Timing issues

[roboconklin]

Has anyone had issues with total timing? I set the base timing at 10 btdc with the vacuum line disconnected . Then plugged the vaccine back in and checked the total ….it was 37. It’s a 429cj with Petronics plate. Done back in90’s A Freind says there is possibility a set screw in the vacuum port. Mine has a port on top and on the end. I took the sensor off the t/s that I think was a ****** system back in the 80’s. That top port is kept plugged. I sill have the sensor , but my car car is a little too modified to worry about
Anyway either the mechanical advance or the vacuum advance needs limited to achieve a 32deg total. What say the experienced ones?

 

[Sheriff41]

The 32° you're pursuing should be your initial timing plus mechanical advance all in at a desired engine RPM. Vacuum advance will be in addition to your "all in" timing. Are you using manifold vacuum for your vacuum source? If so, you may want to try ported vacuum for your vacuum advance. Your actual total advance ( initial + mechanical + vacuum) may end up being 45-50° under certain conditions.

 

[will e]

That's a little high but not excessive. As soon as you goose the throttle the vacuum advance drops as well as with any decent load on the engine it should drop the vacuum advance to zero. When you are idling or in cruise mode the higher timing is fine and expected.

Do you have a timing light with an advance adjustment? They make it much easier to determine total timing mechanical timing. You'll want to disconnect the vacuum advance, confirm the base timing and then have someone rev the engine while you watch the balancer with the timing light. When it no longer advances (moves around), which should typically happen before 3000 RPM, dial the timing light to determine your total advance. Once you know that value you can then rev the engine slowly until you reach that advance. That's the RPM that you will be 'all in' with initial and mechanical.

 

[roboconklin]

The 32° you're pursuing should be your initial timing plus mechanical advance all in at a desired engine RPM. Vacuum advance will be in addition to your "all in" timing. Are you using manifold vacuum for your vacuum source? If so, you may want to try ported vacuum for your vacuum advance. Your actual total advance ( initial + mechanical + vacuum) may end up being 45-50° or more under certain conditions.

That sounds correct. It does go way up after I rev it from the 3k where I check the total on the way down to idle. I’ll try the ported vacuum source on the front base of my Holley carburetor. I’ll get out the vacuum gauge and verify the source it’s hooked to. It kinda has a tip in slight sure and is running hotter than it did 12 years ago.

 

[cjstaci]

36-38 degrees total would be okay for an iron head 429, unfortunately, todays fuel probably won’t allow it if you’re running 10-11:1 compression. On my 429, I ditched the vacuum advance and am using a Mallory unilite with total timing at 34 degrees and depending on the fuel it can still ping. Today’s pump gas sucks. Most contains 10% ethanol which is hard on hoses and gaskets. Google ethanol free gas and you can get a list of stations in your state that offer ethanol free gas. Race fuel is an option but it’s so expensive and at 8 mpg, I would have to sell the car to pay for the gas. Another option is aviation fuel. It’s been a while since I’ve used it, but I did a 50/50 mix and it seemed to work well. Smells good too.

 

[70cobrascj]

Has anyone had issues with total timing? I set the base timing at 10 btdc with the vacuum line disconnected . Then plugged the vaccine back in and checked the total ….it was 37. It’s a 429cj with Petronics plate. Done back in90’s A Freind says there is possibility a set screw in the vacuum port. Mine has a port on top and on the end. I took the sensor off the t/s that I think was a ****** system back in the 80’s. That top port is kept plugged. I sill have the sensor , but my car car is a little too modified to worry about
Anyway either the mechanical advance or the vacuum advance needs limited to achieve a 32deg total. What say the experienced ones?

Make sure your outer dampener isn’t spinning on the inner hub.

 

[basstrix]

. I’ll try the ported vacuum source on the front base of my Holley carburetor. I’ll get out the vacuum gauge and verify the source it’s hooked to.

