Another how to timing question

[nateo]

Well I'm running it on hose right now with outdrive off. Picked me up digital timing gun. Mark bounced around everywhere. Was able to double check rpm with it though still lowest I can get it to run is about 750. Should I be able to run 650 on hose? Also hooked up vac gaude getting 7.5 - 8.25 " vac. Even more confused now. Thinking about taking it in to recommended boat shop for older boats

 

[Rick Stephens]

Well I'm running it on hose right now with outdrive off. Picked me up digital timing gun. Mark bounced around everywhere. Was able to double check rpm with it though still lowest I can get it to run is about 750. Should I be able to run 650 on hose? Also hooked up vac gaude getting 7.5 - 8.25 " vac. Even more confused now. Thinking about taking it in to recommended boat shop for older boats

Not so good vacuum. Should be up twice that. You might check for a vac leak - carb cleaner can serve to spray around intake. Low vac will make it hard to idle. Next is compression test before you know what condition the ring/cylinders are. No need to take it to a shop to run these tests, cost less to do it yourself even if you have to purchase the tools. And the answer is the same whether it comes from a $200/hr shop or your own hands.

 

[Eric 3.7LX Alpha 1]

That's terrible vacuum....

should be between 16-and 22" of vac.. and steady.

Being that low could indicate, an intake or carb vacuum leak, late ignition timing, or worn piston rings. according to this video from Holley:

 

[Eric 3.7LX Alpha 1]

Here's one more to check a vacuum leak

 

[flipbro]

Now your on the write track..

 

[nateo]

Now your on the write track..

Should have hooked up the gauge a long time ago (yes when you told me to), kicking myself for that now. What's weird is I'm not getting any rpm change with the brake cleaner. Also when I tightened the air fuel mixture screws on my carb the engine did indeed die. Compression test came back ok so I don't think it's rings. this issue is a riddle wrapped inside a puzzle.

 

[Eric 3.7LX Alpha 1]

Should have hooked up the gauge a long time ago (yes when you told me to), kicking myself for that now. What's weird is I'm not getting any rpm change with the brake cleaner. Also when I tightened the air fuel mixture screws on my carb the engine did indeed die. Compression test came back ok so I don't think it's rings. this issue is a riddle wrapped inside a puzzle.

did you watch the video I posted in post #23 and 24??...

New brake cleaner, carb cleaner doesn't work as good as the old stuff did at finding vac leaks..........use Propane

and spray around the carb as well.

 

[Rick Stephens]

Eric,

That Eric the Car Guy video is great! (not you is it?)

 

[Eric 3.7LX Alpha 1]

Na... Just another guy with a great name

 

[nateo]

Well I ended up taking the boat in because I've spent a good portion of the summer working on it and just getting burnt out. Got call today. They claimed they usually see 9-10" of vacuum on this motor and don't suspect vacuum leak. They claiming that the secondaries are leaking on my quadrajet and is likely the source of high rpm and want to rebuild her. Does this sound like a accurate diag to anyone?

 

[achris]

If the secondaries were leaking that much, the engine would be running much faster, and you'd have to have the idle screws wound all the way out. Has this engine ever run properly? Has it been pulled apart? (I'm thinking valve timing)....

Chris.....

 

[flipbro]

9 to10 is not normal.unless its a lawnmower engine or you've got a big lumpy cam witch you don't. As for secondaries leaking now way. As Chris explained.

 

[nateo]

If the secondaries were leaking that much, the engine would be running much faster, and you'd have to have the idle screws wound all the way out. Has this engine ever run properly? Has it been pulled apart? (I'm thinking valve timing)....

Chris.....

One head has been off recently and I did the valve adjusting work. Is the adjustment of the valves what you are refering to with valve timing? I know I was on tdc compression stroke adjusted the ones noted in book then turned 360 and adjusted the other half. I tightened until I could no longer spin the push rods then gave her another half turn. Now I was reading a book somewhere that push rods can be reversed, is this true? If so could that be my idle/timing problem?