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Valve train control loss question

hoodeng
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Re: Valve train control loss question

Post by hoodeng » Tue Oct 15, 2019 11:27 am

Mike's suggestion is now first stop.

I would have expected some visual evidence, can you see a single rocker pattern? or is the tip clean?

On the stuff i do i give the tips a light face each time they are apart so i can see if/when something is changing.

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Re: Valve train control loss question

Post by JoePorting » Tue Oct 22, 2019 2:45 am

I'd take a look at the pushrods to see if there's any strange wear patterns on any of them. Maybe they are rubbing against the intake port or valve cover.

Could also be an ignition issue or electrical issue. Maybe sparkplug wires are old. Maybe rotor phasing is off. Maybe run ground wires instead of using a chassis ground. Maybe even a fuel pressure issue. Could be other issues.
Joe Facciano

curtis reed
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Re: Valve train control loss question

Post by curtis reed » Fri Oct 25, 2019 11:17 am

JoePorting wrote:
Tue Oct 22, 2019 2:45 am
I'd take a look at the pushrods to see if there's any strange wear patterns on any of them. Maybe they are rubbing against the intake port or valve cover.

Could also be an ignition issue or electrical issue. Maybe sparkplug wires are old. Maybe rotor phasing is off. Maybe run ground wires instead of using a chassis ground. Maybe even a fuel pressure issue. Could be other issues.
Honestly there isn't any pushrod interference or strange wear patterns on them or the valve tips. I just don't run much 1/4 to be hitting the rpm problem area. I would just like to be able to turn it up to a higher shift point if I wanted to and over 7000 is an issue. Not sure when I will be able to get back out now but I appreciate everyone's input.

hoodeng
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Re: Valve train control loss question

Post by hoodeng » Sun Mar 01, 2020 5:59 pm

As Joe has pointed out, maybe there is a smell of ignition fault emerging here? can you take your complete ignition off and get it tested?

Can you set up an O2 sensor and see what happens in the top end?

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Re: Valve train control loss question

Post by curtis reed » Mon Mar 02, 2020 8:55 am

Well I did find two broken inner springs so I am still leaning toward loss of control. I should get the car out in a couple weeks to do some testing. o2 data doesn't show anything that I can see. If this keeps being a problem I will buy another ignition box to test.

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hoodeng
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Re: Valve train control loss question

Post by hoodeng » Mon Mar 02, 2020 8:27 pm

It breaks down quite suddenly doesn't it ? it almost looks like the rev limiter has kicked in?? fuel airs look very linear,is that 12.8-12.9 fuel air? what was the final egt?

I would have thought with springs the engine would have nosed over first before rattling its guts out if control was lost.

Would it be better to send the ignition to a performance test facility so you don't have to learn everything as you go, if or when it comes back with a clean bill of health and works to expectation you could use your own test station to see what they saw in their test.

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Re: Valve train control loss question

Post by curtis reed » Tue Mar 03, 2020 7:29 am

hoodeng wrote:
Mon Mar 02, 2020 8:27 pm
It breaks down quite suddenly doesn't it ? it almost looks like the rev limiter has kicked in?? I have ran it without a chip in the top side rev limiter and no change.fuel airs look very linear,is that 12.8-12.9 fuel air? what was the final egt? I'm on alcohol so 5.3-5.7 I don't run an egt since I have the o2 data.

I would have thought with springs the engine would have nosed over first before rattling its guts out if control was lost.

Would it be better to send the ignition to a performance test facility so you don't have to learn everything as you go, if or when it comes back with a clean bill of health and works to expectation you could use your own test station to see what they saw in their test. Don't want to be sitting on the sidelines waiting on it to be tested. If I still have this problem first time out I will put another box on it and have this one looked at.

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hoodeng
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Re: Valve train control loss question

Post by hoodeng » Tue Mar 03, 2020 6:04 pm

Sounds like a plan, when i suggested testing the ignition i meant the whole ignition, box,distributor, leads, and power supply.

The breakdown of the engine looks almost immediate?? interestingly the engine was quite happy at the shift [6900] the graph shows a rpm kick up at 7.7-7.8 sec [but no change in drive speed] then falls over badly at 8.5 sec then picks up again and starts to rpm stably at 9.5 sec when you lifted??
The cam guys might be able to read more into your data if they see it as an area of issue.

As you said there was no top chip so that is eliminated in itself as a cause.

I could not see a scale for the 02 line hence my observation,,still,,its linear that's for sure.

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Re: Valve train control loss question

Post by curtis reed » Wed Mar 04, 2020 7:31 am

hoodeng wrote:
Tue Mar 03, 2020 6:04 pm
Sounds like a plan, when i suggested testing the ignition i meant the whole ignition, box,distributor, leads, and power supply.

