When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Those are brand new plugs Dan , only slow driven a 30 miles due the heavy steering then.
What i also didn't thought of : when a plug doesn't fire , the timing light doesn't see the high voltage signal . That will be the reason i thought my timing light went bad , no , it was plug #1 getting bad till zero spark.
My AFR lambda is mounted on the drivers side exhaust .... with missfires we see wrong things. Engine is pumping air in the exhaust , the O2 sensor sees only oxygen , not fuel, so gauge shows "lean".
Almost ready with new plugs and distributor set at 10° advance..... hope it runs
yes !!! it runs OK. Could have it idle at 1000 rpm with 10 to 15° advance. Will test the max "38°" at another location as to spare my neighbors
Idle AFR was 11.7 , to rich. Must see for the mix screw on a Holley , is "in" leaner or richer ??
Thanks gentleman for the tips& advises , i'm afraid here it was "only" the wrong plugs fitted by the German seller/dealer. And i bought the same when the engine started to act strange, thinking they were the right types.....so again problems in short time.
O well, meanwhile i have the new distributor in it , the old one was not so "fresh" inside as i thought .
Yes, tuned in ( CW) is leaner on idle screws. You probably need to play with the screws to see if you are getting any response at idle at all. If not, pull the carb and see what the exposed transition slot in the primary bowls looks like on the bottom below the primary blades when they are at curb idle. You should see roughly a square opening. If you are seeing a longer, rectangular opening, the blades are too far open and the transition slot may be dumping excess fuel into the intake.
I just remembered that you have tri-power. I’m not sure what is usually done with tri-power to lean the idle mixture for big cube engines with big cams. Maybe the outboard carb blades can be opened slightly to allow more air in which would allow closing the center carb blades down a little to lean the idle down. Not sure if the outboard carbs have idle circuits or not. Some of the tri-power guys will need to chime in.
Will drive the car today a bit to see how it performs. At my brother's house ( a remote location with only some horses and a dog ) i can set the max advance , 36...38° and do some WOT testing.
Will mount the AFR temporarily in the car , so i will already have a "idea" of the AFR under load.
I was at 32° all in , dialed it in to 38°. Perhaps better to come back to 36°.
Runs good , but slow driving or starting i have to keep it above 1500, better 2000 rpm , or there can be hesitations. I blame that alu flywheel.
AFR is now good also , 13.5 at idle , 12---13 driving. I think that is fine , on the rich side which is safe.
Steering is still to hard , sure on country roads. Difficult to make and feel little corrections. I will remove that flow restrictor valve and see if it's better.
Also at my brother's home , dialing in advance , i had 2 times the starter motor didn't spin with key turn. Must look for a electric problem ? perhaps the ignition switch ? Is this with a relais to starter motor ??
The plugs Dan , 2 sets ruined in no more then 30 miles.
Didn't look at the first set when i replaced them , but now i already had 3 bad plugs.
Also bad was #1 , which gived those bad timing light flashes. If the plug doesn't fire , the timing light doesn't see the high voltage .
Strange that the engine kept running with bad plugs , but with more and more advance.
I assume the German dealer mounted those plugs ( i remember they looked new when i bought the car ) and once bad running i bought the same plugs thinking they were the right type.... stupid of me . )
Next order from the US i will order Accel 416 plugs . Have now Bosch +6 , a equivalent... i hope
Your plugs show 3 cylinders running rich and 5 running lean. I know they are new and low miles but some color should show on the 5 white plugs. Has me thinking vacuum leak in the manifold maybe? Maybe the three dark cylinders are the only 3 getting proper fuel and trying to carry the load of 5 weak cylinders? Timing needs to be close for sure but total timing can be set at 34 to be safe all in total timing and leave it there until you sort out the rest. Your power and responsiveness will not vary much between 34 and 41 total timing. Maybe you will be 14-20 HP short of max but it is still very close to full power. You have another issue I think with Carb or vacuum leaks.
A 540 in a C2 has so much power it will feel strong even if at less than half power. At full power it will feel like it is twisting your frame on hard acceleration. Your tires won’t stop spinning.
The larger cams won’t want to idle at less than 1,000 RPM but we are still not sure what cam you are trying to tune.
With your aluminum heads and 10.5 compression I would think you will be OK at 36 degrees - but 34 might be a better starting point for getting acquainted with it as long as you can maintain somewhere around 14-15 degrees base timing. I’ve run my 12:1, L88 head 427 at 36 degrees for decades on 93 octane without any issues. Of course with side pipes and old ears it’s hard to tell much about pinging or detonation.
Your plugs show 3 cylinders running rich and 5 running lean. I know they are new and low miles but some color should show on the 5 white plugs. Has me thinking vacuum leak in the manifold maybe? Maybe the three dark cylinders are the only 3 getting proper fuel and trying to carry the load of 5 weak cylinders? Timing needs to be close for sure but total timing can be set at 34 to be safe all in total timing and leave it there until you sort out the rest. Your power and responsiveness will not vary much between 34 and 41 total timing. Maybe you will be 14-20 HP short of max but it is still very close to full power. You have another issue I think with Carb or vacuum leaks.
A 540 in a C2 has so much power it will feel strong even if at less than half power. At full power it will feel like it is twisting your frame on hard acceleration. Your tires won’t stop spinning.
The larger cams won’t want to idle at less than 1,000 RPM but we are still not sure what cam you are trying to tune.
I agree that there seems to be something else going on besides bad plugs. I can't understand why plug #1 would simply refuse to fire unless it is damaged somehow.
The wide differences among the appearances of the plugs also bothers me. I suppose that one explanation could be that the 41 degree initial advance affected each cylinder differently, depending on where that particular was in its combustion cycle. It would be a good idea to put a few miles on the engine and then remove the new plugs for inspection. We would expect them all to look uniform now that the timing has been fixed.
Regarding the possibility that the unstable idle is caused by the engine having a giant cam installed, I was unable to locate any Crane cam with the part number "610/632 HR". I downloaded the 2013 Crane catalog, and the first three digits of their cam part numbers were always the intake duration at .050". For even a "big" cam, that first number should be between 240 and 280.
If anyone here can help with identifying what "610/632" HR means, that would be very helpful.
An alternative approach for identifying the cam would be to use the procedure I outlined in post #54, but instead of looking for the POML, look for the number of degrees duration between the .050" opening point and the .050" closing point on the cylinder #1 intake valve. Note that for this test (looking for the .050" lift points), the dial gauge needs to be on the valve end of the rocker arm.
If the original builder of this engine put a "race cam" in it, it would be normal for the engine to barely run below 1500 rpm and be soggy below 3000 rpm.
The hydraulic roller that matches is a 139741 (old style bolt pattern) or 168741 (Gen 6 style), often called the 741 cam.
The wide 112* LSA made this cam popular in marine and street applications, and with large displacements, but it is a big cam peaking HP @ 6500 rpm. Expect about 13" vacuum at a lumpy 700-1000 rpm idle, and I expect it will need around 18*-20* advance at idle and 38* total (a short 20* mechanical advance curve all in at around 3200 rpm).
OK, cam is known now, it is big but that does not affect the 5 cylinders lean while 3 are very rich. Something is off. Maybe take an IR gun and look at temps for all 8 cylinders right at the exhaust port close to the head. Look for temperature variations. I think the temp variations will match your spark plug colors exactly. Maybe the carb or one carb is leaking extra fuel? I think I saw this is a 3x2 set up?
it runs OK. Could have it idle at 1000 rpm with 10 to 15° advance. Will test the max "38°" at another location as to spare my neighbors 
