Motor won't rev over 5200-5300rpm... WTF???
- Thread starter yullose
- Start date
There is enough adjustment in the chip that I can fine tune it as needed...
The injectors haven't been touched... but they were pulled and put in a container while I had the motor apart... I was super anal about flushing and filtering the fuel system before hooking it to the rails... so the possibility of debris in them is extremely remote.
They will be next on the list if the valve adjustment doesn't help.
- Joined
- May 27, 2001
The cam is a hyd roller and is cherry... I just had it out of the motor for inspection and it still looks like new.
I am glad to hear that the cam is ok.
We have lost 2 rollers in 109 blocks...
It has been several years though.
I got a similar issue as you do but mine is at 6K. Going to an all day track rental tomorrow loaded up with a ton of extra parts to figure this out
The whole theory behind it makes complete sense... adjust valves with preload, and oil pressure (hydraulics) may possibly overcome that preload or the valvesprings, leaving the valves open when the lifter is on the base circle of the cam...
Setting the valves at zero lash, and there is no possibility of the valves hanging open, NONE.
That's my theory and I'm sticking to it. (unless it doesn't fix my problem)
The whole theory behind it makes complete sense... adjust valves with preload, and oil pressure (hydraulics) may possibly overcome that preload or the valvesprings, leaving the valves open when the lifter is on the base circle of the cam...
Setting the valves at zero lash, and there is no possibility of the valves hanging open, NONE.
That's my theory and I'm sticking to it. (unless it doesn't fix my problem)
All you have left mechanically is the lifters so you will have the answer soon.
Yeah no kidding... lol
I've replaced just about everything else...
Funny thing is... I've had a helluva lot less trouble with high-mileage bone stock motors.
Yeah no kidding... lol
I've replaced just about everything else...
Funny thing is... I've had a helluva lot less trouble with high-mileage bone stock motors.
Key word is stock. Thats why it worked. Anytime you start changing major components you open a can of worms. Its almost always worth it when you get it sorted out though.
Exactly why I keep plugging away at it... because I know what it *should* be capable of if I ever get it working right.
- Joined
- Feb 18, 2006
If the valves were hanging open, look out. I'd imagine your in for a whole lot more power.
Post some under hood pics of the nos set up. I'd like to do something like that.
How are you venting the fuel cell?
Post some under hood pics of the nos set up. I'd like to do something like that.
How are you venting the fuel cell?
I'll be taking the car for a test drive shortly and will report back results.
The cell is vented under the car with the coiled 1/2" aluminum fuel line coming out of the top of it...
Here's a couple motor shots...
This is exactly why I prefer not to mess with hydraulic tappets with hp engines. By zeroing your hydraulics, your basically trying to convert to mechanical lifters. Should have just gone with mechanical in the first place.
Here's the thing with zeroing hydraulics. You must be sure the engine is at 'operating temperature' when you do this. As the engine warms, the valvetrain clearance will open up. Expansion and contraction of the valvetrain components, along with the heads and block.
If you weren't quick at adjusting the valves on a fully warmed engine, you're going to end up with an amount of clearance on some of the rockers when things really warm up. When cold, you are still going to have a small amount of preload on the lifter. If you get on it with the valvetrain and engine not up to full temp, you may still get a small amount of lifting.
It's much easier dealing with having to adjust mechanicals every few months than playing around with hydraulics. By zeroing your hydraulics you're going to need to check valve adjustments just as regularly as you would have with mechanicals. Only it's much harder to get a definitive adjustment value with hydraulics (comparing values between hot and cold).
With mechanicals you can get the engine really hot and adjust the clearance on one cylinder real quick. Let the engine cool overnight and check that same cylinder at ambient temp and you will have a good cold adjustment figure to go by. Now you can run the valves at your leisure with a cold engine, not having to rush to make sure some cylinders don't cool down too much and give you differing adjustment values at a particular engine temp. Not sure how you could do that with hydraulics and have the same amount of accuracy.
I suppose you could zero lash everything on a stone cold engine, get it nice and hot and recheck the clearances to see how much growth you're getting on the valvetrain, but how would you translate that figure to a cold setting for a hydraulic?
Adjusting mechanical tappets also gives you the opportunity to inspect the upper valvetrain, check for broken springs, dampeners, and find out if any adjustments radically changed on you, which would be a very important clue to an excessively wearing valvetrain component.
