carb air filter confusion

[Peterjohnbull]

Hi

I want better air filters on my twin carb 1965 P1800S. The current ones sort of crush the paper filters and have a single bolt holding them on (which gets loose, so you need to tighten it, so you end up crushing the paper filter).

I have searched through the various threads on this forum, going back a few years and think I understand my options, but as I am starting from little knowledge, some of the threads have confused me slightly.

As you go down the list, the performance will slightly improve, and likely the noise.

1. Stick with what I have

2. Blue Volvo pancake: which are likely to be a bit better than mine, but not much. They probably won't increase engine noise.

3. Generic chrome pancake filters which are likely to be a bit better, and a bit noisier, but are a bit cheap (e.g. https://www.ebay.co.uk/itm/Chrome-Pa...n/222857629838)

4. K&N pancake - again, even better, noisier and a bit more maintenance (oiling)

4. K&N filters that are taller than the pancake filters. Slightly better than K&N pancake.

Is that about right? Do I simply ask K&N what they have for HS6 Carbs and follow their suggestion?

Any help would be appreciated.

Cheers

Pete

[CLIVERALLY]

Ok
Be careful with cheap ebay filters or those of the RAGE type. The air flow through them is cack. When I had my business I would unbolt and throw them as far as the eye could see. I could never get the car set up right.
The standard ones are more than up to the job but if you want to change and dependant on your budget and availability I would and have always advised K&N , or ITG or Pipercross. I have K&N pancakes on mine..they work fine

[Ron Kwas]

PJB;

Filters with a single bolt which crushes filter material don't sound very effective or original, but without a picture, its tough to know what you have (early [thin] oe filters for SUs had 2 bolts with separate nuts, later [thicker] had 3 bolts into threads in the carb housing). In both cases, securing bolts ran through internal tubes which limited tightening and prevented crushing the filter material...if yours have no such tubes, one has to question the design and quality,, and filtering effectiveness in the first place...replacement with tried and true parts is probably a very good idea!

You must first make the choice original or aftermarket...then options become clear...here are some notes and ideas:

Noise factor for different filters...I expect there are plenty of other noises from engine, exhaust, road-noise, tires, so any change, or purported increase will probably not noticeably or appreciatively change the noise signature of the car.

Notes on filters: Even for 2 bolt carbs, I wouldn't install the thin 2 bolt oe Air Filter now...I'd either install 3 bolt types, or go with an aftermarket like the K&Ns at this point...K&N makes a complete setup...look up PN 56-9098, or just nice tall elements (which I've been eyeing to sandwich between harvested oe filter end-plates) E-9145.

Note also: I like the K&N elements for the fact that they are made of cotton, are cleanable and reusable...I don't like their adverts and claimed improved flow or some other marketing department horse-puckey hokum...don't forget, 15% improvement figures are strictly when the filters are BRAND NEW are perfectly clean, and breathing perfectly clean air in a dynamometer room, and while operating at FULL THROTTLE...so have very little to do with the real world were everybody drives...once a little dust gets on the filter element...ANY filter element from ANY manufacturer, it becomes more restrictive and all those impressive marketing department BS numbers are absolutely worthless!! Besides, there is already a completely restrictive device in the airflow path by which we limit ingested air anyway...its called the throttle! So if your filters are slightly blocked, we are just going to open the throttle a bit more to get an equivalent air ingestion...bottom line is K&N filters perform similarly to filters of other manufacturers in the real world, but are nice in the long run because they can be cleaned and reused.

Cheers

Reference: http://www.sw-em.com/su_carbs.htm#SU%20Upgrades).

[Peterjohnbull]

Here they are:

https://ibb.co/ePyGUf
https://ibb.co/erZqpf

Not sure where the originals one would have got to.

Also, having a middle bolt means you have a middle mounting (albeit not allowing a thick enough filter) and so it is tricky to use an air flow meter to balance the carbs, as the bolt mounting is in front of the hole.

[classicswede]

1) I am sure you are describing the early cast alloy filter housings. You could stick with what you have there
1.5) alter what you have so you can fit a taller K&N type element and have a double locking nut so it will not vibrate loose
2) they work but I'm no fan of them
3) Forget it, they are way too shallow and block the air flow
4/5) options but all the options you have listed so far have the same floor of drawing in hot air from above the exhaust.

6) fit the plastic air filter box with a K&N type panel filter and enjoy the extra power a good cold air feed can give you

[classicswede]

Originally Posted by Peterjohnbull

Here they are:

https://ibb.co/ePyGUf
https://ibb.co/erZqpf

Not sure where the originals one would have got to.

Also, having a middle bolt means you have a middle mounting (albeit not allowing a thick enough filter) and so it is tricky to use an air flow meter to balance the carbs, as the bolt mounting is in front of the hole.

Exactly as a thought pre 65 filter housings.

You can remove the metal A shaped bracket and make a new one that comes out further and use a longer thread allowing taller filters to be used

[classicswede]

Originally Posted by Ron Kwas

.I don't like their adverts and claimed improved flow or some other marketing department horse-puckey hokum...don't forget, 15% improvement figures are strictly when the filters are BRAND NEW are perfectly clean, and breathing perfectly clean air in a dynamometer room, and while operating at FULL THROTTLE...so have very little to do with the real world were everybody drives...once a little dust gets on the filter element...ANY filter element from ANY manufacturer, it becomes more restrictive and all those impressive marketing department BS numbers are absolutely worthless!! .

I have seen testing of K&N filters showing much better flow compared to a paper filter. What was most intersting was then seeing the test for the K&N after competing in a very dusty sand rally. The K&N at the end of that was still flowing slightly better than a new paper filter!

K&N do tend to be overpriced and other makers do offer some decent stuff at reasonable prices however there is a lot of cheap crap on the market that does kill airflow. At least with K&N you know where you stand

[Peterjohnbull]

Yes, Mr Swede, I could remove the A bracket (https://ibb.co/g1HFN0) it is just bolted on.

Then make another one - what would you propose I make it from? I have some small sheets of mild steel that I could use. Unless you have a cunning plan?

People have spoken of the "plastic air filter box" - what is that? Well, it does sound like a box made of plastic used as an air filter - but is it something you buy with SU HS6 mountings on it?

Pete

[mocambique-amazone]

The king filter for fuel is great stuff.
The zip tie to fix a fuel hose I can't believe.
You are worried about the noise the filters will do?
You should be worried about what to tell your insurance company why the P1800 burnt down.

6. Like Dai wrote

The best way to get a B18/B20 engine with carbs to run properly
And swap to a 4 in 2 exhaust manifold and a 2 in 1 "downpipe"

Good luck and a hughe fire extinguisher, latest to x-mas under the tree, Kay

[Peterjohnbull]

None of the people who have looked at the engine ever mentioned the cable tie as a problem (it was on there when I bought it) . And quite a few a mechanics have looked at it. Is that because it doesn't clamp it enough? I can swap for a metal clip easily enough, I have a few spare.

You really looked closely at the picture.

I put the fuel pressure regulator on.

Sorry, I don't really understand your suggestions. Any links I might follow for a better understanding?

I have an extinguisher in the boot.