adjust timing?? [Archive] - Classic Cougar Forums

: adjust timing??



mokankat
August 24th, 2001, 11:02 AM
can anybody give me some tips on the easiest way to adjust the timing on my XR7? it's a 390. i don't see any marks on the cam pulley anywhere to use as indicators. should i just mark my own?? thanks.

Scott
August 24th, 2001, 06:45 PM
They should be there unless you have an aftermarket H Balancer. They are pretty small, and black just like the H balancer. Best way to find them is to look from under the car, have someone bump over the engine and clean it as you go you'll find them. My 390 likes an initial setting of 6 D BTDC with a total of 34 in by 2500 RPM'S.

Good luck

modifiedmark
August 24th, 2001, 09:58 PM
Sometimes all the marks are hard to see so I just make sure I get the TDC line marked and use my timing light with the advance dial on it and then I dont have to worry about it. mm

mokankat
August 26th, 2001, 02:44 PM
hmm...something doesn't seem to be right. if i set it so there's no knock(the orginal reason i started to adjust it) it idles kind of rough and only at about 600rpm. it's also showing the TDC before the number 10 marker. around 5 maybe. from what i have gathered from the other posts here it should be idling at about 800 rpm's right?? and not so rough that the engine wobbles from side to side?? if i bump it up so it idles smoothly at about 800-900 rpm's it knocks fiercly and smokes out the exhuast. am i just thinking it's wrong or even close?? thanks again.

modifiedmark
August 26th, 2001, 08:34 PM
Make sure you set the dwell on your points before setting your timing and then if your idle speed is wrong after adjusting timing, reset your idle speed. If your thinking something isnt right, double check your dampner to make sure the outer ring hasnt moved. Pull #1 plug and carefully stick a long thin screwdriver in the hole as your turn the engine over to TDC and check to make sure your marks are lined up where they are supposed to be. Its not uncommon for the rubber on a 30 year old dampner to deteriorate to the point where it will let the outer ring turn and then your marks wont be in the right place. I have a new one on the shelf to put on mine because of that problem. I have been just to lazy to do it yet because I plan on pulling my engine in a few months for a rebuild and dont want to pull the dampner twice.mm

reward_1000
August 29th, 2001, 07:24 PM
You may have a carb problem also. You may be fiting two problems in one. I am running an edelborck carb, intake and cam, with a uni-lite distributor in my 69 390 cat and I have my timing set at 10deg. for the winter and in the winter for the cold kansas months I bump it up to 12. Good luck;)

mokankat
August 29th, 2001, 09:25 PM
well upon further checking i have discovered that i need to redo all my vacuum lines.(this weekends project). half are broken. others just missing. so i know that the carb is just out of whack too. plus if i set the timing so it doesn't knock it idles too low and really rough. but if i bump it up it diesels when i shut the motor off. sigh...can't win...it's a stock 390 with ford 4 barrel and intake. i'm just trying to get her running smooth for now before i get fancy with anything.

...i see you live in Tongi. i used to live in lawrence up until a month ago. still work there. maybe i could check your cat sometime??

reward_1000
August 30th, 2001, 07:10 PM
I wrk in tongie. If you go to tongie by 24-40hwy. you run into the stoplight and I work at the yellow shop behind the phillips 66, come in whenever and ask for Ray.

badcat427
August 30th, 2001, 09:43 PM
Unless you build an engine your self the timing marks are useless.When they are making the parts such as cam gear,crank gear,crankshaft,timingmarker,etc.they are alowed tolerances of plus or minus 1 to two thousands. the marks could be off as much as 30 to 40 degrees. Start the car and leave it warm up.Advance the timing until you have pre-ignition.[acts like a weak battery when you try to start it]
retard it a little at a time until it is easy to start. tighten the hold down and take it for a run. At about 40 miles an hour step on it, IF YOU DON'T HEAR A RATTLE SOUND YOU HAVE IT PERFECT. If you do,just retard it a little bit more.

modifiedmark
August 30th, 2001, 10:32 PM
Bad Cat, did I understand you right? Did you say the variables in the timing marks from the pointer to the dampner could be off 30-40 degrees? On a 7" dampner that would mean the marks would be off several inches!!! As some one who has degreed in my share of camshafts and always checked the stock pointers and marks when putting an engine together I have never seen one off that far. The only way that could happen is for the outer ring to turn on the hub. I know my ole screwdriver in the spark plug hole is not precision by any means and it can very a few degrees it will tell if one is way off especially if you dont want to pull a head and install a degree wheel to get it perfect. Beside that the cam and crank gear variables would have no effect on ign timing only cam timing. I do however agree with your description of the by ear method of ign timing, as my car is timed that way right now. I hate to say it but are you sure the timing chain hasnt jumped a tooth? I say that assuming that the engine is not freshly rebuilt. I have seen them a tooth off where they will run if the ign is advanced enough, but they dont run very well. mm

badcat427
August 31st, 2001, 09:44 AM
Most of the ford dampers have a circumferance of 22 inches or more. If you check top dead center with a screwdriver or little piece of rubber hose you could probably get it pretty close. But the point was, the timing marks are never near accurate and if you don't know where top dead center is you will never get an engine to run right by going by the marks. If all the tolerences are to the extreme, one way or the other, you could be out more than an inch on the timing. The keyway in the crankshaft and the keyway in the timing damper are just two that could put you out 10 degrees or more.