With aluminum heads and block, you can have as much a .010" lash difference between engine hot and engine cold. Iron block won't be as much, but you are running aluminum heads.
It would be a good idea to get an in-car valve seat spring pressure checker to see if the valve springs have lost any pressure.
By the way, the engine looks HOT!!! :biggrin: You need to add it to the hot engine bay pics thread!
Here's the thing with zeroing hydraulics. You must be sure the engine is at 'operating temperature' when you do this. As the engine warms, the valvetrain clearance will open up. Expansion and contraction of the valvetrain components, along with the heads and block.
If you weren't quick at adjusting the valves on a fully warmed engine, you're going to end up with an amount of clearance on some of the rockers when things really warm up. When cold, you are still going to have a small amount of preload on the lifter. If you get on it with the valvetrain and engine not up to full temp, you may still get a small amount of lifting.
It's much easier dealing with having to adjust mechanicals every few months than playing around with hydraulics. By zeroing your hydraulics you're going to need to check valve adjustments just as regularly as you would have with mechanicals. Only it's much harder to get a definitive adjustment value with hydraulics (comparing values between hot and cold).
With mechanicals you can get the engine really hot and adjust the clearance on one cylinder real quick. Let the engine cool overnight and check that same cylinder at ambient temp and you will have a good cold adjustment figure to go by. Now you can run the valves at your leisure with a cold engine, not having to rush to make sure some cylinders don't cool down too much and give you differing adjustment values at a particular engine temp. Not sure how you could do that with hydraulics and have the same amount of accuracy.
I suppose you could zero lash everything on a stone cold engine, get it nice and hot and recheck the clearances to see how much growth you're getting on the valvetrain, but how would you translate that figure to a cold setting for a hydraulic?
Adjusting mechanical tappets also gives you the opportunity to inspect the upper valvetrain, check for broken springs, dampeners, and find out if any adjustments radically changed on you, which would be a very important clue to an excessively wearing valvetrain component.
With aluminum heads and block, you can have as much a .010" lash difference between engine hot and engine cold. Iron block won't be as much, but you are running aluminum heads.
It would be a good idea to get an in-car valve seat spring pressure checker to see if the valve springs have lost any pressure.
By the way, the engine looks HOT!!!
:biggrin: You need to add it to the hot engine bay pics thread!Is there any knock retard going on when this is occurring? You stated that you're getting a lot of knock when just free revving the engine.
Also, as Ed Valvo suggested, is the cam degreed properly? An overly advanced cam would give the tendency for knock and hurting top end power.
I will be very surprised if the plate fixes this.
Also, as Ed Valvo suggested, is the cam degreed properly? An overly advanced cam would give the tendency for knock and hurting top end power.
I will be very surprised if the plate fixes this.
The RJC plate didn't do anything either...
I thought it felt a little stronger building boost, but the problem remains.
The cam went back in the motor the way it came out. I put a wheel on it to confirm cam timing. I'm not worried about that at all.
Only thing left for me to do is send the injectors to Chuck for inspection.
And yes, I'm seeing KR when this happens... consistently, with or without the RJC plate.
Here is the last brief run...
I thought it felt a little stronger building boost, but the problem remains.
The cam went back in the motor the way it came out. I put a wheel on it to confirm cam timing. I'm not worried about that at all.
Only thing left for me to do is send the injectors to Chuck for inspection.
And yes, I'm seeing KR when this happens... consistently, with or without the RJC plate.
Here is the last brief run...
Overly advanced would cause detonation down low if anything. There woudl be lower bmep as the rpm increased advancing
Some more things going thru my head... just thinking out loud here...
Compressor surge ?
Bad injector(s) ?
Spark plug heat range ? (AR3935's)
Valve float ? (springs @ 140 / 325)
Lifters collapsing ?
ECM swap ? Will and unmodded ECM drive my 83's ? (I have a spare unmodded ECM here to try)
Compressor surge ?
Bad injector(s) ?
Spark plug heat range ? (AR3935's)
Valve float ? (springs @ 140 / 325)
Lifters collapsing ?
ECM swap ? Will and unmodded ECM drive my 83's ? (I have a spare unmodded ECM here to try)
