Measuring carb springs

[John Gervais]

I had an 'AHA' moment yesterday, as I tried a seemingly identical 'Red' HIF carb spring and my mini ran completely different to the way it had previously.

Somewhat perplexed, as I'd altered nothing except for changing the spring, I decided to bring them home and measure the compressed spring pressures on my kitchen scale.  All of the springs I measured are new springs - a pair of 'red' and a single 'yellow'.  And, I found out that all springs are not all created equal, as their colors would suggest.

Here's what I used - a digital kitchen scale, engineering pocket scale (ruler) with sliding depth gauge (pocket clip) and a flat-bottomed steel ashtray to push downwards with to ensure that I would distribute the load across the entire end of the spring as I compressed it.  I adjusted the pocket scale slider so that I'd stop compressing each spring approximately 1" from the top of the kitchen scale, placed each spring on the scale, zero'd the scale (tare button) and I took multiple measurements on each spring.

One brand new 'red' spring measured 4.7 oz, the other 5.6 oz and the 'yellow' measured 8.3 oz. 

My car is running better on the 4.7 oz spring -