JP Timing Chain & Gear Question?

[Mustang_Geezer]

The crank gear is marked +2+4+6 & -2-4-6. If I wanted to advance it, it would be on the "+" side correct?

Dont need no info on how to degree it, thats allready long done.

Just trying to fix some timing & distro issues on my old motor.

Thanks,

Doug

 

[bubba22349]

Yes

 

[rbohm]

8) yep, + = advance, - = retard

 

[MPGmustang]

Mustang_G
just a heads up, just because the key says' +2 or +4 does not mean it's perfect, +2 can mean around 2 so you might et +1 or +3... and +4 can give +3or +5...
It's best practice that you double check with a degree kit.

http://classicinlines.com/CamDegree.asp[/url]":qkl8szdl]If the circumstances were perfect, one would only need to line up the marks on the timing chain sprockets and the cam would be degree'd. In reality, you are dealing with a group of components (the camshaft, crankshaft, timing chain, and sprockets), all with their own standards and tolerances. If these tolerances are off, they can stack up against you and throw your motor out of synchronization. Without degreeing the cam, you can never be sure if all the parts are in correct position at the precise time they are suppose to be. As such, we always recommend that you "degree the camshaft" whenever possible, even if you have to rent or borrow the tools.

 

[Mustang_Geezer]

Thanks guys!!

MPGmustang,

I borrowed Mikes degree kit and degreed it 7 or 8 years ago so I know what it supposed to be.

Now to take it a step further you advance the cam to increase your bottom end torque and retard it to increase your top end correct?

Thanks!

 

[rbohm]

Now to take it a step further you advance the cam to increase your bottom end torque and retard it to increase your top end correct?

Thanks!

8) for the vast majority of the time yes. there are times though when the opposite occurs, but they are rare indeed.

 

[rocklord]

8) for the vast majority of the time yes. there are times though when the opposite occurs, but they are rare indeed.

The 140HP Corvair engine with a Powerglide (automatic) had the cam retarded 4-degrees to increase low end torque, sacrificing top end power. The 140HP with a 4spd had the cam straight up.

So yes, sometimes the opposite occurs.

 

[wsa111]

Doug, the new timing chain will get yout low end & midrange back.
Thats why you never lost trap speed with the worn chain. Retarding the camshaft enhances top end.
I'm anxious to see how your engine reacts to being back to when it was fresh. Bill

 

[Mustang_Geezer]

Thanks! I'm advancing the cam from 2 to 4 degrees so I can pick up a little more on my 60' times at the track.

Bill,

I got the new distributor gear on last weekend and luckily the cam gear was allright! I talked to Performance Distributors yesterday and they are sending me a new FREE pair of advance springs to replace the ones that broke and I bought a new rotor at work so when I get the springs in it should be running good again.

The 2 days it was running (before the distro crapped out) after I replaced the timing chain and gear set it had a LOT more bottom and mid range torque.

If I can get it fixed this week I have a car show to go to this coming weekend then I'm going to a test & tune next Friday if it all works out.

Thanks guys!

Doug

 

[wsa111]

Doug, moroso & i think Mr. Gasket sell hei spring kits.
Just install the correct combination of springs & have the advance in by 2500-2800 rpms.
If you get springs the hei is a GM distributor & the springs are right on top.
Make sure you also use the nylon rotor screws from performance distributors & always check under the rotor cause the electrical field seems to dry out any lube in the advance weight area. Bill

 

[Mustang_Geezer]

Doug, moroso & i think Mr. Gasket sell hei spring kits.
Just install the correct combination of springs & have the advance in by 2500-2800 rpms.
If you get springs the hei is a GM distributor & the springs are right on top.
Make sure you also use the nylon rotor screws from performance distributors & always check under the rotor cause the electrical field seems to dry out any lube in the advance weight area. Bill

Bill,

I got the new springs from Performance Distributors last night and got them installed....Runs GOOD!

Amazing what replacing a wore out gear and wore out timing set can make!

One other question on timing that we were discussing at work.

My cam is advanced 4 degrees so if it shows 38 degrees total advance at the crank (with a dial back lite) is that the true number or is it 42 degrees total? Or is it only 40 degrees total being the cam turns at 1/2 the speed of the crank.

Your light is showing on the crank but the relationship between the crank and cam has now changed being you are triggering the timing lite off the distro which in turn is running off the cam which you now have advanced 4 degrees from the crank.

Understand what I'm saying?

Doesnt much matter because I'm going to tune it for the fastes et's at the track reguardless of what the timing lite says.

Thanks,

Doug

 

[rbohm]

8) cam timing and ignition timing have nothing to do with each other. 38 degrees total ignition timing is still 38 degrees total ignition timing.

 

[wsa111]

Doug, i would retard total to 34-36 total just because you have the aluminium head.
Doing this i would limit the mechanical advance so you can run 16-18 degrees initial & still end up with 34-36 total.
See what your trap speeds are, go for the highest trap speeds & your et will follow cause your chassis is set up right. Bill