Ran JAGUICK Saturday 9.968, 10.008, 10.004, 10.01, 9.986. (10.00 race) Car pulls well till 1000 ft and the RPMs level off. RPMs at 6200 or so thru the traps with only 3.50 gears (28.5 tires). Almost feels like it's got a govenor. Air was kinda nasty, it was 96 deg and 68% humidity. I'm thinking my valve springs are are shot?? (only about 400 passes on them) Would fresh spring perk it up? Are sold cams harder on valve springs? I've gone twice as many passes on BQUICK with hydraulic cam and more RPMs.
Don't have a gauge that I can see going down track. Wouldn't be looking at it anyway....barely get to look at tach and oil pressure. I set it between 8 and 8.5. Could be that the motor was a bit rich for the crappy air conditions. With the solid cam, I used to back off the rocker shafts over the winter but didn't the last 2 years. Could be a few weak springs from being squashed for 6 months. Hydraulic cam bleeds off after a while.....easier on the springs during storage.
Knowing fuel pressure at top end or better yet, exhaust O2 numbers is key. I wouldn't worry about the valve springs, unless they've been compressed past their elastic limit or have been subjected to overheating. No harm is done staying in their compressed position long-term unless something bad has happened to them previously. If they're in question, remove a few and test them. Devon
How far are you from the quickest ET in good air? Maybe it was just down on power due to the higher DA?
Yeah, that would be a good idea. But...I hardly even run my recording tach. Duct tape my cell phone to the rollbar? Gary, yeah it was a couple tenths off but never felt it like this....I was like waiting to get to the finish line....at 135. Could be that the VERY short shutdown area had me anxious to get on the brakes. 75/80 shutdown goes uphill for a little then down hill. Deceiving, you think you have it then you don't.
That's an interesting idea....the aluminum heads grow a lot and the valves were a bit noisy. Excessive clearance....loss of top end power. Hmmm
I doubt even 30F ambient would have any effect on lash if the engine is maintaining operating temperature, so likely no. Devon
Is it all the time or just top end of third? I would either look at the push rod length and/or the valve springs. I would check both.
Acts like a car that's over-geared where it runs past it's peak power band in high gear. But it's not over geared with 3.50 and 28 tires.
Just found the problem. A wire came off my relay for my retard rpm switch. So...I was not getting any retard on top end. Was just staying at 35 and not retarding back to 31 over 5000 rpm. In the cool weather not as much issue but in the heat it took its toll.....wasn't happy pulling in high gear.
Yeah Gary good idea but I don't want to hurt the motor anymore. One spark plug had the side electrode melted off or snapped off from detonation, I guess. My other car BQUICK has the retard working and it loves high gear but then again it's got Stage 2 heads. It wants more than a quarter mile....I have to shut it down but JAGUICK seems or seemed all done approching the quarter. We'll see..... Can I run 9s at Columbus uncertified??? If not, I've gotten pretty good at slowing my cat down lately.:Brow:
If the car acts the same way next time out, look at those valve springs. We have run into this issue twice now and both times it was weak springs from high temp and RPM. I'm looking forward to the next time out with Jenn's dragster with the new valve springs. Let us know how it goes....
95 degrees would be a cool summer day here. its already getting over 100s every day soon to be 115 + every day till winter.
