All Small Six mild 200 rebuild - still dialing in - timing questions

[timson]

500 miles after startup and I want to start focusing on the jetting on my Weber to get it all tuned in, but I have a nagging question: is my valve timing correct?

With a recurved DSII set at 18 degrees initial advance (vacuum tube off and plugged), the motor runs very rough. Giving it more initial advance, like at least 35-40 degrees, makes it much smoother, but the vacuum nipple is bumping against the dipstick.

Additionally, at 18 degrees, manifold vacuum at idle is 13 psi and slightly jerky; more timing brings it closer to 15 psi, but no more. (Here´s a video of the gauge at idle:

.) A check for vacuum leaks around the carb found nothing.

I could restab the dizzy, but the question remains concerning timing, leading me to revisit my valve timing from the rebuild.

So, I am attaching 2 pics: my cam card, with my notes penciled on it from when I degreed the cam; and one of my timing gears at TDC before I buttoned everything up. Timing marks are close, but not dead on. I don´t believe Schneider cams have a 4 degree advance built in.

Am I off a tooth in one direction or the other? Might this be the source of my troubles? Should I just focus more on tuning the Weber with an AFR gauge (my next step)?

Thanks for your comments and ideas!!!
Tim

 

[bubba22349]

On that little vacuum gauge needle bounce check what you have the spark plugs gapped at? It could also have something to do with the Carb tune. So the cam degreed in at 104 degrees so 4 degrees off?

 

[JackFish]

18 degrees seems like a lot of initial advance.
At what rpm?
Have you tried backing it down to say around 12?
Then readjust the carb for optimum idle speed and vacuum.

 

[Econoline]

Your cam is 6 degrees advanced @ 104 centerline. That cam has 2 degrees ground in. Have you tried hooking the dist up to manifold vacuum? That will throw more advance in at idle but won't affect the off idle rpm range. Are you sure your crank damper hasn't slipped?

 

[timson]

Thanks all for your thoughts; keep them coming!

That´s right, Bubba: I found 104* on that "intake lobe", 4* off from the card. You see why I'm wondering if I'm off a tooth or if I should have gone with a crank sprocket that would allow for small adjustments. I made a call to Schneider at the time with my results and he said just put it in. Maybe I need to call again?

Plugs (Autolite 46) are gapped at .040. Flamethrower coil.

Carb is in need of tuning, for sure, but I rebuilt it before startup using jettings listed by Stardiero75. I put it on my 170 with an adapter, where it perked away happily, if not a bit fast. Video here. (Weber suggests 1-1.5 turns on the idle speed screw to adjust mixture, but the 200 won´t idle with less than 2.5 turns on speed screw and i need 3 to make it idle at 700 rpm (This was the opposite on the 170, where idle was hard to lower; didn´t bother with that though).

I´m setting the initial advance at idle speed (4-500 rpm?) with no vacuum to the dizzy, JackFish; when I connect it (to manifold vac), it does settle in a bit, but still the engine will barely run at 12 degrees or less. Vacuum drops and I guess simply doesn´t pull in the gas?

Econoline, given your reading of the card vs. my results, does the timing set alignment look acceptable to you?

I replaced the damper with a rebuilt one at assembly, but will take a close look at it. Sounds like I might need to degree the cam/double check valve timing again as best I can with engine in place, is that right?

Side note: 500 miles in, the engine runs a trick, with pep and verve as i´d hoped. This issue, however, underlies all others (hard start; rough, surging idling; and running hot and rich) as I try to tune it up right.

Thanks again for your ideas and assistance.
Tim

 

[wsa111]

You need to replace your stock timing chain with a JP full roller one. The lower gear can be adjusted in 2 degree increments.
That will get your camshaft back to 2 degrees advanced.
When you get the cam back to 108 thats when you can start dialing in all other component's.
Your curb idle in P or N should be close to 900 rpms, then when you put in D it will drop.
Did i recurve your distributor??? If so what is the number under the housing.
If i didn't what are the Dist. Specs, centrifugal & Vacuum??

 

[timson]

Thanks, Bill!
You did indeed recurve that dizzy, number 198.
I´ll play a bit more with the idle speed/mixture and advance, which is what´s gotten me these 500 miles of break-in. But if that cam advance is an absolute must, given my numbers on the cam card and the alignment in the pic, it looks like I need to start there and dig in.

There´s no way I can use the current timing set (from Schneiders as well) and move the chain a tooth?

