Chrysler 55 timing help

[Turn4fun]

I have a '67 Chrysler 55 hp with type 1 (flywheel magneto) ignition. Actually what I have is a '67 Sea King mod. VWB-19087A. It is a 35 hp but I swapped the powerhead with a '73ish 55 hp powerhead. Everything is identical (except for displacement, head and carb) and installed with no modifications needed.

Now heres where I'm baffled. I have been able to establish both TDC and 28* BTDC but am unsure where the stator plate needs to be in relation. Would I be correct to assume that with the #1 at 28* BTDC, the throttle at WOT and the tower shaft in full advance position, that the follower arm on the point should line up with the index mark on the cam? Mine does not line up. In fact it won't line up until after it has past TDC. There is not enough adjustment in the link rod to make it line up. What am I missing, should it line up at 28* BTDC or TDC? I do have a Seloc manual but can't find the answer.

 

[Frank Acampora]

Re: Chrysler 55 timing help

The mark on the cam is only to establish the widest opening point so you can set the points. It is NOT the point where the magneto will fire. Remember: the gap in the points sets the DWELL. Smaller gap, less dwell--wider gap, more dwell. Dwell is the time a magnetic field is building in the windings. Magneto is different than battery ignition-- I forget if it fires when the points first open, not when they are fully open or when they close. That's the kind of thing that's not important to remember, only that the setting is critical.

So, if you have established where 28 BTDC is, use that for your timing. If your flywheel does not have a mark, put one on, and a matching one on the block at TDC and use them to set the timing.

If your flywheel has two marks 180 degrees apart, use each one to set or check the points on its corresponding cylinder. Reason: a difference of only .0015 between points results in 1 degree difference in timing.

Are you just being careful with timing? Recommended timing is 30 deg BTDC

 

[Turn4fun]

Re: Chrysler 55 timing help

OK that makes sense. My manual specifies 28? for all 55's with flywheel mag from '67 to '77. Mine is old enough that it does not have timing marks or a decal. I wanted to get it as accurate as possible and I know the best way is to use the timing gauge that goes through the spark plug port. These are impossible to find but I am pretty handy with a bench lathe so I dug some brass stock and some drill rod out of my scrap bins and made one.

So I set the point gaps at .020 with the follower lined up with the index mark on the cam. Now if I'm correct, with the piston at 28? BTDC and the tower arm in full advance, the stator position would need to be adjusted until the point just breaks contact, correct? OK so I did this, used a continuity meter determine when it broke contact too. Then I installed the gauge in the lower cylinder and this time adjusted the point itself rather than the stator. Does this sound right?

If this is all correct then it should fire right up but it won't. I've verified spark at both plugs, fuel pump is pumping and the carb has been completely gone through. Not sure why it won't start.

 

[Turn4fun]

Re: Chrysler 55 timing help

OK, I'm really at a loss here. I've got spark, I've got fuel, it should be timed properly yet it won't fire. I've even tried spraying carb cleaner through the carb into the reed block and it still won't light off. I finally resorted to unhooking the spark advance rod from the tower arm and going one turn at a time, hooking it back up and cranking it over. I tried it from as far in as it would adjust to as far out as it would adjust and it just won't fire. I pulled the plugs after every adjustment and dried them off so as to eliminate the possiblity of wet fouling. I know the points, condensers, plugs and coils are good because I used the ones that were on my 35 and it was running very well. Does anyone have any ideas?

 

[Turn4fun]

Re: Chrysler 55 timing help

YEAH!!! I figured it out, and boy do I feel silly. The 55 HP powerhead I had gotten from ebay and although mechanically it seemed sound, the ignition components were kinda suspect so I used the stator from my 35 which I knew to be good. The plugs that came with the 55 were different brands (an AC and a Champion), were not the same size and were really cruddy, so I used the plugs from my 35 also. So with spark and fuel delivery not an issue, and timing & sync being correct, the only thing I could think of was perhaps the compression was too low. I put up another post about compression but those who answered seemed to think it should still run with 120#.

Finally I decided to give up and put the 35 HP back on. I started to remove my plugs and stator and that's when I noticed what had been escaping me for 3 days. The plugs from my 35 were Champion J4C which is the equivalent of the recommended, but obsolete J4J. One of the plugs that came with the 55 was a Champion RL82C which is the equivalent to the obsolete L4J. I double checked the manual and sure enough, L4J is recommended for the 55. I could have sworn it said J4J when I checked the first time.

So what's the difference? The J4C has a 3/8" reach and the RL82C has a 1/2" reach. Instantly it became clear, although I had spark, it was occurring up inside the plug port instead of out in the combustion chamber. On top of that, the shorter reach effectively added half a cubic centimeter of volume to the displacement thereby reducing the already somewhat low compression. I stuck the crappy old plugs back in, turned the key and it fired right up! Well I guess it's off to NAPA to buy some new (but proper) plugs.