Losing power and backfiring in 5th gear

[paulmcconnon]

The car has been running well lately except the other night it would start bucking, backfiring and losing power in 5th gear. So I kept it in 4th. After awhile it started the same stuff in 4th. A little later after doing some limping it seemed to run OK. I checked the fuel filter it was good. I recently replaced the MSD box, distributor and coil ( All MSD).
Any ideas on this hang up?
Paul

[Buzz]

You're probably loading up at extended low rpm cruising and fouling the plugs. If you cruise slowly for a long time in 3rd, does the same condition appear? You may be running a bit rich or your initial timing may be off a few degrees. I have experienced similar symptoms and adjusting the mixture and fixing the timing set everything right again.

[vettestr]

Maybe first check should be starting engine in garage with hood up so you can see all plug wires. Do this in a darker area so you can see any misfires or voltage leaking from wires while running. Use a wooden stick to move wires a little so you do not get zapped but look for sparks jumping to any metal surface. DO NOT gas yourself in garage but a short test in darkness or do it at night in driveway tells a lot. Shorting wires will cause a stumble at loaded cruise RPM for sure.
Check the total timing, that is above 2500 rpm so check at say 2800 to be sure. Verify initial timing while you are there. I would look for numbers in about the 10 to 15 degrees initial and 35 to 39 degrees total. If you do not have a degree'd damper that shows 40 + degrees then masking tape and a mark the same distance as what is marked will get you close. An advancable timing light is worth its weight in gold and maybe a great reason to go get one now! I like the Craftsmen from Sears for bang for your buck.
You said it is a new install so verify coil polarity. Look for spark quality by removing the easiest to get to plug wire and put an old plug in it if you have one, then start with this wire and plug laying on intake so you can see plug fire. The color should be a neon blue, if it is a yellow or orange the coil is probably bad on a MSD system.
I have even money on it being wrong total timing or a bad wire or 2. Let us know what ya find.

[Jerry Clayton]

your probably running out of gas

[xlr8or]

When checking voltage leaks on the wires in the dark make sure you check the coil wire as well. I had a coil wire come loose in the coil tower and basically baked the tower to the point that it was shorting out on the mounting surface.

[paulmcconnon]

vewttestr,
Could you run me through how to set initial and where to set the dial and where to turn it at 2800 to look for final setting?
Any specific instructions would be most appreciated.
Paul

[vettestr]

Paul,
Sure I will try to help.
Clean and timing tab and damper. Mark each with a dot of fingernail polish stolen from wife (white or red works best). Remove and block vac line if you have feature on your distrib. Have pen and paper handy to record readings.
Start and idle engine, use wheel or knob on timing light to return timing marks to read zero or TDC. Now record the point or display on the timing light that it took to bring marks to TDC on engine. This recorded number is the initial or static timing.
Increase engine RPM to say 2500 RPM and repeat above. Turn wheel on light until engine marks return to TDC. Record this number as Total Timing.
To record or chart your timing settings record the RPM and reading on timing light it took to zero engine display every 200 RPM from say 1600 RPM to 2600 RPM. This will chart your initial timimg and how much and when you reach total timing.
Most modified engines like initial timing to be (12 to 20 degrees) and to have full mechanical timing added or be in by about 2200 RPM. Modified engines love initial timing and will increase performance to a noticable point. My engine likes 18 degrees and total is 39 degrees with it all in by 2300 RPM.
If you increase initial it will also increase the total so please check total timing. Too much initial will cause pinging or predetonation. Too much total will hurt rings and engine so CHECK IT. Mechanical timing can be changed by replacing springs or fly weights and MSD also uses COLORED bushings to change settings. It is easy to do it just takes time and a little work.
All engines like initial timing, how much depends on your cam and many things but bet you can use a little more. This belief works for me and just my rule of thumb. Each engine is different so not a perfect number without trial and error on your engine will tell but the above is how you record what you have. Have fun jeff c

[vettestr]

Well Paul?
I wrote the step by step twice because I lost it the 1st time before sending. I took care of another issue and came back to a sleeping computer. Just like me it was in a new world when it woke up.
What is the outcome, is your baby all better now?

[paulmcconnon]

Final resolution--

Had a spark plug wire off. Replaced it and another one popped off the next day.
The timing was just a bit off, I adjusted it and kaboom!! hauling ass again.
Paul

[Jerry Clayton]

It was common that the ford engines in the mid 60s would have the plug wires pop off the plugs--the fix was to take a ice-pick and poke holes in the plug boots to relieve the pressure build up that caused the wires to pop.

I know it sounds wierd, but its a true story.

Jerry

[Michael C Henry]

The higher the gear the lower the misfiring would start sounds like carbon fouling on the plugs. I had a friend in 69 that had a GTO that acted that way. Change the plugs and off it would go.