The breakdown of the engine looks almost immediate?? interestingly the engine was quite happy at the shift [6900] the graph shows a rpm kick up at 7.7-7.8 sec [but no change in drive speed] then falls over badly at 8.5 sec then picks up again and starts to rpm stably at 9.5 sec when you lifted??
The cam guys might be able to read more into your data if they see it as an area of issue.

As you said there was no top chip so that is eliminated in itself as a cause.

I could not see a scale for the 02 line hence my observation,,still,,its linear that's for sure.

Cheers.
The box is the only part that hasn't been changed. Sorry I didn't post that earlier.

When you click on the photo of my data graph if you look to the right you should be able to see the scale. I wish I could make it larger but the way the board is set up this is what I get.

You are right in that it just hits a wall immediately at a specific point. I would like to shift higher but it will do the exact same at the higher shift point.

Thanks for the interest and suggestions.

Curtis

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Re: Valve train control loss question

Post by fdicrasto » Tue Mar 10, 2020 7:55 pm

Poking around and just saw this post. Mike suggested the Isky springs, you have a couple inners broken, check for leak and change springs. Don't get lost in lots of other stuff until you do that and let us know what you find. Chancing a brutal mechanical disaster is a lot more potential money and time down the drain. The fuel and ignition can wait until you do the springs and go the tighter lash. Phil D.

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Re: Valve train control loss question

Post by Rick! » Sun Mar 15, 2020 8:01 pm

What's your recording rate on your O2's? It's not all smoothed out and at a low rate is it?
With all that mayhem in the RPM trace, one would expect subsequent misfiring and lean mixtures.
On my brother's dragster, I can evaluate little bumps and dips in the RPM trace, look at which bank the O2 leans out on and find the bad plug routinely now.
Your AFRs don't move or even bump up during the RPM stuff which means whatever is getting into the cylinder is burning adequately. (Or nothing is getting into the cylinder which is unlikely.)
The semi-regular issues in the RPM trace do not look like a rev limiter. I attached what an MSD rev limiter looks like for reference.
It also doesn't look like an ignition going south but there is maybe some hints at how many cylinders are missing counting the time steps in each little pattern.
Why does the one run show an increase in RPM before its performance falters? It looks like a small nitrous shot.
The other run the RPM trace flattens at 7000 before faltering - do we have the whole story on this situation?

The yellow circle shows misfiring in the RPM trace (red line) and leanness and spikes in the dark green O2 (right bank).
Image
Rev Limiter:
Image

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Re: Valve train control loss question

Post by curtis reed » Mon Mar 16, 2020 1:18 pm

Rick! wrote:
Sun Mar 15, 2020 8:01 pm
What's your recording rate on your O2's? It's not all smoothed out and at a low rate is it?
With all that mayhem in the RPM trace, one would expect subsequent misfiring and lean mixtures.
On my brother's dragster, I can evaluate little bumps and dips in the RPM trace, look at which bank the O2 leans out on and find the bad plug routinely now.
Your AFRs don't move or even bump up during the RPM stuff which means whatever is getting into the cylinder is burning adequately. (Or nothing is getting into the cylinder which is unlikely.)
The semi-regular issues in the RPM trace do not look like a rev limiter. I attached what an MSD rev limiter looks like for reference.
It also doesn't look like an ignition going south but there is maybe some hints at how many cylinders are missing counting the time steps in each little pattern.
Why does the one run show an increase in RPM before its performance falters? It looks like a small nitrous shot.
The other run the RPM trace flattens at 7000 before faltering - do we have the whole story on this situation?

The yellow circle shows misfiring in the RPM trace (red line) and leanness and spikes in the dark green O2 (right bank).
Image
Rev Limiter:
Image
I will have to check on the sampler rate for the o2. Yes it is smoothed but honestly when I turn the smoothing down it really doesn't spike. My o2 is in #7 cyl tube right now. I have one in #8 also but it wasn't working.

I can't answer why the one run shows an increase in rpm. That was from the two time trials and I don't even have nitrous. Getting closer to being able to test. Covid-19 and weather are two things out of my control that may mess with my scheduled opportunities.

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Re: Valve train control loss question

Post by curtis reed » Thu Jul 16, 2020 2:07 pm

Well it's been a tough year to get out to the track. Got out to our first race in April just to get some data with new carb set up and new springs shimmed much closer to coilbind. No they weren't the Isky springs, they were the other half of my springs that were still new. Still did it. Then things got shut down for a while. When they did open back up I caught this stupid virus. Finally got back June 27th for my second race. Couldn't really test anything.

Went out to tnt the next weekend with the lash at .018 int and ex. Ran to the thousandth what it did the week before in almost exact air and still hits a wall at 7100-7200 even with nothing in the rpm chip spot on the ignition box. Only made one run that day and believe I geeked up some bearings so I have it out now.

Just wanted to give an update to you guys that tried to help. While the engine is down I'm going to change the ignition box and go from there. I will get it at some point.

Curtis

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