Hi all. I have been playing with my car for a while now and it just doesn't have any "*****." It'll run good just driving it, but when you push the pedal, the RPM's just go up kind of slow and the car isn't anywhere near as fast as it should be. I have set fuel pressure and timing to every imaginable spot, and they have little to no effect on performance. No engine codes are coming on, and I have a chip burned by TPIS. Is there something internally that could cause this problem? I had a 305 TPI with just a cam that felt faster than this!!! The car will pop every once in a while too if you gradually push on the gas pedal, right around half way down.

TPS is set at .710 volts, fuel PSI is at 42 with vacuum sorce off, timing is at 8*, and I have no idea what could be wrong. This car has been a huge nightmare, and if I can't get it figured out, I may sell it, which I'd rather not do!!

 

I would check for a clogged cat converter.

 

No cats on the car.....has a high flow exhaust and intake, so there are no restrictions there. I just don't know what else could be causing the lack of power.

 

Valve springs worn out? Car feels somewhat ok but never feels like it fully goes into the powerband?

Has the car been tuned?

 

The heads are brand new, so I don't think it is the springs. I had a chip burned for my setup through TPIS, and have adjusted the fuel pressure and timing all over the place and the car never changed. I think theres a problem somewhere else. The other thing is that it pops every once in a while through the intake. Not all the time but every few revs it'll pop, and it's a big pop too. I'm not getting any check engine light either, so i don't know if it's a sensor or not.

I'd really like to get it hooked up to a scanner to see whats going on, but I don't even know what to look for. Anyone by me have the equipment for that? I am at a total loss with this car, and would be willing to even pay someone if you found something out. I'm 15 mins from hartford.

 

Popping out the intake huh? Hmm.

That can be from a slightly bent intake valve, being that this isnt a constant thing, I would lean towards no.

Timing extremely advanced. Once again, not constant, so I am guessing no.

What kind of ignition do you have? Post specs on everything. From distributor, to rotor, to cap, wires, plugs...

 

Stock dist with stock rotor and cap, accel wires (old but they work), MSD coil, and the plugs that trick flow recommends to use with there heads, autolite 3924.

 

Im wondering if youre getting spark scatter. Basically its when the spark is diverted to the wrong cylinder. That could be causing the huge intake backfire.

 

Well the only thing that would point to is the wires, correct? I plan on getting new ones anyways, but it is a huge power loss, and I just don't know if thats all it would be. Me and a freind think my pushrod length may be a factor. I am using 7.1 inch pushrods and stock is 7.4. I have stock rockers, and stock roller lifters with the trickflow heads....anyone have a similiar combo and can tell me thier pushrod length??

 

Have you checked fuel pressure under load conditions? WOT?

You may have a weak pump.

 

Get a pushrod measuring tool from Summit. Trick Flow makes one that is like, $20 at most.

You can always call Trick Flow and ask them what pushrod you would need.

 

The car is doing the popping just standing still and reving it, and the revs are slow and don't jump up to RPMs like cars with similiar power would. Fuel pump is a new holley 255 LPH so I don't think its the problem, and I have always kept at least a quarter tank of gas in the car.
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I called trick flow but they weren't much help....they basically just said that pushrod length will vary with engine combos, and that what I was using they though was probably ok, but I dont like just "probably."

 

By the way, someone told me that if you have a big cam, you can't adjust valve lash by the method of adjusting half the valves at TDC, rotating the motor 360 degrees, and adjusting the other half?? is this true? I mean, it would explain the popping if a few of the valves were hanging open slightly due to being adjusted wrong.......they said you have to adjust one valve at a time while turning the motor to different spots.

 

Valve adjustment: I have always done "one valve at a time" method. Also, I turn the rocker nut 1/4 turn after zero lash. Get the #1 cylinder at Firing TDC and adjust both #1 valves. Then turn the crank exactly 90 degrees and adjust the next cylinder in the firing order, and continue.

Fuel pressure should be set to give you 12.8:1 AFR at WOT. Just trying different fuel pressures is not the right way. Get a wide band on their and adjust it correctly.

The TPS should not be at 0.71V, thats too high; set it to 0.62V at closed throttle.

I was told that popping when you slam the throttle down is a lean condition. Timing can also affect this. Since you have a TPIS chip, you have no idea what timing that you are running. For kicks, install the stock chip and see how it runs.

A scanning could "see" alot about whats going on with your engine.

 

The TPS is actually set at .64v now at closed throttle. I wish I had a wideband but don't as of now. Soon possibly. I have been in contact with Jim from TPIS (great guy), and he said to set the base timing to anywhere from 6 to 10 degrees......basically whatever the car likes the most. I have played with it all in between there, and it does not change the popping or lack of power, and again, I am getting no CEL, which leads me to believe it's valvetrain related. A freind is coming up on friday to check out the valvetrain with me and see if it looks ok. He has a very similiar motor setup but carbed instead of fuel injected. Hopefully we can figure something out, but until then, I am open to ideas! And thanks everyone for the help so far.

And by the way, DOC, do you think by adjusting the valves the way I did, some are hanging open? Cam is a comp XR276 hydraulic roller, 112 LSA, 224/230 @ .50, .503, .510 lift.