I apologize now this is a little long. My car from one race to the next has gone from 6.1xx@ 109 to 6.5/6.6 @102. Car is 2560 going down track. Older square tube chassis 14/32 slicks 406sbc and a glide. Ladder bars/coil over rear 4:56 gears. Ok went to a race in August temps in high 90s car runs normal. Got sick and missed some races, didn’t get back out until mid October. Temps now in the mid 60s. Unload the car that has only sat in the shop nothing done to it not even change oil now all the sudden 60ft is 1.50 from 1.32 et are the above 6.5/6.6. First thought is converter. Send it to ptc, they tell me nothing wrong with it. Have them put it back together and also loosen it up a little. Sent transmission out to be refreshed it is all good just needed a low band. Checked fuel pump by removing lines from bowls will pump 1 1/2 gallons in 22seconds so that should be good. Put trans/converter in car, car is still off the same amount. Did a compression test got 230 to 255 lbs so that looks ok. Checked valve springs and found they are down to 170/180lbs on the seat. That’s down from the 225 were new so have new springs in hand to replace them. Just not confident that will fix it. I have access to another ignition box to try and also other carburetors. Just about to run out of ideas so looking for some suggestions. Car has been rewired after problem arose but that also changed nothing. Starting to get aggravated with it. Thanks for anything you can come up with.

I'd count the turns of the band screw to 72 inch pounds, should be around 3.5 turns. It could be applying the band slightly going down track in high gear.


It needed a band upon rebuild, why? Is the indicator to verify it's not using up the band slightly applying the band in high gear going down track.

Second thing I'd do is put a, pressure guage on the servo port. Check in low and high gear at 2000- 2200rpms. Should be around 215 psi for your power tops Wooley. I'd adjust it if higher than 215psi.

Third I'd check converter pressure at the in cooler line to verify there's no restriction in the cooler. Verify pressure is the same on both sides of the cooler by taking the same reading off the out cooler line on T-brake or footbrake around 3-4000 rpms, shouldn't be higher than 120 psi.

You can rule out it slowing down as a result of losing power according normal observed stall, once you verify the transmission is operating normally according to pressures.

The first thing I check when a guy slows down is the stator tube, as soon as I pull the pump. A miss aligned stator can apply the band slightly in high gear.

This message has been edited. Last edited by: Mike Rietow,

I asked the shop that did the trans to specifically check the stator tube. They told me it was good. As much as I have done on the car the trans is one thing I have never done myself. I will have to get a gauge to check those pressures. I love a reason to buy a new tool.

quote:

Originally posted by Wooley:
I asked the shop that did the trans to specifically check the stator tube. They told me it was good. As much as I have done on the car the trans is one thing I have never done myself. I will have to get a gauge to check those pressures. I love a reason to buy a new tool.

If everything checks good,you'll be able to deck it on the converter. Your normal converter stall will tell ya all about your power. If you lose stall, you lost power.

Wooley I don't see where you have put the car up and checked for brake drag or rear drag? Just a thought.

Curtis

Curtis the car will roll very easy, I can push it myself and on even the slightest incline it will roll if not in park. Mike on the convertereould before going to ptc if I pulled the chip and decked it I would see 5600rpm now I get 6100. That’s with everything warmed up.

Checked the engine timing ??

If PTC loosened the converter 400, I'd tend to believe the valve springs have done the trick. Keeps progress updated. PS you can still purchase them tools. You're not going anywhere! Sooner or later they may come in handy if you're old schoolwith no intentions for racepak like me hehehe!

Just a thought but how old were the tires when you parked the car? I have seen tires start to harden in a matter of weeks. Since you seem to have consistently lost 60' as well as et, I would look at the condition of the tires as well. Had my dragster sit for 6 months in the trailer with new tires (we made 10 passes with the car before parking it. Then when we went to take it back out the tires were junk and needed to be replaced.

Well I will go the simple route all though I never lost that much with being able to hear it but what do the spark plugs look like? Fouled plugs could slow you a bunch.

Tires at the time we’re about 3 months old. Tires do need replacing now and plan to before I go back out. My friend that helps me did confirm that car was not spinning at the line.

I did check timing it is still set where it was. Plugs don’t look bad but are cheap enough that I will change them.

quote:

Originally posted by Wooley:
I did check timing it is still set where it was. Plugs don’t look bad but are cheap enough that I will change them.

Is this a crank trigger? Timing will look right even if it's wrong when the balancer shears the key. Seen it first hand. Almost always will the timing slow down in relation to TDC.

How are the tires, I'm about the same engine combo, weight, and ET's and when my tires are played out even with 1/3 left on markers it does this...just my 2 cents

No crank trigger. Heads are coming off to get new springs installed. New tires are next before next trip to track. Tires only have 47 runs on them but are a year old now.

The tires on my car right now are 5 years old, they were on my old car when I got my new ride out. I put them on new ride last year beings they only had around 50 runs on them and went 5.23 with them, best the car went was 5.21 in killer air the year before with same tires mounted on nonbeadlock wheels. The 5.23 was this year on bearlock wheels. Age doesn’t hurt if stored properly.

Tires are on the car but car is inside a closed shop on jackstands. Tires are off the floor.

It’s not the tires. I’d say maybe if it was off in 60’ but you’re off 7 MPH. That’s horsepower.

Leakdown numbers?

Don’t have a leak down gauge but did a cold compression test Monday. Low of 230psi to high of 250.