i´m new here, my name is Tom i´m 27 years old and i am from Austria.
I´m driving a 68 Mustang convertible 302cui 4V with the Autolite 4100 1.12
Which jets do you guys recommend for this engine?
At this time i´m still driving with one 54F on primary side (the other one is unreadable)! On the secundary side is one 62F and one 54F (i dont know why there are two different jets on ONE side!!!
Which jets should i use for economy drive with enough power???
And where can i buy them???
Thank you for your help
Best regards
Tom
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...these days, so I will tell what I know. A 1.12 4100 is way over carbureted for a SBF. The jets sizes are not the only issue that determine the suitability of a carburetor for a particular motor size. Aside from the booster sizes, there are ports and passages in the body castings that you cannot alter.
If you read back for a number of postings, you will see many statements on this subject.
Be that as it may, you should post the carb number (found on the left front mounting foot, and someone could tell you what the carb was intended for.
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So even though your carb was designed to work on a 352 or probably 390, you might be able to trick it into working on your 302. I don't know, maybe I'm the dumb one; but those jets seem very big for any engine. Example, my 4100 1.12 has 48 primaries and 57 secondaries. If your up in the hills with the music, you'd probably want to drop that further to 47/55 or something like that.
Problem is though - Old Ford jets are hard to find even over here; won't be any easier in Austria. Ebay?
Check the power valve too. I think 6.5 was pretty standard.
Also, check the FE forum - lots of 4100 guys over there.
OR - easiest yet, find a different carb.
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Yes carbs are dumb to an extent, and some carbs are dumber than others. The problem especially with the Autolite is the feedback it recieves from the engine vacuum reacts with the annular boosters and the venting and porting within the venturi area. Now all of a sudden you have a smart carburetor. And it is going to react to that pull from the engine in the way that it was intended to act. Unfortunatly now you have a carburetor that was intended for a completely different cubic inch and style of engine. That 302 acts completely different than a FE ford when under loads and under throttle.
Not only that but your carb was intended to make power for a very large and heavy car.
How good you are at "tricking" it really depends upon what application you are presently using it in and how your driving style corolates to the origianl application.
Unfortunatley these days most people are putting 1.12 carb onto mustangs and expecting to drive them like carrol shelby, and you end up with all sorts of drivability problems, to them make matters worse these carb experts then decide to start modifying like they were Roger Penskes, without a clue of what they are doing and most often they start with the jetting and go from there until the carb is so out of wack guys like Ed or I end up with them to straighten out.
Of course in the meantime they have badmouthed the autolite, installed their buddies 750 holley, or added a manual linkage to the autolite secondaries so it will open.
Ah.... I digress.
My advice get another carb preferably a 1.08. or one that is a closer match to what you application is.
Bill White
White Automotive
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Bill and the others have a point, it is dangerous to mix carbs, they might never run right. I've tried about a dozen 1.12 4100s on our 289 Mustang, 3 or 4 of them run super good. That means, they start and run good, fry the tires with a 3.00 geared stock automatic, and return 60ft and 330ft times as my computer predicts. It runs GOOD, and gets 20mpg on the road.
But again, that is only 3 or 4 out of about 12 carbs we've tried. The little 289 just doesn't "like" certain of them as they are all big block carbs (352-390-410-428).
One of them that runs best is a c4af-r, also a 352 carb but from 1964 instead of 1965 like yours. The stock jets which are in it are 48F primary and 58F secondary and it runs good. I might go to 47F primary but have not tried this.
Also, the booster assy is a "G" in the primary, and most likely a "B" or "BA" in the secondary. Which primary booster you have makes a big difference.
I show your c5af-h carb as a 390 automatic carb, came with 49F and 60F jets.
To look for jets, you might try any later Autolite/Motorcraft 2-barrel carb, they used the same style of jet, just look for the size you need.
I agree that a 1.08 would probably work better but they are hard to find even over here, let alone in Austria.
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I thank you guys for the fast help.
I couldn´t imagine that there are so many parts to consider.
After your helpful opinions i think you´re right and it´s the best decision to look for an other carburetor.
I really prefere the Autolite 1.08, but if i don´t find one, is there any other carburetor you can recommend?
For example Holley.... which model is the best for street use with power at low RPM?
I don´t think that an Edelbrock is the right choice.....
Do you prefere 4bbl or 2bbl?
There are a lot of different opinions about that and i´m far from expert!
Some say that a 2bbl (for example the Holley 2300 500cfm) has more power at low RPM instead the 4bbl....
What do you think about this?
This message has been edited by 68-302 from IP address 90.152.232.37 on Jun 18, 2009 11:16 AM
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Tom,
The only folks I know that would prefer a 2bbl to a 4bbl is in class racing where they have no choice. Otherwise, if you get a big 2bbl the big barrels will be soggy and unresponsive down low. So I'd stay with a 4bbl.
As for which one, other than the 1.12 4100 or the 1.08 4100 if you can find a good one:
I've had good luck with the Autolite 4300 on big blocks but not on the 289. On the 289, it is well behaved, starts good, runs ok, but will not clock as fast as a good 1.12 (or 1.08) 4100.
I've also had good luck with the Edelbrock/Carter/Weber "Performer" 600cfm carb. A bit big for your 289 though. Edel makes a 500cfm version that they say is just like the 600cfm except it has bigger (more responsive) primary boosters. Might be just what you need.
Summit Racing is remaking their clone of the Autolite 4100, not sure if they make a small one or not. I have not run these so can't comment directly.
As for Holley, the closest one you could get would be the Holley 450cfm. In fact, as List 4548 d0pf-u, this was a Ford part number service carb replacement for the 4100/4300 Autolite. It would run good on your 289 - a little less MPG than an Autolite but it will likely run faster, that is my usual experience. I think Holley still sells the 450cfm.
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Thank you for your expirience!
I know the new Summit carburetor and i think it´s a great agreement between Autolite and Holley but there is only the 600cfm aviable.
If i consider the things you say, the Edelbrock is maybe really not so bad.
Here in Austria and Germany it´s verry difficult to find detached opinions between Holley and Edelbrock.
We have Fans from both.
We also have a lot of Fans of the 2bbl Holley, thats why i asked.
The Mustang is with the stock suspension no race car, so i need the power at low RPM, i infrequently drive faster than 70-80mph!
I´ll keep my eyes up for a good Autolite 1.08
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There are a lot of carbs out there, especially on ebay, that are misrepresented or have been altered in one way or another, ie boosters, jets, linkage, etc.
There are also 1.08 carbs out there that were made for big block fords to satisfy California emission requirements. You do not want one of those. There were also 1.12 jack of all trade parts department replacement carbs that could be shown to be for small blocks. You do not want one of those either.
Do not hesitate to ask what the jets sizes and booster numbers are if you find a carb that should be suitable. If they don't want to 'bother' to look for you, then look the other way.
Don't hesitate to post on the forum any question you might have for an aquisition.
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They still do make it. A great little carb. I just sent an old tired marine 4160 450 cfm back to Holley and bit the bullet for their rebuild. It came back real pretty. Don't know how it runs yet as I have not swapped intakes on the boat motor.
I have another boat (slightly larger) with a 5.0 roller cam (69 351w profile) with GT40P heads, edelbrock intake and a Holley marine 4160 600 cfm carb. That motor is a screamer but it is signifigantly hotter than the stock marine 302. I would not want to run a 600 cfm on the stock 8.0:1 marine motor.
As much as I like Holleys, I am trying to get my 4100 together to swap out the 2100 on my stock '65 289 Mustang. I want to stay original on that one.
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HAVE A NICE DAY!!!!