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View Full Version : Only wanted roller rockers: Broke out in a rash--while-i-am-there-itis


DRRICK
03-02-2012, 10:54 PM
So, as the original owner of this 1994 PS 190,LT-1 edition boat, currently with 450 hrs., I neglected her for 1 year, and upon her first startup after the delay, she coughed up a lifter.

I thought it was a valve, but thank goodness it was a collasped lifter, which I am told, can happen.

So clever fella that I am, I figured that I would "Just upgrade the rocker arms"..

As you know, the LT-1's came with a roller cam, roller lifters and STAMPED ROCKER ARMS. Can you believe that? It is like baking a cake and refusing to put icing on it.

I digress.

While I was there (after all, the big work is getting to the pushrod valley, once there, replacing parts adds no further time), I decided to convert to roller rockers and while I was there, I decided to upgrade the lifters to short travel racing lifters (after all these boats run damn near full throttle a lot of time).

Since an increase in the rocker arm ratio would increase the power (uggghaahhhmmmnnee), easily, I ordered 1:6 arms. (recall, the original is 1:5).

And oh by the way, since you have increased the overall travel of the valve stem, you will need to upgrade the springs. So I did. Beehive.

And since the spring tops would now travel more quickly with each revolution, I decided, why not, let us add Titanium valve spring retainers in order to decrease the reciprocating mass. Sounds right to me.

And so I began this journey into what I thought would be a plug and play.

I could go on and on, but the most recent development is that I have to change the lengths of the push rods in order to maintain proper valve train geometry.

Stock pushrod length in LT-1 is 7.2. With my new lifters and rocker arms, 7.2 did not give me the proper geometry, based on testing principles already described, but have to do with marking the top of the valve spring and setting the lash and rotating the engine, noting where on the valve spring the wear pattern is on the top of the valve stem.

Without further ado, I ordered new chrome-moly custum pushrods, 7.0.

They came today. This weekend I will install everything and update this thread

thatsmrmastercraft
03-02-2012, 11:50 PM
Welcome to Team Talk and the MC OCD that comes with it. Good luck with getting your valve-train sorted out. Nothing quite like opening a can of worms. At least you will be an expert when you conquer this can of worms that you opened.

And when you get around to it, post up some pics.

1redTA
03-03-2012, 11:15 AM
Be wary of beehives! they can wear out very fast depending on the manufacturer. as far as lifters GMPP LS7 lifters are $120 and work great

Engine Nut
03-04-2012, 12:56 PM
You need to be careful of changing the way the engine breathes. We built some engines with different ratio rockers and had to make a new ECM calibration to compensate. If you increase the air going through the engine but do not compensate by adding more fuel, the engine may run real good for a short time and then die because it will be lean. The only way to add more fuel is to get into the ECM and modify the fuel table ... and there are not a lot of people that can do that or that I would trust to do that.

1redTA
03-04-2012, 01:31 PM
Is the marine ECM that incapable? with an O2 sensor the stock ECM should have a little bit of adjustment thru STFT to bring the LTFT into the correct adjustment for the long haul

DooSPX
03-06-2012, 09:06 AM
from what I am gathering, the stock marine ECM's are horrid at doing any sort of adjustment... just upgrade to the new holley HP self tuning ECM, people I know who used it, even on LS series love it! its self tune is DEAD on and you still tune it manually.

76S&S
03-06-2012, 01:16 PM
So let me get this straight.

The stock LT ECM doesn't listen to the O2, so no adjustment thru the STFT to correct the LTFT. To correct you need a holley HP ECM that will listen to the O2 thru the STFT to correct the LTFT which should work on a LT or LS.

Glad that's all sorted out....................end sarcasm.

Back on topic.

CantRepeat
03-06-2012, 02:37 PM
So let me get this straight.

The stock LT ECM doesn't listen to the O2, so no adjustment thru the STFT to correct the LTFT. To correct you need a holley HP ECM that will listen to the O2 thru the STFT to correct the LTFT which should work on a LT or LS.

Glad that's all sorted out....................end sarcasm.

Back on topic.

No, it does but it can only do SO much. (edit, I'm not sure if the 94s do or dont, but I would expect them to) Without changing the base pulse width or adjusting the VE table you can run the engine lean. What enginenut is saying is, if you add too much air and do not add fuel you could burn the motor up.

The short and long term block learn modes can only compensate for so much change. IE going up or down in elevation pulling a heavier then normal load. The ECM is not designed to handle major mechanical changes and by changing the rocker arm ration you are changing the cam profile with more lift which should allow more air flow, possibly too much air flow.

Without logging some data from the ECM you wont know if you are running it too lean. I look into getting a copy of Diacom and the cables needed to do the data logging but it was kind of pricy.

DRRICK
08-03-2012, 04:15 PM
So Here we are 5 months later. Got lots of projects..............................anyway, I uploaded the first 10 photos and I will now upload the next 10. Boat is on the water, running very well. Did I notice any change in performance. Yes.

T Scott
08-03-2012, 04:32 PM
I think I'd rather have a root canal than mess with valves, rockers, etc.

1redTA
08-04-2012, 10:12 AM
wondering why you ran ":)self aligning" rockers???

DRRICK
08-08-2012, 04:30 PM
No need for the push rod guides in the LT-1. Not going over 7000RPM. These roller rockers are narrow bodied............................ Uhhhhhhhh.......lets see. These custom length pushrods are crome-moly.....adds expense? the lifters have guide plates.......................

mikeg205
08-08-2012, 05:19 PM
Great project... I have great regard for all of you who understand how to bust down and rebuild an engine and then make it run.

Cool project...to bad you won't see the red rockers when it's put back together.

DRRICK
08-09-2012, 12:46 PM
Great project... I have great regard for all of you who understand how to bust down and rebuild an engine and then make it run.

Cool project...to bad you won't see the red rockers when it's put back together.



Funny you should say that. Anyone know where one can find lexan see through valve covers

cpr05xtr
08-09-2012, 06:23 PM
That looks like it is going to be pure sex. Nice.

46Chief
07-30-2014, 09:51 PM
Any long term reports? This a a cool upgrade, would like to know more.

Jayhawk
07-30-2014, 10:19 PM
I think he's selling it: http://www.mastercraft.com/teamtalk/showthread.php?t=61014

CantRepeat
07-30-2014, 10:49 PM
Back in May of this year.

DRRICK
07-31-2014, 11:42 AM
Update. I have put around 120 hours on the boat since the roller rocker upgrade. the take off with a skier on back is noticeably stronger. Increased top end by around 3-5 mph. No other changes noted.

My kids are out of the house and the boat is sitting. I have hesitated to put it on eBay. Busy etc. Probably asking too much.....

Rossterman
07-31-2014, 12:39 PM
Plugs look slightly rich rather than lean as others expected. If so, and you ran it full throttle so before shutting off you may be good to go!

Sorry-didn't realize the post was that old. Obviously worked out fine,