Rebuilt Autolite 2100 swapped in-won't idle < than 1100 RPM

[MPGmustang]

this has me thinking, your 264/264 110 sounds like it acts like my 264/274 110, we both are to have max vac of 15inches, they run little loopish, I'm just bleeding off DC (dynamic compression) from my longer exhaust timing. I can idle smoothly at ~900rpm smoothly with it running rich. if I lean it out it choopps up. but the main thing I'd like to mention is the vacuum at idle is only 10 inches max, mostly with AC running (closest thing I got to your drive) it's down to 750ish rpm and 6-7 vacuum. now if I raise the idle to 1100 YEAH i'll get the 15 inches vac. I think as ours is simular you'll probably need the close to the same vacuum reading at idle for it to smooth out.

BTW, Faron (FSD) does timing on DSII's and he'll set you up really great.

 

[62Ranchero200]

Good to see you are still at it man. I believe a rebuilt DS2 distributor will only run about 30 40 bucks and would be a good investment at this point if you know it is shot anyway. Drop it in and see if it help the idle enough that you can live with it.

Now if you are still seeing raw fuel AND you can improve the idle by hand choking the engine, that would probably indicate you are running lean in a major way. Try looking for a vacuum leak that would have been carb swap related, mainly the adapter, gaskets etc. Get her running at best idle and spray the adapter plate with small shots of carb cleaner and see if the idle improves. Disconnect and block off all vacuum lines while doing this to eliminate that as a possibility, (except the distributor as the loss of advance would only make it run worse) and hook them back up one at a time. If the idle worsens when a given line is reconnect, then that will need to be explored. (leaky PCV valve, brake booster, heater control etc).

Good luck!

A replacement distributor is in the works, but it might be a week or two before I move on that (eye surgery has been expensive). I did order the phenolic resin spacer from CI though, because the carb gets quite hot by the time the engine is warmed up. I'm not sure if it ever gets hot enough to boil gas out of the bowl, but the spacer is cheap insurance.

I used two carb gaskets (because I couldn't find a thick one) and tightened the mounting nuts as much as I dared. There are only two vacuum lines now, the distributor vacuum advance (from the "spark port" on the carb) and the trans vacuum modulator (connected directly to manifold vacuum). The PVC is no longer connected to vacuum, but rather to the air cleaner. Car doesn't have power brakes or any vacuum connected to climate controls.

Thanks
Bob

 

[62Ranchero200]

this has me thinking, your 264/264 110 sounds like it acts like my 264/274 110, we both are to have max vac of 15inches, they run little loopish, I'm just bleeding off DC (dynamic compression) from my longer exhaust timing. I can idle smoothly at ~900rpm smoothly with it running rich. if I lean it out it choopps up. but the main thing I'd like to mention is the vacuum at idle is only 10 inches max, mostly with AC running (closest thing I got to your drive) it's down to 750ish rpm and 6-7 vacuum. now if I raise the idle to 1100 YEAH i'll get the 15 inches vac. I think as ours is simular you'll probably need the close to the same vacuum reading at idle for it to smooth out.

BTW, Faron (FSD) does timing on DSII's and he'll set you up really great.

Exactly - although the CI catalog says good vacuum for my cam, I'm seeing a fairly rough idle and fairly low vacuum. Maybe this cam will only idle smoothly and give 15" or so of vacuum at idle if it's running a bit rich. Although, I can't know for sure how much of the rough idle is ignition related until I address the ignition.

Thanks
Bob

 

[First Fox]

You will most likely notice an immediate improvement in idle quality by connecting the distributor vacuum advance to manifold vacuum. This has been debated for about 4 million years, but at the end of the day, I believe you need to do whats best for your particular application. You could certainly use the extra vacuum advance at idle. You will absolutely not blow anything up by connecting to it and might likely solve your problem.

The PCV can not be connected to the air cleaner man. It will not function whatsoever in this manner and you can all kinds of problems. This needs to be reconnected to manifold vacuum. The valve is only wide open at WOT and is likely not causing you any headaches. If in doubt, replace it with a new one as they are cheap, but if it's not attached and functioning you are asking for problems.

 

[62Ranchero200]

You will most likely notice an immediate improvement in idle quality by connecting the distributor vacuum advance to manifold vacuum. This has been debated for about 4 million years, but at the end of the day, I believe you need to do whats best for your particular application. You could certainly use the extra vacuum advance at idle. You will absolutely not blow anything up by connecting to it and might likely solve your problem.

The PCV can not be connected to the air cleaner man. It will not function whatsoever in this manner and you can all kinds of problems. This needs to be reconnected to manifold vacuum. The valve is only wide open at WOT and is likely not causing you any headaches. If in doubt, replace it with a new one as they are cheap, but if it's not attached and functioning you are asking for problems.

I have already tried connecting the vacuum advance to manifold vacuum. With the recommended setting of 12 degrees initial advance, connecting to manifold vacuum gives me about a 28 degree advance at idle and the engine actually idles more roughly and at lower RPM with that much advance at idle.

As far as the PVC, I know that I've had cars where the PVC was connected to the air cleaner as a factory setup. There should be a vacuum at the air cleaner inlet (granted, much lower than manifold vacuum). With this vacuum, it should be possible to dispose of the crankcase vapors into the intake air charge. The PVC may be designed to only open wide at WOT with a stock engine and stock cam, but I have lower-than-normal vacuum with the cam I'm running and I think the PVC is going to open wider, sooner under these conditions, adding to the over-lean condition I think I already have. Since I connected the PVC to the air cleaner, the engine idles a little more smoothly, which I attribute to being less over-lean.

Thanks
Bob

 

[First Fox]

OK buddy, Keep us posted.

 

[MPGmustang]

I tried excactly what you are proposing... I put the PCV valve to the air cleaner, then I 'blocked' and closed the breather on the front of the engine. It ran better, but I got 12mpg really soon because it's not working properly.

the PCV is a huge vacuum leak. it's supposed to be. so let it do it's job.

the PCV valve goes to the base of the carb, the valve cover breather goes to the main air filter.

I have already tried connecting the vacuum advance to manifold vacuum. With the recommended setting of 12 degrees initial advance, connecting to manifold vacuum gives me about a 28 degree advance at idle

THIS MEANS IT WAS WORKING PROPERLY!! YAY!!!

okay, to tune a an engine 101... disconnect the vacuum from distributor and plug the line, set to 12* inital timing and tighten it down, no need to chagne that anymore!, plug the vacuum canister back into the manifold vacuum. the timing is suppose to advance!!! meaning vacuum advance is doing it's job!!! when you have vacuum is when you want advance!!! espesially at idle. once it plugs back in the RPM should increase, this is normal, simply adjust the RPM to be about 900rpm with the idle screw. once around 900rpm, use a vacuum guage on the manifold vacuum and tune the idle-air-fuel screw to get the most vacuum you can get. it's going to be low, it's not going to be above 10" of vacuum. it's normal for your 110 lobe center. if you wanted more vacuum then you'll want to switch to a 112 lobe center cam.

I guess you are using a stock torque converter, this is probably why it stalls when you put it in gear, it's too tight for the cam.

the engine actually idles more roughly and at lower RPM with that much advance at idle.

I THINK, this means it's either too rich/lean or too low of an idle setting, I really don't think you'll get your idle any lower than 750rpm, it's not stock anymore so you have to find what it likes the best. play with it, aim for a 900rpm first then slowly work down, and always tune your engine after 30 mins of use for the full temp to seep everywhere. once you get 900 rpm, try adjusting one thing to help lower it a little and drive it after every one thing... it's all about trial and error now

 

[62Ranchero200]

I tried excactly what you are proposing... I put the PCV valve to the air cleaner, then I 'blocked' and closed the breather on the front of the engine. It ran better, but I got 12mpg really soon because it's not working properly.

the PCV is a huge vacuum leak. it's supposed to be. so let it do it's job.

the PCV valve goes to the base of the carb, the valve cover breather goes to the main air filter.

I have already tried connecting the vacuum advance to manifold vacuum. With the recommended setting of 12 degrees initial advance, connecting to manifold vacuum gives me about a 28 degree advance at idle

THIS MEANS IT WAS WORKING PROPERLY!! YAY!!!

okay, to tune a an engine 101... disconnect the vacuum from distributor and plug the line, set to 12* inital timing and tighten it down, no need to chagne that anymore!, plug the vacuum canister back into the manifold vacuum. the timing is suppose to advance!!! meaning vacuum advance is doing it's job!!! when you have vacuum is when you want advance!!! espesially at idle. once it plugs back in the RPM should increase, this is normal, simply adjust the RPM to be about 900rpm with the idle screw. once around 900rpm, use a vacuum guage on the manifold vacuum and tune the idle-air-fuel screw to get the most vacuum you can get. it's going to be low, it's not going to be above 10" of vacuum. it's normal for your 110 lobe center. if you wanted more vacuum then you'll want to switch to a 112 lobe center cam.

I guess you are using a stock torque converter, this is probably why it stalls when you put it in gear, it's too tight for the cam.

the engine actually idles more roughly and at lower RPM with that much advance at idle.

I THINK, this means it's either too rich/lean or too low of an idle setting, I really don't think you'll get your idle any lower than 750rpm, it's not stock anymore so you have to find what it likes the best. play with it, aim for a 900rpm first then slowly work down, and always tune your engine after 30 mins of use for the full temp to seep everywhere. once you get 900 rpm, try adjusting one thing to help lower it a little and drive it after every one thing... it's all about trial and error now

After experimenting with the PCV hooked up to the air cleaner, I returned it to manifold vacuum (pipe plug fitting on the log intake manifold). I don't have a PCV connection at the base of the carb because I am using CI's 2-V carb adapter.

With careful tuning, the leaner power valve (#65), and a lower float level (21/32"), I now have it idling acceptably well both in park and in gear (although it still doesn't idle that smoothly in gear, it doesn't die). I installed a cold air induction from CI, and it seems that this smoothed out the idle a bit. If the engine was running a bit lean and the cold air induction introduced a slight restriction, richening the mixture slightly, that makes sense.

As you point out, that somewhat rough idle and somewhat low vacuum may be the best I can get with this cam ... although I still have ignition improvements to make. My biggest driveability issue now is that off the line, from idle in gear, I have to "feather" the throttle for a second or less ... if I floor it off idle the engine will stumble and possibly die. Once I feather the throttle for an instant, I can put my foot into it as much as I want, and it will respond well.

I haven't had the engine and trans apart yet, but as far as I know I have a stock torque converter. When I purchased the car, the engine was all stock (as far as I can tell) other than the Pacemaker headers. Would there be any identifying marks on the torque converter I could see by removing the dust cover? It's not possible to get any useful information from the previous owner because it was a brokered deal.

Bob the Builder

 

[MPGmustang]

the leaner power valve (#65)

I found that to be too rich for me too soon, I think if you got the 35 (or 3.5 inch vacuum PV) it will help, like my 2.5 helped me!

I'm glad to hear it is idling well enough to drive, looks like you already are ahead of what I thought...

you can smooth that 'drive' idle out a bit, what is your current RPM at idle in drive?

My biggest driveability issue now is that off the line, from idle in gear, I have to "feather" the throttle for a second or less ... if I floor it off idle the engine will stumble and possibly die

I have this problem too, even with my manual trans, I did have a 3.2 rear gear and I always had to rev it high (2100rpm +) then slowly release the clutch, once the engine was 'working' it worked just fine and no issues, what timing chain do you have? I'm using the Classic Inlines double roller, it had a slight 'play' in the chain and didn't worry about it but it would make sense if you have the same issues.

 

[62Ranchero200]

the leaner power valve (#65)

I found that to be too rich for me too soon, I think if you got the 35 (or 3.5 inch vacuum PV) it will help, like my 2.5 helped me!

I'm glad to hear it is idling well enough to drive, looks like you already are ahead of what I thought...

you can smooth that 'drive' idle out a bit, what is your current RPM at idle in drive?

