#4 cylinder not combusting
Posted: Wed Jun 14, 2017 8:37 pm
To the 356 community writ large,
While i am not knew to the Reg, this is my first post. I have a dilemma which I am having difficulty narrowing down...
Background info...
-1958 356A coupe
-Normal 1600 (stock as far as I know)
-I have started the engine once since 1995 (yep, I know...long time, lots of issues)
Issue...#4 cylinder shows no sign of combustion on the spark plug...(I chose the word combustion because I am not sure why it is not combusting). All other cylinder (spark plugs) look good and slightly rich.
-Steps taken to solve issue
--Checked points, gapped to .016" inch
--Check timing (#1 TDC, measure 6.5mm to right of OT mark and set static timing at that mark...~5*BTDC).
--adjusted valve to initially .004 and .006 respectively, however, I then set them at .006 and .008 respectively just to give myself a warm fuzzy that the valve were seating (hasn't run in so long, want to get maximum seating pressure)
--checked #4 spark plug wire...firing with spark plug out and engine cranked
--replaced all spark plug...just to ensure it was not a failed spark plug...same issue with the NGK's
--checked compression on #4...120 after three rotations...It did bleed down slowly, but I am not sure if that was the gauge, the o-ring on the gauge or another issue which I will investigate shortly.
--Rebuilt Zenith carburetors...interestingly enough, the drive side card was not getting a fuel shot from the accelerator pump...removed and again rebuilt and did bench test...found a plugged pump set at the bottom of the accelerator well...accelerator pump working now...adjusted pump rod according to the manual. Did not do a volume test, just adjusted the rod length. however, both carb have same pump shot and are working. Additionally, the driver side carb idle air mixture screw on #4 cylinder does not do anything to the idle quality or the RPM's...this is one area were i need of that Reg expertise, the other area is the distributor.
Soooo, long story getting shorter,
Question, can a Zenith 32 provide fuel in only one venturis? I did check the main jet and the idle jet...both appear to be clean. Is it possible that I am only getting fuel from the same bowl into one of the venturis? I know they are both separate throats, but it is interesting that the engine runs, and rather well...without a load. With a load, forget it...definitely feels like a cylinder is down.
The other question has to do with the distributor...yep, you guessed it...I am running a 009. It was with the car when I purchased it a very long time ago and have not bothered to buy a correct one yet because I wanted to get it running correctly first (I use the term correctly in a lose fashion). I have ordered a BR18...just not here yet. The question is since it is a 009, is it indexed differently than the original or different from how the manual states to install the distributor? I have heard that the 009 is not set the same as the BR18, although the firing order is the same...currently, the 009 int set with the #1 post on the cap at roughly the 5 o'clock position. Would this be correct for this type of distributor...and does it even matter. I am looking at a red herring on this one??
I am sure I have forgot some info which would make it easy to diagnose, but thanks in advance for any thought on this problem...
Adam
While i am not knew to the Reg, this is my first post. I have a dilemma which I am having difficulty narrowing down...
Background info...
-1958 356A coupe
-Normal 1600 (stock as far as I know)
-I have started the engine once since 1995 (yep, I know...long time, lots of issues)
Issue...#4 cylinder shows no sign of combustion on the spark plug...(I chose the word combustion because I am not sure why it is not combusting). All other cylinder (spark plugs) look good and slightly rich.
-Steps taken to solve issue
--Checked points, gapped to .016" inch
--Check timing (#1 TDC, measure 6.5mm to right of OT mark and set static timing at that mark...~5*BTDC).
--adjusted valve to initially .004 and .006 respectively, however, I then set them at .006 and .008 respectively just to give myself a warm fuzzy that the valve were seating (hasn't run in so long, want to get maximum seating pressure)
--checked #4 spark plug wire...firing with spark plug out and engine cranked
--replaced all spark plug...just to ensure it was not a failed spark plug...same issue with the NGK's
--checked compression on #4...120 after three rotations...It did bleed down slowly, but I am not sure if that was the gauge, the o-ring on the gauge or another issue which I will investigate shortly.
--Rebuilt Zenith carburetors...interestingly enough, the drive side card was not getting a fuel shot from the accelerator pump...removed and again rebuilt and did bench test...found a plugged pump set at the bottom of the accelerator well...accelerator pump working now...adjusted pump rod according to the manual. Did not do a volume test, just adjusted the rod length. however, both carb have same pump shot and are working. Additionally, the driver side carb idle air mixture screw on #4 cylinder does not do anything to the idle quality or the RPM's...this is one area were i need of that Reg expertise, the other area is the distributor.
Soooo, long story getting shorter,
Question, can a Zenith 32 provide fuel in only one venturis? I did check the main jet and the idle jet...both appear to be clean. Is it possible that I am only getting fuel from the same bowl into one of the venturis? I know they are both separate throats, but it is interesting that the engine runs, and rather well...without a load. With a load, forget it...definitely feels like a cylinder is down.
The other question has to do with the distributor...yep, you guessed it...I am running a 009. It was with the car when I purchased it a very long time ago and have not bothered to buy a correct one yet because I wanted to get it running correctly first (I use the term correctly in a lose fashion). I have ordered a BR18...just not here yet. The question is since it is a 009, is it indexed differently than the original or different from how the manual states to install the distributor? I have heard that the 009 is not set the same as the BR18, although the firing order is the same...currently, the 009 int set with the #1 post on the cap at roughly the 5 o'clock position. Would this be correct for this type of distributor...and does it even matter. I am looking at a red herring on this one??
I am sure I have forgot some info which would make it easy to diagnose, but thanks in advance for any thought on this problem...
Adam