Webers 40IDA pressure

skyoung · skyoung's Garage

Anyone in the Seattle area who has webers and can give me some direction to the best Carb guy. specefic to dyno tuning and how to regulate the pressure going into the carburetors. any help will be appreciated.

Steve Young

modified 2.4 screamer!!!

Zendalar · 04-19-2002, 10:02 AM

My mechanic told me that 0.35 bar is maximum from the fuel pump. Bigger pump and you need a regulator.

911@b-faster.com

john walker's workshop · 04-19-2002, 11:19 AM

3 to 3.5# is all the carbs can take without the needles getting pushed off their seats. a bit more for racing. holley makes an inline, adjustable regulator, as well as others. start with a low pressure inline pump that is rated at 6# or less. put the reg after the pump. check the pressure with a hand held gauge, or attach a permanent guage to the regulator.

joehahn · joehahn's Garage

Uncle John (Walker's) Band. Great Tune

skyoung · skyoung's Garage

John, thank you for your words of wisdom . I did know about the pressure allotment for these carburetors and I actually had a pinch device on the pressure tube originally. I also had someone tell me that you could install a restrictive device in the line(a jet, brazed to a bronze tube and drilled to allow only so much fuel). Now that seems a lot of work and I was thinking about the pressure regualtor as you mentioned. for the sake of interest, a friend of mine had his identical engine dyno tuned in San Jose four years ago and the treatment gave him about a 30 HP boost. The individual who did the work had a vast knowledge of Webers and with the dyno did a great job. My engine runs like a banshee under power but around town it pops, snorts and is plain unruly. I am not a racer and will never be one but I feel that a good carb tune-up will greatly help. Another question is the size of the venturies recomended. I started out with 34's and am now running 32's?

Steve in Carnation

jabb · 04-19-2002, 04:53 PM

I use the Facet pump with the Holley regulator runnnig 3 1/2 lbs
of pressure.... Take your car to John Walker if you are looking for some help.

john walker's workshop · 04-19-2002, 06:58 PM

32 venturis should be about right. the main reason most carbs spit and pop and have poor driveability at lower rpm is the size of the idle jets. the original .45 and .50mm jets don't cut it anymore with today's crap gas. .55 or even .60mm jets work better. a proper balance and adjustment by a trained ear works wonders, too. also, most shops set the ignition timing considerably less than the 35° total advance that the engine could use for better response.