Setting the cam timing belts on a 355

Thank you!

 

OUTSTANDING WRITE-UP PHIL !!!!!!!!!!!

There you have it boys, how to degree your cams, from the pro that was kind enough to share it.

Thank you Phil.

 

for those who don't know:
Dwell is the degrees of arc of the cranks rotation at the top of the piston stroke. due to the crank throw moving in a circle the rod will stop moving upwards at a few degrees shy and past absolute TDC. so the piston will reach it's top of stroke before the crank reaches TDC.

to get TDC one would mic the piston and note the degree at which the piston stops moving in relation to the crank. then continue past and note the degree at which the piston starts to move again. the difference is the true TDC of the crank. you've just measured the dwell of the engine.

dwell varies from engine to engine based on tolerances and rod/strock ratios etc..

being an anal engineer i did this for each cylinder on my motor. also due to crank twist each piston will vary in it's TDC. but that's another subject for another day.

 

I don't get it...your method that is. I don't want to start a timing holy war.

 

Well since you only like to read coloring books that isn't surprising.

HAHAHAHA!

 

it's not "my" method...

It's my interpretation of the Ferrari manual..

I prefer the max open method...

 

I'd expect that there are several ways to set cam timing, but perhaps only a handful of truly accurate, dependable, quality ways to set it such as your "max open" method.

Would any of the other quality methods be able to set cam timing dependably with the heads still on the engine, rather than removed?

 

what with your obsession about removed heads... you CAN'T time the cams to the pistons if they're not fitted to each other...???

 

Sorry. I just don't understand.

I was under the impression that one could (with one method) accurately time cams by using a degree wheel even if the heads are still bolted onto the block.

 

were you once abducted by aliens?

Somebody give him the Mr Spock sleep grip..PLEASE!!!!

 

ND -- I think you might be confusing the term "heads" with "cam covers"? (As Phil keeps trying to say) Cam timing doesn't exist unless all the mechanical bits between, and including, the crankshaft and the camshafts are in place -- which, on an overhead cam F, includes the cylinder heads but not the cam covers.

(Although I see no way that using a degree wheel would make leaving the cam covers in place while setting/checking cam timing any more practical/doable.)

 

Sorry. Don't know why I thought/typed that. My bad.

 

ND is not totally insane. He got lost because he tried to read Guy's site regarding Engine building. ND did not read my early post that the thread fingers was not about engine timing but engine building. That thread did exactly what I thought it would do which is to confuse everyone.

 

define "totally" Like, he can walk on his hind legs etc, right???

Yeah, I can see now he got lost in terminology...

And to try to further help...

NO, you can't time cams with the cam/valve covers on either... you CAN make sure the pulley reference notches are in correct alignment with the seal carrier marks... but if someone has moved the pulley/s to chase a nano degree as described earlier... they can't be trusted.

 

I did not understand your way either. NoDoubt must be thinking my way because there was no degree wheel in your pics. Everyone else must get it because they like your write up. I do it the dumb billybob way. http://www.alfabb.com/bb/forums/showpost.php?p=288468&postcount=18

 

Oh yeah, I have actually broken bread with NoDoubt. He is a wealth of info but you always should try to confirm what he says because sometimes he collates things he has no firsthand knowledge of but that info may lead you to other more important info, and sometimes he is dead on. The web is the source of great missinformation and until proven otherwise you alwsy have to check the source. That's SOP for the web so I don't think ND does anytjing wrong. In fact He is an asset not a liability and while I stuffed my face with both hands I watched him eat with a fork and drink from a glass so he ain't all that bad.

 

Not to get too off topic here but I have scratched my head many times on ND's responses to questions but, whatever it makes interesting reading, no offence intended.
Anyway FBB the key here on Phil's discription, you need to think hydraulic lifters VS. solid lifters/tappets. Degree wheel for solids or shim adjusting 348s. Phil's disciption for hydraulic 355 & 360. Would that be a good analogy Phil? Regards, Vern

 

Gee Vern I must be extremely dense. I'm not sure how what you post applies. You see hydralic or not you need to establish an accurate way of measuring valve lift per the factory spec. So from a generic sence either the factory has to allow in it's specs that you are measuring on a depressurized hydralic tappet knowing the ultimate result is different from the running state, or you have to remove the hydralic tappet and replace with a solid diagnositic piece. With a solid diagnostic piece you can then accurately measure the valve lift. This is done all the time with say 350 Chevy motors where the hydralics are temporarily replaced with a solid lifter and pushrod so you can dial guage it.

 

You are dealing with the overlap of intake and exhaust valves when you are setting the cam timing of a hyd. lifter system. This is the way I understand it. What you said about the chevys is correct that is why they would change the lifter to a solid unit for measurement because you can't accurately measure the lift of hyd. unit. The 360 WSM has a fairly good discription of setting the timing of that motor which would be the same technique used on a 355. Regards, Vern

 

I can't find my 360 CD but looking at the photo pages of FF Ferrari seems to take into account its specs on a depresurrized hyd tappet or does not care. Overlap is not an issue since you time cams really one bank at a time. Anyway we probably are talking about the same thing just words get lost in typing. Merry Xmas to you and your family.

 

FBB... You're kind of right in your thoughts, but you've taken the official wording "valve lift" too literally..

The manual actually means to measure hydraulic lifter "lift" and not true valve lift.. which is impractical.

355/360/550 etc all run ZERO valve clearance. The hydraulic lifters have little springs inside and run preload. In fact if you ever remove the cams, you have to be VERY careful to not allow the lifters to expand with subsequent loss of compression from open valves upon re-assembly.

The lifters can be squeezed in a vice to expell the oil inside.

I don't like the "lift at TDC" method as it does not allow for any wear on the camshaft. I've never seen any wear yet, but surely one day there will be some.

 

So yes it appears the factory accounts in their use of the lift at TDC the play in the hyd lifter. I like the lift at TDC akaopening at "X.XX"" method because I can see the events relative to crankshaft position. It helps my little brain and keeps me centered when I try to play with overlap/advance/retard. So I guess what you really prefer is the Lobe centerline method but the factory needs to tell you the lobe centerline spec. I do not know enough about cams. Can we find or derive those specs from our cams or caluculate the thoretical lobe centerline from the data they do provide?

 

If you look at the pics I posted, I even gave you my lobe centre calculations...

The lobe centre is the halfway point of duration.

But in practice, the area is so small to work with inaccuracies are hard to avoid.

 

Yes got it. Lobe center = angle between centerline of intake lobe and between exhaust lobe. lobe centerline = angle between lobe center and crank TDC which is what is tweeked to advance/retard cam timing.

 

err.. no.

Lobe centre is the point of max openng of the valve, measured as crank degrees referred to TDC/BDC depending on terminology.

On a symmetrical cam profile (which almost all road cars are), the max open point is halfway between opening and closing.