Cam Cogs

Shaun41178(2) · Post by **Shaun41178(2)** » Tue Jun 14, 2005 7:40 pm

To kohburn. Give me shipping homie and they are yours. Get this mod done for all those other members out there.

Series8217 · Post by **Series8217** » Fri Jun 17, 2005 2:00 am

Kohburn making adjustable cam cogs or something I haven't heard about?
I don't understand why we don't make timing tools that use the holes in the other end of the cam by the endplate to time without removing valve covers and etc or having to put diff cogs on?

Kohburn · Post by **Kohburn** » Fri Jun 17, 2005 7:01 am

there are tons of options - but most always the answer to questions of why isn't something make is just this - money

if its not profitable then the person has to take it apon themselves to do it as a hobby and hope enough people buy it so that they don't get screwed over.

as for the cogs.. for 91-93 you HAVE to remove the cogs to adjust timeing.. so why not replace.. for 94-97 you have to aleast losen the cogs so while you are at it why not just have an ajustable cog so that all you have to do to time the cams is pull the little plastic cover..

SappySE107 · Post by **SappySE107** » Fri Jun 17, 2005 2:47 pm

Kohburn · Post by **Kohburn** » Fri Jun 17, 2005 2:52 pm

SappySE107 wrote:oops, i forgot to send you the one I have. Well, if you can get access to 94-95, those would be the best to use as a basis. 96-97 use a different belt and cogs so you would need to make a different cog for them.

are the idlers and tensioner different for the 96/97? otherwise they could all be converted to use the same belt and cogs.

Series8217 · Post by **Series8217** » Fri Jun 17, 2005 3:31 pm

Kohburn wrote:there are tons of options - but most always the answer to questions of why isn't something make is just this - money

if its not profitable then the person has to take it apon themselves to do it as a hobby and hope enough people buy it so that they don't get screwed over.

as for the cogs.. for 91-93 you HAVE to remove the cogs to adjust timeing.. so why not replace.. for 94-97 you have to aleast losen the cogs so while you are at it why not just have an ajustable cog so that all you have to do to time the cams is pull the little plastic cover..

Ahh thats right, I forgot about the fact that people we need to find the later cogs if you made cam timing easily adjustable via the rear of the cams. I thought my idea could be interesting because it makes it possible to use the exhaust cam as the intake cam and still be able to time it right; if it does indeed have more duration..
For your cogs, are we going to make a degree mark on the ends our cams for 0* and then your cogs will have marks for other positions and we just loosen something and spin the center bolt to make the cam move without the cog? Or do we just time it to standard timing and then the outside part of the cog can move independent of the inside?
Any idea how long it may take to get these produced? The timing tool came out pretty quick.. I'm rebuilding my motor right now, it would be cool to have them evailable at the end of July, but I guess thats pretty soon.

SappySE107 · Post by **SappySE107** » Fri Jun 17, 2005 3:40 pm

Series8217 · Post by **Series8217** » Sat Jun 18, 2005 3:28 am

Why would it be hard to make something like this adjustable without removing the plenum and valve covers? Pull the inspection covers, loosen the three bolts holding the outer part of the cog to the inner part (which is tightened to the cam as stock), turn the inner part/cam using a wrench on the middle nut until the marks are lined up to the desired timing and tighten the three bolts with your other hand so it doesnt slip out of time. Then they can be torqued to spec. Easy as pie, I say!
I drew this up real quick in photoshop. Ohh yeah.

If i had the specs on the stock cogs I could probably whip up some adjustable ones in Solidworks overnight. They're darn simple.[/img]

SappySE107 · Post by **SappySE107** » Sat Jun 18, 2005 1:42 pm

Post by **admin** » Sat Jun 18, 2005 1:52 pm

Why can't you remove the cover like the honda guys so the gears are exposed? They dont' seem to have any problems doing that.