If I understand you correctly, I need to bring that 104 intake lobe measurement to 108 by advancing the cam through the timing set. Will I have to remove the head to check that using the .050" tappet clearance or can an educated guess/reassembly (using the adjustable crank gear) get me there?

Wow. This is frustrating. I thought I was so close and looking forward to focusing on the carb...

Thanks for your help, folks.

 

[wsa111]

Thanks, Bill!
You did indeed recurve that dizzy, number 198.
I´ll play a bit more with the idle speed/mixture and advance, which is what´s gotten me these 500 miles of break-in. But if that cam advance is an absolute must, given my numbers on the cam card and the alignment in the pic, it looks like I need to start there and dig in.

There´s no way I can use the current timing set (from Schneiders as well) and move the chain a tooth?

If I understand you correctly, I need to bring that 104 intake lobe measurement to 108 by advancing the cam through the timing set. Will I have to remove the head to check that using the .050" tappet clearance or can an educated guess/reassembly (using the adjustable crank gear) get me there?

Wow. This is frustrating. I thought I was so close and looking forward to focusing on the carb...

Thanks for your help, folks.

I would just retard the cam 4 degrees with the roller chain lower sprocket. I will check your Dist. setting & contact you.
You can leave the head on. Bill

 

[bubba22349]

Hi Tim, You need to open up the plug gap some to atleast .044 / .045 this is were I start with a stock DuraSpark II ignition system and you will need to work on the carb some more too. But X2 yes you will need to first start back at the cam timing before you can get into working much on the carb tuning. You can't really go one timing gear tooth that's way to much of a timing jump off the top of my head I think at the crankshaft its 13 degrees. Part or all of this 4 degrees cam being off may be from not using an early timing chain gear set (like a 1963 1/2 to 1968 set) so it maybe because of the year group of your timing chain gear set. Do you know which year or part number of your cam gear / or timing chain gear set you have? Besides the full roller timing chain and gear set its the top of the line in quality, you can also use an off set key with your timing set you have to reset the cam degrees they make them in 2 and 4 degree offset keys, Mr. Gasket # 988G is a 4 degree crankshaft key (see below link for more info) their maybe some others brands I don't know about. Best of luck Edited

Mr. Gasket 988G offset crankshaft key

Mr. Gasket 988G Mr. Gasket Crankshaft Keys | Summit Racing

Free Shipping - Mr. Gasket Crankshaft Keys with qualifying orders of $109. Shop Crankshaft Woodruff Keys at Summit Racing.

www.summitracing.com

 

[wsa111]

But that would retard the crank damper 4 degrees also.

 

[bubba22349]

Not if you cut off the back part of the original crankshaft key the part that's under the crankshaft gear and then use this short off set key under the crank gear, leaving the rest of the original front key for the Dampner. They do also make some offset cam gear bushings and keys too.

 

[DannyG]

Just checking, is the dampner new ? If it's original, could it have slipped and the timing marks are not accurate ?

 

[pmuller9]

Concerning the cam card in the first post.
On the .050" intake readings you hand wrote the intake opening at -6 degrees but for the closing point you put a check mark next to 25 degrees ABDC.
Does that mean you measured the .050" closing point at 25 degrees ABDC?

 

[timson]

Yes, that is correct. This was my first attempt at degreeing a cam, but I think I got it right. What I didn´t do, however, was to make the necessary correction with an adjustable crank sprocket...
Thoughts?
Cheers,
Tim

 

[timson]

Hi Tim, You need to open up the plug gap some to atleast .044 / .045 this is were I start with a stock DuraSpark II ignition system and you will need to work on the carb some more too. But X2 yes you will need to first start back at the cam timing before you can get into working much on the carb tuning. You can't really go one timing gear tooth that's way to much of a timing jump off the top of my head I think at the crankshaft its 13 degrees. Part or all of this 4 degrees cam being off may be from not using an early timing chain gear set (like a 1963 1/2 to 1968 set) so it maybe because of the year group of your timing chain gear set. Do you know which year or part number of your cam gear / or timing chain gear set you have? Besides the full roller timing chain and gear set its the top of the line in quality, you can also use an off set key with your timing set you have to reset the cam degrees they make them in 2 and 4 degree offset keys, Mr. Gasket # 988G is a 4 degree crankshaft key (see below link for more info) their maybe some others brands I don't know about. Best of luck Edited

Mr. Gasket 988G offset crankshaft key

Mr. Gasket 988G Mr. Gasket Crankshaft Keys | Summit Racing

Free Shipping - Mr. Gasket Crankshaft Keys with qualifying orders of $109. Shop Crankshaft Woodruff Keys at Summit Racing.

www.summitracing.com

Thanks again for the info, Bubba, Bill and others.