mokankat
August 31st, 2001, 10:33 AM
badcat; i read many reports of people advising not to tune it the "macho way" you described by ear basically. funny thing is. i was messing with it the other night and could get the timing back enough so there was no knock, but then it idled really rough and deiseled real bad when i shut it off. so from what i can tell that means my idle speed is then set too high on the carb, right?

i'm still a little engine ignorant at this point. computers are my specialty, but i'm not afraid to learn!! thanks for all the advise guys!!

modifiedmark
August 31st, 2001, 11:35 AM
Bad Cat I agree that the tolarences on the crank and dampner keyways can very a few thousands and can throw the timing marks off but it takes more than a few thousands to make it move 10 degrees.If you want to get technical the position of your head when reading the marks with a timing light can let it very a couple degrees. Bet your bottom dollar that if you find one that far off it is because the outer ring on the dampner has turned. Take a race car that turns 6-7500 all night and you will find out its pretty common to turn the outer ring on one. I have replaced several and finally went to a fluid dampner to fix the problem. Anyway I dont mean to nit pic but the 30-40 degrees you quoted caught my attention. It sound like Mokankats problems are not just the timing marks of a couple degrees. Mokankat, your problems to me sound like your trouble lies with something besides a simple timing adjustment, Are you sure you plugs are in the right fireing order? After you make a timing adjustment it is not uncommen to reajust your idle speed but you also need to recheck the timing after the Idle speed adjustment.mm

Cougrrcj
August 31st, 2001, 07:33 PM
You don't have to have a high-RPM race motor to have a dampener ring slip. My 'Beta' cat has a stock 351C-4V. I was using it for a backup race duties, running [email protected], shifting at 5200rpm. As the season went on, I noticed my timing mark getting further and further from where it was set. It ultimately got to almost 40 degrees off. It is still on the car even though that really isn't such a good idea. It should be replaced and I know it. Just try to find a CJ dampener these days!

I agree with MM here about the timing not being all Mokankat's problems. First get all your vacuum problems worked out, then adjust the points as best you can, a dwell meter is best. Then work on the carburation. Then, after getting all of that fixed, you can try adjusting your static distributor timing.

You may have to find TDC on your own if your timing marks on the dampener have slipped. Use the screwdriver method or some long semi-rigid piece of copper wire. You can either try to guess when you have reached TDC on #1 cylinder, but that is hard to do because the piston doesn't move all that much while it is up there. Better yet is to check the cylinders that are halfway down their bores. That's the nice thing about V-8s. There are two pistons at each point of the rotation, 90 degrees apart. Two pistons will be on the way up and two on the way down will be exactly halfway when #1 is at TDC. Once you find TDC, make a mark on the damper. You should be able to guesstimate your proper ignition timing from there. At least you'll have a reference for your timing light to read. You might want to try one of those aftermarket timing tapes that stick to the dampener.

modifiedmark
August 31st, 2001, 08:34 PM
Cougar cj how right you are. I didnt bother to bring up the point of checking the other cyls at bottom dead center because I dont know if you could get to them on a 390 with the shock towers in the way.mm

Cougrrcj
September 1st, 2001, 10:55 AM
MM,

If you reread my post you'll see that I am not trying to find the pistons at BDC. That is also where piston speed is the slowest, meaning they stay there for quite some time. The pistons that are halfway down their bores are moving the most per degree of crank rotation. When the ones going up are at the same depth as the ones going down that gives a much easier reference to the other two pairs being at TDC and BDC. If you have an extra short block laying around you'll see what I mean. When four pistons are at the midpoint, two more will be at TDC and the last pair will be at BDC. The midpoint location is just much easier to find by comparing the depth of the upward bound and downward stroke. When the two are at the exact same depth, the other two pairs will be at exact TDC and BDC. Then you can mark your balancer with a reference line or use a timing tape.

I didn't say it would be easy with the engine in the car and shock towers in the way. This is the only sure way to find the exact point of rotation with the engine installed in the chassis without taking a head off.

Logan
September 1st, 2001, 04:52 PM
It's also worthy to note that alot of the time, people assume it's a timing issue when in my experience 99% of the time, people have just grabbed any 'ol carb off the shelf and chucked it on there.

Case in point, my own windsor. I had pinging above 3000rpm under wide-open throttle, so I assumed I must need to adjust the curve on my dist to accomodate. But due to the RPM cam, I'm already running a ton of initial advance, and very little mechanical advance. In the end, it was more a WOT lean condition caused by my mis-tuned carb. I ended up swapping jets and rods on my Edelbrock 750cfm carb to solve it.

My advice, get the timing as good as she'll go under all conditions, then start tuning the air/fuel mixture to rid minor problems.

badcat427
September 1st, 2001, 07:05 PM
With a big block in a cougar, it would be easier to remove a head than find mid bore location. But you do not have to remove a head to find top dead center of number one. And that is all you need.

modifiedmark
September 1st, 2001, 08:47 PM
Cougarcj, I know what you mean. I was just thinking out loud. I was thinking about checking at bottom dead center because it might stay there longer that it dose at top dead center. Understand where my mind was headed? mm