jet sizes on an autolite 110o carb?

[trashline]

im jetting my carb any ideas on a good jet size? i have 67 in there now what do you think ?

 

[xctasy]

I am totallt unaware of the power enrichment circuits of the Autolite 1100.

Un uneducated guess, based on some flow figures I have follows.

It would seem that all Ford's Autolite 1, 2 and 4-bbl jet sizes are similar to the Holley 2300/4150/4160 jets. If that is the case, then one 67 jet is in fact good for about 78 hp flywheel, or about 98 gross in the old money. I'd say it is a 170 carb?

However, Ford may have an auxhillary richening circuit, which may augument the supply of gasoline by another 5 or so hp.

Single jug carbies are simple to tune. There are less variables. Only thing is, Ford have some very specific vacum hoses and rough running problems can occur with these, as well as hot fuel handling problems. The only way to tune it is by testing the actual aie/fuel ratio at the exhast at peak operating temperature. A 13:1 ratio using the older gas anaylsers at wide open throttle, with a lean back to around 17:1 under part throttle cruise at 60 mph is recomended.

 

[trashline]

so you think i should go one size up or stay were im at or even go down?

 

[xctasy]

I'll wait for someone else to respond, but here is my lengthy opinion.

Please don't be alarmed at all the math and rules. You don't have to understand it all!

Here are the flow ratings for each jet 'call size'.

285 cc/min or 60 thou nominal, 60 call size jet
298 cc/min or 60 thou nominal, 61 call size jet
311 cc/min or 61 thou nominal, 62 call size jet
325 cc/min or 62 thou nominal, 63 call size jet
341 cc/min or 64 thou nominal, 64 call size jet
357 cc/min or 65 thou nominal, 65 call size jet
374 cc/min or 66 thou nominal, 66 call size jet
392 cc/min or 68 thou nominal, 67 call size jet
411 cc/min or 69 thou nominal, 68 call size jet
429 cc/min or 70 thou nominal, 69 call size jet
448 cc/min or 73 thou nominal, 70 call size jet
470 cc/min or 76 thou nominal, 71 call size jet
492 cc/min or 79 thou nominal, 72 call size jet
517 cc/min or 79 thou nominal, 73 call size jet
542 cc/min or 81 thou nominal, 74 call size jet
566 cc/min or 82 thou nominal, 75 call size jet
587 cc/min or 84 thou nominal, 76 call size jet
615 cc/min or 86 thou nominal, 77 call size jet
645 cc/min or 89 thou nominal, 78 call size jet
677 cc/min or 91 thou nominal, 79 call size jet
703 cc/min or 93 thou nominal, 80 call size jet
731 cc/min or 93 thou nominal, 81 call size jet
765 cc/min or 93 thou nominal, 82 call size jet

Rule 1: Peak fuel flow Rule I am of the opinion, from all the information searches I've done, that each cc per minute flow can be multiplied by 5.5 to get the flywheel HP the engine should produce.

So I'll answer you question by asking you one. How much HP do you think the engine would produce if it was idealy jetted?

If its 100 hp net (which is 125 hp gross) then use 100 times 5.5, or a 550 cc/min jet. That should make a 74 call size jet.

Rule 2: The ideal jet size rule is the throttle venturi diameter divided by 20. Since I don't know how big an Autolite 1100 is, I don't know the ideal jet size. If the jet gets too big for the venturi size, it won't atomise properly, and will not meter its fuel right. I think most 1100's ran 1 inch venturis, which suggests a 68 thou jet diameter, or a 67 call size jet.

Rule 3: The ideal carburation rule This is a simple square inches of carb venturi verses cubic inches of engine capacity rule. Little base model Falcons and Mustangs in the 1960's were the most under carbed engines on earth. 351Clevelands with 780 cfm Holleys or Autolites were the most over carbed engines. The sixes often had about 1 square inch of carb venturi, and this served 200 cubes of engine. Hotter Small block Ford V8's had only 50 cubes of engine for each 1 square inches of carb venturi. When you have a small carb on a big engine like we do on our sixes, we can often go for a bigger jet than the venturi diameter divided by 20 rule. So you may be able to go over the 67 jet size you have by a considerable margin.