SappySE107 · Post by **SappySE107** » Sat Jun 18, 2005 2:32 pm

Series8217 · Post by **Series8217** » Sat Jun 18, 2005 2:49 pm

Nothing stopping you from turning over the engine to expose the other bolt. You don't have to get it to TDC when adjusting the timing with these cogs.
You could just modify the timing belt cover otherwise. Cut off part of the main cover and attach it to the inspection covers so you can get to the whole gear. Personally, I wouldn't even bother with that as it only takes a few minutes to get the main cover off. Maybe in the Z34 you guys don't have much room to do it? In the Fiero its easy as pie. Release the tensioner & remove the belt (takes a few seconds), then unscrew the inpsection covers and main cover and pull 'em off. It helps to have a map of the bolt positions so you know you got all of 'em.
I just looked through a catalog and it looks like most aftermarket adjustable cam cogs use three bolts to hold the outer toothed part of the cog to the center piece. You could always put detents at various settings to help hold it in position, though you wouldn't have infinite adjustability that way. I don't really think its an issue as long as those three bolts are as far to the outside of the gear as possible and have some decent sized washers on them. If you loosen the inner part that holds it to the cam then you have to have the cam carrier covers off to be able to see where your cam is.. the point of the adjustable cogs is to have your timing marks visible externally (on the inner part of the cam cog which stays with the cam at all times) so you loosen the toothed part of the cog for your adjustments. The bolt that holds the inner part to the cam would stay torqued to 80 or 90 ft/lbs at all times; that part isn't going to come off! If the cog slips out of time, the worst case is you get max retard on that cam. I wouldn't worry about the outer part falling off completely, but a plate on the back could be incorporated into the design to prevent that from happening.

Shaun41178(2) · Post by **Shaun41178(2)** » Sat Jun 18, 2005 4:05 pm

ok well I can't get the cogs off.

I was able to get the bolt out, but I am stumped out to get the cog and even the cam out of the carrier. What am I missing here? When it didnt' pull out like I thought it would I just threw it to the side and said hell with it.

This is what I want to know. Why dont' people just play with the timing in relation to the crank degrees? Or maybe thats how people have done it before.

But it seems to me you can figure out how much you are advancing or retarding the cams based on the cogs.

The cogs have teeth right? ok we all know this. Ok so you can change the timing infinately already with teh stock cogs. However its my opinion based on looking at a head I have sitting here that you dont' even need a tool to advance or retard the timing.

Cam timing is based on crank degrees. Now if you change the cam and not the crank, then you have effectively changed the opening and closing point in relation to the crank.

The cogs have teeth. count how many teeth it has. Now everytime the crank spins around once the cams spin half of that. Do some simple math and you can figure out that if you keep the crank still and move the cam back or forward one notch on the belt, then that will effectively retard or advance the cam X amount of degrees in relation to the crank.

Now why hasnt' anyone done that? You dont' even need tools then.

Series8217 · Post by **Series8217** » Sun Jun 19, 2005 2:27 am

Adjusting timing by moving a tooth? That's like 20 crank degrees. Its too coarse of an adjustment.
What year are those cam cogs? If they are 91-93 you have to use a gear puller to get them off once you get the center bolt out. They have lock rings pressed in to hold them in place. Otherwise they should just tap loose.
Instead of using a gear puller, I use a harmonic balancer puller with some appropriately sized bolts. The heads of the bolts slip into the "keyholes" and then you rotate the whoel thing to lock 'em in. Thats how the factory tool works. As long as you ahve a gear puller that fits, thats fine.
Otherwise I know someone else who has a set of 91-93 cogs sitting around.. Kohburn just send me a message and I'll give you their email if you don't get Shaun's cogs.

SappySE107 · Post by **SappySE107** » Sun Jun 19, 2005 4:09 am

Series8217 · Post by **Series8217** » Sun Jun 19, 2005 4:33 am

Thats a lot of crank.
Get some sleep Ben :salute:

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Jun 19, 2005 10:01 am

See there you go. You do the math and now you get a cookie.

See instead of the 13 degree cam retard you can now do the 1 tooth 12 degree. close to 13 degrees and should yeild similar results.

The Dark Side of Will · Sun Jun 19, 2005 11:11 am

The 13 degree retard IS crank degress. If one tooth is 24 degrees, then one tooth is almost twice the most radical adjustment that we'd want to make to this engine.

The Dark Side of Will · Sun Jun 19, 2005 11:12 am

SappySE107 wrote:Its 12 cam degrees, or 24 crank degrees per 91-95 tooth.

Too tired to think about the rest of that.

12 cam degrees per tooth? So there are 30 teeth on each cog?

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Jun 19, 2005 5:13 pm

oops my bad Will you are right.

It was too early in the morning after a night of drinking. my mind was still clouded from da beeeeer