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Author Topic:   Need Help with adjusting my timing
Clark
Gearhead

Posts: 592
From: Rowlett,Texas
Registered: Aug 99

posted 08-03-2002 06:25 PM     Click Here to See the Profile for Clark   Click Here to Email Clark     Edit/Delete Message   Reply w/Quote
Well, after running the engine through its breakin I am now trying to get the timing right. The engine starts right up and runs pretty smooth at 1000 RPM but the advance is about 40 degrees BTDC and if I try and slow the RPM down it starts to pop and surge. I try and reduce the timing and the engine runs really rough, this also occurs when I remove the vacuum advance which reduces the timing. When I increase the power I see the timing advance with the light so I see the advance working.

I am thinking this is in the distributor because I installed new weight springs,adjustable vacuum advance and pertronix. Any help would be appreciated.

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69 351W Sportsroof Deluxe

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SteveLaRiviere
Administrator

Posts: 33988
From: Saco, Maine
Registered: May 99

posted 08-03-2002 08:19 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
Are you sure your balancer marks are accurate?

You are checking the timing with the vacuum advance unplugged and the vacuum line plugged, right?

------------------
Ford! Because I know the difference!

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Clark
Gearhead

Posts: 592
From: Rowlett,Texas
Registered: Aug 99

posted 08-03-2002 10:45 PM     Click Here to See the Profile for Clark   Click Here to Email Clark     Edit/Delete Message   Reply w/Quote
As best I can remember when I was setting the timing up I degreed the cam so I think it was close. The thing that bothers me is that I had to move the distributor one tooth over so I could get it to time at this point.

Yes, I am checking the timing with the advance unplugged and capped, the difference between connected and disconnected is about 10 degrees.

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DidgeyTrucker
Gearhead

Posts: 1060
From: Greenbrier, TN USA
Registered: Oct 99

posted 08-04-2002 02:04 PM     Click Here to See the Profile for DidgeyTrucker   Click Here to Email DidgeyTrucker     Edit/Delete Message   Reply w/Quote
WHAT? At idle there shouldn't be any vacuum going to the distributor. It only gets vacuum as soon as you open the throttle. That's called "ported" vacuum. If you have a Holley, it's the small fitting above the idle mixture screw on the right (passenger) side of the carb. If that's where it's hooked up, you have the throttle open too much at idle.

A normal timing figure should be between 6-12 degrees BTDC at idle. When you get a vacuum guage (Sears has them) adjust the timing and idle mixture for the highest vacuum.
And if you see the vacuum guage fluctuating, that indicates some problems, usually valve related.

Tracy

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Clark
Gearhead

Posts: 592
From: Rowlett,Texas
Registered: Aug 99

posted 08-05-2002 11:30 AM     Click Here to See the Profile for Clark   Click Here to Email Clark     Edit/Delete Message   Reply w/Quote
Well, I don't know what to tell you Tracy but my 4300 Autolite has a vacuum at the distributor at idle. The hose connects to the base of the carb near the mixture screw.

I will get a gauge and hook up to the port on the intake to see how much vacuum is available. I am assuming that I need to adjust the timing to the highest vacuum as well as looking for fluctuations?

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Jeff
Gearhead

Posts: 280
From: Moore, OK USA
Registered: Mar 2001

posted 08-05-2002 11:47 AM     Click Here to See the Profile for Jeff   Click Here to Email Jeff     Edit/Delete Message   Reply w/Quote
Things to check:

a. Vaccuum line disconnected (else you'll be letting vaccuum advance upset your timing).
b. Rpm low, perhaps 650 or less (else mechanical advance will start coming in).
c. Timing marks accurate (can be off for a number of reasons. Among them: degree ring has slipped; wrong harmonic balancer).
d. Incorrect plug lead selected (Ford uses passenger side for #1 plug lead).

Check for the obvious, sometimes it just isn't and Murphy is standing beside you!

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indyphil
Gearhead

Posts: 877
From: Lafayette, IN, USA
Registered: Jul 2002

posted 08-05-2002 11:55 AM     Click Here to See the Profile for indyphil   Click Here to Email indyphil     Edit/Delete Message   Reply w/Quote
When you break the problem down, clark is saying that his engine wont run well below 40 degrees timing. The timing is indicated by the strobe and the marks on the damper. We must Assume the strobe flashes off cylinder #1 spark plug wire.

vacuum advance doesnt matter because at 1000 RPM the engine shouldnt need 40 degrees timing to run smooth.

