I'm desperate--help me time my engine

[38plymouth]

I'm going to try to make a cruise tonight and I'm still not sure I have my timing right. This is on my 38 with split exhaust and a fenton aluminum head. It was detonating really bad last week going up a hill with 4 people in it. I finally found the timing marks on the pulley and when I checked it with a light the mark was dead center of all the lines on the pulley. When I turned the distributer one way the engine sounded like a tin can with rocks in it. I turned it back the other way and got it to where I think 4 degrees ATDC is. I got that figure out of my manual. I attached photo showing my timing marks, is the top yellow arrow 0, would the blue arrow be 4 degrees? Should I leave the timing at 4 degrees or try it a little higher for better performance.

[Don Coatney]

Forget what the book says. Set your timing with just enough advance where it does not ping. Once there lock the distributor down and enjoy driving it.

[Merle Coggins]

Well, after saving your picture and opening it up with another program so I could zoom in on it, it looks like your red arrow is pointing at 15 degrees (before?). Your blue arrow is pointing to 11 degrees on the other side of TDC (after?). About half way between your two arrows is a mark with a "0" on either side of it. This would be TDC. I don't see the timint pointer in your photo.

Merle

[38plymouth]

I can't really tell what the marks say, it looks look it says something like I/O in three spots near the longer lines. I'm really confused on where to set it and where 0 really is.

[Young Ed]

The 3 lines are -10 0 and +10.

[38plymouth]

I'm sorry about the size of the picture, I can't post it larger for some reason. Is the top yellow arrow pointing at 0 then? Is the bottom arrow pointed at 4 degrees ATDC?

[Jeff Ivan]

Yeah- on these old engines with some miles on them the timing light/timing marks will only get you so far. Here is a trick my late father taught me years ago that I just used recently on my car. Hook up a vacuum gauge to the fitting on the manifold, and turn the distributer back and forth slightly until you have maximum vacuum. This seems to get you close to the best spot no matter where the timing marks are. Tighten distributer hold down and test drive, then maybe advance or retard timing a little (I usually do this step roadside on a steep hill!) until you are happy with it. I am not claiming this is the best method, but it works for me, and just using Dad's 40-50 year old vacuum gauge still in the original box with all the adapters gives me personal satisfaction. Jeff

[Merle Coggins]

I'm sorry about the size of the picture, I can't post it larger for some reason. Is the top yellow arrow pointing at 0 then? Is the bottom arrow pointed at 4 degrees ATDC?

Now you've got it. I can't determine from the photo which direction we are looking at the pully, but if we are looking at the pully from the right side of the vehicle, than your lower mark would be 4 deg ATDC. If viewing from the left side, it's 4 deg ATDC. Depends on the direction of rotation. When rotating the engine in the normal direction of rotation, does the 4 deg mark get to the pointer before or after the "0" mark?

[38plymouth]

I took the photo from the drivers side so the front of the car would be to the left of the picture. Right now then my timing is set around 6 degrees BTDC. I better go advance it then and get it closer to where it should be!

[Merle Coggins]

If you're at 6 BTDC now, and you're shootin' for 4 ATDC from your manual's spec, you need to retard the timing, not advance it. Anyway, your manual's spec probably isn't relevent to your engine now. You stated that you have a performance manifold and head, so you may need to use the advice from the other guys and adjust by feel until it runs good without any detonation under load.

Merle

[Reg Evans]

Yes...the long arrow on the top is pointing at Dead Center..DC..or top dead center.

I always put a dab of whiteout at DC so I can tell what I'm doing while moving the distributor.

Is your engine an original 38 Plymouth? Just wondered how it responded to the speed equipment. My 40 Plymouth 201 is pretty gutless compared to my other stock 218 and 230 cars and could use some help.

I'm sorry about the size of the picture, I can't post it larger for some reason. Is the top yellow arrow pointing at 0 then? Is the bottom arrow pointed at 4 degrees ATDC?

[greg g]

to retard the timing move the diz clockwise. With the higcompression head you will want a bit of initial advance, 4 to 5 sounds about right, If it still pings, retard it with small clockwise adjustments till the pinging stops. If it fails to make a difference, you might need to run premium gas. Driving it with bad pinging under load will pound th crap out of your pistons, and probably the wirst pin bushings also. Sitting in the drive way, advancing will always make a smoother faster idle, but that isn;t the point. You want the advance to come in properly as the engine loads under speed or pulling. To much initial advance causes the plug to fire while the piston is on the compression stroke, the noise you hear is the piston and the flame front battling each other. Also what plugs are you running in you aluminum head???

[38plymouth]

The engine is the original 201. It has more power now and I think it will have more when I get the timing set right. My favorite part of doing this is the sounds of the dual exhaust, it sounds better than I ever imagined it could.

I'm running a stock type champion plug but I can't think of the number right now.

[Lou Earle]

It is exactly as don says- forget the marks if it is starting. warm it up go to a hill and go up hill if pinging retard spark until stops.I simply get to top of hill and pull over and do it there on road and keep trying until it stops pinging then turn back again to ping then back until it stops that way I know it is OK.

Now turn of and re start ti starts good and no ping

LEAVE IT ALONE- WHAT PART OF TIMING MARKS ARE IRRELEVANT EXCEPT AS A STARTING POINT DO WE NOT UNDERSTAND?

The manual actually suggest a slight ping - I do not agree with that but they say it

Lou

[greg g]

The stock plug might be part of your problem. With the Edmund's head I had, the plug reach was longer as the casting of the head was thicker above the combustion chamber. If you are running the short stock plug they are not getting cooled by the incoming intake charge. Wonder if since they may be firing up in the threaded area of the head, that the edges of the spark plug hole are staying hot causing your pre ignition problem, plus any carbon deposited in the threads might be glowing. A couple of guys, Pete Blueskies and Marty Bose are running aluminum heads, you might want to query them to see what plugs they are running. I bought some champion L 90 C, according to the Champion chart they are in the same family as the stock plug, have the same electrode extension but the slightly longer threaded portion that extends into the combustion chamber. The difference is subtle but may be meaningful.

[38plymouth]

I got the timing set last night and it runs great now. I set it according to the factory specs at 4 degrees and took it for a test drive. It still detonated so I pulled over and backed it off a little more. After two adjustments the detonation went away and it was running really nice. I checked the timing with a light at it is right at 0 now. I went and put 89 octane gas in instead of the usual 87 so I may try bumping it up a touch more.

I checked the plugs I'm using in the head before I installed it to make they were the correct ones.

On a side note I went to a car cruise last night with two friends. There were some nice musclecars and a few really nice street rods there. I was pretty surprised that our car was one of the most popular there, it's just a mostly stock 4 door. It was pretty cool.

[greg g]

Good to hear things are back to driveable. Next tune up should be a breeze.