Lehman SP135 Adjusting engine valves

[Forkliftt]

This may not be for everybody- and we are all grown ups and able to determine our risk tolerance, but for those possibly interested I snapped some pics a few weeks ago in case anyone is interested in adjusting their engine valves. This applies to the 135 only.

These first two pics are just removing the valve cover. The 135 valves are adjusted COLD. The intake and exhaust valves are both set at .015" clearance.*

The firing order is 153624. Many years ago I was taught to adjust engine valves using a "parenting cylinder" approach. The advantage is time and simplicity. Instead of two or more hand rotations of the engine you are able to set the valves in only one revolution. This works on any even number cylinder engine.*

The third picture shows the firing order divided in half, so 1/6, 5/2, 3/4 work together. Use a wrench (4th picture) and spin the engine over until the rear cylinder rocker arms, #6, start to overlap. On a high compression engine you may have a hard time as you begin to spin because a cylinder is coming to the top of a compression stroke. If so, wait a few seconds and the compression will bleed past the rings. Overlap means that #6 exhaust valve is closing and #6 intake valve is beginning to open. It is critical that you find the exact location that both are moving at one time. I usually lay my fingers on the rocker arms (5th pic) and will rock the crankshaft back and forth to be sure I have the right spot.

After you have #6 on overlap, you are ready to set the intake/ exhaust valves on #1 cylinder. The SP135 has friction adjusters, and these are easy to work with. More common are the type that have a flat screwdriver head and a jam nut. With the friction adjuster you simply turn it where you want it and it stays. Sometimes it is easier to remove the individual feeler gauge from the rest. The trick here is to*tighten the rocker arm adjuster until you feel a slight drag on the feeler gauge. You should be able to reinsert the gauge with slight pressure. Reset it 4 or 5 times if necessary to get a feel for it until you are happy with the result. After setting both valves, use your wrench to turn the crankshaft clockwise a few degrees until cylinder #2 *goes into overlap. Now you are ready to adjust both valves on cylinder #5. Next is #4 overlap, set #3. Then #1 overlap and set #6 valves.

Continue until 2 and 4 are adjusted, install a new valve cover gasket and you are finished!

 

[Dixie Life]

Great job, I have a 120 an I think the same process will work.

 

[Wxx3]

Thank you so much Forklift.

I have hesitated in doing it just becuase I usually f.. something up the first time which then takes 10 times longer to fix.

THis is rally clear and your explanations give enough detail to understand what is going on.

Very Well Done.

Thanks Again.

 

[FF]

The next trick is to use a go- no go feeler gauge system.

If you need 15 thou if a 14 slides in easily and a 16thou does not go in without hard force , you are as close to 15 as required.

 

[bayview]

Agree the stepped, go no go, gauges will increase confidence for those not familiar with the "feel" of proper adjustment.
here is an example:


Sears.com


I shut the fuel off. It is unlikely that the engine would start but I am cautious.

 

[petdoc4u]

Great instruction....thank you. At what interval should the valves normally be adjusted?
-David

 

[meridian]

1,000 hours I believe were Bob Smith instructions. There may be a question if you should re-torque the head prior.

 

[kchace]

1,000 hours I believe were Bob Smith instructions. There may be a question if you should re-torque the head prior.

On 135's you must absolutely NOT retorque the head. This is spelled out clearly in every manual.

This is an exact cut and paste from the manual:

DUE TO REVISED HEAD GASKET, HEAD GASKET AND HEAD BOLT DESIGN RETORQUING OF CYLINDER HEAD IS NOT REQUIRED. AND MUST NOT BE ATTEMPTED.

Ken

 

[BruceK]

On 135's you must absolutely NOT retorque the head. This is spelled out clearly in every manual:

DUE TO REVISED HEAD GASKET, HEAD GASKET AND HEAD BOLT DESIGN RETORQUING OF CYLINDER HEAD IS NOT REQUIRED. AND MUST NOT BE ATTEMPTED.

Ken

Slight drift, does that apply to the 120 too?

 

[kchace]

Don't think so. I think on the 120 you're supposed to retorque before adjusting valves and that is why the big warning for the 135. This same "no retorque" applies to all the Dover engines.

Ken

 

[psneeld]

The problem is that I have conflicting info even from American Diesel.

My 2 goto engine experts say if you don't know what kind of bolts/head gasket were used last time...it is a crap shoot about retorquing them.

Ski mentioned that he at one time to solve a head gasket issue IIRC, he replaced one bolt at a time and re-torqued with a known quantity.

Makes sense to me....then again....pulling the head and checking everything out, replacing gasket and bolts is some money and labor involved....but if at least a couple thousand hours since the last time...maybe not a bad idea.

On the road...I might try Ski's suggestion...at home port where the next trip could be months away...the full Monty could be in the cards.

 

[kchace]

My 2 goto engine experts say if you don't know what kind of bolts/head gasket were used last time...it is a crap shoot about retorquing them.

Ski mentioned that he at one time to solve a head gasket issue IIRC, he replaced one bolt at a time and re-torqued with a known quantity.

Makes sense to me....then again....pulling the head and checking everything out, replacing gasket and bolts is some money and labor involved....but if at least a couple thousand hours since the last time...maybe not a bad idea.

On the road...I might try Ski's suggestion...at home port where the next trip could be months away...the full Monty could be in the cards.

Speaking of Dover engines only (90, 135, etc.) If we're talking about merely adjusting valves for maintenance purposes only, I think it would be folly to do something that the manual emphatically says not to do. Now if one is away from th dock and you need to try and resolve a problem, try what makes sense under the circumstances.

