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Discussion Starter #1
Okay... I re-ringed my motor, replaced the bearings, and figured I step up a bit. Pulled my 262/274 cam and threw in a 280/294. Also sent my converter to get freshened.

Trans specialties said my sprag was shot and reccomended just converting it to spragless. So I went ahead with it.

Ran at the track last night...

Lost .5 tenths and 4 mph........

Was it the cam or converter??????? I am $1000 broker, and 1/2 sec slower, and 100% pissed....
 

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I guess a good question would be, "what is the stall speed of the convertor now in comparison to before you had the convertor freshened". Also I would check your valve train to make sure you haven't flatten a camshaft (assuming its flat tappet). MPH loss is definatly an indication of losing horsepower. I would also cut your oil filter apart and check for metal. A few years ago I had freshened my engine with a basic rering and bearing replacement and the car was almost 6 tenths slower. I traced the problem to a fuel delivery problem that being a fuel pump. I replaced the pump and the performance came back. 2 years ago I again ran into the same problem with poor performance after a engine freshen but this time traced the problem down to number 8 intake lobe on the camshaft had flattened. That was an expensive fix. You also didn't mention as to how your 60 foot times were affected.
 

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I'd venture a guess that the most of the MPH loss is the converter and the ET loss is 80-90% due to the cam change.
 

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Tomorrow night if the weather cooperates, if not we'll travel a bit further and test Saturday or Sunday. Some time this weekend I'm making some passes somewhere LOL
 

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I guess it goes out to the fact that ATI spent some money to put a full page ad in the dragster, as discussed earlier, to rip the spragless converters, and by all means if it was a good thing they could be pushing the spragless issue also. What would really tick me off would be what real world knowledge or experience has your converter builder had with spragless converters that would give them the confindence to recommend this option. I would be very confident that he has not spent the R&D and money to 100% go that direction.

If it sounds too good to be true it generally is. We racers just can't get rid of that bug to want to go faster and you are not the only one that has lost a bunch of money chasing faster times, and getting no more.
 

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Discussion Starter #8
Well, TS had a patent on the spragless technology back 15 years ago. So I assumed they were and are the "experts".

I am going to pull it Sat. and throw in a 2800 stall that I have, it my mph picks up, then I at least identified the problem.

I also doubt the cam was the issue, but who knows.
 

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I bet that the converter is the largest part of the problem, and I hope that it corrects the issue.
Keep us posted.
 

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My car has picked up right before either an engine or a convertor has blown. New rings might be a little more fricton? and a freshened convertor may have taken out some stall from its worn status. Just a thought, of course it never picked up by 5 tenths but ive seen as much as 2 tenths. Ive seen a couple hundreths before a rocker arm broke.
 

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that's a considerable change in duration, i'm assuming you moved the powerband up a bit with that, did you change your shift points to compensate? i know it seems like it would be a pretty amateur mistake but we've all made them before...
 

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Discussion Starter #12
Good question, I did raise my shift point by 700. The car falls off about 7200, so I shifted the car at 7000. Previously I shifted the car at 6300, went through at 7000.

Now I shift at 7000 and went through at 6500. I believe the converter is the problem, although I may throw the cam back into to verify that.

I just talked to a buddy that runs a SC car. He said that he has seen .8 tenths to over a second loss or gain with a converter change.

My cam guy said barring a broke spring or mechanical issue, it would have to be the converter.
 

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Another thing I would do is if you have a cylinder leak down tester is to check the percentage of cylinder leakage. Its surprising what this can tell you.
 

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I bought a spragless converter from TS about 10 years ago to put in a dragster that ran 4.80's in the 1/8 mile. I immediately slowed to 5.00's and lost 2 mph. I called the converter company and they were very rude and no help, even suggesting I may have to change the combination, rpm's, etc to get the convertor to work properly. They would do nothing about it. Absolutely the worst public relations of any performance company I have ever dealt with.

I then bought an ATI and picked back up all of the lost et and even gained a little mph. The only place I have found a spragless converter to run close to a sprag converter is a very high rpm engine 6500-9000 power range.

PTC makes an excellent converter at a little less money than most of the established big name companies get. I have had excellent results with their products. When calling you get courteous treatment and if you have problems you are not made to feel it is all your fault.

No intent to bash or advertise for anyone, just my experiences over the years.
 

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I've heard a spragless slows the vehicle down a bit, but man, I don't think I'd pay to slow down. Dave
 

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nova10sec said:
Good question, I did raise my shift point by 700. The car falls off about 7200, so I shifted the car at 7000. Previously I shifted the car at 6300, went through at 7000.
You're only good to 7200 with a 280°/294° cam? I would think 8500 rpm would be in the cards. The Durango Deuce motor peaks at 7100 rpm with a 240° cam and my driver 406 will run up to 6100 with a 224° cam. Perhaps you've put too much cam in the car.
 

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Grrrr.!!!

Hey Now! As I read the post, more than one issue has happened. The First item I would have looked at after the mechanical changes; FUEL & Timing. The change in duration will change the timing and fuel mixture from the previous cam. All of your known power band rpm's changed. Respectfully, "Bill's" II :)
 

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You're only good to 7200 with a 280°/294° cam? I would think 8500 rpm would be in the cards
Mike,
My old 406 had a cam that was [email protected] and would rev to 8000 o.k. but, it made peak power at 63-6400!! It ran 10.20's in a 3000lb. car. The cam in my current(dead)engine is even bigger, but makes peak power around 7000. I feel it's way too much cam, but I let the engineers at Lunati design it around the rest of my combo.
I have a friend with a 13-1 406 that runs a 266/[email protected] cam,
and he's about 2/10th's quicker than me(200lbs. lighter too)
 

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Discussion Starter #20
Well, I found at leat some of the problem. Did a compression test, 210,210,210,145.... #7 looked hurt, so I did a leak down test, 97,98,96,30%... Just had my buddy grind the valve, re-cut the seat, cranking comp back up to 210, leak down up to 98%. Finish it this week in time for Sat April 15 T&T..
 
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