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Author
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Topic: autolite 4100
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craigber
Gearhead Posts: 128
From: Vancouver, Canada
Registered: Sep 2000
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posted 03-01-2006 11:31 AM
 
hi everyone...just picked up a 4100 and was wondering about the vacuum secondaries..do they open when manifold vacuum drops? can you test them in the driveway? sorry about the stupid questions but i am here to learn
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 03-01-2006 02:49 PM
Theres a little brass tube above the pri.
booster on the left side. When theres enough
suction there, they hopefully open.If you
take the top off you can test the can on the
back. KP
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-21-2006 02:19 AM
Rather than start another post on the same subject I thought I would resurrect this one. I can't believe I'm gonna ask this question when craigber thought his was stupid.Jake, could you kind of flesh out that test procedure? I'm not sure what you are talking about. Is the tube you are talking about point straight into the primary venturi and labeled "secondary throttle contol vacuum tube" ? On my car that sucker drips gas at idle. That can't be good if it's a vacuum pickup. Should the secondaries open if I just open the throttle fast without a load (like with my head under the hood watching)? Even when they did work it was like a turbo lag. I'm thinking it has to be the diaphragm as I can work the linkage manually but when I do I hear the diphragm sucking. I'd love to get my secondaries working again. That's a rush! Thanks, ------------------
Jerry Cooper
Candy Apple Red, 66' Coupe, Wide Ratio Toploader
9" 3.25 Traction Loc
302 .060 over, Solid Lifter
294 adv. duration,.544 lift,
Eddy RPM intake, Autolite 1.12 Carb,
Hooker Comp. Headers, Dynomax Super Turbos
MSD RTR, Blaster2 Coil
70' 351W Heads home port job
10.5 to 1 CR
15" Styled Steel Wheels
KYB Gas adjust Shocks
620 1" Lowered front springs
1" Front Sway Bar, New 4 leaf
Rear Sway Bar, Shelby Traction Bars
P/S A/C (yep, GirlyMan)
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 04-21-2006 03:18 PM
Yes, the little brass tube that points down
into the driver's side booster. No, gas is
not supposed to be dripping out of it!
As far as how it opens, vac. at that little
tube works the diaphram on the back of the
carb. If you take the top off, you can ck
the diaphram. There's a passage at the top
of it. Work the lever and put your finger
over the hole to see if it leaks. The Holly
Secondary springs fit, if you want to play
with it. Sounds like you need to fix the
dripping prob. first. Kinda hard to tune a
leaky carb. : D Good luck, KP
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-21-2006 07:37 PM
Jake, thanks for getting back so fast! Ok, maybe the gas is just dripping OFF that tube. By looking at the cutaway in the 66' Shop manual I don't see how gas could get in there. I will pull the cover off the diaphragm and check it for holes. Should the secondaries open if I romp on it from under the hood or does it need a load? It would be nice to think it is working before I take it for a tire roasting test. The secondary linkage seems free enough but it definitely does not have that kick in the pants that it had before the last time I took the carb off. I don't know how I could have perforated that diaphragm but it is about 6 years old, just sitting on a shelf.
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 04-21-2006 11:46 PM
Just Ck it out first. Cover the basics.
Then you got a starting point. Keep some
notes. Then you know what works, and what
don't. Always use the "kiss" principle.
Good luck, KP
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 04-21-2006 11:59 PM
The rubber diaphram is kinda fragile.
Carb spray will destroy it.
It will swell up and rupture. Best get a new
one and keep the carb cleaner spray away
from it. Also, if it's dripping, ck. the
pwr. valve. A holly one will fit, keep a spare on hand. The 4100 is a pretty good
street carb, when set up right.
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-22-2006 01:31 AM
Ok, this is what I have figured out so far.
#1. I really suck at this. #2. There are 2 ways to put the top gasket on a 4100. One closes off the funky port in the top cap that would cause a vacuum leak to the diaphragm if it was open and the other way does not. Guess which way I put it on after my carb cleaner session? #3. There are two ways to put the lid back on the secondary assembly. One lines up the vacuum tube passage allowing vacuum to the diaphragm and the other puts it 180 degrees out. Guess which way I think I had it after my top gasket epiphany? #4. I don't have a secondary check ball (at least it didn't roll out when I tipped the carb up) #5. The rebuild kit that I got does not include a diaphragm. #6. It's really fun to get rolling about 20mph in 1st then romp on it and let the backend get squirrely. #7. Still sounds like I may have a power valve issue due to seeing gas dripping at idle (maybe has something to do with why I can't get it to idle below 1200rpm without dying?). I'm sure this thing is no where near dialed in but if I keep making mistakes I will know it inside and out by the time I get there. Thanks KP I really appreciate the help!
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-23-2006 12:52 AM
I ran a secondary test today (actually quite a few). I put a paper clip on the linkage so if the secondaries open the clip would hit the carb and I could see how far they opened. They open 100%. Burnin' Gas and Haulin' A**. Now I need someone to hold the video camera so I can get some tire trashin' home movies.