Ken

 

[psneeld]

Sorry, was talking to the 120 question....

 

[Ski in NC]

I would not retorque any engine head bolts unless being done to solve a specific problem. Or unless the manual specified it, which is very rare.

 

[Jsta_Rebel]

@ Forklift; Thanks for the detailed description on valve adjustment on the SP 135. It went just like you spelled out in your post. Unfortunately, it did not fix my current issue, and I will be starting a new thread regarding my issue to hopefully get a few ideas.

 

[Forkliftt]

Glad I could help . Keep us posted -


1983 Present 42 Sundeck
Twin Lehman 135's

 

[DonF]

Don't think so. I think on the 120 you're supposed to retorque before adjusting valves and that is why the big warning for the 135. This same "no retorque" applies to all the Dover engines.

Ken

I wonder if the 135 head bolts were "torqued to yield"? If they were you have to replace the head bolts! You can't re-torque them or reuse them! Looks like it started in the mid 80s.
Torque-to-yield
In the mid 1980s, we started to see a move in engine fasteners to a new process called torque-to-yield (TTY). Head bolts were the first fasteners affected, although the technology has trickled down to other critical fasteners. The theory holds that the farther we stretch a fastener toward the threshold of yield, the more load it exerts on the joint.

Best to know how your head bolts were torqued before trying to re-torque them!

 

[bgillroy]

AD says for 120 re torque head 500 to 1000 hours...u will know with loss of power ...observe performance.

 

[psneeld]

AD says for 120 re torque head 500 to 1000 hours...u will know with loss of power ...observe performance.

Actually, they won't say for sure depending on who did what last using which bolts, etc...

The only way to do it without question is pull the bolts and head, new gasket and new bolts. Now you know what you have and can go frombtgere...meaning a regular retorque or not.

 

[bgillroy]

The orig spec on engine bolts provides torque details, Relative strength to yield. If torque spec well below yield likely safe use existing if no visual issues. If torque and yield similar id replace all if fasteners are old meaning run in and out over years . Very inexpensive why risk.

 

[psneeld]

Ok.so some mannuals say retorque, some say no. The "experts" say...well it depends...and have heard AD say as long as 2500 hr before worrying about anything.

So what does the average guy do when the history of the engine is unknown....and what references would help clear that up?

So even if you replace everything....500 hrs? 1000 hrs? 2500 hrs?.... or wait till something happens?

 

[bgillroy]

I have become one with my engines embracing their needs have applied custom appliance to rotate and regap so I know valve is correct and applied test instruments to have them speak to me and I go from there , yes I love them those old engines are quite special ..not just power but also friends I look after...

 

[alormaria]

I have become one with my engines embracing their needs have applied custom appliance to rotate and regap so I know valve is correct and applied test instruments to have them speak to me and I go from there , yes I love them those old engines are quite special ..not just power but also friends I look after...

I'm not sure what you're saying here, but I like the way you said it.

 

[somf]

Just for my own info, where did the .015" clearance and set COLD come from? My manual only gives .015 inlet and .018 exhaust set at "normal Operating temperature" I sure like the Cold set idea, much more comfortable in a cool engine room.

 

[psneeld]

Some of the professional engine guys have said for Lehmsns, the difference betweenn hot and cold...no big deal.

The 120 and the 135 are different so make sure you are getting the right clearances.

My 120 was set to 135 clearances by mistake the first 2 years I owners her, American Diesel said no big deal, but the other way around may have been more trouble.....so close tolerances are nice to meet...but real life experiences show that slop here and there is less than critical.

 

[somf]

I guess I answered my own question, I dug out the Ford service manual and it states .015 for both valves on a NA engines hot or cold. Interesting to know how Lehman came up with .015 and .018 in the Owners Manual?

 

[kchace]

I guess I answered my own question, I dug out the Ford service manual and it states .015 for both valves on a NA engines hot or cold. Interesting to know how Lehman came up with .015 and .018 in the Owners Manual?

I have several Ford Lehman manuals and various data in them is all over the place. Like you, the manual I just looked in says .015 for Intake and Exhaust for NA engines. Yet in this same manual, it says to check the valves at the first 50 hours and then it never indicates that they need to be checked again! Another manual I have (my hardcopy) says to check them every 600 hrs. I believe the info that they can be done cold has come from American Diesel. (At least that's what they told me). I think their exact words were "That will get you close enough". One way to prove if its necessary to do hot is to do it hot just as the Owner's manual states, then check them again when the engine is stone cold. If they're still within reason, then it could be done cold.

Ken

 

[psneeld]

Call American Diesel or Bomac...

The specs for the 135 are different from the 120

I was told by American Diesel (and yes they have been known to give different info to different people)...

120 Lehman
Cold Exhaust .010-.014 Intake .014-.018
Hot Exhaust .012 Intake .015

Probably why they told me a 120 set at the 135 .015 is better than a 135 set at 120 specs because you might burn the exhaust valve. Not being a full time mechanic I cant say that's true... but others confirmed the thought.

I have at least 4 manuals for Lehmans and they are all a little different. I find it frustrating not knowing which one to believe.

 

[Ski in NC]

Pretty rare for intake to have more clearance than exhaust, are you sure about that?

 

[psneeld]

Pretty rare for intake to have more clearance than exhaust, are you sure about that?

What Am Diesel gave me and what is in my Saber Lehman manual...just quadruple checked.