Regarding the timing gear set, I ordered one from Scheider´s almost as an afterthought with my cam/lifters order; I have no idea what vintage it might be. Very interesting idea, however, it possibly being of a different alignment...

The dampner is a rebuilt one and doesn´t look like it´s slipped, but I´ll double check its mark against TDC when I have the chance. There has been a squeal at the belt that comes and goes despite cleaning, tightening, and dressing. Could the dampner be slipping and squealing with no visual signs on the rubber part? That opens up a whole new set of questions regarding dizzy alignment; so I´ll check the marks first.

The consensus seems to be, however, that judging by the card, my numbers, and the pic of my gears, I need to "retard" the cam timing by 4*, using either an adjustable timing set or an offset key.

If I understand that correctly, and to get a general sense of what I need to do, the crank shaft needs to be rotated 4* clockwise (relative to it's current position), or the camshaft rotated 4* counter-clockwise, then use the offset key (or adjustable crank sprocket) to lock everything down, right?

Huge thanks to all, even though this is unfortunate news. My wife has long been telling me, correctly of course, that "the Comet will never be done!"

Tim

 

[wsa111]

I believe Bubba is saying cut the 4 degree offset key so it just retards the the timing chain crank gear counter-clockwise. Then cut your stock key just for the Crank Damper which will remain in its original position. Thus the total length of part of the 4 degree key + the part of the crank damper key will be the same length as either the total length of either one so it will fit in the crank snout milled out position for the key.
That will save you the time by verifying the new TDC mark on the damper.
Remember measure twice before cutting either one so you get the correct length on both of them.
I really think the best deal is the full roller timing chain set. Will cost more but will not stretch like the stock chain & you won't have to mickey mouse the keys.

 

[pmuller9]

Concerning the cam card in the first post.
On the .050" intake readings you hand wrote the intake opening at -6 degrees but for the closing point you put a check mark next to 25 degrees ABDC.
Does that mean you measured the .050" closing point at 25 degrees ABDC?

Yes, that is correct. This was my first attempt at degreeing a cam, but I think I got it right. What I didn´t do, however, was to make the necessary correction with an adjustable crank sprocket...
Thoughts?
Cheers,
Tim

If that is true then you measured the .050" intake duration as 199 degrees when it should be 194 degrees. (-6 +180 +25 = 199)
Until you get the .050" readings correct you do not know where the lobe center is.

 

[timson]

Thanks for the clarification, Bill.
I can visualize the setup and am left with a question, that you partially address: how great is the risk of a shorn key? I´ve seen one on the end of a Norton Commando crankshaft and worry that the offset key might not be up to the task as well as simply getting the proper timing set in there.

If I go that way, the timing mark on the damper will show 4 degrees retarded than actual, so I just have to mentally add 4 degrees to whatever the timing strobe indicates, right? If it shows 12, it´s really 16 BTDC, yes?

 

[timson]

If that is true then you measured the .050" intake duration as 199 degrees when it should be 194 degrees. (-6 +180 +25 = 199)
Until you get the .050" readings correct you do not know where the lobe center is.

Thanks for the lesson and explanation, pmuller9. Your math reveals a mistake in my cam degreeing process I wish I had seen earlier. With the same math, my measurement for the exhaust closure also seems off by 2-3 degrees, right?

So basically I need to degree the cam again?
Yeesh.

Can that be done with head on using pushrods to measure tappet lift? i have hydraulic ones of course...

curiouser and curiouser; this is a bummer, dudes.

Thanks for the info, though!
Tim

 

[pmuller9]

Thanks for the lesson and explanation, pmuller9. Your math reveals a mistake in my cam degreeing process I wish I had seen earlier. With the same math, my measurement for the exhaust closure also seems off by 2-3 degrees, right?

So basically I need to degree the cam again?
Yeesh.

Can that be done with head on using pushrods to measure tappet lift? i have hydraulic ones of course...

curiouser and curiouser; this is a bummer, dudes.

Thanks for the info, though!
Tim

Yes. You can use the dial indicator on the end of the pushrod. The dial indicator does not have enough pressure to depress the hydraulic lifter.
Since the head is on the engine you will need a piston stop that screws into the spark plug hole to find TDC on the degree wheel.