Hi, anybody run 48ida's with a/c , i am wondering how the idle would be with the comp. cycling thanks Bob
weber carbs and ac
- Thread starter Bob Peckham
- Start date
Bob,
I ran 48 IDF's for years on a 34 ford street rod with A/C.
It was great at idle and all speeds until you went up in elevation. Then they were the worst. They popped, coughed and used fuel like crazy. As long as you plan not to go into areas of higher elevation then they will be fine.
Hersh
I ran 48 IDF's for years on a 34 ford street rod with A/C.
It was great at idle and all speeds until you went up in elevation. Then they were the worst. They popped, coughed and used fuel like crazy. As long as you plan not to go into areas of higher elevation then they will be fine.
Hersh
Tim Kay
Lifetime Supporter
I currently run 48IDF's and when the a/c is turned on my idle drops 400-500 rpm so to maintain a good idle with a/c on I have the idle set about 1400 rpm with the a/c off. A bit high but I run the air most the time anyway. I am considering a solenoid that will make the adjustment electronically.
Hersh,
In your experience with the Webers, do you recall any such change in rpm’s. BTW, what motor was in your 34 Ford?
Hersh,
In your experience with the Webers, do you recall any such change in rpm’s. BTW, what motor was in your 34 Ford?
Tim,
I never had that situation. My 350 CID chevy ran great on idle with the A/C on or off. There was a drop of 150rpm when turned on but that was about it. I also had an automatic trans. RPM's never dropped below 850 at idle with the A/C on.It stayed around 1000 with it off.
Do you have vacuum plumbing under the manifold ? This has a dramatic effect on the idle if you don't.
Hersh /ubbthreads/images/graemlins/smile.gif
I never had that situation. My 350 CID chevy ran great on idle with the A/C on or off. There was a drop of 150rpm when turned on but that was about it. I also had an automatic trans. RPM's never dropped below 850 at idle with the A/C on.It stayed around 1000 with it off.
Do you have vacuum plumbing under the manifold ? This has a dramatic effect on the idle if you don't.
Hersh /ubbthreads/images/graemlins/smile.gif
Tim Kay
Lifetime Supporter
Hersh,
Vacuum plumbing: Inglese supplied my intake manifold 8+ years ago to the previous owner and it has vacuum plumbing on the exterior which goes to my brake boosters.
When you get a minute please explain the effects of the vacuum lines, with or without. Thanks Hersh.
Vacuum plumbing: Inglese supplied my intake manifold 8+ years ago to the previous owner and it has vacuum plumbing on the exterior which goes to my brake boosters.
When you get a minute please explain the effects of the vacuum lines, with or without. Thanks Hersh.
[ QUOTE ]
It was great at idle and all speeds until you went up in elevation. Then they were the worst. They popped, coughed and used fuel like crazy. As long as you plan not to go into areas of higher elevation then they will be fine.
[/ QUOTE ]
I think that's just a matter of jetting (i.e., the jets ned to be changed for the higher altitude).
It was great at idle and all speeds until you went up in elevation. Then they were the worst. They popped, coughed and used fuel like crazy. As long as you plan not to go into areas of higher elevation then they will be fine.
[/ QUOTE ]
I think that's just a matter of jetting (i.e., the jets ned to be changed for the higher altitude).
You are right Steve. Every thing was fine until I decided to take a drive up to Flagstaff for a carshow. Elevation here in Phoenix is about 1000ft. By the time you get to Flagstaff you're at 7,000ft. Maybe it's just me but it would be a pain in the a$$ to change jets while I was up there for a few days.
Tim. All I know is that I didn't have the vacuum lines at first and it was similar to what you described. When the vacuum lines were installed I had to rejet to .50's and it ran great. I'm no Weber guru but I know it worked. I also had a power brake booster too which was the reason I had the vacuum put on the manifold to begin with.
Hersh /ubbthreads/images/graemlins/smile.gif
Tim. All I know is that I didn't have the vacuum lines at first and it was similar to what you described. When the vacuum lines were installed I had to rejet to .50's and it ran great. I'm no Weber guru but I know it worked. I also had a power brake booster too which was the reason I had the vacuum put on the manifold to begin with.
Hersh /ubbthreads/images/graemlins/smile.gif
I am running 48 IDF's on my 347 , idle is 1000. AC cycling on and off does not affect it more than 100 rpm, and on a CAV you not only have the load of the compressor but the fan on the condensor is addtional load on the alternator. With the right idle jets it is pretty consistent.
[ QUOTE ]
Maybe it's just me but it would be a pain in the a$$ to change jets while I was up there for a few days.
[/ QUOTE ]
That's just one of the things you sign up for when you decide to go with Webers. I never got mine fully sorted, but that was probably the major thing I did when I went to Michigan - find the right jetting for sea level... I had an interesting situation here, as my house is at 6600 feet but most of my driving would have been done down in the valley (4000-4500 feet) or Las Vegas (2000 feet). I certainly didn't want to change jets just to get home, but fully expected to if I went down to Vegas or something. It's quite easy on the IDFs... In theory you'd be changing the jets and idle mixture on any carb over these altitude ranges...