The second assumption and its a big one is that the marks on your damper are correct. I would choose to blame the damper marks at this point. You have to make sure that when cylinder #1 is at top dead center the -0-mark on the damper lines up with the pointer. TDC can be found by inserting stuff into the spark plug hole (some people use old pushrods or pencils). Make sure you get TDC on the compression stroke for #1 cylinder.

The cam timing affects breathing and compression, which might in turn make the engine run poorly, but wont throw the reading you get from the strobe out.

You should get a slight vacuum on the carb at idle (its basically the vacuum generated by the air filter and by the slight flow of air through the carb) That slight vacuum isnt usually enough to make the distributer move the timing, but you should disconnect it anyway. some engines have dual diaphram vacuum units which retard timing based on manifold vacuum, disconnect all hoses from the distributer AND PLUG THEM (without the plugs on the vacuum lines the engine can run rough due to lean conditions)

Think about what the timing light is. It tells you when the spark goes off relative to the piston position (assuming the damper is correctly marked).

Hope this helps

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Clark
Gearhead

Posts: 592
From: Rowlett,Texas
Registered: Aug 99

posted 08-05-2002 02:27 PM     Click Here to See the Profile for Clark   Click Here to Email Clark     Edit/Delete Message   Reply w/Quote
Thanks for all the help, besides checking the vacuum I want to throw something else in the mix. When I purchased this cam it was used and I had to get the specifications off there website and noticed they have two identical cams one for 289/302 and one for 351W. The part numbers have only one digit difference, do you think that the firing order could be off? I know I said the engine runs smooth above 1000 RPM but I am wondering how the engine would run with the wrong firing order? Because 4 of the cylinders fire in the same sequence no matter which cam you have in. I know this sounds like some simple fix but you are all correct when sometimes we need to just step back and take a look at the simple things.

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69 Sportsroof
Gearhead

Posts: 1214
From: Valley, Alabama, USA
Registered: Mar 2002

posted 08-05-2002 02:39 PM     Click Here to See the Profile for 69 Sportsroof   Click Here to Email 69 Sportsroof     Edit/Delete Message   Reply w/Quote
If you installed this cam in a 351 W then you have to use the 289/302 firing order. However, I dont think it would run with the incorrect firing order but if it did it would run horribly. It sounds to me like you have a very bad vacuum leak.

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Clark
Gearhead

Posts: 592
From: Rowlett,Texas
Registered: Aug 99

posted 08-05-2002 03:48 PM     Click Here to See the Profile for Clark   Click Here to Email Clark     Edit/Delete Message   Reply w/Quote
I agree with you 69 but maybe this would explain why the engine does not like to idle under a 1000 RPM and needs so much advance timing
I will take a look tonight by removing the valve cover and watch if the #3 cylinder comes up on compression next. And I will also plug the vacuum tap off the intake because I know there is no leak around the carb unless it is internal.

[This message has been edited by Clark (edited 08-05-2002).]

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69 Sportsroof
Gearhead

Posts: 1214
From: Valley, Alabama, USA
Registered: Mar 2002

posted 08-05-2002 04:35 PM     Click Here to See the Profile for 69 Sportsroof   Click Here to Email 69 Sportsroof     Edit/Delete Message   Reply w/Quote
For what its worth, firing
order for the 302/289 is 1 5 4 2 6 3 7 8
and for the 351W is 1 3 7 2 6 5 4 8. I'm sure you knew this but I'm trying to reach "Gearhead" status. Just a few more to go....

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ewokeric
Gearhead

Posts: 174
From: woodbridge, va united states
Registered: Mar 2002

posted 08-05-2002 04:41 PM     Click Here to See the Profile for ewokeric   Click Here to Email ewokeric     Edit/Delete Message   Reply w/Quote
i have a 351w and a 302 cam i found out and the engine will not even start and when i tries it backfires if that helps.

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Clark
Gearhead

Posts: 592
From: Rowlett,Texas
Registered: Aug 99

posted 08-06-2002 09:52 AM     Click Here to See the Profile for Clark   Click Here to Email Clark     Edit/Delete Message   Reply w/Quote
Well here's the lateset update, I verified the firing order is correct and I was at 18 in. of vacuum @ 1200 RPM. Everytime I tried to reduce the idle down the engine started to bog down. I am at a point where I am wondering what is going on maybe I need to junk the cam?

