Jet Selection for Bored HW 5200- IT RUNS GREAT FINALLY!!!

[MercuryMarc]

OK- I got the ventruis bored from the standard 26/27 mm to 30/32 mm (see the post at: http://fordsix.com/forum/viewtopic.php?t=36105 ).

Pre-boring I ran it with
Prim Air Bleed 180
Secd Air Bleed 180
Main Primary 160
Main Secondary 160
Prim Idle 60
Sec Idle 80

Ran OK a at idle, not much middle or top end power.
I also have some other jets on hand
Air Bleed 150 and 170
Main 132 , 133, 135, and 140

Any suggestions for my initial jet selelction?
I am sure I'll have to buy some new ones to play with.

Thanks!

 

[xctasy]

You may find the car runs better with 160's that are in there, so try them first!

If that doesn't work okay, then just go up in proportion to the increase in venturi.

I always use proportion from known combinations, as it is unlikely to get you into trouble.

According to Dav Vizard and Pat Braden, all tune-up manuals on Webers suggest a baseline start with the main and primary jets around 1/20th the main or primary diameter. So 1/20th of 29 mm is acutally 1.45mm, or 145 microns.

The metric system has some quirks in it, so for your sixes, just take the venturi diameter and multiply by 6. On 4-cyl's, multiply by 5.

If you go through all Ford's Pinto 2.0, 2.3 and Cologne 2.6 and 2.8 jet settings, they were all set up for engines with about 83 to 100 hp net, and generally were about 1/20 th or so. You find the base jet sizes for primary and secondaries with the stock 26/27 venturis is about 4.8 times. On a six, the engines are pulling more vaccum, but not significantly more power. As an example:


Stock 26 = 130
and 27 = 135

So moddified to 29 =145
And 31 =155.


As you increase venturi size, you get less suction, and so need to use a little more jet size.

If you've had to run 160's to get it to run right, then go up to 178 and 184. You'll have to use the RougeS jet interchange graph to source these.

Jets sizes from a 38 DGAS on a European 135 to 140 hp Renault R30 or Capri 3000 will be fine. You must change the air correctors by proportion.

The jets for the 34ADM and ADF were about 157 and 200, from memory for a 121 to 138 hp net. That was with two 29 mm venturis.

That should get you in ball park for 130 or so hp.

 

[MercuryMarc]

Thanks for the great info!

 

[MercuryMarc]

Got the carb in and ran it for a test tonight-
WOW- what great top end oomph!!!
Feels like a passing gear when the secondary throttle is opened up!
Idles fine (1 3/4 turns out) on the idle mixture screw - just roughly did it by ear. Soon will do it with my tachometer. I'll run a tank of gas then check my MPG but so far so good- seems to be a vast acceleration improvement with the same jets
180/180 air bleeds
160/160 mains
60/80 idle

I might try a slightly smaller primary main and a slightly larger secondary main with the same air injectors..

Thanks for all the help and patience! I'll have to change my signature from Holley 1940 carb to bored out HW 5200 soon...

 

[Anonymous]

still using that thing X, lol, i'm too much of a traitor anymore 8)

....thinking about someday getting me an I6 bird again, probably older than the 65 to mess with.

 

[xctasy]

I'm delighted to be able to steal off you, RS. Even better, is that you still come to watch the true hot rodding here.

MercuryMarc, much of what we learn is 10 parts inspiration to 90 parts perspiration.

The precendent from all Fords 2-bbl engines over the years is simple. You can undercarb them only so much, and then you reach a super critical flow rate where you loose a lot of power. On 250 cube engines, that's always about 3500 to 4500 rpm when you run a Pinto carb.


If you work out the total cubic inches of the engine, and divided it by the square inches of the carb venturis, then you can have no more than 125 cubic inches per square inch of carby venturi. The moment you have more than 125 cubes for every square inch, the engine heals over above 4000 rpm.

A 32/36 or 5200 has 1.71 sq in of venturi stock. An ADM 34 has 2.05 sq in. Your bored out 5200 has 2.19 sq in

On the Pinto 2.0, that was 71 cubes per square
On the Pinto 2.3, that was 82 cubes per square
On the Capri 2600, that was 91 cubes per square
On the Mustang 2.8, that was 100 cubes per square
On the Aussie Falcon 4.1 with ADM 34, that was 122 cubes per square, and even with the alloy x-flow head, they healed over past 4000 rpm.
On your 250, it was 146 cubes per square with the stock 5200, and 114 cubes per square with your mods.

Plainly, just a little work with your amazing Addo-inspired tools, you've dropped the air speed a massive 28%, and given the engine a new lease on life.

Interestingly, a stock 1-bbl can be undercarbed quite a lot without problems. Later 200's had about 0.994 sq inches, and about 201 cubes per square. Your 250 would have been up to about 250 cubes per square with the 1940 Holley. I suspect the 300 sits at about 250 cubes per square as well. I think the 300 carbs had a much larger venturi.

So endeth the lesson.

 

[Anonymous]

Have to get away from the 'swarm' on the other places. I have gained a lot from being a member here.