FrontEngineDragsters.Org Forum

Technical => Spud Miller's Cave => Topic started by: matt b on July 30, 2018, 12:58:48 PM

Title: Interesting Hilborn problem - advice?
Post by: matt b on July 30, 2018, 12:58:48 PM

Hi y'all. Got the 406 in my MW car fired up this weekend. 406 / 3 piece Hilborn / DSR pump / 36 degrees timing / 115 main bypass/ 90 high speed at 50# on alcohol.

Started with BV leaked to 25% - small adjustments leaner have it idling pretty well and it's crisp on the throttle once I blow it out.

Passenger side cylinders seem very fat - 2/4/6/8 - most particularly #2 and #6. They are blowing lots of raw fuel at idle. They clean out fine when I hit the throttle but they appear to be very very rich.

Checked nozzles last night (clean), checked valve lash (all good at .02), fresh spark plugs. Going to check / gauge butterfly adjustment on that bank tonight after work.

Anybody wanna take a stab at why it's really good on one bank and super fat on the other....got butterfly adjustment in my head....what else might I be missing?

Thanks in advance!

Title: Re: Interesting Hilborn problem - advice?
Post by: masracingtd1167 on July 30, 2018, 01:23:17 PM

Throttle plates side to side adjustment is off ! One side is open more than the other !

Title: Re: Interesting Hilborn problem - advice?
Post by: matt b on July 30, 2018, 01:32:26 PM

Thanks - I’ve breathed enough alcohol fumes this weekend to be second guessing myself!
Will check and set them tonight and report back.

Title: Re: Interesting Hilborn problem - advice?
Post by: Paul New on July 30, 2018, 02:41:00 PM

Stack injection is difficult to get even out! 

Title: Re: Interesting Hilborn problem - advice?
Post by: masracingtd1167 on July 30, 2018, 03:16:20 PM

I used to use a uni sync tool to adjust them

Title: Interesting Hilborn problem - advice?
Post by: cad500justin on July 30, 2018, 10:32:37 PM

Phone won’t let me copy a link, but spud has an article on his site called belligerent butterfly’s that should help.

Title: Re: Interesting Hilborn problem - advice?
Post by: Paul New on July 31, 2018, 06:43:31 AM

Quote from: cad500justin on July 30, 2018, 10:32:37 PM

Phone won’t let me copy a link, but spud has an article on his site called belligerent butterfly’s that should help.

Here you go
http://www.fuelinjectionent.com/butterflies.php

My phone worked  ;D

Title: Re: Interesting Hilborn problem - advice?
Post by: matt b on July 31, 2018, 07:35:59 AM

Thanks for that!

Glad to report success - reset butterflies, adjusted BV to 25% and fired right up. Went about three flats leaner and while it's not quite perfect it's 100% better than it was.

Now that I've heard it run and filled my shop with methanol fumes....out it comes. Needs a new pan gasket and it's finally time for chassis paint, re-cert and assembly!

Thanks all.

MB

Title: Re: Interesting Hilborn problem - advice?
Post by: Paul New on July 31, 2018, 08:23:55 AM

Get the cert prior to paint just in case!

Title: Re: Interesting Hilborn problem - advice?
Post by: matt b on July 31, 2018, 10:43:24 AM

Yah - absolutely!