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Healey 100M Cold Air Box Hose Fitting

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Papa Law

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I have purchased an original reproduction Healey 100M 4" rubberized canvas over wire air box hose from A H SPARES in the U.K.. It will collapse and clamp on the end of the cold air box as it came from the factory. However, I am not sure how to approach the fitting. Do you have to cut the bottom of the hose so it can overlap and secure a tight fitting? I don't want to start cutting if there is another method as the hose was expensive.
Thanks for any help!
 
If you have the correct hose and CAB the hose should go over the end of the box and secure with a hose clamp. This assumes that your car is equipped with the special angled support for the shroud that creates room for the hose, even with the correct bracket--or no bracket at all as some folks have done--in any case it is not an easy job to do. DW sells, or used to sell, a rectangle to round sheet metal adaptor that plugs into the end of the CAB and offers a circular end that more easily and neatly fits to the hose, but even with it I still had problems making the hose transition from the grill to the CAB and had a custom-made aluminum adaptor made.

After many years of struggling I recently removed the CAB as I was tired of slicing up my hands and arm when attempting to adjust the carbs, etc. It's an iconic piece of gear but it is questionable whether it really delivers any performance benefits and it certainly has its drawbacks.

All that said, good luck!
 
Thanks for the info, I have experienced every thing you said, but was hoping for a silver bullitt I am currently running a David Welsch sausage filter which is easy to work on carbs, runs well but obviously does not look as good as the CAB.
Working in the CAB area has a way of eating your hands up!
 
I've had the same problem trying to fit the hose. I also don't like the idea of not having a filter. I tried adding a K&N filter and mounting to the wheel well but had trouble keeping it in place. I read on this forum (can't find the reference) or somewhere else that testing showed velocity stacks added more to performance than the CAB. I've also seen examples of people drilling a hole in the end of the CAB because they felt that back carb was getting starved. All that said, I think going to velocity stacks with filters is my next step.
 
MikeAH100M said:
I've had the same problem trying to fit the hose. I also don't like the idea of not having a filter. I tried adding a K&N filter and mounting to the wheel well but had trouble keeping it in place. I read on this forum (can't find the reference) or somewhere else that testing showed velocity stacks added more to performance than the CAB. I've also seen examples of people drilling a hole in the end of the CAB because they felt that back carb was getting starved. All that said, I think going to velocity stacks with filters is my next step.
Click to expand...

That may have been me. I read an article years ago about a 100 racer who tested on a dyno and found velocity stacks yielded more HP than the CAB. I used the DWR adapter and some of the rigid tubing as used in the fresh air port, fashioned an adapter bolted it to the top of the steering box with a K&N filter (the adapter had to be modified to fit the tubing).

IMG_1398.JPG

IMG_1401.JPG
 
Last edited:
Never thought of strapping it to the steering box. Great idea! Thanks
 
Bob_Spidell said:
That may have been me. I read an article years ago about a 100 racer who tested on a dyno and found velocity stacks yielded more HP than the CAB. I used the DWR adapter and some of the rigid tubing as used in the fresh air port, fashioned an adapter bolted it to the top of the steering box with a K&N filter (the adapter had to be modified to fit the tubing).

View attachment 49123

View attachment 49124
Click to expand...

You can do both the CAB and Low Profile Velocity stacks like this (https://www.minimania.com/part/SS53/Austin-Mini-Stub-Stack-For-The-Hif44-Billet-Aluminum) They make them for 1.5, 1.75 & 2" SU's I used to use this type on my Spridget Racer years ago and they do work well.

Cheers,
Dan M.
 
IIRC, the CAB is fitted with studs that go through the carb bodies. I don't see how you'd fit these in a CAB. I do have these on my BJ8 with K&N filters.
 
I recently put in velocity stacks in place of the CAB. I really have not noticed any increase in performance but they look and sound great and my forearms appreciate the swap. At the time of this photo a small breather/reservoir venting from the valve cover was still installed, clamped to the front velocity stack, but I removed it when I last adjusted the carbs and have gone to a straight hose since there is no perceptible blow-by.
 

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Bob_Spidell said:
IIRC, the CAB is fitted with studs that go through the carb bodies. I don't see how you'd fit these in a CAB. I do have these on my BJ8 with K&N filters.
Click to expand...
Probably have to replace the studs with bolts & nuts. Might be a bit fiddly, but I bet it could be modified to work.

Dan M.
 
The original cold air box was attached with bolts. Unlike one replica version of the CAB that apparently uses some form of nutsert fixed to the aluminum box, the originals had a metal plate with welded nuts that was riveted to the inside of the CAB. I have seen that Sports and Classics (NFI) sells a replica that uses this OEM style mounting. The OE style would definitely not allow fitting of any sort of velocity stack. The "other" replica could probably be modified to allow use of the Low Profile Velocity stacks without too much trouble.

It would be very easy to fit studs to an OE CAB, although that might actually make it harder to get all 4 lined up at one time. I have considered doing this on several occasions.

Currently my CAB is on the shelf awaiting some crack repairs. In its place I have fitted the low profile velocity stacks inside a pair of Lynx-type foam filters. Hope to find out shortly how it runs and sounds with this setup.
 
CraigC said:
The original cold air box was attached with bolts. Unlike one replica version of the CAB that apparently uses some form of nutsert fixed to the aluminum box, the originals had a metal plate with welded nuts that was riveted to the inside of the CAB. I have seen that Sports and Classics (NFI) sells a replica that uses this OEM style mounting. The OE style would definitely not allow fitting of any sort of velocity stack. The "other" replica could probably be modified to allow use of the Low Profile Velocity stacks without too much trouble.

It would be very easy to fit studs to an OE CAB, although that might actually make it harder to get all 4 lined up at one time. I have considered doing this on several occasions.

Currently my CAB is on the shelf awaiting some crack repairs. In its place I have fitted the low profile velocity stacks inside a pair of Lynx-type foam filters. Hope to find out shortly how it runs and sounds with this setup.
Click to expand...

Ignoring the fact that my engine has a couple of extra cylinders (and 3X the openings) that's pretty much how this unified air filter housing & low profile velocity stub-stacks are attached. The Webers already have studs in them (5 or 6 mm dia./nuts are 10 mm across flats, and requires a highly modified open-end wrench to access them). Standard Weber rectangular x 1-3/4" high filter elements straddle the stubs-stacks, and a stainless steel panel slips in to secure them.

I made the box a 2-piece design in the likeness of a 100M CAB, but it would've starved the engine of air without the added holes in the ss panel and the box itself.

cai_003.jpg


Test-fitting the cover, before holes were punched. Hard to describe, but with slots in the top of the box, it slips inside the opening at the ends and bottom for a very secure fit, only requiring screws along the top (had to be able to remove/replace cover for filter maint.).

cai_001.jpg


IMG_6657.jpg


Holes were cut with a Greenlee 1/2" conduit K/O punch (7/8" dia.) and then belled with a punch & die a machinist friend made for me.

IMG_7097.jpg
 
Bob_Spidell said:
That may have been me. I read an article years ago about a 100 racer who tested on a dyno and found velocity stacks yielded more HP than the CAB. I used the DWR adapter and some of the rigid tubing as used in the fresh air port, fashioned an adapter bolted it to the top of the steering box with a K&N filter (the adapter had to be modified to fit the tubing).

View attachment 49123

View attachment 49124I have ordered a K&N RU2590 filter and will try to match your setup. Someone posted to use a trimmed tuna can to give it support. Here is the post I found: This read-only message was archived from a public mail list.
Mail From: Dave & Marlene <(email redacted)>

Hi Juanito,
Cold air boxes can be quite effective to increase engine power. ie. air
density increases about 2% for each 10 degreeF drop in air temperature.
An example would be a drop from 200 degrees engine bay temperature to
100 degrees outside temperature would give 20% increase in intake air
density & 20% increase in engine power. You might need to use the richer
OA6 carb needles in place of the standard OA7 needles. Where else can
you get so much gain for so little work? A secondary benefit is that the
carbs run much cooler also.

As far as filters, I have had good results with a K&N cone type filter
mounted on the forward end of the air duct. To make servicing the filter
easier, I used wing nuts on the upper grille mounting studs. You can
reach in through the front wheel openings & remove the wing nuts without
raising the car. Once the upper nuts are removed, the grille just swings
out at the top & unplugs from it's lower mounting pegs. A straight &
open access to the filter which doesn't need to be serviced very often
anyway.

I used a K&N # RU2590 filter. It is a truncated cone with a 4" ID rubber
connecting flange, 5 3/8" diameter at the base, 4 3/8" diameter at the
end, & is 7" long.

To ease removal & installation of the box to carbs, I secured studs in
the air box threads with Loctite & use nuts on the carb side of the
studs. Much easier to push four studs into their respective carb flanges
than to fight each bolt one at a time into the holes. Once the air box
is on, it doesn't need to be removed very often.

As you probably know, the front top shroud bracket needs to be replaced
with an offset bracket & the vertical shroud support bracket bent
outboard to match the offset bracket.

I can give further info & pics if you wish.

Dave Russell
BN2
Click to expand...
 
I recently added a small set screw at the front of the CAB to keep the adapter from sliding out. I try to keep this car as original as possible, but I'm not fanatic about it (note the rigid tubing and adapter aren't OEM; at the factory they just slapped some flimsy SCAT-type tubing on it with a band clamp and called it a day) . I live in the (sometimes very dusty Central Valley) so going filter-less isn't an option IMO. Now, I have to take it all apart to figure out how to get corn head grease into the steering box (a buddy sent me a couple tubes kinda as a joke when my box peed all over the garage floor, but I'm going to give it a go; a very respected Canadian restorer said he puts in all the cars he fixes).

CABs and modified intakes are a subject of much debate; I've seen dyno runs (on TV) where they'll add maybe 5HP to a 500HP engine; and my sorta uprated Mustang came with the GT350 CAB, throttle body and intake and probably a 'tune' and supposedly is capable of 20 more HP than a stock GT (480 vs 460). The one on the M cars is a real PITA to work with/around, but they do look cool. Aftermarket CAB kits for modern cars got popular maybe 20 years ago, so DMH and Geoff were ahead of the curve.
 
Michael Oritt said:
...

After many years of struggling I recently removed the CAB as I was tired of slicing up my hands and arm when attempting to adjust the carbs, etc. It's an iconic piece of gear but it is questionable whether it really delivers any performance benefits and it certainly has its drawbacks.

All that said, good luck!
Click to expand...

I've seriously considered that myself, and may yet swap in a couple K&Ns.

One thing Dave R. didn't consider, apparently, is that forcing the cold air to make a sharp 90deg turn to the carburettors probably obviates the advantage of the air charge being cooler (hence the advantage of velocity stacks; IIRC, Dougie has those on his racer).
 
I've been a big fan and user of stub stacks for several years because they fit inside air cleaners and can work just as well as velocity stacks. Picture of a page in How To Build Horsepower by David Vizard (c 1996) shows changes in airflow for various different shapes/sizes of ram pipes and a stub stack - of all of these the stub stack gave the biggest improvement.
IMG_4425.jpg

Dave
 
Michael Oritt said:
If you have the correct hose and CAB the hose should go over the end of the box and secure with a hose clamp. This assumes that your car is equipped with the special angled support for the shroud that creates room for the hose, even with the correct bracket--or no bracket at all as some folks have done--in any case it is not an easy job to do. DW sells, or used to sell, a rectangle to round sheet metal adaptor that plugs into the end of the CAB and offers a circular end that more easily and neatly fits to the hose, but even with it I still had problems making the hose transition from the grill to the CAB and had a custom-made aluminum adaptor made.

After many years of struggling I recently removed the CAB as I was tired of slicing up my hands and arm when attempting to adjust the carbs, etc. It's an iconic piece of gear but it is questionable whether it really delivers any performance benefits and it certainly has its drawbacks.

All that said, good luck!
Click to expand...
I ordered the Dennis Welsh CAB adapter/filter kit. Unfortunately I could not install it as the adapter adapts the rectangular box to a larger 4.5 inch round hose not the factory 4” hose. The large, rigid hose they supply will not fit past the original factory 100M shroud bracket.
 
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