Distributor rotor misaligning with Comp Cam

[timos]

Hello to all Strokers out there.

I build my 4.6l Stroker 2010 and it is used in a 91 Jeep Wrangler YJ with an AW4 swap (Trany from a XJ) for weekend sandpit playing. My intention was to gain torque for off-roading and cruising at low speed and RPM on-road.
It runs for the last 6 years but I’m sure there still are some issues with my Stroker:

Stroker Issues:

• When cruising at low RPM (1500-2000) at high gear everting is fine, but if I push the pedal for acceleration (without kick-down) the motor (exhaust) sound gets louder but the car not faster (not as it should, where is the torque at low RPM).
• With kick-down the acceleration is … OK, but over 3500 rpm the acceleration stalls.
• After driving other cars with stock 4L I would assert that my stroker has not glaring more power.
• The motor is loud and tickers like a diesel. I think of valve train sound.

Stroker Configuration:

• 4.2l crank and rods
• Sealed Power pistons525P (+ .030)
• Cloyes double chain timing gear set
• Comp Cam 68-232-4
• Crane Lifters 99278-12
• Harald Sharp Roller Rockers S40196
• Mopar performance valve springs P5249464
• No head changes (7120 Cast with a little homemade porting)
• Accel 26 lbs Injectors 150126
• Block deck grinded from 240,20mm to 238,85mm --> Quench Height at .040
• Push Rods with 9,594 lengths to compensate block deck grinding. To gain 1mm pre-pressure on the lifters I used shims under the roller rockers.

So it comes to a CR of approx. 10:1 without pinging when using premium fuel with 100 octane.

Why I ask now, 6 years later?
It’s not starting anymore! First I checked the distributor (at TDC) and found that the rotor does not line up with the normal position (3cm from the rubber). I tried to change that, but then it is also wrong (in the other direction).
I can’t remember how I assembled it 6 years ago, but it runs until last week (with the issues above). Maybe a sensor is gone, I think it’s not a cam timing problem (Cloyes double chain fail), because the piston to valve clearing is so small it would block. Further a compression test shows between 12,2 and 13bar for each cylinder.

Questions:

1) Is it a known issue of the Comp Cam 68-232-4 not lining up with the right distributor rotor position? Or any other Idea that cause the misaligning!
2) Should I remove the notches of the Distributor and turn the rotor in the right position?
3) Any ideas because of the Issues?

[Cheromaniac]

You may have to cut off one of the ears either side of the clamp bolt mounting hole to rotate the distributor body a few degrees to the desired position. This is often required with aftermarket cams due to the variance in the position of the gear teeth and it could transform the engine's performance.

[Russ Pottenger]

Am I understanding you correctly that at TDC your piston is .040 to the cylinder head factoring in the head gasket thickness?
If so i'm guessing you're closer to 11.1:1 than to 10.1:1 depending on how much you surfaced your head.

[Cheromaniac]

He had 0.053" taken off the block so the pistons are now 0.003" above the deck at TDC. With a 0.043" head gasket, the quench is indeed at 0.040". Assuming 57cc chambers, 15cc pistons, and a 9cc head gasket, the SCR comes in at 10.5:1. Any head surfacing will add a further 0.15:1 to the SCR for every 0.010" shaved.
Anyway, he needs to index the distributor and if the engine still doesn't start, either the CPS or the cam position sensor could be at fault.

[timos]

Head is not machined and pistons should have 17,5cc. The head gasket is a .051er, but my old calculations are with the planed performance gasket, my fault. So I come to the approx. 10:1 with a 0.048 quench height.

I built the stroker first without grinding the deck and drove it for a year with 0.050 deck clearance with approx 9:1 CR. But I thought I need more compression to gain more power (see issues above). I wanted to archive a zero deck clearance but the machinist grinded 0,053 instead of 0.050. Was not my best idea to gain best quench possible. Anyway it was not worth it.

I have a ping with 95 octane (EU-ROZ) in low RPM at >50% throttle (see issue 1). This is gone with >100 octane fuel. So I need premium fuel but output power is still worse.

[timos]

I changed the crank shaft position sensor (CPS), the cam position sensor (sync signal generator), distributor cap, rotor, cables and spark plucks additionally I aligned the Distributor to the first cylinder according to the FAQ.

I ensured valve timing with a dial indicator and degree wheel. Also checked valve pre-loads.

Now it starts and runs like before, but after warm-up (ca. 10min of driving) it comes to “backfire” in the exhaust even in idle. It is not a bang is more like a puff. It gets more when pressing gas pedal under load and a leak of power can be recognized.

Any ideas (also additional test I should execute)?

[indian]

I have the same problem. With comp cam 232-4 installed the engine will not start (distributor in the same position like before cam install). After I rotate it, no problem, engine runs well.

I checked it today with DRB III and the position was 25 deg off. When I rotate it to the desired position 0 deg, the engine backfired in intake and stalled. So I rotate it back to +25 deg and all is OK. Power is present, engine runs well. I don't know why.

[konacustom]

A couple of years ago I replaced the distributor in my 1995 4.0L. There was a little bit of a miss and I noticed that the distributor shaft was pretty sloppy in the housing. For almost two years the engine would not run right no matter what I tried. I tried everything I could think of including all of the things you mentioned pretty much. About six months ago, I finally had the time to mess with it again and decided once and for all, I would find out what the hell the problem was. I was sick and tired of the hard starting and it generally just running shitty. I got a timing light and noticed that it was 23 deg advanced and no matter what I did to try to stab the distributor into the block and get it timed right, I could not get it any better. just by chance, I ran into a video on youtube of a tech school instructor troubleshooting a jeep 4.0 with the same symptoms I had. It turned out that the distributor gear on the rebuilt distributor I put in was 180 deg turned around....backwards if you will. The gear has 17 teeth on it which would not get me to the necessary 23 deg to get it timed correctly so I KNEW that this had to be my problem as well...esp given they had all the exact symptoms I had. So, I pulled the distributor out once more, got a drift punch and removed the roll pin and rotated the gear 180 deg. I put it all back together and timed the distributor just as I had always been doing before and VOILA !! It runs perfect to this day, just as it should have and did before I started getting a 'misfire'. As it turns out, the misfire was because my valve guides were so worn out that my valves were no longer seating properly....even longer story. I got that taken care of also and now I have a great running engine. I didn't see that you mentioned you replaced your distributor in your rebuild but its a mundane enough part that you might not have thought it necessary to mention it. If nothing else, I hope this helps somebody else.

let us know if you find out what it was please

[konacustom]

Clarification: The engine would not run right for 2 years after I replaced the distributor no matter what I did.