Timing, or dirty fuel line?

[74ausfiat]

hey gang. I've been trying to scour the boards before posting this. but I'm just getting more confused.

heres the deal, i replaced (the non existent) o ring on my distributor . when we pulled it out we marked it so we would have a rough guide as to where the distributor was previous to the pull.

great? great.

car runs worse now.

thru 1st, and 2nd gear while accelerating there are hiccups in power.

i just assumed the timing was off... there is no audible sound when the power kind of slumps. it honestly feels like there is gas restriction. (though this is probably just a miss fire ?)

so i popped the hood and turned the distributor clockwise to pick up the speed a little. and the problem seemed to disappear.
but when the engine warms up, the problem seemed to come back.

I've read something about timing and the rpms are supposed to rest at 850, true?
there aren't even marks on the tack until like 1500. so. do i turn the distributor and get it to a lower rpm, and then adjust the screw (i forget what its called) on the carb to. do.. something?

how do i know where 850 rpms are?

is there another secret fuel filter someplace?

please keep in mind when you respond. i don't know what in gods name I'm doing! I've never moved an engine to TDC, or used a timing light. is this something i should be doing by ear once the engine has run for 10-15 minutes?

thanks for all our input everyone. and your patience

[74ausfiat]

should have stated. its a stock carb (34DMSA) on a 74 and an electronic ignition.




and the idle when when warm dips in rpms. almost like its going to stall out.

[Fi8spider]

Very strange.
At a guess.
Check that you haven't damage any of the ignition leads (spark plug cables) when you removed the dizzy.

[kmead]

First off you can't set timing by ear, you need a timing light.

To set the timing properly the car should be warmed up with the cooling fan cycling, set the idle around 1000 rpm to start and then use the timing light to set it to the correct degree btdc. After getting its set properly, readjust the idle down to around 800 which you can estimate but keep in mind a tach is not always the most accurate device, recheck the timing.

Generally if you don't have an accurate tach, set the idle such that it is stable, the engine isn't running rough/bucking and get close to 1000rpm indicated.

Karl

[RRoller123]

We used to do it with a vaccum gauge. Get the highest steady, stable vacuum possible. Takes a little trial and error but gives really good performance results.

[74ausfiat]

First off you can't set timing by ear, you need a timing light.

To set the timing properly the car should be warmed up with the cooling fan cycling, set the idle around 1000 rpm to start and then use the timing light to set it to the correct degree btdc. After getting its set properly, readjust the idle down to around 800 which you can estimate but keep in mind a tach is not always the most accurate device, recheck the timing.

Generally if you don't have an accurate tach, set the idle such that it is stable, the engine isn't running rough/bucking and get close to 1000rpm indicated.

Karl

should i adjust it by turning the distributor, or by some other method?
and if i adjust it once, only to drop it down. what was the point of setting it at 1000 rpms?

and what does btdc stand for?

ha. looks like i need to read some information on timing.

[4uall]

and what does btdc stand for?

Definition: A common term used to indicate the amount of ignition advance. For instance, 10 degrees BTDC indicates the ignition timing is set 10 degrees before top-dead-center.
Examples:
Setting the ignition timing, so that the spark is initiated before top-dead-center, is necessary because of the time delay before the explosion reaches maximum force. The objective is to ensure the piston has begun its downward (power) stroke as the expanding gases reach their maximum pressure.

[azruss]

a timing light is very easy to use. there is a huge range in quality and price. dont get the cheapest. get one with an induction clip that clips over the spark plug wire. the more expensive ones have a brighter light. It is a lifetime investment. you dont need one that has a delay adjustment on it. as the guys have said, you cant set the timing by ear.

[74ausfiat]

ok so I'm starting to understand the process.

i need to take off the valve covers (both sides?) and possibly clean them and replace gaskets.

rotate the engine to dtc. (would this mean the number 4 cylinder is actually at tdc, and the 1st cylinder is almost at the compression stage?)

i don't have a timing cover and i believe thats what had the degrees set on it. but there is actually marks on the engine block right?
am i matching up the notches in that or going off of something else?

so once those are lined up i start the engine and re adjust at 1,000 rpm so I'm looking at roughly 0 degrees. correct?
and how will i see what zero degrees is?

so many questions. thanks everyone!!!