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-23-2006 02:23 AM
Jake, I was just reading up on the "Power Valve". I bet you are right and that is my idle problem. I remember at least once at first start up I had a backfire through the carb (timing issues) and from what I understand that can blow the power valve diaphragm. So, then it does not react correctly to idle vacuum (holding the power valve closed) and dumps fuel into the engine during idle (that would be the fuel I see dripping off the secondary vacuum pickup) so it needs the high idle to burn the gas to keep running. Looks like I'll be changing the power valve in the AM. Thanks for the insight!
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 04-23-2006 04:53 PM
: D
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-23-2006 05:06 PM
Jake, you nailed it. I could only find a 6.5 and I don't know what was in it before (probably doesn't matter as I had it blown before I ever got the car started). I couldn't really tell by looking if the original was blown but it must have been. Different car now. It now idles nicely, loping between 850 and 950 (this cam has some lope to it so I don't think I want it lower) and I don't have to slip the clutch so much to get it rolling. WAY better. Thanks!
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jww_289
Journeyman Posts: 71
From: Victoria Australia
Registered: Feb 2006
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posted 04-26-2006 07:22 PM
At the risk of seeming just too stupid I thought I would add to this post, I had messed with the spring in the secondary diaphragm a while ago and convinced myself I had made a difference - doh  - after reading sprcoops adventures with the gaskets I walked out to the shed; took the air cleaner off and guess what - the diaphragm cover was installed 90 deg out, no vacuum feed to the diaphragm - dunno how I missed it as it stuck out like black balls on a white dog, going to reverse that now take it for a drive.BTW: I have seen the question asked - should the secondaries come in while giving it some revs in the driveway - but I have not seen any definitive answers, I would have thought the answer was yes as the air flow through the primary venturi would be the same at 3000 rpm whether in gear or not, is this right or is it another "john" moment  TIA,
John......
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-27-2006 01:20 AM
jww_289, you have been successful in the ultimate lesson learned. I have always said the only thing better than learning from your own mistakes is learning from someone elses. Now if I could just do that.I'm glad that one of my many mistakes could help. That's why I post them. After many searches the definite answer from all the pro's is "no, the secondaries will not open in the driveway, it needs more load than that". If you want I could take a picture of my paper clip attachment that told me I'm getting 100% secondaries and post it.
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jww_289
Journeyman Posts: 71
From: Victoria Australia
Registered: Feb 2006
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posted 04-27-2006 03:41 PM
quote:
I have always said the only thing better than learning from your own mistakes is learning from someone else's. Now if I could just do that.
How true That would be great if you could share the paper clip thing, even a description may help and not have the hassle of a pic, it would be really good to know just how far mine are opening. I was thinking about having the day off today and sorting this out once and for all, ya gotta get your priorities right hey TIA,
John...... ------------------
1966 fastback
- 4v 289
- T10 4 speed
- Pony interior
JWW_289 Home Page
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-27-2006 04:22 PM
Ok, here's the description. If that doesn't get it done the picture thing is not that big of a deal.Get a fairly large, but not too big (you'll see why) paper clip. Clip it onto the secondary linkage perpendicular to the linkage so the bottom hangs down far enough to hit the carb base. If you open the throttle a little (to get the linkage out of the way) then manually open the secondaries it should push the bottom of the paper clip back towards the firewall. When you let go it will stay in that position. Put it back to perpendicular and go romp on it. When you get back you can manually open the secondaries and see exactly how far they opened during your romp session. Let me know if you need a photo. Not a big deal. HTH
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jww_289
Journeyman Posts: 71
From: Victoria Australia
Registered: Feb 2006
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posted 04-27-2006 04:47 PM
Makes sense to me, another 1/2 hour and it will be light, get the youngest boy off to school, give the neighbors time to wake up and I will be out there.Much appreciated. BTW: if I was going to play with the jet sizes is it OK to do it on the car, with fuel in the bowls ??
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sprcoop
Gearhead Posts: 780
From: Tucson, AZ usa
Registered: Jan 2000
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posted 04-27-2006 05:31 PM
I don't think you are supposed to do too much work on a carb while on the car in case anything falls into the intake. Ever see "My Cousin Vinny"? That is where I get most of my automotive knowledge. Mostly from Marisa Tomei (Yowza!) not Joe Pesci.
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jww_289
Journeyman Posts: 71
From: Victoria Australia
Registered: Feb 2006
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posted 04-27-2006 06:07 PM
Just picked the DVD up on special, you are absolutly correct, Marisa is the girl, not only on automotive facts but legal as well quote:
He has to, by law, you're entitled. It's called disclosure, you dickhead! He has to show you everything, otherwise it could be a mistrial. He has to give you a list of all his witnesses, you can talk to all his witnesses, he's not allowed any surprises.
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