ArdWrknTrk Posted June 27, 2021 Share Posted June 27, 2021 Have you checked for vacuum? Perhaps the timing chain has worn or slipped? That would seriously effect vacuum, and cause the carb to spit under wide throttle openings. Maybe try putting a breaker bar on the crank pulley (15/16 deep socket) and remove the distributor cap. Rock the crank back and forth while looking at the distributor rotor. It will be pretty apparent if the rotor does not reverse direction immediately. The only thing I've done is watched the rotor spin while I jumper the starter relay (and pump fuel to whatever carb is there). OK, it's pretty easy to turn it over with a breaker bar, I can do that tomorrow morning, too. :) Do you have a vacuum gauge? (Or a Mity Vac? You can use it for a gauge. ) Intake valves closing late would explain no power, and no boost for the brakes. Also, without vacuum, the secondaries are going to have a hard time coming off. But it's just an idea. I notice your Holley has the quick change lid on the secondary spring. There's an o-ring in that cap along with the diaphragm. I have a couple of 4V carbs. But I think the carburetion is a symptom, not the cause. Link to comment Share on other sites More sharing options...
ctubutis Posted June 27, 2021 Author Share Posted June 27, 2021 But I think the carburetion is a symptom, not the cause. Yeah, I have a vacuum gauge, but I agree, the carbs are showing symptoms; 2 carbs with the same symptoms, something else is wrong. At least we know what it's NOT, I guess. Last night, I sent those 2 videos to my machinist/engine-builder-guy who did all of that work on it in 2005, we'll see what he says.... Link to comment Share on other sites More sharing options...
ctubutis Posted June 27, 2021 Author Share Posted June 27, 2021 But I think the carburetion is a symptom, not the cause.Yeah, I have a vacuum gauge, but I agree, the carbs are showing symptoms; 2 carbs with the same symptoms, something else is wrong.At least we know what it's NOT, I guess.Last night, I sent those 2 videos to my machinist/engine-builder-guy who did all of that work on it in 2005, we'll see what he says....Copied from FTE.... OK, here is where I'm at today... It starts but doesn't run well below 2500-ish RPM. See videos 1 & 2. I wasn't able to actually see my 0/10/20° BDC markings on the balancer when I tried to check the timing, that really concerned me... so I did the crank pulley with a breaker bar stuff, I can't see there being any way in h3ll that chain could have slipped. This engine was built in 2005 (maybe 06) and the entire truck has easily got less than 10K miles on it since then, it's mostly a firewood-getter in the wintertime. Plugs all look the same; I dropped #8 on the ground, but its gap seems to be unaffected. Everybody's getting a lot of gas, I can see that. Guess I'll do a compression check at this point, it's what I'm set up for.... Pictures.... Plugs 1-4: Plugs 5-8: The morning attempts to start it & take measurements, it didn't go any better than it has in the past... Video 1: Video 2: YouTube says it's still processing the HD versions, but I expect it to be completed shortly (within the hour, I'd hope) but it probably doesn't really matter.... Gonna post the same update to Gary's site..... this is trying HTML format in an attempt to get the embedded youtube clips.... Link to comment Share on other sites More sharing options...
ctubutis Posted June 27, 2021 Author Share Posted June 27, 2021 Copied from FTE.... OK, here is where I'm at today... It starts but doesn't run well below 2500-ish RPM. See videos 1 & 2. I wasn't able to actually see my 0/10/20° BDC markings on the balancer when I tried to check the timing, that really concerned me... so I did the crank pulley with a breaker bar stuff, I can't see there being any way in h3ll that chain could have slipped. This engine was built in 2005 (maybe 06) and the entire truck has easily got less than 10K miles on it since then, it's mostly a firewood-getter in the wintertime. Plugs all look the same; I dropped #8 on the ground, but its gap seems to be unaffected. Everybody's getting a lot of gas, I can see that. Guess I'll do a compression check at this point, it's what I'm set up for.... Pictures.... Plugs 1-4: Plugs 5-8: The morning attempts to start it & take measurements, it didn't go any better than it has in the past... Video 1: Video 2: YouTube says it's still processing the HD versions, but I expect it to be completed shortly (within the hour, I'd hope) but it probably doesn't really matter.... Gonna post the same update to Gary's site..... this is trying HTML format in an attempt to get the embedded youtube clips....Begin here, CC to FTE...Prepping to do a compression test and I noticed... I'm back to fuel supply, the filter is empty.... *sigh*I'm still doing the compression test first, one thing at a time... Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 27, 2021 Share Posted June 27, 2021 Begin here, CC to FTE... Prepping to do a compression test and I noticed... I'm back to fuel supply, the filter is empty.... *sigh* I'm still doing the compression test first, one thing at a time... Yeah, it sounds like you are way short of fuel. But that doesn't explain the lack of vacuum showing. However, you obviously have some vacuum or it wouldn't run at all, so maybe the vacuum line didn't get connected after the carb swap? Or got knocked off? Link to comment Share on other sites More sharing options...
