I'm having an issue with my car. In high gear (powerglide) the car will want to hang at 5500rpm. Fuel is 10.3-10.6 E85 CSU dual float bowls, brpv's, plugs show very rich, timing is 30deg. locked, digital 6 box, hei distributor. I have fuel, I don't have any detonation or misfires. I recently rebuilt my transmission and while it was out I had my PTC converter tightened a little, since it always seemed a little loose on the street. At the track the converter gives me immediate spool and I leave at 4500rpm. If the converter were too tight then it wouldn't spool, if it were too loose then it would rev high on the big end???? Right??? I bought a billet msd distributor and coil so I'm going to try that this week. I've seen bad issues with the digital 6 boxes so I'm also going to borrow a regular old 6al as well. Any ideas? Can the converter do this?
Despite these issues I did have some decent times.
13 psi, 4500rpm launch, all three passes.

1st pass. 1.58, 10.42@135 Car hung at 5500 in low and high gear. 10.6 afr at wot 150deg water temp
2nd pass 1.44, 9.61@143 Car went through 1st good, short shifted at 6000, hung at 5500 in high gear, 10.3 at wot 180deg water temp
3rd pass 1.44, 9.70@143 Car went through 1st okay, shifted at 6000, hung at 5500 in high gear, I let out about 100ft early, 10.7afr at wot 190 water temp (hot lapped)

I'm very open to suggestions, I'm freaking the hell out on this deal. This is the same issue I had last year! Obviously I'm making more power with my new heads, it would have taken me over 20psi to get these times last year. Thanks.

 

Whats the timing at?

 

30degrees locked out. I questioned my timing mark and balancer. I used a spark plug style TDC stop and found that the balancer was correct. Also note that I never had this problem at all until I put in my custom turbo cam. The cam is installed straight up.

 

So the converter is the same before the cam swap? What are the cam specs?

 

First off the car is hauling ass and when you TIGHTEN up that converter it will haul even more.

You don't need to be in the 10's with E85, I'd dyno it and watch the power jump when you get into the 11's Air Fuel Ratio.

But your issue is the converter is too loose up top. You're only getting a 500 rpm drop after the shift and there seems to be a consensus that a 700-800 rpm drop is common ( depends on power band ). The cars tune is not helping up top since it's fat but it's still making so much power that it's blowing through the converter. The funny thing is a leaner tune would probably make it a tad worse.

You should contact your PTC retailer, PTC themselves or talk to a guy named Dusty Bradford. He's a PTC dealer and runs something like 8's on his PTC converter. You might need a bolt together converter so you can dial it in yourself yet see around 2% up top.

BTW, if you were to make a full pass your trap RPM would help PTC out as they'll know your converter efficiency and be able to dial it in from there.

 

So your saying the converter is too loose when it will hang at a certain RPM? In my experience a loose converter will allow the car to over rev at the big end. Kenny at PTC actually thought what I had would be perfect. I asked him to tighten it a little to make street driving better.

 

Ya your most likely blowing through it with your power and the rpm drops are pretty low which can be the result of the converter being too loose and/or your car being too powerful for the converter setup.

I'd do a full pass and keep track of trap rpm.

What is your desired shift rpm, 6k or were they all short shifts at 6k?
If you want a higher shift rpm I'd do it in 1st and/or 2nd on the street and see if it comes back to 5500rpm regardless of shift rpm.

All this info will help Kenny.

FWIW, my Precision Industries 5 Disc Converter is a tad loose in 1st and 2nd and it shifts from 5500 to 47-4800rpm but then we lock it in 3rd for a 100% power transfer.

 

I'm confused. If my converter was too loose it would rev to the moon in in high gear due to slip. If I were to plug the numbers into a calculator the way it is now I'd get -6% slip, that's NEGATIVE.

 

What are your #'s?

Trap RPM
Tire Height
Rear End Gear
Trans Ratio
MPH

Are you staying in it the whole way down the track?

 

Yes, that's my point at WOT in high gear it hangs at 5500rpm. My original question was can a converter issue cause this? The converter is not to loose.

 

I have heard of too loose of a converter "Hanging" on the 1/2 shift like you're explaining if it is still "Stalling" during the 1/2 shift. But you're seeing this in High Gear. Typically after "Hanging" at the stall speed on the 1/2 Shift for a short period, the engine will then pick up and drive on out. That is a matter of incorrect stall speed. I'm assuming you don't have a data logger to compare engine / driveshaft RPM. If it were my car I would run it down the track and try and "Drive thru" it first. Assuming this isn't an Ignition Problem, then sometimes changing rear gears will help. Other than that, it may be a stall speed problem. My 2 cents...

 

By hanging I mean it won't pull past 5500. I should have it running tonight. I think I'm going to mount my camera on the guages, poor mans data log.

 

The first thing I would do is pull some fuel out. At 13psi mine likes to be around 12.0-12.2. I fatten it up for higher boost but anything richer than 10.8 and it starts to break up

 

Yeah that's what Kevin said also. What bothers me with doing this is that I read 10.3-10.6 on the guage, and the log on my LM-1 said 11.8-12. I'm hating the LM-1 more and more these days. The plugs show rich though.

 

Ya somethings not right as the only way I was able to get it into slippage was to move your rear end gear to 3.23 and that was like mid 2% which is awesome.

 

Update time. I installed the MSD distributor and it definitely helped out the car over all, made a noticeable difference in drive ability. Went to the track, the track sucked. I started off with the timing very low 22deg, and the car was a pig. I increased the timing to 30 and ran again, it was better but a pig. I took the jetting down to 72 and 73, which netted 10.8 afr. It ran much better but the track couldn't hold it. It now pulls hard through both gears. My best of the night was only a 10.1 @ 144mph. My 60ft was down and I was spinning badly. I'll be back at the track on Sunday, I think I'm going to lean it out some more and hopefully hook better. What's awesome is that my CSU carb is running 72 and 73 jets to get me 10.8 afr on E85!

 

well did it hang up at 5500 rpm again?

 

No

 

Do you think it was an ignition problem or that it was just too rich?

 

I think it was a combo nation of both. With my old distributor the timing seemed a little eratic when I had the timing light on it. It would increase a little with RPM even though the timing was locked out. It's steady now. Taking fuel away made a huge difference though. Even with the new distributor with it jetted higher it just wouldn't run through the RPM hard. Getting it in the 10.8 range made it pull hard through the gears.