Anyone else have any issues with their car laying over on top end? Mine was doing it really bad about a month and I though I had it fixed, but I guess not. What it is doing is laying over, and the more boost I give it the worse it gets and less power it makes.
I figured it was the valve springs so I replaced them with some Tooley racing springs with .030 shims and I though I had it fixed cause it went away on the street. But I went to the track yesterday and it is back.

I can't tell if I'm blowing the spark out or if it is valve spring related. I'm running a 9 heat range NGK plug gapped at .023 or .025 (can't remember).

Data logs on the Holley system show perfect AFR and timing.

Here is a vid you can hear the exhaust change tone when it lays over.

Thanks for any input.
Frank

 

Can we get more specs on the motor and setup

 

408 ci 9-1 cr with twin 67mm precisions, holley dominator efi with stock truck coils. 231/237 custom cam

This combo was running 156mph last year at only 15psi! I haven't changed anything in the tune.

Basically I'm curious if there is any way for me to tell if I'm getting valve float or blowing out the spark? Is there anything in the data log that would indicate one way or the other? I'm just not sure which way to attack this gremlin yet.

 

nothing has changed? does it still run the same 330 & 1/8 mile times or is it lacking the whole run?

could it be trans or converter related?

sounds like it drops a cylinder when u shift into high gear

 

Trans and converter are the same, just freshened. The only thing I did change was the gear ratio. It was out of gear with the 3.50s so I swapped to 3.20s. I'm crossing the traps at 6500. You can hear the exhaust change tone when it flattens out. I went my best mph yesterday at my lowest boost level. 15psi was 149, 17 psi was 145, 19 psi was 144mph. Lost power every time I added boost.

 

Sounds like it has a miss. Compression/ leak down look ok? Spark plug wire? Maybe coil?

My car had a wire that would only miss when it was under a hard load or trying to go into heavy boost. It was strange. Plugs would look good but I chased it for about a month till I seen it arcing with the hood up and pitch dark. When I cut the wires to length crimped the terminal on and pushed the boot on the fero spiral wrap around the wire core was pushed flush with the edge of the boot. It would randomly arc to my downpipe about 3 inches away.

 

Yes I put new plugs in it when I changed the valve springs last month and did a compression test and leak down at that time. All results were perfect.

The funny thing is that it got better when I changed the springs to the point that I thought I had it fixed. It feels 10x better than it did. It would make that same exhaust tone change on the street with only 10psi, now it doesn't seem to do it at all on the street, but I can only hit it for short burst since it just spins at anything under 60mph.

 

I don't know what fuel your running but I can tell you they will flutter if they go into detonation bad enuff. and fall off in high gear. that's what my brothers procharged car was doing when the meth popped a fuse . afr was still good just not enuff octaine.

 

its defiantly load related. Have you tried a hotter plug?

I'd double and then triple check the wires & try an 8 or even 7 plug at .024 gap

 

YenkoMike, coincidentally my meth tank/pump setup was leaking meth when I parked the car in the garage after my runs. I will pop it apart tonight to see what was going on. There is a chance the meth was not working. I did notice the computer adding quite a bit of fuel when I looked at the learn table which is odd considering I had the tune very close. I keep it in closed loop just in case the meth were to quit on me.

Thanks,
Frank

 

I haven't tried that yet SAM, but it did run 156 mph last year with the same plugs at the same gap. I do plan to switch to some Autolite racing plugs and give them a try.

 

that sounds like it could be the issue his meth was blowing the fuse do to a week ground.the ground connection to the body whould get hot and the fuse whould pop . we fixed the ground and it stopped. but we did rewire the meth so it got power when we turned it on instead of all the time .

his car is 15# boost and 27* timing so it needs meth to live. with no meth it ran good to the 1/8 then start loosing mph and finally flutter crossing the finish line. we found it fast in about 1.5 runs and it seems to have lived.

 

I tested the Meth kit last night and it is working fine. Actually I can't get it to leak now!? Anyway I was looking through the logs and ran across a bigger issue. I'm loosing tons of oil pressure. My oil pressure goes from 67psi down to 5 or 10 psi at the top of 1st gear! I looked back at my logs and it has been doing it for 2 years..
I pulled my filter last night and I don't see anything alarming in it, just typical dirt and debris.

I wonder if the drop in oil pressure could be collapsing the lifters and not opening the valves enough. hmm

 

Put some solid lifters in there and see what happens????
Not a cheap way to test but it would prove out your theory (which is a good one).

 

I'm going to try over filling the oil pan and making some test hits first. I have to pull the engine to pull the heads on this motor. It is set back in to the firewall for weight dist. Not to mention that would require a cam and valvespring change as well.

 

Yea, good point.

Hope an extra quart or two helps!

 

Are you using a stock pan?

 

Yes. F-body pan.

 

thats the reason i went to the moroso pan. hear storries like this that thje pick up in the pan isnt in a good spot for higher hp cars.

have you measured the back pressure?

 

Ive never heard of adding more oil. What's the thought behind that?