470 Has Me Stumped

[Failproof]

Re: 470 Has Me Stumped

Rotor tips are big like that because the spark duration is long enough that it needs the extra time as the rotor is moving. If the rotor is almost there or still has about half the tip still to go past then you are close enough. First off, verify that the timing mark 0 degrees or TDC lines up when the PISTON used for timing is at TDC. If not then find out why before moving on.

 

[Eric 3.7LX Alpha 1]

Re: 470 Has Me Stumped

Just looked at your timing marks picture with the damper.... You are not off 20?.... looks like you are right on your marks, close to 0? actually if I am seeing it correctly... or you've moved it closer at some point?

click on the 2nd pic I have attached with the timing marks close up

 

[Scrambler99]

Re: 470 Has Me Stumped

Yes My mark is at zero degrees. I cranked it over until I found TDC. I was checking rotor alignment to number one plug. I was doing what stonyloam suggested a few posts above. My mark was about 1/8 off of rotor alignment mark.

 

[stonyloam]

Re: 470 Has Me Stumped

To me it looks like everything in the ignition is set up correctly. So when you are running the timing light shows the mark on the rotor way off to the starboard side from the timing marks on the cover? Does the idle adjust screw do anything?

 

[Scrambler99]

Re: 470 Has Me Stumped

Just looked at your timing marks picture with the damper.... You are not off 20?.... looks like you are right on your marks, close to 0? actually if I am seeing it correctly... or you've moved it closer at some point?

click on the 2nd pic I have attached with the timing marks close up

Yes when I am running the timing light my mark is way over in the red circle that you have labeled "NOT HERE" from your post earlier Eric.

 

[Scrambler99]

Re: 470 Has Me Stumped

To me it looks like everything in the ignition is set up correctly. So when you are running the timing light shows the mark on the rotor way off to the starboard side from the timing marks on the cover? Does the idle adjust screw do anything?

The idle screw does seem to be working to an extent. Maybe I am moving the distributor too much at one time without bringing idle up. I am going to try and work on it in the morning and get that mark as close to 4 degrees as possible with it still being able to idle at 650-700 after I check dwell and get that within spec. I will keep you guys posted on progress. Thanks

 

[Eric 3.7LX Alpha 1]

Re: 470 Has Me Stumped

Is it possible that when you tightened down the points screw it may have moved some ...closing the points gap?

Creating more dwell and more timing?

 

[Scrambler99]

Re: 470 Has Me Stumped

Is it possible that when you tightened down the points screw it may gaphave moved some ...closing the points gap?

Creating more dwell and more timing?

It is possible that it moved. I will double check the gap to make sure it is .022. Then I will check dwell. Thanks

 

[Maclin]

Re: 470 Has Me Stumped

Check the dwell first, that will tell you if the gap changed.

 

[Scrambler99]

Re: 470 Has Me Stumped

I just checked dwell it is at 31

 

[Maclin]

Re: 470 Has Me Stumped

I think that is in range, but is that what you set it to the first time?

 

[Scrambler99]

Re: 470 Has Me Stumped

I never had a dwell meter the first time to check it. I set the gap and that was it. Funny thing though, after I checked dwell and that was within spec, I figured I would try to fire her up and check timing. It started up the best it ever had. I went to WOT and then backed her down to about 1/4 throttle and after a few cranks it was running! I was shocked as usually it is about a 2-4 minute job just to get her running at a cold start. After she was running a bit I checked timing and got it adjusted down to about 5 to 6 degrees. I messed with the idle screw to increase rpm's and got it to where it would stay running and sounded good. I don't know how accurate the tach in the boat is but it was right around 700 rpms. I tried to give her quick throttle and it bogged down and backfired on me and eventually died. It started up again though. If I ease into throttle it seems not to stumble as much and will gain rpm. I'm thinking a carb rebuild is next on the list and see if I can get rid of the stumble on quick throttle. I just have to find time to do it. At least I got the timing set down close to where it needs to be. What a relief! Suggestions are always appreciated and thanks again everyone!

 

[Maclin]

I tried to give her quick throttle and it bogged down and backfired on me and eventually died. It started up again though. If I ease into throttle it seems not to stumble as much and will gain rpm. I'm thinking a carb rebuild is next on the list and see if I can get rid of the stumble on quick throttle.

A carb rebuild should take care of this as it sounds like the accelerator pump inside is tired or just needs attention. The accelerator pump is actuated by throttle movement and squirts fuel into the bores as the throttle is opened to cover up the now-lean lean condition until the carb has time to start flowing thru the main jets.

 

[Eric 3.7LX Alpha 1]

Re: 470 Has Me Stumped

Nice... getting closer!

Here are a series of videos posted by Alpheus here on Iboats on rebuilding a rochester:
http://forums.iboats.com/showthread.php?t=362542

 

[stonyloam]

Re: 470 Has Me Stumped

I tried to give her quick throttle and it bogged down and backfired on me and eventually died. It started up again though. If I ease into throttle it seems not to stumble as much and will gain rpm. I'm thinking a carb rebuild is next on the list and see if I can get rid of the stumble on quick throttle. I just have to find time to do it. At least I got the timing set down close to where it needs to be. What a relief! Suggestions are always appreciated and thanks again everyone!

If the engine was not fully warmed up and the choke opened you might see some hesitation with a quick hit on the throttle. Give it enough time to fully warm up until the temperature gauge has stabilized. Then set your idle. Use the tach on your dwell meter to check your boat gauge. Glad things are looking better.