Only one nippleIf there are two vacuum nipples on the distributor vacuum advance canister- do NOT use the inner one that faces up. Don't plug it either. Use only the outer horizonal vacuum nipple.
Only one nippleIf there are two vacuum nipples on the distributor vacuum advance canister- do NOT use the inner one that faces up. Don't plug it either. Use only the outer horizonal vacuum nipple.


I did exhaust and manifold vacuum tests today. I dropped the exhaust pipe from the manifold after warming it up. I could only get it to rev to 3500 in second gear, less than with the exhaust connected. (3700)Dustyford to do & check off list:
(tests and findings will be posted here for reference)
Engine Initial Timing 10-12 degrees ok
• Timing mark on flywheel damper: ok
• Engine Compression: ok
• Camshaft Degree: ok
• Fuel Pressure: 3 lbs. ok
• Distributor: run vacuum canister leak down test. ok
• Fuel: Using ethanol free. questionable
• Ignition Coil Test: ok
Do these tests in order:
1• Test Carburetor Idle Circuit:
2• Exhaust Restriction Test:
Remove Exhaust Down pipe from exhaust manifold outlet.
3• Check the vacuum at Wide Open Throttle under full load @ 3,000 rpm on the highway for 5 to 10 seconds.
To do the test:
Buy a cheap small roll of vacuum hose so you’re able to mount the vacuum gauge on the windshield with duct tape. Mount the gauge where you’re able to see it without obstructing your view.
Note:
The vacuum hose should be able to be ran between the fender and side of hood or between back of hood and near fire wall without pinching the hose totally shut.
I hope soJust for clarification: checking that the throttle is fully opened at WOT is done with the engine off.
Throttle plate was 90% open at full pedal. I adjusted for WOT. Will test tomorrowOk, what you need to check is if the throttle is opening fully at WOT.
Wedge the throttle pedal fully to the floor with something that will hold it to the floor. Then check to make sure the carburetor throttle plate is opened fully. If it is not opening fully, adjust them until they open fully then do the test again.
If the throttle plate is open fully, then your carburetor is too small. Vacuum should be under 1” preferably close to zero.
Tested again today and vacuum dropped to 1” or slightly below. Then it rose slowly to 3” during the ten second span.Ok, what you need to check is if the throttle plate is opening fully at WOT.
Wedge the throttle pedal fully to the floor with something that will hold it to the floor. Then check to make sure the carburetor throttle plate is opened fully. If it is not open fully, adjust it until it’s opening fully then do the test again.
If the throttle plate is open fully, then your carburetor is too small. Vacuum should be under 1” preferably close to zero.
It varied. I tried different speeds to start out. It started out at zero and went up every rpm. No it didn’t make any difference in performance.Do you know what rpm’s the engine was running when the engine was drawing 3 “ of manifold vacuum? (Please try to be as accurate as you can.)
More questions:
• Did the car run better since you adjusted the throttle linkage to open a 100%?
• Did it feel stronger?
• Was it faster when accelerating?
• Did it feel like it was struggling less?
Thats how I get my rpm numbersDo you have a tach?
Ok. I’ll floor it at a smooth 2500 and record vacuum at 3000 and 3500.Give us two readings.
3” vacuum. Start at 2,500 rpm’s and get readings at 3,000 rpm and 3,500 rpm’s
Try third gear.
Question:Not recently but the ‘68 does have a factory hole in the throttle plate. It came off a car with AT. Maybe that’s why. My car has a T5 now, originally a 3sp.
The presence of WOT vacuum eliminates the exhaust backpressure theory. Which you already confirmed with the pipe removal test.Ok. I’ll floor it at a smooth 2500 and record vacuum at 3000 and 3500.