Imp Tune-Up

[cloudcap]

I've been prepping my 1404 Imp for the upcoming season the past couple weeks and could use some tune-up advice. It wasn't idling too well last year so I put a carburetor kit into it and was rather pleased that I didn't have any parts left over after reassembling the carb. I appear to be having a lot better luck with my Imp than my previous two-seater (a Triumph TR-6). And this afternoon I reinstalled the carb and was able to start it up! Amazing...

So a few questions on how to tune-up the engine. It has the stock Ford V-4 and my specs say that the timing is supposed to be set to 8 degrees ADC and the dwell at 48 degrees. What I'm not sure about is:

• Where are the timing marks? My recollection from high school auto shop is that they should be on one of the pulleys at the front of the engine, but I couldn't find them.
• What should I set the idle speed to? I'm guessing 800 RPM, but I'm also open to suggestion.
• How do I set the idle mixture? Mixture adjustments have always seemed like black magic to me. I know it is important, but I have no idea how to do it.

Thanks for your help.

Ron

 

[loboloco]

I've been prepping my 1404 Imp for the upcoming season the past couple weeks and could use some tune-up advice. It wasn't idling too well last year so I put a carburetor kit into it and was rather pleased that I didn't have any parts left over after reassembling the carb. I appear to be having a lot better luck with my Imp than my previous two-seater (a Triumph TR-6). And this afternoon I reinstalled the carb and was able to start it up! Amazing...

So a few questions on how to tune-up the engine. It has the stock Ford V-4 and my specs say that the timing is supposed to be set to 8 degrees ADC and the dwell at 48 degrees. What I'm not sure about is:

• Where are the timing marks? My recollection from high school auto shop is that they should be on one of the pulleys at the front of the engine, but I couldn't find them.
• What should I set the idle speed to? I'm guessing 800 RPM, but I'm also open to suggestion.
• How do I set the idle mixture? Mixture adjustments have always seemed like black magic to me. I know it is important, but I have no idea how to do it.

Thanks for your help.

Ron

Ron, the timing marks are usually located on the crankshaft pulley at the front of the motor. Not sure abt a V-4 as I have only dealt w/ straight 4's, but on all the 6 & 8's that is where it has been located.

Idle between 600-800 sounds ok to me.
Idle mix, I have always set by ear. Roughness or throatiness of the engine while adjusting. This will get a rough in, but for fine stuff I always called somebody who knew what they were doing.

Good job on the carb, I always wind up with a spring or two I can't account for, and wind up taking it to one of my friends who has knowledge in that area.

 

[Snowtrac Nome]

Cloud cap the last time i worked on a ford v-4 was when i was just out of high school as far as dwell anngle that is the time the point's are open you set that with a feeler gauge set your point gap at about .025 t0 .020 inch than set your timing as your point gap will affect timing i would set your points on the to allow for cam wear also youu want to lightly lube the cam lobes in the distributor your timing mark should br on thr crank shaft it could be on the crank pulley ,harmonic balancer behind the crank pulley or on some impliments have a window in the bell housing and the mark is on the flywheel. if all else failes i can walk you through how to find top dead center next is mixture adjustments back both idle mixture adjustment screws out about 3 or 4 whole turns from bottom start the engine adjust curb idle to about650 rpm adjust each screw in until the engine idle starts to drop than back out screw 1/2 turn and adjust curb idle where desired . hope this helps if you have a problem pm me for a phone numder and i can walk you through it on the phone.

 

[cloudcap]

Progress.

I was able to find the timing marks -- on the pulley at the front of the engine where you'd expect them to be. The tricky bit was getting to where you can see them. You have to pull the passenger-side engine cover off, stick your head under the dash, snuggle up to the alternator close enough to kiss it, and then peer over the front of the alternator with your nose about 1" from the spinning cooling blades. That's a little more intimate with my snow cat than I care to get. Unfortunately, I was so close my ancient eyes couldn't make out the detail. Eventually I resorted to an old-man trick -- take a picture with a digital camera and then blow it up with the computer.



I haven't tried actually setting the timing just yet, but I'll give it a shot next weekend. I've got an inspection mirror that I'm going to tape to the timing light and hopefully I can use it to peer over the top of the engine far enough to see the timing marks (without getting into the fan). I'll keep you posted. In the mean time, if anyone has ever set the timing on an Imp then I'd love to hear whatever tricks you used.

 

[fogtender]

When I did the timing on my Imp, I had to use a mirror to see the marks to set them. Bit awkward to get to just the right spot when the engine is running, but worth it when you get them set properly. Do the dwell first if you have a dwell meter, otherwise, you may just have to settle on setting the points as close as possible with the feeler gauges (which is the dwell). Every one degree of dwell is two degrees of timing.