ctubutis Posted June 27, 2021 Author Share Posted June 27, 2021 Begin here, CC to FTE... Prepping to do a compression test and I noticed... I'm back to fuel supply, the filter is empty.... *sigh* I'm still doing the compression test first, one thing at a time... Never mind, the fuel filter is just full. ~~ OK, results of the compression test: 1= 155 2= 155 3= 100 w/oil = 150 4= 150 5= 165 6= 165 7= 100 w/oil = 125 8= 155 Not real encouraging. ~~ I'm gonna put it back together, I guess, as I'm not real sure where to go from here... what does everybody think? It's current condition, installation is the exact reverse of removal: Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 27, 2021 Share Posted June 27, 2021 Never mind, the fuel filter is just full. ~~ OK, results of the compression test: 1= 155 2= 155 3= 100 w/oil = 150 4= 150 5= 165 6= 165 7= 100 w/oil = 125 8= 155 Not real encouraging. ~~ I'm gonna put it back together, I guess, as I'm not real sure where to go from here... what does everybody think? It's current condition, installation is the exact reverse of removal: Obviously you have a problem with 3 and 7. BUT, that doesn't explain the way it is running. I've seen engines with far lower compression run nicely at idle and rev in neutral like there was nothing wrong. And if the fuel filter is full and you have the same symptoms with two different carbs then it probably isn't the carb. But it could be bad gas. Do you have a way to run it off new gas in a gas can? Or it could be ignition, or the lack thereof. Have you checked for a strong blue or white spark? And did you ever figure out what the timing is doing? Last, once you figure out why it won't run at the moment, you might want to do a leak-down test to figure out what is wrong with 3 & 7. However, given how much the compression came up with oil I suspect that you'll find the rings are leaking into the sump. Link to comment Share on other sites More sharing options...
ctubutis Posted June 27, 2021 Author Share Posted June 27, 2021 Obviously you have a problem with 3 and 7. BUT, that doesn't explain the way it is running. I've seen engines with far lower compression run nicely at idle and rev in neutral like there was nothing wrong. And if the fuel filter is full and you have the same symptoms with two different carbs then it probably isn't the carb. But it could be bad gas. Do you have a way to run it off new gas in a gas can? Or it could be ignition, or the lack thereof. Have you checked for a strong blue or white spark? And did you ever figure out what the timing is doing? Last, once you figure out why it won't run at the moment, you might want to do a leak-down test to figure out what is wrong with 3 & 7. However, given how much the compression came up with oil I suspect that you'll find the rings are leaking into the sump. Yeah, I've also seen (and had) engines with "low" compression run fine. The timing light thing freaks me out a bit I can verify with a different timing light, but I doubt it's the problem. But this brings up a good point, that dang DuraSpark box... I *think* I have another one around here someplace, I'll have to look. It's cloudy & rainy again, so I'm in the garage working on the Taurus... Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 27, 2021 Share Posted June 27, 2021 Yeah, I've also seen (and had) engines with "low" compression run fine. The timing light thing freaks me out a bit I can verify with a different timing light, but I doubt it's the problem. But this brings up a good point, that dang DuraSpark box... I *think* I have another one around here someplace, I'll have to look. It's cloudy & rainy again, so I'm in the garage working on the Taurus... I had a brand new DS-II module go bad when I fired Big Blue's engine up for the first time last year. Got it to run for the needed 20+ minutes to break in the cam, but it wouldn't rev past a certain RPM so I just babied it. It ran, but horribly, so once it was broken in I swapped out the box and the engine ran fine. Link to comment Share on other sites More sharing options...
ctubutis Posted June 27, 2021 Author Share Posted June 27, 2021 I had a brand new DS-II module go bad when I fired Big Blue's engine up for the first time last year. Got it to run for the needed 20+ minutes to break in the cam, but it wouldn't rev past a certain RPM so I just babied it. It ran, but horribly, so once it was broken in I swapped out the box and the engine ran fine. Found my spare DS2 box (in a plastic Truck Box behind the seat, contains spares & tools & such) so I'll go back to the truck tomorrow, I guess. The other component is that distributor PIP thing. But the DS2 is easiest to swap out. Matthewq4b & Ken Blythen on FTE are saying basically the same thing, go after the ignition. Tomorrow; the rest of tonight is SHO air conditioning compressor. :) Link to comment Share on other sites More sharing options...
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