All Small Six 1967 bronco 170 six vacuum test

[iSense67]

I have been having a jerking issue after the engine drives for a half hour or so. So I rebuilt the carb. My question is I am now checking my vacuums. Can someone please looked at the two videos I made and see if I am in normal ranges?

Connected the vacuum gauge to the Pcv port on carb for both tests.

1. First test was at idle after warm up and it appears steady around 17

2. Second test I increased the throttle

Do both of these tests appear to be normal performance?

My next test will be to test vacuum on the distributor to see if it advances. Any advice on that test? Following the distributor I will test the mechanical vacuum fuel pump. Any advice on that test ie pressures level and I can I simply connect to the wiper vacuum port on the pump?
View attachment IMG_4056.MOV
View attachment IMG_4059.MOV

 

[iSense67]

Another question I have is when I rebuilt the carb I noticed the power valve was sticking and I cleaned it the best I could and was able to get it to freely move up and down. But if I pushed it all the way down it stuck. It also moved right and left and stuck. So I centered it before installing but I’m thinking it could be my engine issue after warming up as it jerks and eventually loses power. I bought I compression plug and was going to remove the plug and try to clean it out. I watched the mikes carb video on how to. Any advice and also I was able to get a new plug but 1/2 but it looks a little deeper than the original. Does that matter? Here odd a photo of new plug….

 

[iSense67]

Fuel pump test questions..

Fuel pump vacuum test question….

I connected the vacuum tester at the port on the fuel pump for the wipers and it tested initially at 23 idle. When I increased the throttle it jumped up to 25 and stayed there after I went back to idle. Anything on this test if my fuel pump is the issue or is that normal? Here is a video of that test…
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[Frank]

greetings iSense67. Your engine vacuum tests looked excellent. That was with the distributor vacuum advance operational? I can't speak to the WW vacuum, but high and steady seems right.
I'll let others speak to the carb specifics, no hands-on of that model for me.
I'm not totally sure what "jerking" means. You mean, surging, power fluctuating up/down? Be sure it's not an ignition miss.
If the power valve is sticking, it will have these symptoms: If sticking shut, cruise throttle is unaffected, but engine will go lean and loose power at heavy throttle. If sticking open, light and cruise throttle will be too rich. This could cause a surging of the engine. It may produce light black smoke, so check the mirror for that. Look at the tailpipe, see if it's heavy with sooty carbon. And your mileage will be noticeably reduced. Mike's carbs has a good selection of quality parts. You may do well to replace the power piston if he has one available.

 

[iSense67]

greetings iSense67. Your engine vacuum tests looked excellent. That was with the distributor vacuum advance operational? I can't speak to the WW vacuum, but high and steady seems right.
I'll let others speak to the carb specifics, no hands-on of that model for me.
I'm not totally sure what "jerking" means. You mean, surging, power fluctuating up/down? Be sure it's not an ignition miss.
If the power valve is sticking, it will have these symptoms: If sticking shut, cruise throttle is unaffected, but engine will go lean and loose power at heavy throttle. If sticking open, light and cruise throttle will be too rich. This could cause a surging of the engine. It may produce light black smoke, so check the mirror for that. Look at the tailpipe, see if it's heavy with sooty carbon. And your mileage will be noticeably reduced. Mike's carbs has a good selection of quality parts. You may do well to replace the power piston if he has one available.

I rebuilt the carb last weekend and the power valve was sticking. So I just removed it today and I am trying to do what Mike’s video showed and I gave it mostly corrected but it still sticks a little. I removed the compression plug and cleaned that area it wasn’t bad. Sends like the top of the arm sticks on the metal ball when I push it hard.

 

[bubba22349]

Hi iSense67, I can see a very slight movement of the Vacuum Gauge Needle in those first two tests. Things I would check out that can cause that type gauge movement are the Spark Plug Gap (Has a little bit tighter Gap then it should) and the Carb's Mixture Adjustment.

