What else can I check-engine won't rev past 5k

Similar issue

I had a very similar problem a few weeks back. Mine was very simple. Before i figured it out and of course posted my problem here- I did replace the coil, retime, etc. etc. Turned out it was a plastic tee to both carbs that was crimped too hard. My mistake as I tightened everything thinking I was sucking air somewhere. But what I did was tighten too much. So at idle and thru lower gears it was fine. But as rmps increased not enough fuel was getting to carbs. Swapped with a copper tee and no fuel problems.
 
rotors

come in two varieties. One is curved or hooked and has a limiting feature. Not surprisingly, that one cuts the spark at somewhere near where you're referring to in the rpm range. Throw that one away.

The other is a T shape, no limiter. Parts guys will sell you anything sometimes. It pays to get Bosch points, etc, but quality control is am elusive state of mind sometimes. Not a problem when back when Germany was making them. Same for your coil.

Distributer- timing is all in at about 3000 rpm depending upon specific model. So it's doughtful something's wrong with weights. But, a spring can break, the plate/ weights get gummed up,, etc. You can pull it, disassemble, clean, lube or do the quick dose of penetratining oil or solvent and re-oil. If the center wick is dry- a teaspoon of oil should get it down to where it does the good, A good shake will tell you if the weights are flopping about. A good timing light with advance will do the same.

Your real clue seems to me that the timing was changed and it ran smooth. That means really retarded which fires fine when vacuum is present, hit the gas and no vacuum and no spark when it's needed. Black smoke when it slows down enough and vacuum gets added and it sparks.

How does the pointer and ball look with the timing light on it? Steady and there's no need to look at the ignition circuit.
 
OK, here's the update. Finally got the car back from the car shop. Kinda bummed with the shop because I think the carbs are still not right, but they did get it to rev out by advancing the timing and getting the secondaries to open. Apparently the vacuum advance isn't working and otherwise the maximum advance falls 4 degrees short of the maximum of where it should be. I'm not sure if this all makes sense to me but it sounds like I need a new distributor or at least a vacuum advance unit. It runs better but still not right. I checked the timing and its advanced beyond where the ball is visible. Something is definitely screwy with the ignition timing. Car still had weird miss while cruising and Idles like crap which is probably somewhat due to the advanced timing. I think I will replace the distributor and see where that gets me. Only problem is it seems like distributors are hard to come by.
 
I would get the distributor rebuilt by a specialist, after all it will have 40+ years of wear on it and you can then eliminate it from the list of suspects, time it up properly and then set the carbs up. I am going to do this on mine as a priority.
 
dwell

is the first thing to check with a meter not a feeler guage. If the point gap is not correct, no amount of timing will fix it. Is the timing steady? Meaning does the ball in the timing window to pointer stay steady?

Many people report changing advance vacuum from ported ( carb) to unported ( manifold) improved the engine. Free and worth a shot. But confirm the diaphram will hold vacumm. You can move the plate in the distributer with a screwdriver- if that moves and your holding vacuum then there's nothing wrong with that.

Weights sticking- usually manifests itself as the idle won't return to normal or sometime does or not. Not maximum advance. Typical early Porsche and VW problem.

Oil that distributer after you take off the rotor. Cars can sit a long time, owners forget, etc. If you're comfortable removing the distributer, then dose that puppy in cleaner and reoil. Taking the distributer apart is not that hard. Look for Dequincy's distributer rebuild post.

Manually check TDC and rotor position. It's terribly important. Who knows what work was done in the past. Then check rotor position and the mark on the edge of the distributer body. If it doesn't line up then something's wrong.

Work on one system at a time. Meaning fix the timing BEFORE turning to the carbs. Vacuum leaks occur in a lot of places check all your hoses, caps, connections, nuts, etc. Be methodical.
 
My engine was a tooth off on the timing chain. As 61P says, put your engine at TDC:

Remove spark plugs
Rotate crank until the balancer line lines up with the line on the chain cover.
Look in the timing window to see that the TDC ball is there (not the "Z" ball which is the advance ball)
Pull the valve cover and make sure your chain sproket is lined up:

http://www.e9coupe.com/forum/showthread.php?t=12831


If all ok then confirm secondaries are opening and that it is timed to the "Z" ball. You have Pertronix so no points to worry about.


I have a 123ignition distributor and it is great, no points, condensor, and programmable advance curve:

http://www.e9coupe.com/forum/showthread.php?t=16396
 
Steve, I just read one of your old threads about TDC with the various marks and cam and will pop the valve cover to check that out. That was really informative. Your programable 123 distributor is super cool. With what replacement distributors cost and recurving that seems like the way to go if you have mods or your distributor is toast.

Andrew, I checked out the website for the distributor shop link you posted. Has a 5 wk turnaround so I think I will dive in. Worst case, I will send my distributor bits to them if I fail.

