Shovel timing

[pansshovelsandknucks]

I've read a bunch of threads on timing for the cone shovels here and other places, but I can't find an answer to my question. I have a 74 shovelhead with circuit breaker timing and mechanical advance assy. Engine has been apart prior as it has unique engravings on crank wheel. I got it about a year ago, was not running but engine felt tight with good compression. Had to run oil lines, fuel lines, fix wiring, voltage regulator etc. Got bike to start (kick only) without adjusting timing. Then set timing in accordance with manual. Had problems kickstarting so set timing according to shovelhead.us method where advance mechanism is held in full advance, front piston is put at advance location according to line etched on wheel. Verified front piston on compression by watching pushrods, both are slack and piston is on the way up rotating engine in operating direction. Set points gap at .018, put new NGK R5670-5 gapped at .03. Got bike to start reliably and have been rising a few hundred miles. The timing plate ended up being rotated almost as far as it would go clockwise(advanced), which gave me hesitation. I checked many times that timing was set according to instructions. I even turned the plate with bike idling. Strongest idle was always with plate turned clockwise a lot. Noticed some pinging under load, so rotated plate back a little ccw, rode again, pinging, rotate ccw... did this about 3 times. Today I went riding after rotating the plate a bit ccw (plate is close to middle of adjustment slots now)
Hardly any pinging except when I really lugged it. Bike died at a couple of stops, seemed idle needed to be increased.

This is my question- is it logical for the timing to be correct as far as no detonation but for idle to be a little weaker? Or is this indicative of a crappy advance mechanism, intake leak, or some other problem? I have replaced o rings on intake when I was getting bike ready to fire. Bike still starts well and runs well throughout rpm range.

I'm not sure of other engine work done. Compression feels high as I'm 200# and sometimes struggle to kcik through compression strokes. I'm pulling heads in next couple of weeks as they are seeping oil so putting James fire rings in. I plan to check stroke and bore at that time. Am I over thinking this and should I just retard timing to prevent pinging and turn the idle up slightly and ride the fucking thing? Thanks

[JBinNC]

Of course an advance unit in good condition is essential for the motor to function properly.

If you do have high compression and/ or a stroker motor, the first step is to tune the advance unit with heavier springs to slow the advance curve. The problem is that those heavier springs are thin on the ground these days.

It goes without saying that shovels should be run on premium gas, as they are prone to both spark knock and detonation (which are two very different things). The only exception is if you have a shovel motor purposely built with low compression pistons (7:1 or 7.5:1) but why would you want to do that?

Do a compression test before you take the heads off. (Good idea to do a valve adjustment before testing.) That will give you an idea of what you are dealing with.

A cam with a later intake closing spec (50 degrees or more at .050 lift) will definitely help a high compression combo, and is almost essential to keep a high compression shovel out of detonation.

Retarding the spark to crutch a bad combo is NOT a good strategy, as retarded timing builds heat and kills power.

You have some tuning to do. Good luck with it, it will be a good learning experience.

Jim

[Guest]

and try to avoid after market advance mech & points plate,
the after market advances are often set to the wrong degree of advance & wear out quickly,
& some aftermarket points plates are often not very good, they try to make them fit both horizontal post & vertical post mounting,
you need the right one for the bike or you can end up without the correct amount of adjustment in the slots or jammed up at one end rather than in the middle

[JBinNC]

It is not unusual for a motor to have the point plate or pickup at the ends of the slots, or even having to file the slots longer to achieve correct timing. That has to do with variation in the location of the slot in the nose of the cam into which the advance unit or timer rotor registers. There are also stack-up tolerances of all of these components from the pinion shaft to the points themselves. Give the motor what it wants, don't worry about where you are in the slots.

Jim

[pansshovelsandknucks]

I didn't mention it, but I run 93 octane gas. I checked the advance mechanism by hand and it rotated freely. I also check to be sure the small roll pin was there as I read another thread where it was gone and was causing problems. The ignition and advance mechanism was in the bike when I got it, looked new, and looked aftermarket. I put a new blue streak condenser in there and it seems that the points plate has the same mark as other blue streak plates, so I think that's what it is. I put a new condenser in when I was having hell kick starting the bike. I ordered some heavier advance springs, unfortunately they are v twin as that's all I could find. I'll put em in when they get here. I have been looking at the prime mfg advance unit - seems high quality, but springs are oem curve. I'm doubting whether the line on the crank is in the correct advance position to get correct static settings. I guess to get a valid baseline I really need to get a piston stop and degree wheel on the crank and check the mark. I plan to install the heavier springs and see what happens. The bike runs well, and it has since I did the normal tune up stuff and got it starting easily. Just noticing the pinging under load, which is all but gone now. I don't want to change a bunch of shit and make more problems, haha! But I don't want to mask other problems by retarding timing unnecessarily as you mention Jim. Seems the last 5 or 10% of tuning is always the most challenging to get.

I will check compression before I pull the heads. And adjust valves. I adjusted them not long ago when I was fighting the kickstart issues. It does have solid lifters. I had a dowel down the spark plug hole as well to make sure piston was on the way up. Judging by the feel, the pistons are domed. Just some other info in case it helps.

[Tattooo]

Can you post a pic of your points setup??????

Also what manual do you have??????

Oh by the way thanks for responding in detail to peoples questions..........

[pansshovelsandknucks]

I'm out of town for a couple days but will post pics of ignition when I get back.

I've been reading posts here for years, and I know the frustrations when people post questions without relavent info or just vanish after asking a question. I know there are some folks posting here regularly that really know what they are talking about, so I'll give all the info I have.

I appreciate everyone's help.

[pansshovelsandknucks]

This is the manual I have

[Tattooo]

This is the manual I have

[ATTACH=CONFIG]107157[/ATTACH]

Awesome that's a good one............ I have the same one..........

[pansshovelsandknucks]

Got home early - here are some pics of my ignition and advance. That's where I have the plate set now with all pinging almost gone. Static advance timing puts it about 1/4" further clockwise. If I start the bike and turn the plate at idle, idle gets stronger the further I go clockwise all the way to the end of the slots. Bike runs well at all positions, just noticed after retarding timing the last time that I needed to increase idle speed slightly to prevent dying at stop lights.

[pansshovelsandknucks]

I don't know why they are rotated or how to fix it. They're not on my phone

[JBinNC]

May want to pull that advance unit and grease it. That needs to be done on an annual basis. Looks like it may have some vestiges of antisieze compound on it. I personally think that is lousy lubricant, and I prefer a light grease like a white lithium grease. Lubriplate is what I use; it's in common use in machine shops all over the country.

Jim

[pansshovelsandknucks]

I'll pull the advance and lube it as well as install the heavier springs. I did a compression test earlier after a 30 min ride. Started at around 60 psi and ended at 90 psi for both front and rear cylinders. Thats holding throttle plate open. Seems like normal compression but it's hard to kick through like it is higher. Maybe after I do the head gaskets I'll get higher readings.

Bike ran great and idled well after bumping up idle speed. Maybe it's just a compromise I'll have to find between strong idle and proper advance at higher rpm. And maybe the heavier springs will allow me to advance the timing more and not get pinging in low rpm high load situations.

I'm planning to pick up an old panhead chopper in the next few days so I'd like to wait until I have that prior to taking the shovel apart.

[Tattooo]

I might have missed it but have you adjusted your valves lately?

[pansshovelsandknucks]

Yes, I adjusted them a couple of weeks ago. Solid lifters and one was making racket. Ended up being slightly tight but just barely. Probably just a feel thing with whoever spun them last.