Finally got out and did my test run

[kent olsen]

Finally got out and did my test run
Got my AFR installed and finally made the test run. Idle, steady 2,3,4,5000rpm I'm getting 10.7. Wide open is 13.5. As typical with webers there is still a transistion stumble about 3000 I can hold but with more/less throttle opening it goes away. F3 emulsions, 50 idle jets and 160 mains with both main and idle correction jets. Modified to 42mm by Paul Abbott. It has a special cam from Dougherty and makes 245hp @ 6900 and 230 ft/lbs at 4800rpm.

This may seem a little rich but after playing with these webers, with help from Paul, for years it seems to be what the engine likes. I've autoxed and tracked the car for years (249,000 miles, about 20,000 on my rebuild).

[kent olsen]

IMG_IMG_0412.JPG0412.jpg (128.3 KB)

[72targa]

Sorry for yet another dumb question. AFR?

[Chuck Miller]

I'm think'n it's an Air/Fuel/Ratio meter

[1QuickS]

Hey Kent,

I had a 3000 RPM stumble that I could not jet around but after installing a set of these air horns it went away.

[tom1394racing]

Hey Kent,

I had a 3000 RPM stumble that I could not jet around but after installing a set of these air horns it went away.

Paul

Can you tell us more about those air horns? Where did you get them and how tall/ID are they?

[1QuickS]

https://www.dellorto.co.uk/shop/full...m-x-50mm-long/

I spend a little time on these after I get them to improve smoothness of internal shape and to increase the inside diameter to 46mm which is the diameter at the top of all triple throat Webers. I doubt these "improvements" significantly tweak their performance. Also, if emulsion well air screens are used between the air horns then the bottom flanges need to be relieved to accept the installation of these screens: see photo of my Weber to understand this better.

[tom1394racing]

Thanks Paul

I hate to hijack this thread, but I will anyway since this topic is likely of general interest.

I have a 3.0 twin plug with DC 60 cams , 46 mm PMO's and 10.5 CR P&C's in my RSR Tribute car. There is a persistent stumble as the engine transitions from 3,000 to 4,000 RPM. It is almost not noticeable at partial throttle but is annoying at WOT. It has been suggested to me that I go one size smaller in venturi I could minimize the stumble at the expense of the higher end power. I have not tried this but your post on these air horns has me wondering if they might be worth a try.

[kent olsen]

Hey Paul I remember seeing those the last time I was over to see you. Are they something you are selling? If so send me a text and mayhaps I'll get some. Oh can K&N filters fit over them??

[1QuickS]

Hi Tom,

PM sent