Important Note:-

Some believe these formulae over jet engines as they are of the opinion they don't allow for the extra squirting of the power valve channels. The forumula does incorparate this, so it will be very close. However, some engines have very big power valve channel restrictions, and these can make these selections I suggest too rich. So the idea is to find the likely maximum size jet, and try jetting upwards in small degrees by road testing and then gas analyser checking until you get it working well.



There's a bit in it, you can check this thread if you want to get confused! Already, I'm checking just how much the power valve enriches the high rpm fuel supply.

http://fordsix.com/forum/viewtopic.php?t=8106

http://fordsix.com/forum/viewtopic.php?t=7015

 

[xctasy]

Please check this.http://www.tffn.net/1960.html

Autolite 1100/1101 1 Barrel:

This was introduced in 1963 and was used on all 144/170 and 200 cubic inch engines. Ford made different venturi sizes for each engine. All carburetor bores are 1 and 7/16 inch. A teflon type insert is placed in the bore to adjust the true venturi size. The 144 used a 1.0 inch, the 170 a 1.10 inch and the 200 a 1.20 inch venturi.

Notes on the autolite series

*All of these were manual choke until the 65 model year.



Identification:

*On this model the engineering number is stamped in the base area near the throttle shaft arm. If you can’t find a number use the below rules.

Through 1967 production year- manual trans cars had one diaphram on the side of the float bowl. Auto trans cars had two-the second acting as an anti-stall dashpot.
Locate the area where the spark control valve is. (Passenger side towards rear of carburetor) Presence of spark control valve means 1963-67, no spark control valve means 1968 and 1969 (or 1966-67 California Emissions)
Remove the top and measure the venturi diameter. 1.20" means 200 C.I., 1.10" means 170 C.I. and 1.00" means it’s a 144 unit.
Note: The final authority on Ford carburetors is Pony Carburetors,2001 Delphi Road, New Woodstock, NY 13122. They make an excellent pocket sized guide which lists all the engineering numbers and list numbers. They also rebuild carburetors. Plus if your numbers are not in the book they can find out what it is and whether or not it can be used on your application.

 

[MustangSix]

Great calcs, X! Let me throw in just one more little thing to consider. A jet will flow a calculated amount of fuel, but that is at a particular pressure drop. The pressure drop is proportionate to the amount of airflow across the venturi. The carb is actually sucking fuel thru the various circuits. The principle is pretty much the same no matter what kind of carb you use. However, some carbs are far more efficient than others.

Depending on the type and position of booster, the shape and finish of the venturi itself, emulsion tube design, air correction, etc., there may be significant differences in the pressure drop encountered from carb to carb even a the same airflow.

Because you are dealing with dynamics inside the carb throat, there will be a airflow range where the carb works well. At one end of the limit, the carb will be too large for the application and the airflow will be too low to generate sufficient pressure drop to overcome the restriction of the fuel passage. On the other end of the limit, the air flow may approach Mach, setting up a shock wave that shears past the venturi, again halting fuel flow.

There are practical limits, but that would still tend to give you a range of fuel flow and not necessarily a set number based on jet size. Different carbs may approach these limits in different fashions.

That's why some carbs can deliver improved hp and fuel economy over another design even with the same size jets. It may be simply be more efficient.

I think your chart is a great guide to offer a starting point. If you grab a 4bbl Holley of the shelf, it will probably be jetted wrong. Using your chart would allow you to select a reasonable starting point.

 

[addo]

If you grab a 4bbl Holley of the shelf, it will probably be jetted wrong.

How true. They should sell them without jets, and only after discussion with a tech line, supply you with some...

 

[simon]

One stupid question:

Where do I get jets for autolite1100 carbs? Carter RBS?

Everywhere I asked I was told "Sorry man, outta stock, and outta production as well. Can´t help ya"

 

[trashline]

whoooo a boat load of info. got to the point quick. im not positive on the purchase of jets. i thought they were all the same. theres a carb place by me ill go and ask them. let me know what jet sizes you want and if they have them il let you know. ok so now from what ive been reading i think im gonna grab sizes 68 - 80 but il do every other im hoping there not expensive but i want the best performance out of this carb. also anybody looking on info about this stuff the falcon 6 performance handbook is a great purchase.