223cid Slow revving problem...page 2

[59F100]

there...that's better...

So I went out and did a compression test on 4 of 6 cylinders before my battery gave out. Anyone do this with the engine RUNNING?

Anyway...not sure how accurate the gauge is. It is pretty ratty, BUT if it is correct, then the 4 cylinders I tested only had about 75lbs of cranking compression with choke and throttle plates helpd open.

I hope that is wrong. Gonna get a new gauge and try again. That's all I got time to do....

Also checked plugs again...they are all black in some form or fashion except for one. the tip (the part you bend) was white and ashy looking. The compression read the same as the other cylinders (as reliable as that could be...not much)... what you think?

 

[Drumhead_Dan]

You need to reset your valves before running your compression test. Charge that battery!

 

[59F100]

I'll get them reset to 0.019 a re-do the test...and charge the battery.

 

[59F100]

Trying to get back on my engine problem here (amazing how time flies by).

Refresh: 59 F100, 223ci six, single 1904 carb, sparkomatic distributor, engine has a HEAVY bog when you tip open the throttle blades. You can get past it and rpm the engine, but the bog is so bad that the truck is un-driveable. An uphill stop sign would be the end of my travels.

So...oil bath air cleaner installed, vacuum lines all connected, but I have not measured the vacuum; distributor is set up properly with new components.
Tried setting timing everywhere from 0-18 degs BTDC with no change
Tried summer/winter positions on acc pump, nice squirt of fuel, no change
Tried disconnecting acc pump, no change

Something really simple has to be causing this. Pretty sure it has low compression due to blow by but I dont think that would cause my problem. I am leaning towards the carb. Opinions?

 

[godheadcustoms]

Go back and run through the basics, one step at a time. Only make one change per round, and note any differences-good or bad.

Set your valves to whatever your preference is-IIRC, .019" cold is factory spec. Also take a look at the rockers and arms and make sure, as best as possible, that nothing is amiss or not staying set. i.e.- a rocker nut that won't stay tightened down and lets the valve clearence change.

Do a compression check, note the readings. Add a teaspoon or so of oil down the spark plug hole, spin the motor a few times and recheck the compression. The oil will temp. seal the rings (if they are going bad) and the reading will go up. If you have low comp. the first round, and the numbers go up a signifigant amount after the oil, you know your rings are going south. If the reading stays low, or mostly the same, you can now deduce that the valves guides are loose. Hopefully your numbers will be acceptable. You also want the cylinders to be within 10% of each other. If the valves aren't set properly before the comp test, the readings won't mean much. Air pressure will just sail past the partly opened valves.

Set the dizzy to factory specs. Check to see that the vacumn is working on the dizzy end. If you don't have a Mittyvac or similar; rent, buy or steal one. You have to be able to know when, and how many degrees the dizzy will advance with vacumn. Especially with the LOM system since it has no cent. advance. Write down the results and compare to specs. I like to note when it starts coming in and how much, max advance and when, and a place or two in the middle to get a "feel" for the curve. All at the advance at the end, while it may spec out fine, isn't really going to be working as it should, compared to a nice even progression.

Finally, check the carb. Not just the idle mixture, and pump squirt, but more importantly the spark valve. I don't remember if there even IS a way to check it other than replacing the valve with a known good one. But by that time, you've been through just about everything else and have either found your problem(S), or can rule them out.

HTH, and let us know what you find.

 

[59F100]

Thanks for chiming in Zac, here is what I got so far...

Go back and run through the basics, one step at a time. ...
Set your valves to whatever your preference is-IIRC, .019" cold is factory spec. ...have already set them, but I will re-check
Do a compression check,...started this in december, killed the battery, never finished...will purchase compression tester and re-do measurements (my original gauge was a pos)
Set the dizzy to factory specs. ...gap and dwell already set and checked several times
Check to see that the vacumn is working on the dizzy end.....vacuum is working...I can get a 9-11 degree (appr) swing in the timing...have not actually measured the vacuum that I recall.
Finally, check the carb. Not just the idle mixture, and pump squirt...idle mixture...ran screw in until motor starts to die...back out to highest idle (note: when I back screw out, rpm will come up, then I can keep on backing screw with no effect on rpm, almost like I could completely remove the screw.) Pump squirt is fine in both summer/winter positions
but more importantly the spark valve. I don't remember if there even IS a way to check it other than replacing the valve with a known good one. But by that time, you've been through just about everything else and have either found your problem(S), or can rule them out....have not changed out the scv...

HTH, and let us know what you find.

This is the umpteenth time I have done all of this... and I believe, or am leaning towards, this all being a carb problem. I do not believe that low compression will cause my bog...I do not believe my timing is the issue...when I tip into the throttle and it starts to bog, you can back off slightly or feather it and the motor will recover and get past the bog and rev as high as you want it.

 

[godheadcustoms]

I agree with you, it sounds like a carb/LOM issue. But, by going through everything else first it does a few things. First, it makes you aware of any potential/unseen problems and ensures that the rest of the engine is up to snuff. Secondly, it should positvely eliminate other sources of problems. Nothing is worse than chasing your tail over a carb problem that turns out to be a dizzy problem. And while low compression won't neccessarily cause a bog, it's still nice to know what you are playing with. An almost dead engine will never really run right, no matter how spot on you get the carbs and timing.

Have you checked for vaucumn leaks? Blown gasket? Again, just throwing things out there to check and cross off the list.

Has the bog been a recent addition or been hanging around awhile?

Have you checked for a dripping cluster while hot? My truck runs pretty good, but not great (I need to take some of my own advice and run through it )...but after running down the road on a hot day, it starts getting kinda fussy and it's a bitch to restart. It also bogs and "kicks" a little bit under certain conditions. I finally looked into it a little bit and saw gas just running down the throat while hot. It doesn't appear to be a dropped float since it only does it hot, so I'm thinking it's because the fuel is boiling out since the PO left out the carb insulator. At least I'm guessing there's suppossed to be one there. I've already rebuilt the carb, but it's so worn out it wasn't really worth the $30.00 for the carb kit. And I didn't even think about the insulator not being there at the time. Oops.

 

[59F100]

...Have you checked for vaucumn leaks? Blown gasket? ...

No blown gaskets that I can tell. Have not really checked for vacuum leaks. The LOM is operating as indicated by the timing mark jumping around. Whether or not it is all operating properly is unknown. Again, dont think the timing is causing this. It is not a run of the mill "hesitation" mind you, this is a boggggggg...I really need to post a video of what I am seeing. I had an old weed whacker that did the same thing...messed with it for two years and threw it in the trash. :roll:

...Has the bog been a recent addition or been hanging around awhile? ...

Bog has been there since I got it...one reason the guy sold it. "No power and deosnt run very well" he said. He didnt notice the 1/8" clearance on the rockers or the rocker shaft bolts that backed out of the head either...fixing all that made a huge difference. Would start on the first try, idle all day long...then it came down to fixing the bog.

...Have you checked for a dripping cluster while hot? ...

<insert joke here> I left that one alone...

 

[fmartin_gila]

Several years ago, I had a 'fuel boiling' problem with my 223. I installed all the gaskets I could get in there and still get a full nut on the hold-downs. Has been working good this way utilizing the stack of gaskets as an isolator.

Fred