Camshaft tuning/talk thread:

[F34R]

So I am adjusting my camshaft on my m20 and I made a tool. I would like to talk a bit about proper degrees and how to check valve list etc. I have poured myself in just about any thread I can read on here and e30tech. Best one I found was with Nando I believe on his stroker:

http://www.e30tech.com/forum/showthread.php?t=92227

Also found some great advice here:

http://deltacam.com/tech.php

I have an SETA bottom end with an 885 head, IE rockers, Schrick springs and a Sckrick 288 camshaft.

Before I stored the car for the winter I had the timing off too much in both advance(First) and retarded. First time was ALMOST perfect, but it was a tooth off and I thought I made a mistake(turned out a good one). So I fixed the timing from being off one tooth and then there was no top end when before I had power straight through 1,200rpm to redline. Problem was I had to retard it a bit to smooth out the hard starts. I did not know that at the time.

Under more research I found my first error advanced it enough to be almost perfect except for a hard start(too much advance). My first timing was off 1.5 tooth, so what I did was retard my cam gear half that amount. That should be right in the middle of what it was before.

I have not started it as the the weather turned to complete down pour. Can see the engine getting wet in first picture.

Let's hear some input and this is an on going thread for ANYONE that is having camshaft issues with tuning.

Here is the tool I made:

Handle is about 9" long and allows you to bolt straight up to the adapter lock on the camshaft gear. It turns with EASE, I am not sure if there was an easy way to do this, but this tool made it easy.

[LJ851]

???

Your camshaft is designed to be timed in relation to the crank, why is it not set to factory (schrick) specs?

The #'s on your adj cam gear are relative, you have no idea how close you are correct cam timing without actually setting the cam timing.
Since you are not speaking with cam timing #'s i am assuming you have not done this. I am baffled why so few BMW enthusiasts really set their cam timing.

After that, fine tuning on the dyno is the only way forward, maybe a few crank degrees either way.

[digger]

with a schrick 288 i found that if you install it as is with stock gear it was slightly advanced by approx. 4* which is a good place to start if the valves don’t hit the pistons. A bit of advance never goes astray from a performance POV especially since the belt aint rigid. Also since it stops you blowing the fresh charge back into the intake manifold at low and midrange when velocity aren’t that high, on an M20 with lower than ideal static CR advance will make it crisper all over the rpm band
Since with a 288 both lobes are almost the same at worst set it so that both valves are open the same amount (whatever amount that ends up being) when the crank is at TDC.
The only reason to spend a lot of time degreeing a cam is so you know where it is at. If you get it close and dial it in on the dyno then who cares where it is (along as it don’t smash into something) except next time when you can then set it closer to the mark straight off the bat or do a timing belt and its out due to some slight differences then you know where it needs to be.

[nando]

???

Your camshaft is designed to be timed in relation to the crank, why is it not set to factory (schrick) specs?

The #'s on your adj cam gear are relative, you have no idea how close you are correct cam timing without actually setting the cam timing.
Since you are not speaking with cam timing #'s i am assuming you have not done this. I am baffled why so few BMW enthusiasts really set their cam timing.

After that, fine tuning on the dyno is the only way forward, maybe a few crank degrees either way.

because they aren't adjustable without aftermarket parts, and even with aftermarket parts adjustment isn't painless (cap and rotor in the way, typically).

[F34R]

Thanks for the advice guys, I am going to tinker with it when the weather warms up a bit more. I had it pretty good but wanted to fine tune it a bit more to smooth out the hard start. Now it fires alright but lacks a ton of power.

As Nando said in our PMing: "1.5 teeth is not 1.5 degrees. I think there are 48 teeth, so 1 tooth is 7.5 degrees' I was off with the teeth as I had no clue.

When I first put everything together I was off a bit on the crank TDC. That in turn made the camshaft off TDC. That was really close to being spot on, drove and pulled HARD. It was a blast, just when I hit the key to start it would take 5 seconds or so to fire up. I checked the timing after setting the bottom end. I saw it was off by eye of around 1.5 tooth. So I tore it down to reset it...dumb. Should have just retarded it a little bit.

More info about the changes in advancing and retarding timing. Posting for future members trying to resolve thier own problems.

http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx

[jlevie]

As far as I know even an aftermarket cam will correctly timed when the marks align if the head hasn't been decked. If the head has been decked the cam will be retarded. A retarded cam increases peak torque at the expense of midrange and advance has the opposite affect. The right way to check cam timing is to check the amount of valve opening at TDC on valve overlap. For a stock cam the intake valve will be open 0.005" more than the exhaust. For a Shrick (or other aftermarket) you have the maker what they want to see.

I do this by removing all valve clearance on an intake and exhaust for one cylinder with a dial gauge registering one each spring washer. I tighten down the eccentric until the needle just wants to move when that cylinder in at the firing stroke (both valves closed). Then rotate the crank 360 degrees and see how much each valve is open. The amount of advance or retard can then be adjusted to achieve the desired values. An adjustable cam sprocket makes this easy. That establishes the baseline timing.

Depending on what you want out of the engine dyno tuning may be desirable. You can adjust cam timing to move the torque peak around. But for overall performance remember that the are under the torque curve is what is usually important.

I don't trust adjustable cam sprockets over the long term. So once I know how much advance or retard I want I'll calculate how much offset I want in a bushing that goes into the cam sprocket. The cam sprocket index pin hole gets bored out to 1/2" and I make up 1/2" bushing with the index hole in the bushing offset enough to get the desired timing (you calculate that).

[LJ851]

As Nando said in our PMing: "1.5 teeth is not 1.5 degrees. I think there are 48 teeth, so 1 tooth is 7.5 degrees' I was off with the teeth as I had no clue.

Remember to multiply that number by 2 since cam timing is measured in crank degrees and the cam spins half speed. With 48 teeth each tooth is 15 degrees, a huge amount.