Stock Factory Tune Up Specs for a 1966 & 1967 Ford Bronco with a 170 Six and a Manual 3 Speed Trans
1. For a stock Ford 170 Six with a Point Ignition with stock Autolite BF82 Plug's their Gap is set to .034.
2. Set the Point Dwell Angle to 40 Degrees.
3. With the engine warmed up good (to Operating Temperature) set the Valve Lash on the Intake and exhaust to .018.
4. The Stock Base Timing is set to 6 Degrees BTDC.
5. With the Engine Warmed Up good set the Carb's Mixture Screw to the "Lean Best Idle".
6. With the engine warmed up good then set the Carb's Curb Idle to 650 RPM.

X2 make sure to get the Ignition system in top shape and dial in it's settings first.

The Fuel Pump test Pressure should be at 4 to 6 PSI. On the Vacuum Gauge test that you did of the fuel pump, this wont have any affect the engines tune unless there is a Vacuum leak there or in it's connecting lines. This unit mounted on the fuel pump is only used to amplify and stabilize the Vacuum source for better performance of the Windshield Wiper Motor.

On the Engines Cranking Compression Test result should be at 175 PSI.

Have you tested the Coil Primary and Secondary with a Volt Ohm Meter yet?

Check to see if the Muffler Flows good too. Best of luck

 

[78_200_C4]

The 1/2" expansion plug should be aluminum. That plug may damage the carb.
Some people use JB Weld on the outside of a used soft plug to seal it.
Clean the power valve until it doesn't stick.
Check for a cracked fuel line near the tank that is sucking air.
If no cracks: Test drive it with the gas cap off.
Floor it at lower speed at the start up a long hill to see if it sputters-jerks and or quits.
New Autolite 1100 carbs can be bought on ebay for a good price but may not cure the jerking sputtering problem.
Check your point gap and point resistance or replace and gap the points.

1/2 Aluminum expansion plug 85-58

www.carburetor-parts.com

 

[iSense67]

greetings iSense67. Your engine vacuum tests looked excellent. That was with the distributor vacuum advance operational? I can't speak to the WW vacuum, but high and steady seems right.
I'll let others speak to the carb specifics, no hands-on of that model for me.
I'm not totally sure what "jerking" means. You mean, surging, power fluctuating up/down? Be sure it's not an ignition miss.
If the power valve is sticking, it will have these symptoms: If sticking shut, cruise throttle is unaffected, but engine will go lean and loose power at heavy throttle. If sticking open, light and cruise throttle will be too rich. This could cause a surging of the engine. It may produce light black smoke, so check the mirror for that. Look at the tailpipe, see if it's heavy with sooty carbon. And your mileage will be noticeably reduced. Mike's carbs has a good selection of quality parts. You may do well to replace the power piston if he has one available.

That sounds very much like my problem. I have been trying to make the power valve consistently not stick it works great but it occasionally catches. I cleaned it out wells and now have it back together. Tomorrow I will drive it and see what happens! Thank you for your insights

 

[iSense67]

In the end my problem is the fuel pump. I have electric wipers being installed so I don’t need the vacuum version that runs much more that the stock Carter replacement. That said I found non vacuum versions but I read that the cam might be different does anyone know if that’s true? More important where can I can get one? Here is a link to one without the vacuum will the cam be different than the original Carter I gave now with the vacuum?

Mechanical Fuel Pump - NO Vacuum, 170/200 6cyl, 69-72 Ford Bronco

New Mechanical Fuel Pump for 66-69 Classic Ford Broncos with 170 or 200 Straight Six-Cylinder Engines. This fuel pump does NOT have vacuum ports. It will not directly replace a vacuum style fuel pump as the fuel pump arm is shaped differently.

tomsoffroad.com

 

[iSense67]

That sounds very much like my problem. I have been trying to make the power valve consistently not stick it works great but it occasionally catches. I cleaned it out wells and now have it back together. Tomorrow I will drive it and see what happens! Thank you for your insights

Curious if you fixed your issue? If so what was it?

 

[bubba22349]

The Fuel Pumps are fully interchangeable and there is no need to change the Camshaft.