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Thread: Cams + Crank Timing Chain Question..Mating Marks..

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Posts: 21-30 of 36
2011-05-26 00:39:24
#21
Originally Posted by ashtonsser
LOL, dude ive been doing this a long long time. Im not that young but yes maybe younger than you. But ive built and built and built SR after SR and if the timing chain is off one tooth on the crank you are talking about 15 deg or so. Which is highly noticeable on both checking with an extension down on the piston and looking at the cam sprockets and where they are supposed to be at. The dowell pins are supposed to be at 12 oclock exhaust and 10 oclock on the intake. The 12 oclock on the exhaust is the easiest to eyeball. If you have even one tooth off on the cam which is about 7 deg or so you will still easily be able to tell its not exactly at 12 oclock on the dowel pin. Once you have the exhaust perfectly at 12 oclock count 20 pins on the chain over to the next dot. You have to have 20 pins inbetween. If you do then you know your intake cam is at the right position as well and the cams are timed with each other and the crank.

Not hard man. You dont need the links to tell you where exactly they need to be at. thats for manufacturing purposes only and for full rebuild purposes only. Not trying to start a pissing match but ive done this way too many times and yeah, I can tell by looking at it. And since his car is still running really really good its more than likely his cam timing is correct. His issue with the whole cant get any more than 15 deg out of the distributor is something else. Either not in timing mode correctly or its something with the jwt ecu.

Its definatly not the ECU, do you know how shitty it would run with the timing that advanced? The thing would be knocking like crazy if the base timing was at like 27 degrees or whatever? It HAS to be something mechanical , as thats what the base timing is, simply mechanical timing, and the ECU digitaly changes the ignition timing. I'm thinking maybe the camshaft may be ground wrong or something...either that or maybe the timing chain is streched that far? Thats a possibility as well...lets work on figuring out what it IS not what its NOT, the mechanical timing orientation of the cams to the crank.
2011-05-26 01:14:13
#22
Originally Posted by SENTRASER
I'm thinking maybe the camshaft may be ground wrong or something...either that or maybe the timing chain is streched that far? Thats a possibility as well...lets work on figuring out what it IS not what its NOT, the mechanical timing orientation of the cams to the crank.


Remember that this timing issue was going on before we did the s4 swap so it's probably not the cams.
2011-05-26 01:37:32
#23
Could be a tensioner problem. If you have the old style tensioner I would recommend replacing it very soon.
2011-05-26 02:10:49
#24
Originally Posted by ashtonsser
Could be a tensioner problem. If you have the old style tensioner I would recommend replacing it very soon.


hmmm, ordering one now.
2011-05-26 13:40:12
#25
Originally Posted by ashtonsser
Could be a tensioner problem. If you have the old style tensioner I would recommend replacing it very soon.


A tensioner would only affect the slack side of the chain, keeping it from jumping time on the intake cam; the distance between the exhaust cam sprocket dot and the crank sproket dot is where the stretch would affect the physical timing, the only real solution is to replace the timing chain, if it is in-fact

The updated tensioner only disallows the oil from draining back when the engine is off making the tensioner not rattle on a cold startup. Lucas does your tensioner rattle on a cold morning when starting? If bot, then it's a waste of money IMHO.
Last edited by SENTRASER on 2011-05-26 at 13-43-52.
2011-05-26 13:50:56
#26
I wouldn't go so far as to say it is a waste of money, maybe not a necessity, but it is easy to change, reduces valvetrain noises, and has finer teeth for more finite adjustments.

I still do not understand why you are asking about this. What is the problem, again?

You have said general things but not asked a question or I have not discovered what your problem was, yet.
2011-05-26 16:08:06
#27
Originally Posted by SENTRASER
A tensioner would only affect the slack side of the chain, keeping it from jumping time on the intake cam; the distance between the exhaust cam sprocket dot and the crank sproket dot is where the stretch would affect the physical timing, the only real solution is to replace the timing chain, if it is in-fact

The updated tensioner only disallows the oil from draining back when the engine is off making the tensioner not rattle on a cold startup. Lucas does your tensioner rattle on a cold morning when starting? If bot, then it's a waste of money IMHO.


It's already ordered.

I didn't notice any rattling. I remember when we did the S4 cams we heard some rattling of the chain like it was hitting the valve cover or something but that seems to have corrected itself over time.
Last edited by gomba on 2011-05-26 at 16-11-38.
2011-05-26 17:20:16
#28
Originally Posted by Viprdude
I wouldn't go so far as to say it is a waste of money, maybe not a necessity, but it is easy to change, reduces valvetrain noises, and has finer teeth for more finite adjustments.

I still do not understand why you are asking about this. What is the problem, again?

You have said general things but not asked a question or I have not discovered what your problem was, yet.


Agreed, it's not a waste of money, but it's fixing what ain't broke.

The problem is the distibutor is almost all the way advanced to get a base timing of 15°.

GOMBA did you order it from gregv? If not you'll need the updated gasket to replace at the same time, as I think Greg sells then as a 'kit', although you might check anyway.
Last edited by SENTRASER on 2011-05-26 at 17-23-49.
2011-05-26 18:29:18
#29
Whoever installed the cams had some slack between the exhaust cam and the crank gear. This moves the 15* base timing forward.

I had the same, exact thing happen to me when I installed Briawn Crower Stage 2 cams. I popped the valve cover off, took off the exhaust cam and put it back on making no slack in the chain between the exhaust cam gear and the crank gear.

Just like that, the base timing of 15* was close to where it was originally. On my car, 15* appears slightly retarded (towards the firewall with a larger gap in the top slot of the dizzy groove). My JWT ECU requires base timing of the dizzy to be at 25* so I had to advance it a lot and I could only get 15* by damn near completely advancing it fully.

Weird, it happens, I remedied it after 5 weeks of dicking around.
2011-05-26 19:41:43
#30
Originally Posted by SENTRASER
Agreed, it's not a waste of money, but it's fixing what ain't broke.

The problem is the distibutor is almost all the way advanced to get a base timing of 15°.

GOMBA did you order it from gregv? If not you'll need the updated gasket to replace at the same time, as I think Greg sells then as a 'kit', although you might check anyway.


yes, GregV

Originally Posted by Viprdude
Whoever installed the cams had some slack between the exhaust cam and the crank gear. This moves the 15* base timing forward.

I had the same, exact thing happen to me when I installed Briawn Crower Stage 2 cams. I popped the valve cover off, took off the exhaust cam and put it back on making no slack in the chain between the exhaust cam gear and the crank gear.

Just like that, the base timing of 15* was close to where it was originally. On my car, 15* appears slightly retarded (towards the firewall with a larger gap in the top slot of the dizzy groove). My JWT ECU requires base timing of the dizzy to be at 25* so I had to advance it a lot and I could only get 15* by damn near completely advancing it fully.

Weird, it happens, I remedied it after 5 weeks of dicking around.


You checked your cam timing and it was fine before you took the exhaust cam off? Wouldn't your suggestion move the dimple marks on the cam gear relative to the # of links in the chain? I think you'd essentially be moving the chain a tooth or two. Also, I've had this issue prior to S4 cam install, although we zip tied the chain and such so if it was a problem before, it would have still been a problem after S4 cam install.

My cam timing, using all the methods, is perfect.

-G
Last edited by gomba on 2011-05-26 at 19-47-22.
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