Don Terrill’s Speed-Talk

Guys , a while back I posted about the carb problems I was having and my search for another filter base after seeing how bad the spun aluminum base I was using was . I want to thank everyone who made suggestions ... and especially 88FBird for his comment about the L88 base . Long story short , I put the L88 base on the car and was able to get a 3" tall element on the carb . Hood clearance is really tight ( Cobra replica with a 482 FE engine and a Pro Sysytems 950 carb ) which placed some limits on what I could do . Before , the carb never really responded to changes the way it should have and fuel distribution was poor , per plug readings .
The carb now responds to changes the way it should , fuel distribution is much better and the car has never run better . The two things this base allowed me to do is get a better flow path and increased the clearance between the vent tubes and the air cleaner lid to almost 1" now . Now to see what I can do to my dual quad 427 Galaxie
I`m attaching some photos to show what I had and what I now have . Now trying to decide if it`s worthwhile to modify the lid by removing the " air director " in the center .
Again , thanks for the help !

Good to see the carb tune come around for ya. I have been toting (and proving) the benefit of this filter base shape and how important how and where the airflow goes into the carb entry, for a long time.
And showing it to others on their car too.

"Ok now go buy your own. This one's mine"

Show us what you do with your dual quad. I have a future plan to do a dual quad induction system on my
406 sbc. If I ever get to it.
Thanks for the follow up and mention.

F-Bird ~88 .... just so you know , you also made me revisit my views on PCV systems and actually learn how they work and what they do . You can`t see it clearly on the photos , but I now have a functioning PCV system on the car that works . The actual PCV valve is for a 2003 F150 5.4 L truck ! Thanks for making me learn something .
Also , I made an " improvement " to the L88 base around the lip where the base sets on the carb . I filled the "cavity" in and smoothed it out so air wouldn`t hit it and maybe cause some turbulence .

BTW , ever notice .... F-Bird 88 and L88 Base have something in common ??

Anyone thinking of doing up a cold air/ram air system should look at GM Hi-Perf snorkled air cleaners, circa 1970 +/- a couple of years. They have the same base contour as the L-88 part...
http://www.google.ca/search?q=1970+Z28+ ... d=0CCYQsAQ

MadBill wrote:Anyone thinking of doing up a cold air/ram air system should look at GM Hi-Perf snorkled air cleaners, circa 1970 +/- a couple of years. They have the same base contour as the L-88 part...
http://www.google.ca/search?q=1970+Z28+ ... d=0CCYQsAQ

Madbill: I am going to have to watch for one of these. wonder why the aftermarket has not picked up on this.

Wonder where the old GM sheet metal stamping dies for these parts got to.

I tested that same spun base against two others I had on hand. One was the common drop base you get with most other aircleaner assemblies, and the 3rd was a zero-drop but with a mild radius entering the carb.



Here are the chassis dyno results.


Beyond a doubt, that spun base costs hp!

the top of carb bowl vents have to be at least 1/2" away from the air cleaner top to let out the bowl pressure. cutting the vent tops on a 45 degree angle is also needed as all original GM carbs had this

LnL wrote:I tested that same spun base against two others I had on hand. One was the common drop base you get with most other aircleaner assemblies, and the 3rd was a zero-drop but with a mild radius entering the carb...
Beyond a doubt, that spun base costs hp!

Good data! (and mirrors flow tests I've done on spun Vs. L-88 bases)

Nice to see hard data rather than my seat of the pants feel , which said there was an improvement . Now I`m curious to know if anyone has any flow data on the lids . As can be seen from my photos , I`m still using the spun lid with the "dimple" in the center that supposedly directs air into the carb . I`m considering cutting that out/off and making the lid curvature in the center equal to the rest of the lid .

63qcar wrote:Nice to see hard data rather than my seat of the pants feel , which said there was an improvement . Now I`m curious to know if anyone has any flow data on the lids . As can be seen from my photos , I`m still using the spun lid with the "dimple" in the center that supposedly directs air into the carb . I`m considering cutting that out/off and making the lid curvature in the center equal to the rest of the lid .

It wasn't quite the same shape (a little less 'bulge'), but I flowed such a lid at the same time as I compared bases (circa 1990). Despite its great looks, the spun lid with a wide cone down to the mounting flange was a flow disaster. (I suspect due to the large size of the flat area for the nut) I had picked up the lid, base and filter cheap as an assembly at a flea market; ended up pitching all but the element..

lnl
could you verify which color base goes with which color line
hard to tell with these old eyes
I may be off base
and
thanks for the info

Good info. Interesting that the "common" drop base with sharp corners really didn't give up anything to the radius flat base.

Also, the printout is for peak HP, at which point the curves are much closer than elsewhere, e.g. ~ 132 MPH, where the deep spun base is down ~ 20 HP...

MadBill wrote:Also, the printout is for peak HP, at which point the curves are much closer than elsewhere, e.g. ~ 132 MPH, where the deep spun base is down ~ 20 HP...

Also I wonder if mine at 6" with the spun base is the the same? The problem I had was the Dominator base. Not having the L88 base at my disposal.

I'd say the filter diameter would be the biggest factor. A 16" diameter one should leave enough room for the spun center to not block airflow.