Could somebody enlighten me as to MOCO ACR's and how they operate? I understand the basic concept. However....my questions are the simple things:

1. How do you do a compression test with ACR's installed?

2. They bleed off compression, how much?

3. Where do these things vent?

4. Since they are electronically actuated/opened, are they electronically closed?

5. How does one test them?

The reason I ask is that I have an 07 FLHP with factory ACR's. I have just instllalled Andrews 54H cams, TP roller rockers, stock pushrods. I have no spark and cannot get get the bike to fire. CKP is good. New battery. I have 12v to coil but no signal from ECM to coil to trigger spark. I am told that ECM must "sense compresion" to fire. I don't quite understand that concept. No I have not done a compression test but one thing I noticed is that I can spin the engine, spark plugs out, finger over spark plug hole and the compression generated does not really push my finger off. Now, while doing this, I am on the right hand side of the bike and I noticed air movement from between the valley in the area of the respective cylinder head under the lower rocker box area. You can feel air escaping from each cylinder head on respective compression stroke. As they are electronically opened, I assume that they are electronically closed. I don't know that for a fact.

The other issue I am struggling with is whether or not, I bent a valve or two or three or four. The reason I am having trouble with this is that I did the swap by the book. Before I tried to fire the engine, I turned it by hand and did not noticed anything that would have suggested piston to valve interference. I would like to do compression test but this bleed off will not allow me to do this. Or at least it won't give me an accurate reading.

Now, if I bent a valve,and that valve was stuck in a position that held the valve off the respective seat, and I put that cam lobe on to its base circle, would there not be significant slop in that respective rocker/pushrod?

I have pulled the rocker boxe covers a couple of times and when I spin the engine, everything appears to functioning as it should. There has never been any unusual noises. There does not appear to be any excess play in any area of the valvetrain that would suggest that a valve is being held off its seat.

Also, I have disconneted the electrical connector to each ACR, and I still get this blow by from valley on the intake side.

Any help/insight would be appreciated.

 

The HD ACRs are "vented" into the exhaust port of the cylinder head. You would not/should not notice any release of pressure from the area between the heads near the throttle body from the ACRs. If you did not pull the heads, there is no way for compression to be released into this area.

You are correct on the newer engines, no compression, the ECM will not provide spark. Cam timing? Are you absolutely sure you have the timing marks lined up properly both on the cam to cam and then cam to crank marks?

I dont have enough info yet but I have a couple of guesses. Are the TP roller rockers of a different geometry than stock? There have been some issues with TPs and their geometry in the past. Did you buy them directly from TP?

Using stock pushrods, they are different lengths for intake and exhaust, and you may have installed them in the wrong holes, double check the install, but again, I am not sure the stock pushrods will work withthe TP roller rockers. I am very confused as to why using roller rockers in the first place, completely uneccessary with that cam and engine configuration.

Yes, if you had the wrong pushrods in the wrong holes, and the rocker geometry is off you could have bent a valve, but I would check all other items first. I am betting you will find that either cam timing is way off or that it is a pushrod/rocker issue.

 

One thing you could try is to unplug the ACR's and then try to start the bike.

 

Dalton: Thank you for your insight. Let me answer the questions you posed.

Why the TP rollers? Because I could. If nothing more, roller tips should equate to less wear on the valve stem tip and over the long haul should equate to less wear on the valve guides. They were advertised to me as being stock ratio. I purchased them from a HDF member.

I could be wrong, but I believe I bought an SE compensator from you. So I generally trust other members. I could be wrong.

Regarding the timing marks, I am certain they are absolutely spot on. I have now had the cam chest opened twice and when you line up the spot on the crank gear with the line on the cam plate, the cam drive gear mark is in line. They are absolutely opposed. Remove the cam drive gear, the crank drive gear and the chain, the appropriate cam markings are opposite each other. Just like in the manual. If need be, I will take pics for show and tell.

I am aware that the stock pushrods are of different length. When I removed them, I marked them front cylinder intake/exhaust and rear cylinder intake/exhaust and in to their respective zip lock bags they went.

I clearly have some sort of venting compression going on between the rocker box lower and the cylinder head. I noticed it when I was on my knees on the right side of the bike while spinning the engine. Engine was spinning without any wierd noises and I noticed a breeze. It is definitely coming from the valley between the intakes. It is bizarre.

Neon, I disconnected the ACR's from their respective plugs. No change. I still have this "venting" issue from the valley (of death?).