Congrats on the Carb work! I would check it again though, you are suppose to have parts left over.....

 

[Snowtrac Nome]

here is a vw trick set your points move the engine around to where your timing mark on the crank puppey lines up with the index mark on your timing plate pull the coil wire stick a spark plug in it and ground the plug to the engine with the ignition on rotate the distributor back and forth stop where you get a snap from the spark plug and tighten down the distributor. in therory your not taking in to account for cintrifigual advance after checking mine several times with a light it's been so close it's not worth monkeying with it.

 

[fogtender]

here is a vw trick set your points move the engine around to where your timing mark on the crank puppey lines up with the index mark on your timing plate pull the coil wire stick a spark plug in it and ground the plug to the engine with the ignition on rotate the distributor back and forth stop where you get a snap from the spark plug and tighten down the distributor. in therory your not taking in to account for cintrifigual advance after checking mine several times with a light it's been so close it's not worth monkeying with it.

If you do that, you want to turn the distributor in the direction of the rotation, and then turn it back against the rotation for the spark, although it will spark in both direction when the points open. That takes as much of the slop out as you can get, if you do the cold timing in the direction of rotation, you could be off by about four degrees from the other direction just due to the lag. Still would do a backup check with a timing light and mirror though. A few degrees off in either direction and you can lose horse power or burn your valves prematurely.

Cold timing is how I set up all the engines I rebuild. It give you a good place to start from. Normall like DDS said, you are pretty much on the mark if done correctly. The timing light just makes it more precise.

Good Luck.

 

[Alaska Snow Cat]

Paint your timing marks with a white paint or use welders chalk or white crayon. Makes it very easy to see with a timing light.

 

[cloudcap]

Made a bit of progress today, but I still haven't slayed this particular dragon.


A few things worked rather nicely:

• I taped an inspection mirror to the cab above the alternator and that allowed me to see the fixed timing marks without having to go through contortions.
• I got tired of fiddling around with a flashlight and flooded the engine compartment with as much light as I could -- big improvement.
• I also replaced my 30 year old dwell/tach meter and timing light with a new combination unit (red instrument sitting on the floor).

This allowed me to get the dwell zeroed in -- the digital meter was much more stable and accurate than my old analog one.

The new timing light is smaller and can be more easily aimed at the timing marks. It also has an adjustable advance, so you "scroll around" looking for timing marks without having to actually twist the distributor. Very handy.

But ultimately I was never able to find the timing mark on the front pulley / vibration damper. I scrolled from 0 degrees of advance to 90 and could see the pulley "move" under the timing light, but didn't see any distinctive marks. I also tried moving the pickup to all four cylinders in case I wasn't actually looking at #1. Nada.

I eventually advanced the distributor as far as it would go (counter clockwise till it was up against the stop). The engine runs well like this, but I have no idea if it is where it needs to be. I was also able to drop the idle to a hair under 1,000 RPM.

I may button it up at this point and see how it behaves in the wild. If it runs acceptably then maybe that's all that really matters.

 

[fubar]

Ron:
I don't know if any of this applies to your engine but I have found....
Are you sure it says ADC and not BDC or BTDC?
Did you pull the vacuum line off the dist? (get off the vacuum advance) Plug the line if you do, otherwise you have the equivelent of a vacuum leak.
Idle her down as far as you can while you are setting your timing,

 

[fogtender]

Made a bit of progress today, but I still haven't slayed this particular dragon.

View attachment 49248


A few things worked rather nicely:

• I taped an inspection mirror to the cab above the alternator and that allowed me to see the fixed timing marks without having to go through contortions.
• I got tired of fiddling around with a flashlight and flooded the engine compartment with as much light as I could -- big improvement.
• I also replaced my 30 year old dwell/tach meter and timing light with a new combination unit (red instrument sitting on the floor).

This allowed me to get the dwell zeroed in -- the digital meter was much more stable and accurate than my old analog one.

The new timing light is smaller and can be more easily aimed at the timing marks. It also has an adjustable advance, so you "scroll around" looking for timing marks without having to actually twist the distributor. Very handy.

But ultimately I was never able to find the timing mark on the front pulley / vibration damper. I scrolled from 0 degrees of advance to 90 and could see the pulley "move" under the timing light, but didn't see any distinctive marks. I also tried moving the pickup to all four cylinders in case I wasn't actually looking at #1. Nada.

I eventually advanced the distributor as far as it would go (counter clockwise till it was up against the stop). The engine runs well like this, but I have no idea if it is where it needs to be. I was also able to drop the idle to a hair under 1,000 RPM.

