Saturday 11 November 2023

Engine flooding / running rich issue.

Engine flooding / running rich issue.

I have been chasing an intermitant issue with my Motorcraft 4300 (square bore) for a few months now.



It would start up fine and run with no issues. Then I head out on the highway and after a number of K's down the road (I'm in Australia so no miles here lol) I would back off and the thing would run very rich (I have a O2 sensor on one bank of the exhaust). Normally it runs lean heading down the highway but when it starts to play up, it would run very rich and start to miss fire and blow smoke and at idle all be it a very rough idle.


I know the carby is fine as I purchased it fully restored and rebuilt (by a carby expert). 

I also rechecked the float level.

My car is a 351C H code that I converted from 2V to 4V using a local "small port" 4v inlet manifold to match the 2v heads.


I also rebuilt the distributor as its vacuum advance was sticking.


In doing some research I found a few video's talking about the secondary inlet valve on these carbs is known to be a problem as it is only held by gravity. Also they are prone to issues when fuel pumps are feeding at a higher pressure than the base 5 or 6psi. Last year I replaced my original 1972 factory one with a stock replacement so I suspect it is pushing a little more than 6psi.


I found this video that talks about the secondary inlet. See from about the 5:30 min mark.


- https://l.facebook.com/l.php?u=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DcxN1OxF9858%26t%3D479s%26fbclid%3DIwAR2Xl1T23Yt8s-rg64Fb5DqbfB8utdzyy5C_MQxTpnHbFjc33Lom1QxgHPg&h=AT0uys9ymYRmHxCM5NlAPybp6JYfnaih9OlkEoqavKL4cxSgg-Mz_OYc0M-ZUtz24bVze1GQMlMrCcpHMMkM2QqC_jjaa33PMYZxwjgBzcJJsBuW7-2N_DHuqLsW5Cta7nSfHQ


As the car is a driver and not a drag racer (stock FMX trans, 2.75 diff etc), I felt that if I follow the advance then I wound have any issues as I am unlikely to be driving the card hard enough for the fuel in the bowl to run out!


Basically the advice was to either replace the secondary inlet valve with a bung or block up the factory one.




From https://www.carburetor-parts.com/75-45 (Mikes Carburetor Parts)




I opted to modify mine my removing the needle and soldered up the hole.

To do this I found a small screw that fit in side the valve snugly and then proceeded to add solder.

As the valve is brass the solder adhears to the brass nicly and a standard soldering iron with a fine tip did the job.


I then reinstalled into the carb and reinstalled back into the car.


I have now been on 2 drives trying to make the engine play up as it was before the change and thankfully, it no longer seems to have the issue.


Of note, when I parked the car after a drive before the change, the garage would always smell of fuel. Now it does not.


I suspect a combination of a slightly higher pressure new fuel pump (stock off the shelf type) plus the gravity design of the needle in the secondary value was the cause of the issue.


I can now comfortably drive it on long runs with out the concern of it failing and or playing up.

Mustang round up

 Mustang round up in Dandenong

This year I attended the Mustang round up hosted by the Mustang Club of Australia (Victoria division).

Had a great day with over 450 Mustangs on display.

























Plenty of cars to see!


New stripes installed

 Stripe install complete

The stripe install is finally complete just in time for the mustang round up hosted by the Victorian Mustang Club.

As part of the install, I also purchased the lower stripe kit.












Now onto the show!



Monday 2 October 2023

Stripe removal and replacement

 Those damaged stripes have to go!

One thnig that has bugged me for a while has been the misalignment of the stripes and the fact that they are damaged / perished in parts.

I decided that I would remove the old stripes and then install some new ones.




As can be seen, if you stand back the stripes look ok. But on closer inspection, they are damaged in a number of places.

Well, the removal process did not go so well or as simply as I thought. I managed to remove the main part of the sripes with a heat gung but they perished as I pulled them off.

What was left behind is the main issue. According to a car painter friend, it looks like when they repainted the car with acrylic they did not let the paint dry and set properly and installed the stripes. This then sucked some of the adhesive into the paint and left a nasty tell tail glue behind. Add to that, a good 30 + years of California and Texas sun baked the glue into the paint also. This is what was left when I removed the stripes.





