autocross using an autolite 4100 carb - Vintage Mustang Forums
 7Likes
  • 1 Post By Jsams
  • 3 Post By Klutch
  • 2 Post By Lightning
  • 1 Post By paraman31
 
Thread Tools
post #1 of 15 (permalink) Old 06-17-2019, 02:08 PM Thread Starter
Junior Member
 
Join Date: Aug 2015
Posts: 17
autocross using an autolite 4100 carb

hi, i'm wondering if anybody has done some autocrossing using a 4100 autolite carb? me and my son just got back from the rocky mountain mustang rally in steamboat springs over the weekend and he signed up for the autocross event. he loved the SoT coilovers but fell a little flat on the course! didnt know if it was fuel starvation or fuel was spilling over into the engine cutting out but figure i ask the folks out there that autocross. he really loves the autolite 4100 that was his first project rebuild going old school instead of going with a holley or edelbrock carb that we see at most shows. don't really want to go efi and since he doesn't autocross other than that show just wondering if any tips out there from veteran 4100 autolite users? sorry for the long post! thanks in advance for any info! robert
paraman31 is offline  
Sponsored Links
Advertisement
 
post #2 of 15 (permalink) Old 06-17-2019, 02:25 PM
Senior Member
 
myfirstcar66's Avatar
 
Join Date: Jan 2019
Location: Auburn University, Alabama
Posts: 1,552
Garage
I don't autocross but I do spirited driving now and then Haha! The 4100 is the only carb I've had that does NOT stumble coming out of hard turns. Took off my Edelbrock 1406 because I couldn't "tune" that out. With the 4100 there is no more -blah- it's all WHHAAAA....

My 1st car...
'66 Tahoe Turquoise/ Aqua coupe
•289 / 4100 •C4 Auto •Disc Brakes
•Dual Exhaust •Quick Manual Steering
•Rally Pac •Console •Deluxe Belts
•LOTS of Rotunda accessories

Older son's 1st car...
'66 Emberglo / Parchment deluxe coupe
•289 / 2100 •C4 Auto
•Dealer A/C • Console
•Dual Exhaust • Power Steering

Younger son's 1st car...
'66 Nightmist / Blue & white deluxe coupe
•289 / 2100 •C4 Auto
•Factory A/C •Console
WAITING FOR RESTORATION

myfirstcar66 is offline  
post #3 of 15 (permalink) Old 06-17-2019, 04:24 PM Thread Starter
Junior Member
 
Join Date: Aug 2015
Posts: 17
thx 66 for the reply! his car has great response thru canyon sweepers but during the course it stumbled coming out of a tight turn into the slalom so he was actually kinda shocked cuz he's got great throttle response all the time until he ran the course. haha!
paraman31 is offline  
 
post #4 of 15 (permalink) Old 06-17-2019, 05:24 PM
Senior Member
 
Join Date: May 2005
Location: Charlotte NC
Posts: 1,639
Maybe your float level is a little too high and its spitting gas out the vent tubes under heavy braking?
2nd 66 likes this.
Jsams is offline  
post #5 of 15 (permalink) Old 06-17-2019, 07:57 PM
Senior Member
 
Join Date: Jun 2011
Location: Colorado Springs
Posts: 9,382
I drove my recently completed Mach 1 project to the Roundup and also participated in the autocross. I'm running a Summit Racing carburetor which is very similar to the 4100. On my 2nd and 3rd runs, my engine fell on its face right after the start. I think it's a vapor lock issue. Some friends of mine recommended revving the engine a little before the start and that really helped on my 4th run. In fact, I did a bit of a burnout at the start.

Consider Steamboat Springs is between 6,000 and 7,000 feet above sea level. That's a BIG factor for vapor lock issues. Combine that with ethanol in the fuel and it becomes an even bigger problem. There's a gas station on Lincoln Street in Steamboat which sells 100% gasoline. Although the premium is $3.70 a gallon, it would be worth it next time. (My friend who brought his 1970 Boss 429 reported his idle jumped up a full 250 RPM when he ran 100% gasoline.)

Fuel line routing is a critical factor for preventing vapor lock. I think that was my issue. I have an aluminum fuel filter and it's very close to the top of the engine. I'm going to try re-routing that to see if it helps.

Does the car have a phenolic spacer under the carb? If not, that might help. Also, as suggested, definitely check the float levels.

Anyway, I don't think the 4100 is the problem. That's a very good carb used by many a racer for many years.
2nd 66, myfirstcar66 and Grimbrand like this.

