170 rough acceleration, unless choked.

I can't remember when the LOM starts to activate the vacuum port, but isn't it around this? It can be that once you fix the fuel mix, you may have to adjust your timing.

It is also possible to have the timing too far advanced which would increase idle speed. I remember this happening to me a few years ago. I would adjust the carb, timing would be off, then adjust timing and carb would be off again.

Not saying that's it...but it may be worth dialing the timing back to see, especially if you aren't 100% sure your timing mark is spot on.
 
Adam, to answer your question: 'Yes', I was able to get the idle rpm down around 550 to 600rpm, give or take. If I am not mistaken, you need to back off the idle speed to where it is not even making contact, and adjust the fuel mixture screw first to the approximately 3 to 4 turns out; and then adjust your idle rpm after you have set the fuel mixture screw. It may be necessary to have the idle screw set at very low rpms in order to keep the engine from stalling possibly (?), but I definitely would start by having the idle screw all the way out on your first try. I got this info/specs' from an older Manual that my Dad had given me many years ago. I found on a website (I believe it may have been from 'The Carburetor Doctor'?) that the number on my Autolite 1100 carb (#C3OF-9510-A) was from a 1963 Fairlane with a 170cid engine with a standard transmission. The Manual says for this particular carb, that the "Mixture Screws Turns Open" should be 3-4 turns. If you get a chance to check the # on your carb, I will cross reference the number for you to the numbers that my Manual has listed for 1963; they show about 9 different numbers for a single barrel; some of them for the 144cid engines, one for a 200cid engine, and the rest are for the 170cid engines (not counting the V-8's). Good Luck; let us know what you find out. Jim
 
Hi Gentlemen,

I did verify that the TDC mark on my balancer is dead-on. I used the "bust up an old spark plug and put a clear vinyl tube into it to make a manometer" method - and verified that indeed the mark is right on. My static timing, vacuum removed from distributor, is set at 6* BTDC.

That's all I got to this weekend. Didn't have much extra time, as I discovered that water has been seeping in from the bed into the cab - so I spent most of my available time pulling the carpet up and trying to get it dried out and sealed. Luckily there isn't much rust...yet <SIGH>.

Thanks for all the help so far, I'll update as I'm able to try more of your ideas.

Adam
 
8) since you have verified your timing marks, set your initial timing to 12 degrees initial rather than the oem setting of 6 degrees.
 
Quick update -

Adjusted my timing up to 12* BTDC and then I adjusted my idle down to 590-610 rpm by, as Jim suggested, cranking the idle control screw down until it didn't make contact and then back up just a little, I did this slowly as I turned out the idle mixture screw. It took about 20 minutes to get it right. When I was finished, the mixture screw was out about 3 1/2 turns - good call Jim. The idle's so low now that I feel like it's going to die when I stop because I'm not used to the quiet :)

I haven't tested the acceleration yet - tomorrow on the way to work maybe :)

I was looking at my accelerator pump - is there anything to adjust other than just the "hi/low" cam on there? On my old pickup the accelerator pump wouldn't do anything for the first "inch" or two of gas pedal depression - but on the engine in question it squirts with any movement of the throttle...is that normal?

Thanks again guys -

Adam
 
Adam, glad to hear things appear to be going better. As far as setting the "Fast Idle" adjustment, my manual gives a 'fast idle rpm' of "1500" for a 1963 6-170 standard transmission. It has this note as far as setting the fast idle rpm: "WITH IDLE SPEED AND MIXTURE PROPERLY ADJUSTED AND WITH ENGINE AT NORMAL OPERATING TEMPERATURE, PLACE FAST IDLE SCREW ON KICKDOWN STEP OF CAM. THEN ADJUST SCREW TO THE R.P.M. SPECIFIED" (in this case 1500rpm). Hope this helps as well. If you are going to open up your carb to check 'Float Level', or need the 'Dashpot Setting', etc., let me know and I will write the notes given in the Manual for these settings. Good Luck, James
 
Which is the 'fast idle screw'? Mine is manual choke - I'm thinking it might not have one? Does anyone have a pic or diagram?
 
Adam, I forgot you have a manual choke on your carburetor. Yes, I believe you are correct in that the 'fast idle setting' is for an automatic choke. Sorry about that. I also noticed from one of your previous posts that you were inquiring about the "Float Level". My Manual (for the 63' 6 - 170 Standard Trans - Carb) shows a "Dry Float Level - of 1 inch"; which is measured with the top of the carburetor removed and held upside down as you mentioned in your earlier post. They show a 'float level' of 1" w/rubber float, and 1 and 3/32" w/metal float on the "Carburetor Doctor" website. Try the 'Carburetor Doctor' website (http://www.carburetor.ca/carbs/tech); you can click on the following: Carbs Parts Index,....then click on the 1100 series..., then click on "Here" under the 'Manuals Section' and you should be able to get a lot of good information on rebuilding the 1100 carb, along with pictures included. Hope this helps? I know it helped me a lot when I was rebuilding my carburetor. Good Luck, James
 
Update -

So I've driven it a few days now. The acceleration roughness is unchanged with the choke fully pushed in. Pulling the choke out a little fixes this problem, as before.

Sprayed down the carb and all gaskets and I'm pretty sure the spray is just going in through the choke shaft and that's the only area where there is any leakage I can detect.

CobraSix - I think you are on the money with your power circuit identification. As you suggested I got it up to around 2000 rpm (no tach so it's an estimate) and pushed the choke all the way - stomping on the pedal causes definite roughness. It does accelerate but not as responsively or as smoothly as if I had the choke pulled open just a bit. With the choke pulled just a bit - it's fine. So, I think I'm in the market for a new carb - or maybe a full rebuild to see if that helps.

Deceleration in gear from high rpm still causes some ridiculous exhaust noise - so I try not to do that, usually put it in neutral first.

James - thanks for that info, that site is awesome and will definitely come in handy as I work on the carb.

Thanks for all the helpful ideas.

Adam
 
The deceleration pooping can be caused by the lean condition being caused with a clogged circuit. Your engine is drawing a large vacuum but getting even less fuel than it should get under normal engine braking.

I'd just rebuild it. Not hard. Or do like I do. Buy a new carb, swap it out and keep the other as a spare. Rebuild it when you get the chance. Swap carbs every few years.
 
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