11 replies to this topic

[jcslocum]

I have a '67 mini with a 998cc engine in it. I'm 99.9% sure this is not the original engine and I have a question about the crankcase breather hookup. Right now the hose from the canister that is attached to the side of the engine goes direct to the base of the carb. This location draws a LOT of vacuum and if the oil cap is off, the engine essentially won't run. Even pulling the oil dip stick, causes a significant change in idle speed. So, is this the right location for this hose or should this location be blocked off and this hose just run up to the nipple on the air-cleaner?

 

 

 

Thanks for any help!

[Dan]

It's right as it is, it's not meant to run with the cap off. Although it's essential that you are using the right cap which is vented. The port on the air cleaner is usually blanked, it's for a different model. If it weren't connected to the carb it would need a control valve.

[Spider]

I'm pretty sure the 998 engines had a restrictor fitted at the carb, these reduced the port size from the 5/16" it is down to about 3/32".

 

It is actually a very good set up.

[jcslocum]

OK, here is some more info:

 

The nipple on the breather is 1/2" as this is the hose size I just used to renew the hose. The nipple on the carb is about 3/8" so the hose clamp has to be really tightened to make it fit tight and not leak. This seems wrong, maybe I'm missing a molded hose or something that has a reduction in it??

 

I found a pic of what it could be like

 

 

See how the breather hose goes to the aircleaner??

[Dan]

The right part always helps!

http://www.minispare...|Back to search

[jcslocum]

THIS is why I came here for the answer!!  Dan, you are the man. One last question, the cap is not vented. I tested with the old mouth on the cap test by blowing and there is no leakage. Can I just drill sa amll hole in the cap?? Any idea what size it should be?

[gazza82]

While you are buying the pipe ...

 

http://www.minispare...|Back to search

 

 

or

 

http://www.minispare...|Back to search

 

Edited by gazza82, 19 December 2014 - 02:24 PM.

[jcslocum]

Gazza,

 

I'm a cheep ass Yankee so I can make a copper adapter to go from 1/2" to 5/16" and drill a teeny hole in the cap!!

 

Thanks all for the input and letting me know what parts are needed.

[sheree21]

It same case with my old car

 

[Dan]

  I can't say I know what size hole to drill but I do know it is a specific size as it is designed to allow a specific amount of flow through the engine.  Maybe ⅛ or 3/16?  The vented caps also include an inlet filter of wire gauze though.

[RELF]

I have a 1966 Riley Elf which has the original 998cc engine. The breather hose runs to the air filter as per the second photo earlier in this thread. I have just replaced my hose with 1/2" C-AHH8537 Oil Cooler Hose from Mini Spares which fits nicely at both ends.

(I am no expert, but I have never seen the hose taken direct to the carb.).

 

Best of luck.

[Dan]

That's a different, and far less effective and clean, breather system. The breathers were changed many times in the early years as the engines were developed. Later carbs than yours have a port specifically for the breather and where present it really should be used on a road car.