Tuning stock 8a
 

Hi All,

I am trying to tune/solve problems with my 8Ba and am hoping I can recieve some guidance,

Problem one is that I have a 94 carb and it is running super rich at idle ( fumigating the shed rich), I turned the mixture screws all the way in and the engine responded very little other than idling a bit rough then eventually died after 30 or 40 secs. I do remember reading that someone had a similar issue but I cannot find the post to see what the actions where to work through. I assume it has to be float level or leaking power valve? As it must be flooding/running off main circuit somehow?

It is a brand new ( reproduction) carb, could anyone offer.

My other issue idle trying to find a good guide to
Tuning the engine in a step by step guide ( not tuned to much before) including,

1. Using the vacuum gauge and the best spot to connect, what different reading mean.

2. Setting the gap on the points, what to set at etc

3. Setting the timing, what to set at? Do I disconnect vacuum advance to set initial or leave it on etc.

Is there a good guide/page someone can suggest that is detailed on the above info or what order to do it in.

I have seen a heap of posts etc but have not found a full guide on what to do and the sequence.

Appreciate any information

Cheers

Corey

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Re: Tuning stock 8a
 

Hi All,

As to the mixture screws doing very little to nothing when screwed right in, would the float level be the first thing to check? Should be back at the truck tonight and would like to try something to fix it, or should I check something else first?

Appreciate any thoughts

Cheers

Corey

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Re: Tuning stock 8a
 

I would suspect a leaking power valve. Try this. Pull the top off of the carburetor and fill the bowl with gas. Come back and check it several hours later, If the float bowl is empty or down a significant amount, you've found the problem. Holley, in their infinite wisdom, made the later power valves look almost exactly like the ones needed for 94's. They even have the same threads and screw right into the carb body. Unfortunately, the mating surface is different and they leak badly. A lot of rebuild kits come with the wrong power valves.

That you state it is a "reproduction" carb also gives me pause. I think that a few years ago, one of the major suppliers (Carpenter or Drake?) offered some repops that were satisfactory. I have become aware that there are now some that come directly from China. I have no idea as to their quality, but the track record ain't the best.

Re: Tuning stock 8a
 

Thankyou mate,

I will do that tonight if I can and see how I go, i did read about the powervalve issues but was thinking it maybe did not apply to these but maybe it does.

I will also check the float level while I have it apart. I did have the measurement somewhere so will go find what it needs to be.

Thankyou for the advice

Cheers

Corey

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Re: Tuning stock 8a
 

So I completed the power valve as suggested, I filled to the small hole that leads into the pump shaft, over approx 2.5hrs it dropped approx 2mm. Also checked the float level which was not set correct and was to high, if this was the case would the fuel run into the hole in the pump shaft and cause it to run rich?

Cheers

Coreyhttps://uploads.tapatalk-cdn.com/202...c1fefe7e3a.jpg

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Re: Tuning stock 8a
 

Carpenter was making the quality reproduction Holley 94s, and they are / weren't cheap (I don't know if they have quit production, they are listed as "out of stock" on their website: https://www.dennis-carpenter.com/car...buretor-94-p65). I have had friends purchase the Carpenter carburetors with good results. My only complain with them is they come with #51 or #52 jets and run a little bit rich on the road.

The pictured carburetor appears to me to be aluminum, and I suspect is is the low cost Chinese offering. I have no experience with those carburetors, but I am not encouraged about the quality of the unit from the looks of the two piece accelerator pump actuation arm (original carburetors that is one piece). You may or may not be able to get that carburetor to run right.

As far as good tune up procedure, I highly recommend following Ford's directions as provided in any 1949 to 1953 car or truck shop manual. Since your vehicle is an earlier truck and you will only be following the engine part of the manual it really doesn't make much difference which manual you end up with as long as the engine tune up part is in decent condition.