"For those who like that sort of thing, it's the sort of thing they would like." /ubbthreads/images/graemlins/smile.gif
Oh yeah, and just to make an on-topic comment: I had no trouble with the idle when turning the A/C on.
Maybe it's just me but it would be a pain in the a$$ to change jets while I was up there for a few days.
[/ QUOTE ]
That's just one of the things you sign up for when you decide to go with Webers. I never got mine fully sorted, but that was probably the major thing I did when I went to Michigan - find the right jetting for sea level... I had an interesting situation here, as my house is at 6600 feet but most of my driving would have been done down in the valley (4000-4500 feet) or Las Vegas (2000 feet). I certainly didn't want to change jets just to get home, but fully expected to if I went down to Vegas or something. It's quite easy on the IDFs... In theory you'd be changing the jets and idle mixture on any carb over these altitude ranges...
"For those who like that sort of thing, it's the sort of thing they would like." /ubbthreads/images/graemlins/smile.gif
Oh yeah, and just to make an on-topic comment: I had no trouble with the idle when turning the A/C on.
no problems on my ida's with a 330 inch and sankyo rotary compressor. Idle at a little shy of 1,000. I experimented with the compressor versus alternator draw for and found that the increase alternator draw for the condensor fan. The fan hurt the idle more than the compressor clutch electrical drag and engaged compressor.
Chuck
Chuck
Thanks for all the info Bob
Tim Kay
Lifetime Supporter
Listen to this one, if you got a minute /ubbthreads/images/graemlins/shocked.gif
Just the other day I ask a good friend if he would like to drive the GT40 knowing full well he wouldn’t refuse. His hand was outstretched for the key before I could think which pocket I dropped it in /ubbthreads/images/graemlins/shocked.gif He said “you drive with me” and I said “no, no I’ll wait here”.
Frankly, I’m a terrible passenger in my own car so I thought best not to go /ubbthreads/images/graemlins/crazy.gif
He came back about 20 minutes later with that feeling I’m sure only few cars can offer and words can’t describe. After a few minutes of letting his heart recover to 140 bpm and high fives all around I happen to look under the motor (by habit I’m sure) and spotted fluid /ubbthreads/images/graemlins/ooo.gif It was yellow?! It’s not motor oil, it feels like oil but looks kinda like anti-freeze but not. What was it? Maybe it was there before the car was parked over it? All these questions raced through my mind /ubbthreads/images/graemlins/confused.gif
Popped the rear clip and further inspection revealed my A\C line had sprung a leak at the fitting to the compressor (never new the oil had yellow die in it). Compressor fittings are low slung close to the lower tube frame and my only conclusion is that something in the road must have banged it.
Anyway, to get to my point, things happen and for the best sometimes. Remember back in this thread I mentioned my idle dropped dramatically when the A\C is turned on, enough to cause my 1100 rpm idle to drop and kill the motor.
Turns out through the replacement of the fitting and recharging the system that my charge was too high originally and in some why putting undue stress on the compressor. Now with the correct charge I have cold air AND my idle only drops 200 rpm /ubbthreads/images/graemlins/grin.gif
So now I must go back and explain to my friend how he did me a great big favor then apologize for kick’n his a** /ubbthreads/images/graemlins/blush.gif
Just kidding, he really felt bad and now he’ll be relieved it all turned out for the better /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/wink.gif
Just the other day I ask a good friend if he would like to drive the GT40 knowing full well he wouldn’t refuse. His hand was outstretched for the key before I could think which pocket I dropped it in /ubbthreads/images/graemlins/shocked.gif He said “you drive with me” and I said “no, no I’ll wait here”.
Frankly, I’m a terrible passenger in my own car so I thought best not to go /ubbthreads/images/graemlins/crazy.gif
He came back about 20 minutes later with that feeling I’m sure only few cars can offer and words can’t describe. After a few minutes of letting his heart recover to 140 bpm and high fives all around I happen to look under the motor (by habit I’m sure) and spotted fluid /ubbthreads/images/graemlins/ooo.gif It was yellow?! It’s not motor oil, it feels like oil but looks kinda like anti-freeze but not. What was it? Maybe it was there before the car was parked over it? All these questions raced through my mind /ubbthreads/images/graemlins/confused.gif
Popped the rear clip and further inspection revealed my A\C line had sprung a leak at the fitting to the compressor (never new the oil had yellow die in it). Compressor fittings are low slung close to the lower tube frame and my only conclusion is that something in the road must have banged it.
Anyway, to get to my point, things happen and for the best sometimes. Remember back in this thread I mentioned my idle dropped dramatically when the A\C is turned on, enough to cause my 1100 rpm idle to drop and kill the motor.
Turns out through the replacement of the fitting and recharging the system that my charge was too high originally and in some why putting undue stress on the compressor. Now with the correct charge I have cold air AND my idle only drops 200 rpm /ubbthreads/images/graemlins/grin.gif
So now I must go back and explain to my friend how he did me a great big favor then apologize for kick’n his a** /ubbthreads/images/graemlins/blush.gif
Just kidding, he really felt bad and now he’ll be relieved it all turned out for the better /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/wink.gif