I may button it up at this point and see how it behaves in the wild. If it runs acceptably then maybe that's all that really matters.

Um, it sounds like you may not have the timing light on the proper firing wire on the Number one spark plug, that would be why you can't find the mark, as you turn the distributor, it will move the mark, but it may be 180 degrees off if you are on either #3 or #2 cylinders.

Turn the engine by hand and set the mark to where the pulley and the timing mark line up (mark with white paint or other light colors), take the distributor cap off and see where the rotor is pointing, that will be the one wire you can use since that is on the TDC firing point of either #1 or #4 (Firing order of #1, #3 #4 #2). Don't matter, the other two cylinders (#3 and #2) that fire when it comes to timing will be on the bottom of the pulley so you can't see it, the cylinders are 180 degrees off and if you are on either one of those, you won't see the mark at all.

As a side note, the engine may run and sound fine when you are past top dead center on the timing, but won't have any power, what it will be doing is firing the cylinder "After" the piston has already started on the down stroke. While the engine may "Run" smooth, what it is doing is making the exhaust go over the valves still burning, and in short order, you valves will get hot and burn out or worse, drop off and go through the top of your piston... It will also make the exhaust manifold red hot and be a good source of starting a fire. So in as much as it is a pain to do the timing, it is important for the engine to run properly.

Good Luck!

 

[cloudcap]

Turn the engine by hand and set the mark to where the pulley and the timing mark line up (mark with white paint or other light colors), take the distributor cap off and see where the rotor is pointing, that will be the one wire you can use since that is on the TDC firing point of either #1 or #4 (Firing order of #1, #3 #4 #2). Don't matter, the other two cylinders (#3 and #2) that fire when it comes to timing will be on the bottom of the pulley so you can't see it, the cylinders are 180 degrees off and if you are on either one of those, you won't see the mark at all.

So what's the secret to turning the engine over by hand? Back when I worked on VWs it was a piece of cake -- just grab the generator pulley and twist. But on the Imp I can't find anything to work with. The alternator looks promising, but the belt isn't tight enough to actually turn the motor over. I'm thinking about pulling the plugs and trying again -- that would make the engine easier to turn over and it would also let me check the #1 piston for TDC.

 

[fogtender]

So what's the secret to turning the engine over by hand? Back when I worked on VWs it was a piece of cake -- just grab the generator pulley and twist. But on the Imp I can't find anything to work with. The alternator looks promising, but the belt isn't tight enough to actually turn the motor over. I'm thinking about pulling the plugs and trying again -- that would make the engine easier to turn over and it would also let me check the #1 piston for TDC.

Put the rear Axle in neutral, and then take the top cover off the front transmission tunnel so you can look down and see the front transmission and drive-line from the driver's seat (or passenger). Put the front transmission in third gear, then use a big screwdriver in the U-joints on the drive shaft to rotate the engine. The gear reduction is in your favor and easy to turn over the engine that way when in third gear. Not fast, but sure is a lot easier on the fingers!

The other choice is to just move your timing light clamp to the next spark plug wire, it will be the right one.... only a four cylinder engine so you have a 50/50 shot at being on the right one, or wrong one!

NOTE: Um, before cranking the engine over, make sure the battery is disconnected and the key out and maybe even the coil wire is pulled... Won't get into why I would suggest doing that, but it was I think Will Rogers, that said "Experience comes from bad decisions"....

 

[cloudcap]

Success!

I pulled the plugs and then used fogtender's trick of turning over the engine by levering the front u-joints on the drive line with a screw driver. I was able to find TDC by poking another screwdriver through the sparkplug hole and turning the engine till the piston was at the top of the cylinder. And then timing marks were right were they were supposed to be!


I like the idea of painting the timing marks white for better visibility, but that will have to wait till I have better access to the front of the engine.

Next I set the timing by twisting the distributor till the points opened up and sparked. It was *way* different from what I'd had it set to before -- something like 15 or 20 degrees.

Unfortunately, I wasn't able to verify the timing with the engine running and the timing light -- the timing marks had advanced to where I could no longer see them. But I'm calling this "good enough" for now. The engine is running better and idling moderately well at ~800 RPM. We could have snow here in the Cascades in another week or so, so maybe I'll be able to give it a test drive over Thanksgiving weekend. We'll see.

Thank you to both Don and fogtender for your advice -- you each provided tricks which made the job a lot easier (if not possible). As with many jobs, the first time through is the hardest -- I suspect I could work through this again in the future in a quarter of the time.

Regards

Ron