Loss of power, torque, dead spot, hesitation whatever you want to call it! (1 Viewer)
- Thread starter LandoNick
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- #82
I have the emissions vacuum map I can not for the life of me figure it out
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- #83
I’m at 700 feet
cwwfj60
Supporting Vendor
I am still following along, but a little lost at this point….is the only issue pinging under load?
The smaller outboard vacuum actuator on the distributor shouldn’t have any vacuum applied to it below 4000ft elevation as @g-man stated.
Since you’re at 700 ft elevation, pull the vacuum hose off the smaller outboard distributor vacuum actuator and plug that hose. When that diaphragm gets vacuum, it advances the timing another 6° which you don’t want at your altitude. It would definitely cause pinging.
The fact that there is vacuum at that hose at idle at your altitude means either the vac hose routing is wrong or the HAC valve is wacked.
Since you’re at 700 ft elevation, pull the vacuum hose off the smaller outboard distributor vacuum actuator and plug that hose. When that diaphragm gets vacuum, it advances the timing another 6° which you don’t want at your altitude. It would definitely cause pinging.
The fact that there is vacuum at that hose at idle at your altitude means either the vac hose routing is wrong or the HAC valve is wacked.
g-man
SILVER Star
it helps to under stand that the dots that are numbered 1 thru 12 represent the ends of the cluster of vacuum pipes near the carb. Just below the 12 dots is a corresponding list of where the vacuum hose from those ports is to go. the upper right corner is a picture of the side of the carb that faces the valve cover each of these hoses connects to a vacuum pipe that should be stacked in the same order.
g-man
SILVER Star
You should follow the vacuum piping on the secondary or outer dizzy advancer port to see where it goes. It should go to the HAC valve. If it does you may want to test the valve. You may find it goes directly to vacuum source ...like the 3 pronged gas filter on the intake in front of the carb. This would be wrong.
g-man
SILVER Star
Here's how the secondary vacuum line is routed.
g-man
SILVER Star
Ok...it does sort of go to the gas filter as it is "T"d off to it. But when it goes to the HAC valve port B is closed and port A is open. This closes vacuum to the dizzy. If you go over 4k ft then the bellows open in the HAC and port A closes and port B opens to pull vacuum on the dizzy advancer. The other lines coming off the HAC go to the carb to push air into the carb to assist correcting the air/fuel ratio as it gets richer with altitude. Clear as mud?
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- #90
One of the hoses to the hac was disconnected. I reconnected and did not have vacuum at the secondary. Will put it together and report back.
Blew in the one of the top hoses of the HAC no air came out the bottom so I assum in low altitude mode.
So essentially I was at 14 BTDC. ADVANCED
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- #91
All right we have some good movement. The hose that went to the upper right on the HAC re-hooked that up. Checked if there was vacuum at the secondary port on the Distributer. There was no vacuum. I then capped both vacuum ports and hoses on the Dizzy and set the Timing at 7 degrees BTDC. Took it for a drive. the ping is considerably less. Maybe just a tiny bit. so then I switched the vacuum hoses on the Dizzy and it pinged more. So drove it back and put the hoses back. checked the Vacuum at idle I was at 19 which is slightly lower then before., so I'm not sure what that means. I still have the EGR capped off should I re install the vac line?
g-man
SILVER Star
to test your modulator, you need a vacuum gauge. One that can pull vacuum. And you'll need to get your EGR valve to a working state or use someone else's truck. The 2f emissions manual shows how to test.
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- #94
Like a Manual vacuum gauge?
g-man
SILVER Star
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- #96
In related news I have an exhaust manifold leak. Now a question I have is the air rail a part of the exhaust or separate all together. Same question for the j pipe on the EGR?
In the olden days, before the new fangled dialable timing light, we had to adjust timing by vacuum gauge. We'd advance just far enough to get our best idle vacuum, back off a hair or two and take it for a drive. If it pinged, back it off another hair or two until it didnt ping.
Your best vacuum at idle will probably be too advanced. A couple inches lower is better
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- #98
ping was a little more apparent then last night. So leaned dropped, timed it at 7 BTDC. Vacuum hose installed on top of EGR to modulator. PING in 3rd and 4th under load. Pulled the hose off the EGR and capped both on the Modulator and the top of the EGR itself. Drove ping seemed worse. Drove back home change the timing to 3 degrees BTDC then reinstalled the vacuum hose to the modulator and EGR. Ping a lot lower. Came home capped the EGR and modulator, drove ping was worse then with the vac line installed. so for some reason at 7 degrees BTDC mi 60 runs lean. I'm not sure why that would be. When the EGR is capped I am under the understanding that that eliminates the EGR system? is that right. So if the ping get worse then I think my EGR is changing something. I am getting a vacuum gauge to test the EGR system tomorrow. I do think its Directly affected by the dizzy. so maybe now it time to look at the stop pin. I have the spacers coming tomorrow also. I am running 87 octane. also have a exhaust manifold leak. I don't know if that changes running conditions or is just annoying.
g-man
SILVER Star
I'd hold off on pulling the dizzy. You are not sure about stabbing it back correctly and you don't want to add to any timing issues until you resolve the one you have. AND...I'm pretty sure a lot of us have run for years with the stop pin bushing destroyed and didn't even know it. Perhaps pulling vacuum on the EGR valve with the mityvac you can get the engine to stall at idle...meaning it IS in fact opening. Have you downloaded the 2f emissions manual yet. You really should study the EGR system section and do the vacuum tests on the modulator and the VSV for the EGR.
Exhaust manifold leaks are mostly annoying but usually don't affect running. But if it's a huge leak it may be affecting the EGR valve. You know the big vacuum line that comes off of it goes to the bottom of the modulator ...that line PUSHES exhaust toward the modulator to help open the modulator valve.
I had an exhaust smell for years that I could not pinpoint. It was leaking from the air rail. A pea sized hole on one of the down pipes that goes the air injector.
The EGR pipe can be source of an exhaust leak and is usually at the flange where there are 2 studs that hold it to the bottom of the manifold and less likely but occasionally at the egr cooler. I recently replaced mine with a stainless steel SOR pipe. The flange on mine was completely toasted...bent, thin metal, you could see right through the weld cracks where the pipe is welded to the flange. No matter how many gaskets I tried or even double gaskets ..it wouldn't hold. FYI the stainless pipe is about $120 USD but the spring kit for the dizzy is $20 Amazon product ASIN B00029JLEA
Exhaust manifold leaks are mostly annoying but usually don't affect running. But if it's a huge leak it may be affecting the EGR valve. You know the big vacuum line that comes off of it goes to the bottom of the modulator ...that line PUSHES exhaust toward the modulator to help open the modulator valve.
I had an exhaust smell for years that I could not pinpoint. It was leaking from the air rail. A pea sized hole on one of the down pipes that goes the air injector.
The EGR pipe can be source of an exhaust leak and is usually at the flange where there are 2 studs that hold it to the bottom of the manifold and less likely but occasionally at the egr cooler. I recently replaced mine with a stainless steel SOR pipe. The flange on mine was completely toasted...bent, thin metal, you could see right through the weld cracks where the pipe is welded to the flange. No matter how many gaskets I tried or even double gaskets ..it wouldn't hold. FYI the stainless pipe is about $120 USD but the spring kit for the dizzy is $20 Amazon product ASIN B00029JLEA
g-man
SILVER Star
Post up some wide angle images of your engine, vacuum lines etc, both sides. Far enough away to see everything. Maybe we can pick something out that is connected wrong or missing etc.