[azruss]

you have 2 things you need to coordinate. the first is timing the crank to the cams. if you have a later model, there are timing marks at about the 10 o'clock position of the crank pulley. The older models use the marks on the belt cover. they are around the 2 o'clock position. If you have neither of these marks, you can make your own. Doc Graphic just got done doing this process. first, rotate the motor so that the little holes in the cam pulleys align with the 2 pointers. At this point you should see a small notch in the crank pulley and this should be aligning with one of the 3 timing marks. the timing marks go like this. the big mark is 0 btdc, the mark next to it is 5 btdc, and the last mark is 10 btdc. most of these cars are timed at 10 btdc. if you dont have timing marks, you can locate top dead center (tdc) by pulling #1 plug and using a straw are something similar, you put the straw in the hole til it hits the top of the piston. as the motor rotates, the straw moves up and down. when it is in its highest position, this is top dead center. On all in-line 4s, #1 and #4 move together, #2 and #3 180 degrees off. At tdc, the cams should locate to the pointers and the crank pulley should align with the big mark (0 btc).
next thing is the ignition timing. this is where you use the timing light. the timing light flashes everytime it is triggered. if the induction clamp is clamped on #1, it will flash when #1 fires. Start the motor and aim the light at the crank pulley. the stobe effect will "stop" the notch in the crank pulley at the firing position. by rotating the distributor, you can move this mark to the desired location.
Here is the tricky part. you have both a mechanical and vaccuum advance. they change the timing as the rpms change. you can see this happen if you rev the motor with the timing light. you will see the notch on the crank pulley advance. So you need to look at the RPMs when you set the timing. as you advance the timing, the rpms go up. It may require adjusting the idle on the carb to get the rpms correct for timing.

[74ausfiat]

you have 2 things you need to coordinate. the first is timing the crank to the cams. if you have a later model, there are timing marks at about the 10 o'clock position of the crank pulley. The older models use the marks on the belt cover. they are around the 2 o'clock position. If you have neither of these marks, you can make your own. Doc Graphic just got done doing this process. first, rotate the motor so that the little holes in the cam pulleys align with the 2 pointers. At this point you should see a small notch in the crank pulley and this should be aligning with one of the 3 timing marks. the timing marks go like this. the big mark is 0 btdc, the mark next to it is 5 btdc, and the last mark is 10 btdc. most of these cars are timed at 10 btdc. if you dont have timing marks, you can locate top dead center (tdc) by pulling #1 plug and using a straw are something similar, you put the straw in the hole til it hits the top of the piston. as the motor rotates, the straw moves up and down. when it is in its highest position, this is top dead center. On all in-line 4s, #1 and #4 move together, #2 and #3 180 degrees off. At tdc, the cams should locate to the pointers and the crank pulley should align with the big mark (0 btc).
next thing is the ignition timing. this is where you use the timing light. the timing light flashes everytime it is triggered. if the induction clamp is clamped on #1, it will flash when #1 fires. Start the motor and aim the light at the crank pulley. the stobe effect will "stop" the notch in the crank pulley at the firing position. by rotating the distributor, you can move this mark to the desired location.
Here is the tricky part. you have both a mechanical and vaccuum advance. they change the timing as the rpms change. you can see this happen if you rev the motor with the timing light. you will see the notch on the crank pulley advance. So you need to look at the RPMs when you set the timing. as you advance the timing, the rpms go up. It may require adjusting the idle on the carb to get the rpms correct for timing.

wow thats some great info!
so im not really timing the crank to the cams I'm just getting it at 0 btdc as a baseline. then ill turn the distributor until it peaks at 10 btdc ?

[azruss]

that is right. the cam to crank timing is determined by the belt and isnt adjustable. this may be diddled with with performance cams. on your car, these are probably set correctly. It is worth checking it out anyhow as it takes just a few minutes to check. If the cam timing is off, you will never get anything right.
Ignition timing is actually locating where the fuel ignition occurs in the compression cycle.

[wikkid]

A good, basic dwell tach, like this one by Actron, will set you back about $25. This will be better for setting your idle.

[74ausfiat]

ok. new question along the same line,

the car is starting to overheat. i think the issue is

car is set to idle at 1500 rpms waaaayyy higher than the 850 called for.

this would cause an overheating problem, yes?


you guys have all provided some great info. thanks for everyones input!!!

[redcars]

No a high idle will not cause it to over heat. I would first check and see if the bottom of the radiator is hot when it is over heating. If the bottom of the radiator is cool then you have to burp the radiator, that is get all of the air out of it or it will never cool. If the bottom of the radiator is hot is the fan coming on.