At this point....besides trying to glue my hair back in place, I am going to (yet again) pull the rocker box covers and install the stock rockers and see what I get. With the rockers out, and both valves closed, I am going to pressurize the cylinders and see if I have leakage past the valve seats. If I bunged the valves...downside is I will have to send the heads out. The upside....a little porting to clean things up! The real downside...getting 6 Pella windows installed at the house next week. Pretty much takes up all available cash. I thought I would tell my wife we can only afford 5 windows. She will shoot me. It could be a really long summer.

If I have to open the cam chest one more time...I will put the stock cams back in and call it a day.

 

Quick update....I am sure this is self inflicted.....not the ACR's. I will sort this out later.
I imagine it will be a long summer.

 

Im not sure how the ACRs work, NOR how a TP rocker box fits... but look and see if there is any interference between the two? Maybe the TPs hit the ACRs and damaged them?

ACRs vent into exhaust port, so if you are getting compression blowing out under the rocker boxes, something is broken. With the rocker boxes off, check on tightness of ACRs, etc. Something is leaking too much compression, the ECM can tell how much voltage it takes to make a spark jump the gap. Too little voltage, means there is not enough compression, and after a 'test fire' the ECM will no longer command a spark. It takes MORE voltage to fire a plug under compression, and the ECM can tell the differences.

Don't give up and go back to stock. Sometimes (for me anyways) to make it all 100% perfect takes a bit of effort.

Where are you from?

 

I saw the post about being self inflicted so I am now very curious. wurk-truck, I think he only installed the roller rockers, not the boxes unless I misread the post. The ACRs will not hit the bottoms of the rocker boxes so there is not a problem there. Now, if the ACRs were removed for any reason and not reinstalled, well, that is the only thing I know of that will be having compression coming out from under the rocker boxes unles a head cracked, but that is extremely rare.

And yes, FLHP, I do beleive you were the one that bought the comp from me. I was not inferring that someone sold you bad items, just that there was a run of bad TP rockers that I was aware of.

 

Wurk: did not install TP rocker boxes, just roller tipped rockers. I will ask questions regarding these gems later.

Dalton: Still have not installed the comp....after this episode.....

OK....ACR's are definitely not at fault. The learning curve on this one is still stee. But I will tell this...the front rocker box is getting pressurized and that is where the breeze eminates from....good lord.... I have a friend who has a Snap on fiber optic scope...I would like to look down the spark plug hole and get a looksee at the piston crown.....

Don't know if that will happen today. My time is short. I work out of town during the week and will most likely be gittin' after it next weekend. While everybody else is out riding.

RE: TP "bad rockers"??????? Where the hell was I??? Where can I get some info on this? My 'roids are starting to throb......

 

Dalton/Wurk Truk: put your thinking caps on...front cylinder rocker assy. out. Valves closed. Pull spark plug. Pressurize cylinder with 100 psi holding rubber tipped air nozzle into spark plug hole. I am pretty certain no air escaping past valves. I cannot hear any hissing on the intake side with the throttle held open. I cannot comment on exhaust side as pipes are on but I don't think so. However, there is faint hissing coming up through the pushrod tubes. If I pull the nozzle out of spark plug hole I get a firm, loud pop. Which is what I would have expected. OK, so TC do not have the rotating breather assembly like an evo did, right? They breath through that one way flapper valve in the head, correct? Then why am I getting air movement through pushrod tubes? This is also where it was escaping when I discovered that the front rocker box was getting pressurized. When I spin the engine with the starter, plug in,rocker assy out, valves closed, I definitely get compressed air coming up the pushrod tube(s). I perceive it to be right at TDC. Are we certain that MOCO ACR vent to exhaust? and not to crankcase? Just sayin...why vent to exhaust side when you would have exhaust pressure conceivably pushing ACR valve off its seat? Just thinking out loud.....

 

Attached are pictures of a head machined for ACRs.

I just had another thought and I know this will sound completely impossible, but bear with me. One of my friends did a build, and had similar issues, Did a leak down check and had air coming from the oiling system. Tore the engine apart three times and finally he changed the oil filter, and problem solved. Check valve in the filter was bad. Did you change the oil filter when you did the build? Actually what was happening was the crankcase pressure was backfeeding into the oiling system and pumping up the lifters and hanging the valves open enough that the engine would not start. Sounds implausible, but he and I racked our brains for a week and this is what it was.

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