OK, long story short. GTX is a dog, punch it from a stop and it will just chirp the tires. I can't feel a hesitate or bog it just doesn't have any power (been this way for years).

Here is what it has:

440 .030 over
forged six pack replacement pistons
old (20 years old) 284/484 cam
ported 906's
Edelbrock RPM manifold w/Holley 750 Advenger carb
~18 inital timing, ~34 total
727 w/340 converter
3.55 suregrip.

I know the cam, car weight, converter, and rear end aren't matched the best but it can't even turn over the tires.

Before I painted the car I could get it to break the tires loose through the gears and only thing I changed was the converter. I took out a stock looking converter and replaced it with the 340 converter thinking it would help.

So, is my setup so miss-matched that I'm screwed or do I just need to go out and buy another converter? I would think that this combo should be able to shred the tires with a stock converter????

Did you feed it breakfast?

I wish it was that simple!!

It sounds GREAT but has no teeth. My small block Demon will blow it off the road!!!

How quick does it rev up when it's in neutral? And does it have six pack rods also?

I learned many years ago to put a decent stall converter behind even the 474 mopar cam on a 440 car. I have not bought one since 1978 but a B&M super holeshot turned the 440 cuda into a tire shredder. I currently have a 500" low deck with a PTC 9.5 and it rocks.

Did u degree the cam.also 484 likes a 2500 stall

If you have the old converter still put it back in
I don't and won't use any of the newer Mopar Purple Shaft street Hemi grinds, especially the famous 284 street hemi grinds

Seems to be fine in neutral.

I have a PTC in the Demon and it rocks!!! I think it flashes around 3700 but I don't want that for the GTX, I'm looking for something a little more streetable if possible.

I didn't build the engine, it was build 20+ years ago and has about 5000 miles on it.

I looked up the part number for the 284/484 cam it in and it's the old one. He gave me a pile of receipts two inches thick for the motor/trans.

I know a converter can really wake up an engine but shouldn't an engine like this be able to put some hurt on the rear tires even with a stock converter?

I would get a cranking compression number & maybe a leakdown also

Maybe the '340 converter' isn't really a 340 converter, or it's bound up inside for some reason. If it started doing this right after installing it, I'd say it's the converter. If you don't have the old one, maybe borrow one from somebody before buying a new one, if you don't mind removing the trans a few times.

How tall are the rear tires? They look tall. Was the cam degreed in? It could be retarded. What type of fan on the engine, solid mount or clutch fan? is the carb a vac secondary or mechanical? What ignition system? How tight are the engine clearances? I agree that your 484 cam likes a converter.

The 484 is not a hemi grind cam. The 474 is and I don't think it works very well at all.

The tires are 28" (275/60/15) I don't about the clearances, I didn't put the engine together. I don't know that the cam is degreed either.

I have the receipt for the converter and it shows 7642 and I believe the 764 is the 340 converter.

So it sounds like my assumption about a mild 440 being able to smoke the tires with any converter is BS.

I'd make sure it's getting full throttle first, and if it is.......I'd see if I could borrow a different carb.
I'd be looking for a 750DP if it were me.

As long as the converter isn't broken/defective, and assuming there was a good carb on it, that combo should run pretty good.

I second the thought of doing a compression test on a least a couple cylinders, just so you know where it's at.

I took off a 750 DP because I was told the mechanical secondaries were compounding my problem. Unfortunately the carb sold with my barracuda a couple of years ago.

I'll have to compression test.

OK, I made one mistake. I looked up the part number for the pistons (2286P) and that shows a stock replacement piston the six-pack piston so my compression is lower. BUT, like I said, when I first got the car it would shred the tires with this same engine...

Also, I just remembered that I had to back off the timing due to bad predetonation during hard throttle. Still has that problem a little bit. Compression ratio should be good...

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

Ive found out the 284 and 292 mopar cams need alot of stall and low gears for sure to get out of the hole. There was an article in a mopar mag a few years back of a 70 roadrunner that had the 284 mopar cam and was a dog, they swapped in a XE comp cam and it came alive and picked up HP.

That doesn't come as a big surprise given Comp is a big advertiser there.

Kevin

Thanks for the help. I'm going to throw a converter at it and go from there.

Gonna throw it thru the window? Or at the dudes that say to get another carb?

OP - please check your inbox.

I replied. Thanks!

I have damn near the same setup except I DO have the TRW six pack pistons which give more compression and I have the 284 installed 4 degrees advanced and a Mopar performance 2500 stall convertor. I have 323 gears. stock 452 heads and stock intake with a modified TQ. This is in my 1972 dart. It will burn the tires off until I let out of it!! My only complaint is that it quits pulling after 5500 rpm. I need more flow at high rpm! I want some better heads!

My thoughts exactly. If all you did was change the convertor and now it's a dog, get rid of that convertor.

The advanced cam timing is taking away the top end, change that first.

I have that same cam in my Ramcharger. 21 degrees initial 17 degrees mechanical.

well my personal experience I went from the mopar 292 cam to a XE294 in a low compression 440 and my ET dropped and the drivability improved and I get no check or funds from Comp cams for saying this statement.

As is the case with the magazine reference, without seeing the rest of the cam specs/ICL we could speculate all day on why that happened.

If the MP cam in the magazine was installed say 4 deg retarded either deliberately or because whoever just lined up the dots and the Comp was dialed in properly and installed 4 deg advanced, it should come as no surprise that "it came alive" especially if it was a low compression engine and the cam specs are similar ie same lift and duration @.050, overlap LSA etc.

Kevin

True... that's why I threw my real world experience in there on the 292 cam to xe294 cam. We could speculate all day on comp being an advertiser there and what really happened as you said.

How do the cam specs compare between your cams, LSA ICL Dur@.050 etc?

Kevin

I'm waiting for the results of the stall test.

Maybe....
Don't most stock iron heads drop off after 5500 rpms anyway? Maybe not a cam problem in his case.

I have had the stock 906s pull good to 6500, solid and roller cams. I had a stock 77 440 with the 509 cam go dead at 5000, same cam in a 383 pull to 6500, degree the same, cam, lifters, chain, rockers, springs changed from one to the other.