My biggest driveability issue now is that off the line, from idle in gear, I have to "feather" the throttle for a second or less ... if I floor it off idle the engine will stumble and possibly die

I have this problem too, even with my manual trans, I did have a 3.2 rear gear and I always had to rev it high (2100rpm +) then slowly release the clutch, once the engine was 'working' it worked just fine and no issues, what timing chain do you have? I'm using the Classic Inlines double roller, it had a slight 'play' in the chain and didn't worry about it but it would make sense if you have the same issues.

The Autolite 2100 came with a #75 power valve. I'm prepared to go even lower on the power valve if that will help, but it seems to be running well except for the off-idle stumble.

Maybe idling 750-800 RPM in gear now. That's a reasonable idle speed, it's just a bit "choppy".

When I rebuilt the engine a few months ago, I picked up a new timing chain at my local O'Reilly. I didn't think a double roller was necessary because I'm still using the stock dished pistons and I haven't milled or decked, so piston to valve clearance should be plenty;and the engine won't see over 5,000 RPM on purpose. Have driven very few miles since then (take the car to a local rally every 2-4 weeks, have another car as daily driver).

I have the stock 7.5" with 3.50 gears.

Thanks
Bob

 

[62Ranchero200]

I THINK, this means it's either too rich/lean or too low of an idle setting, I really don't think you'll get your idle any lower than 750rpm, it's not stock anymore so you have to find what it likes the best. play with it, aim for a 900rpm first then slowly work down, and always tune your engine after 30 mins of use for the full temp to seep everywhere. once you get 900 rpm, try adjusting one thing to help lower it a little and drive it after every one thing... it's all about trial and error now

Received the phenolic resin spacer from CI and installed it yesterday. The engine almost never dies at idle now, and idles reasonably smoothly in park, a bit roughly in gear. I think I'm done with the carb adjustments. The engine cruises and accelerates well, and I wouldn't want to do anything to jeopardize that, just for a smoother idle. To summarize:

* Took the carb apart to check for cracks, missing parts and gaskets, blew carb cleaner through passages etc. (all was in order)
* Lowered the dry float setting to 21/32" (this is specific to a '62 vintage carb; was originally quite a bit higher)
* Replaced the power valve (#75) with a leaner one (#65)
* Adjusted the choke to a richer setting
* Left the PCV connected to manifold vacuum (no PCV connection on CI spacer)
* Replaced the open element air cleaner with a CI cold air induction (this introduced a slight air restriction)
* Installed an under-hood fuel pressure gauge (fuel pressure is not too high; it's fluctuating rapidly but I'll start another thread for that)
* Double-checked that the initial timing was set to 12 degrees and vacuum advance is connected (DS II)

Thanks for all the help with this issue, especially Bubba, FirstFox, Jackfish and Luke.

Bob the Builder

 

[First Fox]

Glad you figured it out man! Make sure you let us know when you are ready to blow through that finely tuned carburetor. I understand they work pretty well for that.

Cheers.

 

[bubba22349]

Congrats now you can drive and enjoy it

 

[MPGmustang]

Awesome!! glad you're satisfied with it, it's always a pita when getting to where you think it should be and also learn/accept the new animal it is. :mrgreen:

 

[Luke76]

Hey Bob, glad to hear it. I didn't post here but I was following along in the shadows. I think your notes will help me when it comes time to tune my own carb so I'm bookmarking your thread. Enjoy your ride!


Luke

 

[nickstewartroc]

Nice to see you got it running (Yes I know, old thread blah blah blah) but do you still have the dripping problem from the venturis?

-Nick

 

[62Ranchero200]

Nice to see you got it running (Yes I know, old thread blah blah blah) but do you still have the dripping problem from the venturis?-Nick

That engine is no longer running - it developed excessive blow-by and I have a 250 at the machine shop being built to replace the 200. I think the fuel droplets dripping from the venturi was caused by heat soak though, and a phenolic resin adapter from CI resolved that issue.

Thank you,
Bob