After a heap of trial and error... I found a process that worked that did not effect the paint on the car. That is, leave the car out in the warm sun for a number of hours, then start with pure eucalyptus oil to get the soft parts off. The eucalytus softened parts that I was able to then scrape off with my finger nail.

I then used an adhesive remover that was a bit stronger called Zof. This worked well to soften some of the glue, then again I used my nail to remove the soften parts. Then finally I found a product called Goo Off from the local hardware store. With some careful and persistent rubbing this removed the remained. But this time I did not use my nail as the goo off softened the paint a but and my nail could then scratch the paint.

This is the final result.





Upon close inpspection, the lines can be seen due to the hot sun fading the paint around the old stripes. The next step is to cut back the paint using a cutting compound to remove the rub marks and install the new stripes.

Needless to say, my right pointer finger is worn out. I ended up getting some thick dish washing gloves and cut the finger off the top of the glove and used that on my finger like a old fashioned rubber thimble. This saved my finger from the chemicales but still have a few blisters from all the rubbing over many hours.

I picked up some locally made stripes in Mildura about 12 months ago but they had been sitting in a warm shed for a number of years so I ater found out that they are not useable.

I purchased a new set of repro stripes from Griffs in Ballarat and will install the new ones at the right height once the cut and polish is done.

Stay tuned.


Wednesday 6 September 2023

Distributor rebuild and install

 Disy reinstall

Now the distributor has been rebuilt and recurved to suit more modern fuels, it was then time to reinstall.

Here are a few pictures of the freshly rebuilt distributor with the Pertronix I reinstalled and ready to fire.

The unit has been adjusted to run at 10 to 12deg rather than the factory 6deg and the mechanical advance has been recurved.




  The units is now installed and the engine is purring nicely.

Saturday 8 July 2023

Annoying intermittent misfire

 Intermittent issue.

For some time now I have been chasing an issue where, after a long run, I would slow to a stop or a roundabout and the engine would start to misfire and stall.

I had checked the carb to ensure it was not leaking fuel.

I checked the plugs and plug leads with no obvious issue.

I checked the voltage on the Pertronix electronic points to make sure that the coil and points were getting the right voltage. I did find an issue here and rewired the ignition system to use a relay to supply full 12v to the Pertronix coil and made it look factory.

I checked the timing and vacuum levels.

The issue was impossible to "make" happen and was intermittent.

I installed an O2 sensor on the exhaust to see what was happening.

When it happened the car would run mega rich and stall but would rev no problem.

Last week the issue happened again and this time with the O2 sensor I could see it want from a slightly lean 15.9 when driving at 100KM/h to 10 and would not move from 10 no matter what I did.

I was able to limp the car home and set about diagnosing the issue.

In talking to my great mate Nev, we determined that the issue must be timing and probably the distributor as this is the only thing I had not changed. Other than going from stock mechanical points to the Pertronix.

I gave the internals a good squirt of WD40 and checked the vacuum advance was working.

We determined that the distributor needed to come out and he would loan me one while I get this original one serviced.

The following are pictures of the distributor when I pulled it out. YUK is all I can say..

On the surface all looks ok.. Right.??


Well no, I pulled the distributor and thought that the base had been broken. It looked that bad!



After a quick wipe, the crud came away to find that all was well at it was just 170,000km of crud!

I then removed the Pertronix to find that vacuum advance plate to be very rough and caked in crud!

This is the underside of the vacuum advance plate.

This is the top of the vacuum advance pate. I was actually able to make it stick while still in the distributor. So I think we have found the problem.

Here is the distributor with out the vacuum advance plate. The liquid in the bottom is just excess WD40. I then cleaned this out.

I ahve reassembled the unit and taken it to Nev who will take it to Performance Ignitions in Nunawading to be rebuilt and adjusted to make better use of modern fuels.

Nev has loaned me a Bosh unit that were used in Australian built Clevelands while mine is repaired.
I could have cleaned it out myself, but figured it is better to get it serviced and retuned.

Looking forward to getting it back.



Engine flooding / running rich issue.

Engine flooding / running rich issue. I have been chasing an intermitant issue with my Motorcraft 4300 (square bore) for a few months now. I...