OMC Cross Charge Mod questions

**Freddie Webb** · 12-19-2011, 01:04 PM

When you get the jetting close you need a choke button on the steering wheel or somewhere close so you can choke it before you lift the throttle. I could run mine flat out for a half mile set up for drag racing but if I lifted without hitting electric choke it would burn one everytime. That might not be your case but it is definitely food for thought.

**930turbo** · 12-19-2011, 01:06 PM

Riverman, the carbs looked great, 73 mains in all. The best I can tell, it’s a ’76 135 power head with the horseshoe type ignition – one pack. The water deflectors are in place and in good shape. </SPAN>

Riverratt, this is what I suspect. Did you rebuild again and replace the pack? If so did the problem go away? I had to change the timer base because it mysteriously lost spark on two cylinders after sitting on the bench during the rebuild (same side as the failure). I did not replace the pack.</SPAN>

Click image for larger version.

Name: Powerhead.jpg
Views: 71
Size: 99.9 KB
ID: 248353

**930turbo** · 12-19-2011, 01:10 PM

Interesting point Freddie, it did stick during the lift. However, the jetting appears to be stock according to all the resouces I've reseached for the '76 135.

**Forkin' Crazy** · 12-19-2011, 03:03 PM

Originally Posted by Freddie Webb

When you get the jetting close you need a choke button on the steering wheel or somewhere close so you can choke it before you lift the throttle. I could run mine flat out for a half mile set up for drag racing but if I lifted without hitting electric choke it would burn one everytime. That might not be your case but it is definitely food for thought.

I've never had that happen on a crossflow.

Since you did all the porting work, maybe a couple size larger jets would be in order, at least to start with. You need to set your timing at 4500 RPM or so and under a load as Jeff mentioned.

Did it just stick, or did it burn off the corners of the defector then stick?

**Riverman** · 12-19-2011, 03:16 PM

If you decide to switch to the later two-pack ignition system you will need a set of coil brackets like these. Let me know.

**Forkin' Crazy** · 12-19-2011, 03:24 PM

Great idea Jeff. Love the flywheel too! That's trick!

**Riverratt** · 12-19-2011, 03:38 PM

Yes I rebuilt it and changed the pack and it was fixed. Mine had the 2 packs but I chased it for a long time. I set the timing based on that cylinder and backed it down plus fattened the jets and still blew it up. Changed the pack and it was good to go. Like mentioned above I always set the timing in the water at around 5000 rpms.

**930turbo** · 12-19-2011, 03:39 PM

Forkin', there's metal on the plug. That's as far as I went. I'll assume meltdown. What number am I looking for @4500 RPM under load? I set it at 22 cranking speed. Jeff, you've got the coolest toy.

**Cavit8** · 12-19-2011, 03:48 PM

Originally Posted by Riverman

If you decide to switch to the later two-pack ignition system you will need a set of coil brackets like these. Let me know.

Sexy!

**Riverman** · 12-19-2011, 03:50 PM

Originally Posted by Forkin' Crazy

Great idea Jeff. Love the flywheel too! That's trick!

Yeah, but did you notice the titanium bolts?

**930turbo** · 12-19-2011, 03:53 PM

I have a bicycle covered with titanium bolts. It adds great contrast to the carbon fiber everything else.

**Riverman** · 12-19-2011, 03:54 PM

Originally Posted by 930turbo

Forkin', there's metal on the plug. That's as far as I went. I'll assume meltdown. What number am I looking for @4500 RPM under load? I set it at 22 cranking speed. Jeff, you've got the coolest toy.

If it's just the one cylinder I bet it was double firing as mentioned, Freddie is the man to get good info from. I drag raced mine at 28 degrees this year, ran the river at 26.

**930turbo** · 12-19-2011, 04:03 PM

I guess another way to ask this question, what additional advance should I expect between cranking speed and 4500 RPM's. My past experience was there was little to nothing between the two. I also don't understand the full load deal. There's nothing load specific with relation to the advance mechanism on these things that I'm aware of. No vacuum related compensations. I free rev should produce the same results, shouldn't it? I believe the factory recommended setting is 26 degrees. It had 18 degrees when I checked it after the first melt -down. The stop turned way in. I brought it up to 22 degrees. I still think there must be something changing because of how hard I drove it so many times without failure. No hint of hesitation, full throttle runs with the exception of the chicken-ness that cause the brief back pedalling to save my @$$.