Originally Posted by Biggzed View Post
Just thinking out loud like iclick...

Stock TC 88 pushrods:

Intake (silver colored) 10.375"
Exhaust (black colored) 10.500"
If the stock push rods depress the lifter plunger by .100" like you owuld set an adjustable push rod, then the above length would indicate the intake valve would stay open appx .025" if the exhaust push rod was installed on the intake lifter.

Someone check my math there. If it's right, then I can easily see that compression would come way down. I don't think ccp of 50 would be enough to fire.

Zach



Interesting. are you using your old PR or did you buy new ones?
If new are they the right ones?

 

If they were for a OE TC engine 88,96 or (103 police 2007-2010)) pushrods are the same from 2010 all the way back to their introduction in 1999.
Exhaust PN 17922-99 (10.536)
Intake PN 17923-99 (10.418)
Specs and Part numbers from H-D parts manuals

 

This is getting good, I plan on duing 255's in my 07 next week and want to see where this leads.

 

Thanks to all of you keeping an eye on this one. I will try to answer evrything in the latest posts. Yes same stock push rods and marked them with tape and put them exacty where and how they came out. I have done this twice now and looked at them to confirm that two other times pulling the pushrod covers. I did pysically check them for lenth black ones were longer than the silver. I did all of my testing with the throttle body open with a socket holding it open turning the motor wont do it with the TBW. I also have done the compression tests with and without rockers covers. I checked the lifters for correct part number already confirmed. I can always spin the push rods when on base circle have not come across a time when I put a cyl on TDC I could not spin them. I do have the anti rotation pins in.

I am going to get new gaskets and go back at it Friday night. Tearing her completly down pulling the cam plate and comparing the cams to stock and timing dots, lobe seperation, inpecting the cam plate for cracks and what not and intall it all again. I am going to get tappered adjustable push rods because I am not taking the top end apart again. And my suggestion if it is worth a damn thing go this route dont waste the time to save the 120 bucks it would have been nice to retain the stock push rods for reliability and costs but I am way over that now.

I thought on one thing that I will look in to when I pull the cam plate off. The secondary cam chain tensioner had fallen off on my shop rag on the bench when I was taking the cams out. I am not sure if I saw the spring and the spring dentend in there. I don't know it is the only thing I can trace back and not confirm in my mind confidently. I don't know how much this wouldbe the cause of the problem because like I have said that the cam dots line up. I had not trouble with oil pressure and when messing with the chain tensionerswith and without them it looks like about a max of 8 degrees of potential movement change. So I will report more as I know of it and look forward to all of your comments.

 

Something just popped into my head based on a comment by someone on an old cam thread. It was mentioned that it isn't unknown for cams to have the dots in the wrong locations, but I can't say how true this is or when it has occurred in the past. If it did occur I don't think it would affect a compression reading, however, since the lobes would still be in their proper positions, just out of alignment with the other cylinder. Am I thinking right here? It's late and the brain was ready for bed an hour ago. To continue, if this happened you would get a normal valve reaction from either cylinder, but wouldn't run properly since it would be out of alignment with the other cylinder.

That said, it might even be possible that the lobes are ground wrong, and if one is ground wrong it would seem possible the other might be also. You could get a general idea by comparing the relative positions of the lobes with your stock cams. Since conventional ideas aren't working here, I'm injecting some far-out ideas.

I'm not following this. Are you saying you're not sure if the spring and piston is in one of the tensioners?

 

Something just popped into my head based on a comment by someone on an old cam thread. It was mentioned that it isn't unknown for cams to have the dots in the wrong locations, but I can't say how true this is or when it has occurred in the past. If it did occur I don't think it would affect a compression reading, however, since the lobes would still be in their proper positions, just out of alignment with the other cylinder. Am I thinking right here? It's late and the brain was ready for bed an hour ago. To continue, if this happened you would get a normal valve reaction from either cylinder, but wouldn't run properly since it would be out of alignment with the other cylinder. If this is the case it's not the problem, but I'm putting it up in case I'm missing something.

That said, it might even be possible that the lobes are ground wrong, and if one is thus affected it would seem possible the other might be also. You could get a general idea by comparing the relative positions of the lobes with your stock cams. However, it wouldn't seem like it would take much error to cause a compression problem, and a minor one might not be noticeable with the naked eye. Since conventional ideas aren't working here, I'm injecting some far-out ones.

I'm not following this. Are you saying you're not sure if the spring and piston is in one of the tensioners? If so and even thought that might cause an alignment problem I think it would be the same effect as if the dots were machined in the wrong location of one or both cams. The cam lobes are in the right places and a compression test should work normally on either cylinder. A compression test works for one cylinder and alignment doesn't play a part in it...I think. I'll be back tomorrow after two cups of coffee and may edit this message!

 

Leaving the secondary tensioner spring/plunger out would only affect the front cylinder cam timing, the rear would still be ok.

When your on the base circle, are you on TDC of a piston? The fact that you can spin the push rods and blow smoke thru the intake does't make sense unless the intake valve is hung up.

I think your idea of putting in adjustable pushrods at this point is a good one, since its a pita to tear off the rockers each time. Putting in the old cams and lifters is what I would do next, get it running, then start over.
I find it hard to believe the cams are ground or marked wrong but is allways a possibility
Hang in there, it will run, and remember it is very easy to keep making the same mistake over and over, don't ask me how I know.

 

Sickbagger,

When yoiu pull the push rods out again, don't forget this post before you put the new ones in. Dang good advice in this post especially if you are going to tear it down again.

 

YOU NEED to CHECK....
In H-D Tech Tip #296 dated 3-8-07
it gives instructions to check and see if you have a cam with a bad timing mark. Evidently there were some that got out.
If DAWG has access he can post the drawing that is included with the tech tip....I can't post pics or images.
Anyway this only affects the rear cam.....correct position of the timing mark is.....
locate the wide tooth on the rear cam spline where the cam gear syncronizes to the spline...count in a clockwise direction....6 valleys of the spline teeth and this should be where the mark is located.

you will better understand it if someone can post the TT#296

 

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