Currently working on a 1970 Mach 1 project. See it here: http://forums.vintage-mustang.com/vi...ode-build.html
Klutch is offline  
post #6 of 15 (permalink) Old 06-17-2019, 08:27 PM Thread Starter
Junior Member
 
Join Date: Aug 2015
Posts: 17
thx jsams, i was thinking the same thing so that's something worth looking into! hey klutch that's cool that you were also at the rmmr! that was an awesome show on yampa! getting back to the question , my son's 67 didn't have any problems with vapor lock driving up from utah since we are pretty close to the same elevation as colorado. the cruise went great even tho we got separated from our group when we stopped to help a fellow mustanger who did have vapor lock. his car runs really strong normally up until he started his autocross runs, haha!but he had a great time still so that's all that matters! i'm kinda leaning towards what jsams was saying and will look into that! appreciate al the info guys!! btw klutch my kid's car was the 67 coupe bullitt green with the green halo headlights driving around!
paraman31 is offline  
post #7 of 15 (permalink) Old 06-17-2019, 08:38 PM
Member
 
Join Date: Aug 2005
Location: Hawaii
Posts: 71
Quote:
Originally Posted by Klutch View Post
...Although the premium is $3.70 a gallon...
Just for a little perspective about the cost of premium gas. Regular unleaded with ethanol is currently $3.64.9 / gallon here on Oahu.

Not trying to hijack this thread. We now return you to the 4100 discussion.

Harry Z
HarryZ is offline  
post #8 of 15 (permalink) Old 06-17-2019, 08:47 PM
Senior Member
 
2nd 66's Avatar
 
Join Date: Aug 2013
Location: New York
Posts: 9,643
Garage
I autox (not as of yet this year ,RAIN) with a 1406 with out that issue. I'd check float level . It helps to get some heat in the engine sometimes for better velocity and atomization .Then again I'm at about 400' above see level vs you in the mile high club.
Trying ethanol free will help with percolation along with a phenolic spacer


Brad

Last edited by 2nd 66; 06-17-2019 at 08:49 PM.
2nd 66 is offline  
post #9 of 15 (permalink) Old 06-17-2019, 09:35 PM
Senior Member
 
Join Date: Jun 2011
Location: Colorado Springs
Posts: 9,382
Quote:
Originally Posted by paraman31 View Post
btw klutch my kid's car was the 67 coupe bullitt green with the green halo headlights driving around!
Not sure if I saw that car. Mine was the Calypso Coral (orange) '70 Mach 1 with the hood tach. I ran in the PM1 autocross session. I was parked near 8th street with three other Mach 1s.

Currently working on a 1970 Mach 1 project. See it here: http://forums.vintage-mustang.com/vi...ode-build.html
Klutch is offline  
post #10 of 15 (permalink) Old 06-17-2019, 09:47 PM
Senior Member
 
Join Date: Jun 2003
Posts: 1,366
I think a properly adjusted 4100 is a better carb than a holley or edelbrock of similar size.
myfirstcar66 and Grimbrand like this.

65 coupe 5.0L/5 speed
2001 Lightning #1757
Lightning is offline  
post #11 of 15 (permalink) Old 06-17-2019, 10:11 PM Thread Starter
Junior Member
 
Join Date: Aug 2015
Posts: 17
i agree lightning! hey klutch my son also ran the pm session right before the ac cobra's and the rain! haha he was the first car running with the other 65-66 stangs. he was parked across of sunpie's bistro. awesome place btw!
paraman31 is offline  
post #12 of 15 (permalink) Old 06-17-2019, 10:40 PM Thread Starter
Junior Member
 
Join Date: Aug 2015
Posts: 17
thx for the info 2nd66! we did put a spacer plate on his car. so far he's been lucky that he hasn't had any vapor lock ! runs great other than the autocross course. maybe the float is set high and it overflows when it's sloshing around
2nd 66 likes this.
paraman31 is offline  
post #13 of 15 (permalink) Old 06-17-2019, 10:53 PM
Senior Member
 
66ryan's Avatar
 
Join Date: Apr 2016
Location: Raleigh NC
Posts: 292
What material is the spacer plate?

66ryan is offline  
post #14 of 15 (permalink) Old 06-17-2019, 11:02 PM
Senior Member
 
2nd 66's Avatar
 
Join Date: Aug 2013
Location: New York
Posts: 9,643
Garage
Quote:
Originally Posted by paraman31 View Post
thx for the info 2nd66! we did put a spacer plate on his car. so far he's been lucky that he hasn't had any vapor lock ! runs great other than the autocross course. maybe the float is set high and it overflows when it's sloshing around
vapor lock and percolation aren't the same thing
Percolation happens in the carb when gas gets to hot

vapor lock happens in the line when the fuel gets to hot and the pump can't provide enough fuel


Brad
2nd 66 is offline  
post #15 of 15 (permalink) Old 06-18-2019, 12:30 AM Thread Starter
Junior Member
 
Join Date: Aug 2015
Posts: 17
hey 66ryan, we have the 1" 4 hole carb spacer plate with the vacuum port in back which i want to say is made out of cast along with a thin aluminum heat spacer plate. the fuel bowls are cool to the touch when running hard so i'm thinking the fuel isn't percolating in the bowls but i could be wrong. after my kid's autocross lap the car is fine once the car slows down at the end of the run,just has issues when doing the tight turns back and forth
paraman31 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Vintage Mustang Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome