Air Filters for Triple Webers, BT7

[Bugeye58]

A friend is having trouble with filters on his BT7. He's running triple SK's, which are a virtual DCOE clone, and the K&N # 56-1310's are too deep to mount. They're 1.750", and he's looking for something thinner, preferably 1 1/2" or less. Do any of you have a recommendation I can pass along to him?
Thanks,
Jeff

 

[Randy Forbes]

When I first installed the 45 DCOEs on my car, I had to modify the rearmost airfilter to fit between the carb and pedalbox. I was using filters that held a piece of filter/foam between an inner and outer boundary (3 separate pieces) of expanded metal screen, thus, it was easily modified to be shallower.

When the whole car was dismantled, I modified the pedalbox so that I could fit "store-bought" airfilter elements (approximately 1-3/4" x 3 x 5). The three (3) elements are concealed inside one (1) airbox.

First picture shows removeable s/s cover before the holes were cut & belled.

 

[healeynut]

What the heck is that big monster tube you have running from the truss to the kickpanel/door hinge pillar? Is that for T-bone crash safety? If so, how is it fixed on the other side of the kick panel?

 

[GregW]

Hi Jeff,
I had a heck of a time finding a filter to fit my Mikuni carbs. The problem was (is) the assembly process of the K&Ns. The rubber ends cover a lot of the filter element itself. So a 1 ½” high filter has about a ½” of filterable height, same goes for those green filters. I wound up making my own filters using Uni foam and some spare aluminum I had lying around, .090 I think. Here’s a picture to get the creative juices flowing. The end caps were aluminum brazed together.

 

[BlueRidge2]

What the heck is that big monster tube you have running from the truss to the kickpanel/door hinge pillar? Is that for T-bone crash safety? If so, how is it fixed on the other side of the kick panel?

Just a guess but I would think to take the flex or twist out of the chassis whilst charging hard in and out of sharp corners. Br2

 

[GregJ]

one thing to be careful of is the distance between the air intake trumpet and the cold airbox wall. In order to draw sufficient air for optimum horsepower the distance from the end of the airhorn (or what ever opening you have) should be 2 times the diameter of the air opening itself. I would be concerned by the air management in the set-up of Randy Forbes car as pictured in the previous post.

GregJ

 

[GregJ]

I also would have a hard time being comfortable with the position of the brake reservoir so close to the exhaust manifold, especailly with no heat shielding.

GregJ

 

[Randy Forbes]

... I would be concerned by the air management in the set-up of Randy Forbes car as pictured in the previous post.

GregJ

And:

I also would have a hard time being comfortable with the position of the brake reservoir so close to the exhaust manifold, especailly with no heat shielding.

GregJ

Fortunately for you, you don't have to be comfortable with my car.

FYI: The airfilter elements are the same ones as supplied by any of the popular Weber suppliers, they're just in a different box (same height parameter). I wanted the three (3) carbs to be tied together so the linkage acted uniformly; with soft mounts, it's easy to have one carb flex up and another down. Hence the common airbox.

Sure, I would've liked to have enough room for a full works style induction setup, but in 1986, these manifolds were all that was available for a LHD car. Besides that, I wasn't up for modifying the shroud for access. Back then, the all-up price was about $600.00 (SC Austin-Healey UK). Kinda hard to touch them for that price today.

I've never had a problem with my brake fluid catching on fire either; the headers and reservoir have been that close since 1978, when I bought it.

 

[Randy Forbes]

What the heck is that big monster tube you have running from the truss to the kickpanel/door hinge pillar? Is that for T-bone crash safety? If so, how is it fixed on the other side of the kick panel?

The main hoop diagonal bar has been reconfigured since this original "out of body" shot was taken, but you get the idea of the network. Not shown are the connectors inside the front rectangle tubes; all four (4) corners of this chassis are firmly tied together. The entire cage fastens to the chassis at fifteen (15) points.

Revised main hoop diagonal:

 

[GregJ]

Randy,

Your doing fine...I did not intend to imply your set-up is "wack." I just commenterd in case others were interested ( like the original poster) regarding constructing air intake boxes for the carbutetors. My 100 has weber carbs (45mmDCO3's) and I had the same problem of space with air intake. Really the best solution is foam filter "socks" as they will bend around any obstrucion without creating a solid baririer. To each his own...

Regarding the brake fluid reservoir...same comment. For sure I would not expect your brake fluid to catch fire???? However frequent heavy brake use, like under racing conditions, would soon heat-up the fluid. That situation together with the proxiominty to the radiant heat from the exhaust manifold, you would soon realise reduced braking efficiency. Again my observation for anyone contemplating a similar set-up when deciding how to deal with the filter problem.

Just my $0.02...probably worth less than that.

GregJ