61Porsche, With the encouragement of you and Dequincy's photos, I'm going to pull the distributor and disassemble. In all of my mechanical pursuits, I have always taken the lowly distributor for granted and never really had to mess with the internals other than just points. Current setup has Pertronix but was acting the same with properly adjusted points. Just ordered a new timing light with advance so I can check to see if the advance curve matches the specs I found in a manual. I've heard of different stock distributors with different advance curves but my book only has one table so I'm guessing that the different curves fall within the +/- values. As to the vacuum advance, if it holds a vacuum and the plate moves, is there any other way or knowing whether it is doing it job correctly?
 

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Find

the distributer markings on the side and report back which one of possible 6 distributers that I know of. The end numbers are what I look for- 001 or 005 which equals an advance curve and they aren't the same. There were euro, US, emissions, etc. So they aren't all the same if we're going to get downright picky.

Vacuum advance can range 8-12 degrees. So being 4 degrees off is with BMW's written program. ( I can't believe I said that.) Disconnect the vacuum, hook up your light and check the movement in the timing window is a good gut check.

But if you have a vacuum pump like a Mightvac, you can actually check advance by the amount of vacuum applied. 115hg start to 280 stop would tell you if you can guage the crank/ flywheel movement. ( Timing tape, flywheel teeth, etc.) That's how the factory did it.

You can do it by rpm but first you have to be certain which model distributer is in the car.

My bluebook has the program tests in the front. It's missing on the registry website. 25 pages I think with all the technical information on tune up.
 
Checking cam timing. Pulled off valve cover. Pointer on timing cover on OTmark,
flywheel window has OT ball showing. #1 valves closed, TDC right? Indent on cam sprocket is at about 5 o'clock instead of 12 o'clock as shown in picture. Can this be right or did I screw something up. Can't believe it could be this far off and run at all. Thoughts?
 

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Pull

your distributer cap and see if the rotor is pointing at a scribe mark on the rim of the distributer body.

Cam wheel bolt lines up with center of boss. Unless you indexed the cam and know for vey certain what that mark means.
 
Rev limiting distributor rotor arm?

Do you have one of those rev limiting rotor arms in the distributor, if so that must be worth a look.
Otherwise, drive it on torque up to 5,000 revs only!
Good luck
C
 
Looks like TDC, but yes check your rotor position on the distributor, should point to the scribe mark like 61P says. About 8 o'clock or so:

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brian c said:
Checking cam timing. Pulled off valve cover. Pointer on timing cover on OTmark,
flywheel window has OT ball showing. #1 valves closed, TDC right? Indent on cam sprocket is at about 5 o'clock instead of 12 o'clock as shown in picture. Can this be right or did I screw something up. Can't believe it could be this far off and run at all. Thoughts?
Click to expand...
 
I disabled the mechanism on those so they don't limit anymore :smile:

Cornishman said:
Do you have one of those rev limiting rotor arms in the distributor, if so that must be worth a look.
Otherwise, drive it on torque up to 5,000 revs only!
Good luck
C
Click to expand...
 
Time to check that your mechanical advance is working, use your new timing light for this at various rpm's.
 
I get the cam timing now. I was thinking the ref point on the sprocket flange was the unthreaded indent not the bolt hole so I guess that looks fine.

The rotor is more at 9 o'clock, a ways beyond the scribe mark. I went ahead and pulled the distributor and disassembled it. Nothing looked completely out of order. The moveable plate that the points mount to didn't move super freely. I cleaned and lubed it and seems smooth now. Weights and springs seem OK. That thin fiber gasket piece under the weights is broken. Any ideas on what to use to replace this that is readily available. I saw DeQuincy used a circuit board but I have no idea where I would get one so thin. Is there a good reason to take the drive gear off. Seems to spin freely and has no play so I'm hesitant to drive the pin out since I don't have a replacement.

Vacuum advance unit seems to work. I don't have a mighty vac but it seems to move and hold vacuum just with human suction. Hmmm.

Dist is a 0231162002

Thanks again everyone for all of the input and guidance. It's much appreciated.
 

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For what it's worth, I always mark the flywheel with silver paint at TDC and again at 22 degrees where the ball is. If your timing is off you will run dead lean at WOT and struggle to go over 5k rpm. Lots of cars get timed 22 degrees off.
 
If

your advance diaphragm is holding. The chances are it's ok.

Phenolic sheet is available. But there are Bosch distributer specialists here. try one of them. Or just use epoxy to fix yours if it's not disintegrated. DQ? I bet has has some to spare.

Move the distributer to where the factory says. Your off. Make sure number 1 on the cap and the wires are not one off too.

002 is the right one for a stock engine. Vacuum off- all in advance is 31-35 deg. at 3500 rpm. When you connect it again at say 1000 rpm it should move timing 10-16 degrees. ( Low side/ high side) if you're off more than that something's wrong.
 
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