For Timing Experts 355 & 360 question

There is no mistake in the WSM. You did something wrong.

 

I'm not a pro, My 2 cents.

Forget the 355, similar but different engine.

I assume it ran fine before you did the work, right?

Which of the 3 intake valves did u use?

I'd pull the aft cam inspection covers get the engine at tdc and see how far off u are from the factory marks. I know they can be off, but I bet Alberto in the factory got it closer than you did.

If the marks are close make sure you buttoned it up correctly, vacuum lines, electrical coils attached properly, etc. may want to do this first.

I followed the wsm to the letter except I used cylinders other than 1 & 8 for ease of access.

Sorry I'm on iPhone and my brain is exploding trying to figure out your question on specifics of timing question. I'll look at it later again on computer.


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Alberto at the factory is a big part of the problem.

 

Brian, I know that's what you have said in the past and I accept your expertise.

My point was not the factory marks are correct. Only I would have, and did use the scribed marks as a check for my degreeing. If I was off from those the first time I degreed it did it I would double, and triple check my procedure and not first assume the factory marks were off.

Can we assume the car left the factory with the engine timed to the marks Alberto made on the cams?


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One of the issues with the factory marks is the crude mark and width. You can be within the mark and still have a variance of a couple degrees from one extreme to the other of the mark.

My understand is those marks are only for initial assembly.

 

He is talking about the marks made on the back of the cam by the guy who assembled it.
The one I am doing now is a good example. Out of 4 cams 2 have assemblers marks.

 

Back to the original question. What the WSM is trying to say is they want to see a deflection of 0.6mm at 9 degrees BTDC. Instead of starting at 0 and rotate to 351 degrees, they start at 351 degrees and rotate to a flat part of the cam.

 

Thanks - I have 3 of my 4 CAMs here - I'll go have a look

 

Good point Dave, on mine the reference mark on cap was > 1mm thick and the scribed mark on cam was literally a hair thickness.

Still, I took an impression of these marks before, and after I did mine. Much closer or spot on after degreeing as compared to prior. Car ran fine before, and runs fine now.


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MD

Let's not try to troubleshoot the WSM. Let's see what you did.

How did you time the exhaust cam?

M

 

Ok, I am no pro. In an effort to get filleted by the pro’s here I’ll take a stab at your questions.


Your question:


For the 360 Modena, first of all there appears to be an error. On the table shown with the timing, for the Exhaust Valves it should be End AFTER TDC 9 degrees +-1

NOT before TDC…


I believe BEFORE is correct, not AFTER, and the WSM data agree with the WSM procedure. Appears to be similar to the 355 (16 degrees retarded as stated in the 355 WSM as compared to 9 degrees BEFORE TDC from the 360 WSM). As to why the engines were designed this way, that is beyond my expertise, but I’m sure google can be your friend.


Your question:


For EXHAUST you reset dial gauge at 9 degrees prior to TDC of exhaust cycle and rotate further until the valve closes to find 0.60mm (This procedure confuses me, why you would reset at 9 degrees prior to TDC ??? Why not reset at 0 degrees TDC and rotate until the valves close to get a reading of 0.60mm (as you would on the F355) Is this another error on the WSM ??)


comparing the 355 to the 360. The excerpt you have from the 355 WSM is incomplete, and thus vague. I don’t think it is correct as you state it because the exhaust valve closes at 16 degrees retarded (i.e. BEFORE TDC). Are you referencing the intake? The difference seems to be the 355 procedure measures the entire valve lift. I will defer to someone that has the entire WSM available, and has done it.


As far as why at 9 degrees before TDC you make an interesting point. There is still 0.6mm travel in the bucket left from it’s position at 9 degrees BEFORE TDC to full travel (sometime between 9 degrees BEFORE TDC and TDC) I believe this is the cam clearance ramp. From a cam website I found Web Cam Inc. - Performance and Racing Camshafts







CLEARANCE RAMPS



The portion of the cam lobe adjacent to the base circle which lifts at a constant slow speed. It's purpose, is to compensate for small deflections and take up the slack in the valve train created by the valve lash. The opening ramp takes up all clearances in the valve train and causes the valve to be on the verge of opening. The closing ramp begins when the valve touches the valve seat and ends when the tappet returns to the base circle. Ramp designs have a tremendous effect on power output and valve train reliability.




I justify the last 0.60mm is the “play” in the hydraulic lifter,( and a minor component from the valve stem to bucket contact 0.025). So the valve may actually be closed at 9 degrees BEFORE TDC, despite the last 0.6mm travel up of the hydraulic lifter.


FBB has some excellent threads on degreeing cams on fchat, with contributions from some pro’s, and other very knowledgeable folks here. Most can wrench circles around me, and have a much better understanding of the engineering theory than I. Here is a link to FBB’s thread, a lot more theory than needed to do the 360 engine (whose procedure is very simple in comparison), but I found it very educational and reviewed it before embarking on my 360 degreeing.


http://www.ferrarichat.com/forum/technical-q/148917-degreeing-cams.html



-Ray

 

excellent idea, lets be pragmatic. again you can always remove the aft cam inspection covers, and check your accuracy as compared to the factory marks. This may give you a ball park idea if you are way off, or if it is a different problem not directly related to the degreeing (see my prior post). Also how was the car running before the belts and degreeing? was this just maintenance, or were you hoping to correct something?

 

And forget the 360 WSM - everything you need is in the 355 WSM

 

I think he is working on a 360.


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I then retract that statement

 

I'm not valve timing expert, but I do know how to read. I don't see any problem, other than how people are interpreting the WSM. For the exhaust side they are just giving reference points. It says rotate the crank so that it is 9 degrees before TDC on the crossover phase (i.e. where exhaust is closing and intake will start opening, or, if you like, TDC of the exhaust stroke). Set the dial indicator to 0. Rotate further until the gage is stable (i.e. exhaust is closed and bucket is on the base circle of the cam). The dial indicator should read 0.6 mm.

All that means is that when the cams are correctly timed the measured lift for the exhaust valve at 9 degrees BTDC on the exhaust stroke is 0.6 mm. If more that 0.6mm is shown, then the exhaust cam needs to be advanced somewhat. If less than 0.6 it needs to be retarded.

That is what the WSM says. Whether it's correct or not I don't know.

 

https://aldousvoice.com/2016/04/24/ferrari-360-engine-timing/

 

You can not compare the 360 to the 355. The 360 has variable timing on the exhaust cams. The specs are for setting up the timing with variators disabled. Running timing/overlap changes with rpm.

 

Experts and timing

I was at a toyota engineering demonstration years ago that had all the best factory techs around the US to go over proper procedures. These guys/girls were top notch.

What we found was no one got the same results until the toyota procedure was followed correctly. Simply following the workshop manual was not enough.

I would find the best factory trained tech and take their work as fact

 

Which 2, do they happen to be exhaust cams, and was this a variator campaign engine?


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