A curious noise coming from an overhauled engine

[watson2]

Your brake booster could be starting to fail. I've changed a lot of them over the years.

Yes , I think so.
Nobody has an opinion about the noise in my msg #70 ?

P.S. I'm a Ferrari fan since my childhood and I have a 246 gt since 1971. So, please, authorize an 'out of theme' : let me rejoice fot Sepang and Losail victories. It was time !

[ja17]

Still think its an issue with the rocker arm double contacting (message  #62).

[Garry]

Flavio,

You can post a picture of your Ferarri in the “Other Cars” area of the forum.   ;D

Garry

[watson2]

Still think its an issue with the rocker arm double contacting (message  #62).

Hi Joe. Your message #62 was read with great attention and it was object of discussion. My mechanic, as I told you some pages ago, knew the problem and avoided contacts with a thicker device nr.85 in the pevious drawing. But so this solution has brought the arm too low on the ball pin side, so as Benz Dr. has remarked.  Just tomorrow (I'm tracking the package) I'll have 8 shims purchased by Metric.  I hope that these tribulations have end ...


@Garry : thank you,  Garry . I did .
P.S. you live in a beautifull country. I was there in September 2013 and I was fascinated with the nature, the the serious organization of your state apparatus , the people and their friendliness. Beautiful places, beautiful people .

[Benz Dr.]

As long as the valve guides haven't been damaged the cam shims will probably do the trick.

[watson2]

Measuring a cylinder head seems simple enough but we often cut the top of the head to make it straight and level with the bottom of the head. This would leave the impression that the head is under the minimum 84.00 mm spec and yet it isn't. Most cylinder heads are also warped on the top surface as well as the bottom. You can straighten a cylinder head by heating it in an oven and pulling it straight. Done properly, only a minimal cut is required to make it level again. The top of the head should be checked and planed as well if needed.
 

Your informations are absolutely priceless. But I would like to have some more information about the procedure to pull the heads straight. If you can say something more about the oven, the temperature to be reached, the physical way in which the head is straightened and if the workshop where this work is made is a grinding workshop or not. In short, as many details as you can.
Thank you.

P.S. The shims are here . 7 days from CA.
 

[Benz Dr.]

I'm going by description here because I've never actually seen this done.

Basically, you strip the head of all parts, place it in an oven and put two steel blocks under each end of the head. This will leave the middle of the head unsupported which is what you want.
In the middle of the head, or where the warp is highest, you place another bar across the top of the head from side to side. This bar will have a hole on each end where threaded rods run from the floor of the oven, through the holes in the bar and are held in place by nuts and a washer. By tightening the nuts and heating the head you pull the head straight again. Anything over .010'' warp will probably take two heatings. I was told that it gets pullled a little bit past straight because it will pull back up due to elastic memory.

I'm not sure how hot they set the oven but 300 degrees F seems to stick in my head. This isn't like your oven at home - it's designed for this kind of work so don't even think about trying it yourself. The head is cleaned first and prepared properly. This is the only way to deal with a warped head. Once straighted it may only take a .005'' cut to smooth the surface. Cutting the head without straightening first will leave it milled heavily on each end ( number 1 and 6 cumbustion chambers ) and reduce the service life of the head. What could take several small cuts over many years would now be reduced to two or three if milled when warped.

What many places tend to miss is the fact that the top of the head may also be a mess and it will need to be planed as well. This is where cam shims become vital. Anything you remove from the top of the head or the valve seats has to be added back to base measurements. Planing the top of the head can save you the possibility of breaking a cam and destroying other nearby parts. After you have your cam tightened down ( full torque ) it should move freely by hand if everything is right. If it won't move freely the head is probably not straight so take it back off and start over again.

 

[watson2]

Great Benz Dr. ! No, I'm not going to make this by myself. Simply when I'll meet my next    head , I will be able to explain to someone what could be done in case of warping. Thank you for your detailed explanation.

[watson2]

Joe,
Metric Motors sell them in different thicknesses, you do have to modify the rear one to allow the oil to drain back into the sump.

I attach here an image of one of the shims with numbers in several areas. If you don't want to modify the image with your drawing, can you tell me , please , where and how we have to pay attention for the passage of the oil . When you say rear you mean the last one near to cylinder nr. 5 and 6?

[tel76]

Yes, the rear of the engine near the bulkhead.
Place the shim into position(without the camshaft bearing) and you will see if there is an adequate space available for the oil to drain down the hole at the rear of the cylinder head into the cylinder block, it is very noticeable if the shim blocks the oil drain passageway, you just cut the shim to allow the oil to drain, Dan C did indicate that not all heads had this problem.
Is your engine in the car or out?
I had to obtain another cylinder head for my engine, with this replacement cylinder head i had to carry out the shim modification, I will look at the old cylinder head from the 1970 280sl tomorrow and determine if the modification would have been required.

[watson2]

Thank you Eric. The engine in this moment is on the car.  They will set the play of the tappets and will give again the correct torque to the head
The positioning of the shims will not require to pull out the engine.

By the way . I will not accept to have an head like mine, without a proper combustion chamber. If anyone has a head for the 230 please tell me.
I found one in good conditions. But it was of an egnine with carburators. I dont think that I'll find anyone that will make the holes and threads for injectors.

[ja17]

Watson, the fuel injected head has a much wider chain gallery than the carbureted heads. A carbureted head cannot be used.

[watson2]

 you do have to modify the rear one to allow the oil to drain back into the sump.

I looked at the detail you mentioned on a 280 head and I found 'the hole'. If the 230 head has the same passage,
is it enough to cut , i.e., the 50% of the shim to allow the passage of the oil or is it necessary a cut in the whole width?

[tel76]

Is it possible for you to fit the shim and post a picture ? or trim the shim to match the contours of the camshaft tower/bearing.
With the shim in position does it restrict the oil return hole?

[watson2]

Is it possible for you to fit the shim and post a picture ? or trim the shim to match the contours of the camshaft tower/bearing.
With the shim in position does it restrict the oil return hole?

Excuse me Eric.  Sorry for the late response
The car is 55 Km far away and so I cannot make the foto when the shims will be put in place. I can ask to the mechanic to make it for me, if he will remember to do it.
But I think that it will be necessary to cut a large part of the shim, if the hole in 127.981 engines is the same.
I will inform you about the installation.

[watson2]

Well, the car is at home ...
The after 1500 Km the correct torque of the head has been renewed, the tappets have been verified and the shims got by Metric were installed (0,35 mm) .
The brake booster overhaul had a good result: when the brake pedal is pressed that 500 rpm augmentation is disappeared. No changes in rpm.

The engine is only a little less noisy. But there are many reasons to make me a little sad:  the noise that the engine produces is different every day
and speaking about mechanics this is not a good sign. The engine doesn't idle smooth , it's a little rough and has a reduced sensibility to the air screw movement.
The car runs in a good way between 1500 and 4000 rpm, and when you stop the car, the engine can run at 800 rpm for minutes without problems.

But as the engine drops under 700 rpm it looses 1 or 2 cylinders. You can hear the tipical rattle of an engine without one or two cyl.
One of these times in which the engine is not running smooth I stopped the engine and I watched the plugs. and this was the look.
They are almost white. Non one is dirty. What is happenig?
 

[Benz Dr.]

Ohhhhh.......... that's lean!

[Cees Klumper]

Have you considered taking the car to a different specialized mechanic? It seems your current one has exhausted his knowledge but there are still some issues to be sorted out. Perhaps it's a few minor things that need the experienced eye to sort out. What we don't want is for something major to happen to the engine because of some relatively minor issue as described by Joe, Dan and others. Sorry I can't be more helpful but for peace of mind I would take it to someone else at this stage.

[stickandrudderman]

Indeed, I would suggest you find someone endowed with significantly more competence than your current supplier of services.

[watson2]

Yes Cees and yes Stick. You find me in complete accordance with you!!! The noise , other details , and after the matter of the valve guides I began to have a suspect.  Now the things tell to me to do what you suggest. I already phoned to a specialist ( ) in Brescia that was named by my friends. In these days he is not in his workshop because he was called by someone in the Mille Miglia race. I have an appointment monday morning.
The workshop is 150 km from Milan but I hope it's worth to do some kilometers.

[ctaylor738]

He will probably tell you that you are running lean and suggest going a couple off clicks rich on the main rack adjustment.  You could try that yourself and see if it helps.

[watson2]

He will probably tell you that you are running lean and suggest going a couple off clicks rich on the main rack adjustment.  You could try that yourself and see if it helps.

Done, Chuck. I gave 5 clicks clockwise and nothing changed. A friend of mine (old MB mechanic now retired) has a CO meter and he came to my house for a 'home visit' at the bedside.
I don't know if that machine was correctly working , but the display initially marked 0.4.   After the 5 clicks the value was 0.9 .
When I kept the car on saturday the mechanic spoked about 2.5 . 
There is a low sensibility to the changes of the screw of the air on the intake manifold.
Now the engine is even worse. It sounds as if there was a valve opened.....
TO morrow I return for the last time to Milan. After this I will stop.

[Benz Dr.]

I think maybe you might be turning the idle mixture knob on the back of the pump when it's a screw inside the back cover that's being referred to?
 I've been using the barometric compensator for major mixture changes with pretty good sucess. It's a whole lot easier to get at and fairly easy to adjust once you figure out how it works - if in fact it really is.

[ctaylor738]

Agree with Dr. Dan.  Adjusting the idle mixture is not going to solve your problem.

You are lean on the main rack setting, that's why you can't get the idle CO up to at least the 4% needed to idle well.

The main rack adjustment is done by removing a screw on the back of the pump and inserting a long, thin flat screwdriver in the hole.  Once you find the adjusting screw, you push it in to engage the adjuster.  It is the opposite of the other adjustments.  Left is rich, right is lean.  The procedure is described in the Technical Manual and the Haynes manual.

Dr. Dan's method of unscrewing the barometric compensator will achieve the same result, but I think the main rack adjustment is the proper way to go.

The main rack adjustment will richen the mixture under all conditions, so then you can adjust the idle mixture with the external thumbscrew.

I have observed that rebuilt pumps need 1-3 clicks rich to get the car to run right.

Cheers,

CT

[Benz Dr.]

The compensator works the same way in that it affects all mixtures across the entire range. If you run out of adjustment on the idle mxture knob and your idle mixture is still too rich, then the rack will need to be moved to a leaner position. This adjustment will give you a lot more room on the mixture knob when you had none before.