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69 Sportsroof
Gearhead

Posts: 1214
From: Valley, Alabama, USA
Registered: Mar 2002

posted 08-06-2002 11:27 AM     Click Here to See the Profile for 69 Sportsroof   Click Here to Email 69 Sportsroof     Edit/Delete Message   Reply w/Quote
I'm still thinking vacuum leak. 18 inches at 1200 RPM is too low. Do you have an open PCV port on your carb? Did you verify that the vacuum line to your trans is conncted at the trans? It seems to me that the most obvious things are the ones I tend to overlook. Up to 99....

[This message has been edited by 69 Sportsroof (edited 08-06-2002).]

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mustangboy
Gearhead

Posts: 670
From: Ont, Canada
Registered: Mar 2002

posted 08-06-2002 01:38 PM     Click Here to See the Profile for mustangboy     Edit/Delete Message   Reply w/Quote
I have the same problem with my engine.Its a 302 with a big cam [email protected] and I have verified with a TDC stop that the balancer ring has not slipped.I have disconnected the vacuum advance and the idle is around [email protected] inches of vaccum.The engine runs very poorly below about 40 degrees of advance.If I rev it up it gets an additonal 10 degrees so the mechanical advance isn't coming in yet. No one can seem to figure this out.

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Clark
Gearhead

Posts: 592
From: Rowlett,Texas
Registered: Aug 99

posted 08-13-2002 10:35 AM     Click Here to See the Profile for Clark   Click Here to Email Clark     Edit/Delete Message   Reply w/Quote
Mustang boy when I fix this I will let you know because we sure seem to have a similar problem.

I went and pulled the plugs out and found the #8 cylinder a little sooty so I changed the plugs and also did a compression check. The highest cylinder was 200 and the lowest 180 so for a new engine that is barely broke in, I think I am ok.

I restarted the engine and the only problem is when I turning the idle down and get close to 1000 RPM then it starts to pop. Not a backfire but a noticeable pop. I am starting to wonder if there is some kind of carb problem. I have a 4300 Autolite that has been restored by pony carbs a few years ago and have had no problems since reinstalling after the rebuild. Any more ideas?

[This message has been edited by Clark (edited 08-13-2002).]

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bibbs68
Gearhead

Posts: 1113
From: Jackson, TN
Registered: Sep 2000

posted 08-14-2002 03:49 PM     Click Here to See the Profile for bibbs68   Click Here to Email bibbs68     Edit/Delete Message   Reply w/Quote
I may have missed this above, but, as Jeff said, look at the obvious. Are you sure that you are not off a tooth or two on the dist.? Just a thought.

------------------
Jeremy
'68 Coupe
M&M Member #685
MCA Member #49134
Help make the world a better place, drive a Ford and race a slot car!

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69Cat
Journeyman

Posts: 28
From: Sask., Canada
Registered: Apr 2002

posted 08-14-2002 10:30 PM     Click Here to See the Profile for 69Cat     Edit/Delete Message   Reply w/Quote
Another thought for what its worth:
How are you droping the idle? Using the throttle stop I would guess and not the mixture screws. Seems you are running OK with the throttle plates open and via the associated fuel metering circuit. But when you close the plates to what would be a normal idle position the idle circuits are not working. Remember different fuel metering circuits come into play here.

The vacuum adavance you see would be a result of the amount that you have the primaries open in order to keep the carb working 'above the idle circuits' (for lack of better term).

Can't explain the 40 deg timing but seems that the idle circuits aren't working on carb therefore you are keeping it running with the primaries open - therefore you have a vacuum signal to the vacuum advance. My guess is that surging and popping would be due to fuel starvation when transfering to the idle circuits.

Ken

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Clark
Gearhead

Posts: 592
From: Rowlett,Texas
Registered: Aug 99

posted 08-17-2002 12:06 PM     Click Here to See the Profile for Clark   Click Here to Email Clark     Edit/Delete Message   Reply w/Quote
Well fellas here is the latest update and I hope this will narrow down the problem. The main thing is that the engine indicated 40 degrees of advance timing but would not idle down below 1000 RPM.
Last night I moved the distributor back one tooth and now the engine is acting different. The timing is now at about 10-12 degrees with the vacuum connected to the distributor. I can idle the engine down as low as I want but here is the catch. My engine seems to idle better the more I try and advance the timing, but the vacuum advance keeps me from advancing any further. The engine defintely is vibrating alot and I can only get 14 in. of vacuum.
I thought that if I moved the distributor one tooth it would give me the adjustment I would need. Am I missing something easy?

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