Miss on high G corners

[O Racer]

I have a 1991 Caterham with the stock 1700cc cross flow engine with 40mm Webers

 

I have started to track day the car, twice since Nov. at Laguna Seca

 

A miss has developed exiting turn six going up hill and turn ten downhill both left corners, also a bit exiting two

 

Fuel system, stock gas tank, Facet 35gph electric pump, Facit filter mounted near pump, another small in line filter before Webers, removed air cleaners just straight velocity stacks

 

Seems like it got worse from first track day in Nov to second one in early Feb

 

Any ideas, what is correct fuel pressure for Webers, is 35gph pump adequate?

 

Thanks for your help

[xcarguy]

O Racer,

 

A couple of ideas (simply ideas; I have no experience with Webers).

 

1) high G load has allowed debris in tank to find its way into the filters and/or carbs.*

 

2) fuel/air mixture of the Webers was originally tuned for airflow through the filter vs. running without a filter.

 

X

[xcarguy]

One other thought: fuel starvation under high G load which doesn't present itself until exiting the LH turn (possibly due to a combination of tank design, fuel pickup point and/ fuel level used during the track session).

[bball7754]

I had the same problem with my '98 Crossflow Caterham, and it was the rubber engine mounts. They had collapsed and the bottom of the carbs were hitting the frame member on hard left hand turns creating an air leak.

 

They've improved the design (somewhat), and they are supposed to last longer.

 

Steve

[Kitcat]

Ditto dx by bball, on my X-Flow Caterham as well. The engine mounts wear out very fast, then the motor moves around and then bad things happen. I replaced the mounts 2x during my 4 years/15K miles of ownership. Each time it fixed the mystery engine problem (wh/only occurred on high G track day curves). BTW, I may have some left in my basement, PM me if in need.

[ayseven]

Would installing a fuel swirl pot help?

[rx7locost]

I have no direct personal knowledge:

 

If your problem disappers with a full tank, then fuel starvation is at the tank pickup.

 

Commonly mentioned on other forums I visit: Stock Facet fuel pump pressure is too high for Webers. Facet normally runs 4-6 lbs. Add a regulator set to 2.5 lbs.

 

More internet wisdom: You should also run the soft mount kit.

[twnpipe]

What happened to me this past weekend again - ongoing for 2 many track days. The keyed ignition switch had a dead spot which showed up only at certain times on the track, it momentarily turned off the ignition then back on. This switch was replaced last year just in case that was happening. Just a gentle nudge on key turned off car. Duct tape solution for that day,

 

Where you running next? we should meet up. I need to build a quiet muffler for Seca, I have been running Buttonwillow and Streets.

[MichaelD]

I had a similar issue with my Zetec. It always occured in the same turns with a low fuel tank. The fuel pump what changed. A dual pickup was installed to pull from both sides of the tank and it still occured *5$@X*

 

After about two years, it turned out to be caused by the g force in a certain turn was enoung to pull a lose wire near the cutoff switch into the terminals cuttin out the switch. Zip tie the wire away....problem solved.

Edited March 12, 2013 by MichaelD

[coffee break]

Simple problems like that will drive you NUTZ!!!!