451 stroker rear gears question

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matty wardle

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hi have a fresh 451 in my 73 cuda,with a comp cams extreme energy hi lift hydraulic 285 241/247 @50.i put the motor together myself and fully rebuilt the trans with all good frictions ect,the car has a 4;10 rear and 26 inch mickey thompson street tyres,ptc done my converter i put down 50% drag and 50% street john cope said it was about 4500,4800 stall,the msd has 18 degrees initial and 36 total,the problem is you would think this car would hammer off the line,but it just revs alot and you dont get that thrown back in the seat type of feeling,i took the car to the track with this setup and it ran 106 for a 12.2 the car was at 106 with 100 metres to go and was just sitting on 7000 rpm for the remainder just doing nothing,i did 2 runs like this and realised i was being a dickhead and the exercise was fruitless,i havnt the money to buy gears at the moment however i have a set of 3.23s which im going to put back in for the time being,i also now have 28 inch slicks that i bought.can you have to low of diff gears and it just skips through the engines powerband,this engine gets to 6000 so quick without any real seat of your pants pulling power ,will it feel faster with the 3.23s on the street ,will it hold it in its torque band better?
 
I think (before you'll be pouring in a thousand of more on parts) I would head over to a chassis dyno and see what the engine/combo actually produces through it's rpm-range.

Maybe something is still wrong like cam-timing, fuel delivery or some high rpm ignition issues.
 
if your engine revs real fast like you say it must be makin power I would find out where its going (ie) converter or tranny . even ptc is capable of the odd mistake .I would think you loosing close to a second .
 
matty wardle said:
hi have a fresh 451 in my 73 cuda,with a comp cams extreme energy hi lift hydraulic 285 241/247 @50.i put the motor together myself and fully rebuilt the trans with all good frictions ect,the car has a 4;10 rear and 26 inch mickey thompson street tyres,ptc done my converter i put down 50% drag and 50% street john cope said it was about 4500,4800 stall,the msd has 18 degrees initial and 36 total,the problem is you would think this car would hammer off the line,but it just revs alot and you dont get that thrown back in the seat type of feeling,i took the car to the track with this setup and it ran 106 for a 12.2 the car was at 106 with 100 metres to go and was just sitting on 7000 rpm for the remainder just doing nothing,i did 2 runs like this and realised i was being a dickhead and the exercise was fruitless,i havnt the money to buy gears at the moment however i have a set of 3.23s which im going to put back in for the time being,i also now have 28 inch slicks that i bought.can you have to low of diff gears and it just skips through the engines powerband,this engine gets to 6000 so quick without any real seat of your pants pulling power ,will it feel faster with the 3.23s on the street ,will it hold it in its torque band better?
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Holy Mackerel Matty, 7,000 rpm with the XE285HL? That cam will make peak horsepower @ 5,600-5,800 rpm, maybe even less. If you flash to 4,500-4,800 rpm you will already be above the engines peak torque plus you've only got a 1,000-1,200 rpm pull before it's time to shift. Even Comp cams recommends a 3,000 rpm stall. You could try the tires first, they're the easiest and the 3.23 gear should be no problem on the street or track.
 
IQ52 said:
Holy Mackerel Matty, 7,000 rpm with the XE285HL? That cam will make peak horsepower @ 5,600-5,800 rpm, maybe even less. If you flash to 4,500-4,800 rpm you will already be above the engines peak torque plus you've only got a 1,000-1,200 rpm pull before it's time to shift. Even Comp cams recommends a 3,000 rpm stall. You could try the tires first, they're the easiest and the 3.23 gear should be no problem on the street or track.
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thats exactly what happens in first by the time the converter locks up it screams its head off and im into 2nd and then im going into 3rd in no time but not really going anywhere in a hurry,i think the converter slips too much and the gears are too low ,thats why im thinking the 3.23s might feel better cause the engine will stay in its torque/rpm band a little longer,is it possable to have too short of gears in a quick reving stroker big block??
 
I think the convertor is totally wrong or broken. New doesn't mean good, even from good suppliers. It's too loose. You should be trapping at 6200ish for 102mph so something's off. I don't know what John was thinking - you sure you/he heard him/you right? I'd get it back to PTC first to inspect it, second to lower the brake stall by 1800rpm and give it a flash around 3500.
 
We were discussing thia very subject last Tuesday with my tranny builder. There are compromises with a street/strip converter so you can live with it on the street. Having a high stall converter is cool for a while but unless you like hearing the motor scream it gets ol rather quickly. My converter is 2400 rpm and we decided against a 2800 because it will slip on the highway until about 62 mph with 4.10 gears and 28" tire. If you have a quality converter you can have it adjusted. As 5sec dart says, a 3.23 gear will make it worse because it will never get to it's lockup. Loose converters make heat, heat kills trannys. Hope this helps, "Waltzin' Matilda"
 
well i put the 3:23 s in,car is much better loads the engine up and pulls hard now,converter is too loose though still flashes to 4000,i,ll take it back to the strip and see what it does,because i dont think the converter will affect strip performance at all,just a bit loose for the street,only miled an hour at 106 before with the 4;10s so hopefully now it,ll get 120 or or so ,we,ll see what happens
 
5 sec dart said:
the converter is too loose. Putting a 3.23 gear in will make it a lot looser.
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I 100% agree. The stall speed and attitude of a torque converter changes a lot depending on load. Going from a 4.10 to a 3.23 is going to put the converter under a lot more load and drive the stall speed up even more. I would get a tighter converter and go from there.
 
Converter, as others have mentioned, is likely miles off. IMO, horrible selection for what you have. What size is it, an 8"?

New converters aren't and shouldn't be comparable to 80-90's units that slip like crazy on cruise. Plenty of new converters will flash to 3800-4000 and run tight when under light loads. Many run tighter on cruise than cheapy lower stall units. A 9.5" unit that is well built will get you in the right area.

IQ is on as well, the cam should be done around 5600ish, so the flash speed is a bit close to peak HP.

7000 with a 26" tire and 4.10 gears, I get ~20% slip... THAT'S FRICKEN HORRIBLE!!!
 
matty wardle said:
hi have a fresh 451 in my 73 cuda,with a comp cams extreme energy hi lift hydraulic 285 241/247 @50.i put the motor together myself and fully rebuilt the trans with all good frictions ect,the car has a 4;10 rear and 26 inch mickey thompson street tyres,ptc done my converter i put down 50% drag and 50% street john cope said it was about 4500,4800 stall,the msd has 18 degrees initial and 36 total,the problem is you would think this car would hammer off the line,but it just revs alot and you dont get that thrown back in the seat type of feeling,i took the car to the track with this setup and it ran 106 for a 12.2 the car was at 106 with 100 metres to go and was just sitting on 7000 rpm for the remainder just doing nothing,i did 2 runs like this and realised i was being a dickhead and the exercise was fruitless,i havnt the money to buy gears at the moment however i have a set of 3.23s which im going to put back in for the time being,i also now have 28 inch slicks that i bought.can you have to low of diff gears and it just skips through the engines powerband,this engine gets to 6000 so quick without any real seat of your pants pulling power ,will it feel faster with the 3.23s on the street ,will it hold it in its torque band better?
Click to expand...

I run 4.56's with a 28" tire and it's at 6200RPm at 114mph. I'd say something is wrong.

Also your convertor is too high. Mine makes peak torque at 3500. You don't need to be stalling 1000-1500 over your peak torque.

I don't know how you are seeing 7,000 rpm reliably out of a hyd cam engine? Also there is no reason to spin that combo like that.

I would put the 3:23's in it until you figure out what you want to do.

My setup runs a GVOD with 4:56's and 28's. I would never run those gears and tires on the street without the GVOD.
 
anyone got a converter they wanna sell me that will suit this combo??,box it up and ship to australia
 
crackedback said:
Converter, as others have mentioned, is likely miles off. IMO, horrible selection for what you have. What size is it, an 8"?

New converters aren't and shouldn't be comparable to 80-90's units that slip like crazy on cruise. Plenty of new converters will flash to 3800-4000 and run tight when under light loads. Many run tighter on cruise than cheapy lower stall units. A 9.5" unit that is well built will get you in the right area.

IQ is on as well, the cam should be done around 5600ish, so the flash speed is a bit close to peak HP.

7000 with a 26" tire and 4.10 gears, I get ~20% slip... THAT'S FRICKEN HORRIBLE!!!
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I agree. I have a PTC 9.5 inch 4000 stall behind my 440. I also have an A-518 overdrive and 4,57 gears. The converter works absolutely perfect with my combo and unlike some of the old high stall converters I used years back, it does not slip a lot under part throttle cruise. In fact I drive the car to and from the track 110 miles each way and the overdrive gives me a final drive ratio of 3.15. I get 11.5 mpg on the highway. Converter technology keeps improving just like everything else.
 
matty wardle said:
hi have a fresh 451 in my 73 cuda,with a comp cams extreme energy hi lift hydraulic 285 241/247 @50.i put the motor together myself and fully rebuilt the trans with all good frictions ect,the car has a 4;10 rear and 26 inch mickey thompson street tyres,ptc done my converter i put down 50% drag and 50% street john cope said it was about 4500,4800 stall,the msd has 18 degrees initial and 36 total,the problem is you would think this car would hammer off the line,but it just revs alot and you dont get that thrown back in the seat type of feeling,i took the car to the track with this setup and it ran 106 for a 12.2 the car was at 106 with 100 metres to go and was just sitting on 7000 rpm for the remainder just doing nothing,i did 2 runs like this and realised i was being a dickhead and the exercise was fruitless,i havnt the money to buy gears at the moment however i have a set of 3.23s which im going to put back in for the time being,i also now have 28 inch slicks that i bought.can you have to low of diff gears and it just skips through the engines powerband,this engine gets to 6000 so quick without any real seat of your pants pulling power ,will it feel faster with the 3.23s on the street ,will it hold it in its torque band better?
Click to expand...
I bought my PTC 9.5 inch from John Cope also. He asked for every single detail about my combo, EVERYTHING. He nailed it dead on with my car, it works perfectly. Best torque converter I've ever had, hands down. I'm starting to think you may have a defective converter.
 
crackedback said:
New converters aren't and shouldn't be comparable to 80-90's units that slip like crazy on cruise. Plenty of new converters will flash to 3800-4000 and run tight when under light loads.
Click to expand...

To give you an example, my convertor flashes to 3500 but will only foot brake to about 1000 or 1200. At cruise you don't even notice its' there unless you push abruptly on the throttle.
 
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