The new carb didn't do away with the problem. So going back to a double pumper won't help it either. The only thing he did to the car, that most likely caused the problem, was the converter change = it's too tight a converter, and it won't let the engine get up into the torque range, so it bogs down and is doggy.

Sooooooooo............

Car shreds tires.......change converter......... car is a mutt.........now it needs a different carb??

That must be an interesting trouble shooting chart.

Neither cam is the problem. I ran the 474 in a reringed 440 and the car (70 Charger) ran strong. It would smoke a peg leg 3.23 for as long as I had my foot in it. 3.91s and a 275-60-15 got me an ET of 14.00 at 101 with a sad 2.2 60 foot. I am not a drag racer so forgive the terrible 60' time!
The 284/484 cam isn't my favorite but I ran one in a 9.0 to 1 440 in a 5000 lb 1 ton 2wd Dodge truck. It would smoke the 4.10 gear 33" mud tire for 50-75 feet. Both the car and truck had 11" converters with an unknown stall rating.
I doubt it is the cam. I think it is the tune.

Maybe it's the paint job?

That motor is gonna want 38° of timing to make max power. Anything less will hurt it. Those low comp flattops and open chamber 906 heads need timing and will not be very pump gas friendly no matter what.
That cam is not that bad...I had one in a 440 in my car and it ran real good. Having said that, the 484 and 509 purpleshaft cams need some converter to run real well.
Like Fast68 said, if the problem started when the converter was changed, I'd be looking no further. Spend 400-500 bucks and get a decent 9.5" or 10" converter from someone like Ultimate or PTC and have fun w/ it.

I agree with the guys on the converter, but you said you dropped the timing because of detonation, before or after it became lazy? Was it pinging? With those pistons and 906s it doesn't sound like too much compression unless it's very lean, in both carbs. I always had to do some work on the carb with cams like you have and stock converters. Like one said, if not a dead vert, a tuning issue. Also make sure no wiped cam lobes. Maybe the painter guys screwed up something playing around with the car. All a guess without seeing, touching car.

Sounds like the typical DC484/DC509 thread... Low compression, no stall, no gear, no performance. Cam probably also wasn't degreed.

I'd check your cranking compression, its probably like 125. Does this engine have headers?

It sounds like your biggest problem is the converter.

The info I found on the 2286p piston is 1.94c/h.
So, unless there has been a bunch of head/block milling...... The motor is in the low 8's for compression.

I have used the 484 cam in a couple of re-ringed, low cr 400's before, with pretty good results........ But they had 10" converters behind them.

A compression test should shed some light on things.

I checked a motor for a customer and freind that been built by another local machine shop had new pistons and a "284" Purple shaft cam in it, it had 7.6 to 1 compression and the cam was installed 7 degrees retarded from straight up on both lobes
He said it ran fine before we started degreeing the cam and doing the math on the compression ratio
I built him a 446 C.I. 440 motor with a small hydraulic lifter Lunati cam he bought and a set of Max wedge replacement heads and a cross ram with two 600 Eddy carbs. He hasn't and won't drive the car at WOT from a dead stop to 5000 + RPM into 3rd gear, it is to fast so he lets off when the speed gets to high
I tried talking him into a better cam and a longer stroke but he declined That was probably a good thing for him
OP, you can fix it, start with the converter

Ok, so its a dog off the line but at 3500 rpm's how does it pull. This will mostly take the converter out of the equation. It should pull real hard from that point on up to 6000 rpm or so.

whats your vacuum at idle?

Heres my tale on that cam except mine is/was in a 69 superbee with a 383.

284/484-108 cl

Ancient TRW'S 12.5 domed pistons

906 heads-mild port work and polisted

Edelbrock RPM INTAKE

850 Holley dp. 83's up front 87's in the rear.

MP dizzy....but I was told by Arlen Vanke to REMOVE ONE SPRING from the dizzy and set the timing and tune for the best performance you can.

PTC 3000rpm stall converter.

3.54 geared DANA 60

My car ran decent aND wouldn't melt the tires off the rims for any long distance but would initially off the line.

I was never super impressed with that cam but it sure did sound bad azz!!

Got a whole 11mpg but it was dependable.


I....like everyone else has said, change the converter and maybe try my trick of removing one advance spring and dial in the timing so that it runs the best.

sounds typical for the internet