On holleys, the ported/timed vacuum port is typically a port on the right side of primary metering block. The baseplate ports are typically manifold vacuum. Your plan of verifying with a gauge is your best bet to verify you're connecting to the desired type of vacuum.

 

[roboconklin]

36-38 degrees total would be okay for an iron head 429, unfortunately, todays fuel probably won’t allow it if you’re running 10-11:1 compression. On my 429, I ditched the vacuum advance and am using a Mallory unilite with total timing at 34 degrees and depending on the fuel it can still ping. Today’s pump gas sucks. Most contains 10% ethanol which is hard on hoses and gaskets. Google ethanol free gas and you can get a list of stations in your state that offer ethanol free gas. Race fuel is an option but it’s so expensive and at 8 mpg, I would have to sell the car to pay for the gas. Another option is aviation fuel. It’s been a while since I’ve used it, but I did a 50/50 mix and it seemed to work well. Smells good too.

I use Race Track boat fuel for the reasons you mentioned and only 1 mile away. It is 89 octane and ethanol free . Doesn’t ping so much , but runs on 2seconds at shut down when near 200 degrees. I got Octanium by VR fuels from Autozone for $25 bucks. I could get possibly three tanks top off from one bottle. I just want to get adjustments under wraps and a good plug reading first. It even has lead substitute in it. Yes I got approved guide for unleaded fuel. Thanks for the insight . I’m mainly concerned with steady idle rpm and power. I still got the OEM distributor as I mentioned. I got a MSD unilight in my parts car’s engine 3514v/cj or boss. IDK until I break it down and identify it.

 

[Hemikiller]

When referring to "total" timing, it's the sum of the initial timing, plus the mechanical advance. Vacuum is separate and not factored into the "total" for performance purposes. Ford used ported timing on these engines. As Basstrix noted, the ported vacuum on most Holley carbs is the port on the passenger side of the primary metering block. Your vacuum advance reading is about 10° high compared to the published specs in the Ford shop manual, so something has been changed. A factory 71 429CJ/SCJ w/C6 will have a D1AF-NA distributor. Keep in mind the advance angles below are in distributor or camshaft degrees, and have to be doubled for crankshaft readings. This generation of advance cannisters has springs and limiter blocks that can be swapped out by removing the front plug, and the originals were intended to be installed in a replacement canister.

I would disconnect and plug the vacuum advance for now. Verify you have a factory distributor and that it's advance curve checks out before you start chasing other issues. The 429 Megasite has a section dedicated to these parts.

http://429mustangcougarinfo.50megs.com/ignition.htm

 

[roboconklin]

When referring to "total" timing, it's the sum of the initial timing, plus the mechanical advance. Vacuum is separate and not factored into the "total" for performance purposes. Ford used ported timing on these engines. As Basstrix noted, the ported vacuum on most Holley carbs is the port on the passenger side of the primary metering block. Your vacuum advance reading is about 10° high compared to the published specs in the Ford shop manual, so something has been changed. A factory 71 429CJ/SCJ w/C6 will have a D1AF-NA distributor. Keep in mind the advance angles below are in distributor or camshaft degrees, and have to be doubled for crankshaft readings. This generation of advance cannisters has springs and limiter blocks that can be swapped out by removing the front plug, and the originals were intended to be installed in a replacement canister.

I would disconnect and plug the vacuum advance for now. Verify you have a factory distributor and that it's advance curve checks out before you start chasing other issues. The 429 Megasite has a section dedicated to these parts.

http://429mustangcougarinfo.50megs.com/ignition.htm

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Yes it is the factory one. I did as you suggested. I set the initial at 730 RPm’s to 8 BTDC and checked it with out vacuum advance. At 3k it had 36 including the initial..so 28deg mechanical advance. I wanted 36 with vacuum on. Road tested it,and it was fine. Good power while running cooler than before. I don’t understand how I got so much mechanical advance,but 36 was the objective. Thanks for your help