free hit
counters
Direction of the carb spacers... and what are these? - Fuel System/Carbs - The Lotus Forums Jump to content
Sign in to follow this  
DrieStone

Direction of the carb spacers... and what are these?

Recommended Posts

I can't seem to find any kind of guidence as to what direction the spacers for the carbs should go. I assumed the narrow end goes toward the carb, but I'm not sure.

Also, as part of my rebuild kit I had a bag of rubber rings. 8 rings for the carb spacers, 2 rings of approximately the same diameter, but of thinner material, and 2 rings that "U" shaped with a spring wrapped around the inside. Any idea what these other bits are for/from? I don't recognize them.

f05WJ.jpg

Share this post


Link to post
Share on other sites
Upgrade today to remove Google ads and support TLF.

If it was from a cylinder head gasket set they will be the camshaft seals ( both ends, the U shaped one goes at the pulley end. The O ring goes at the other end )

John

Share this post


Link to post
Share on other sites

I think you can work out which way round they go from the parts list. The Anti reversion plates have the sharp end into the engine, to stop the charge from going the wrong way at high valve lift cross over...something like that I think!

Buddsy

Share this post


Link to post
Share on other sites

I can't seem to find any kind of guidence as to what direction the spacers for the carbs should go. I assumed the narrow end goes toward the carb, but I'm not sure.

That's wrong way, if you fit them that way round you won't be able to open the throttle more than a few degrees (been there, done that) :thumbdown:

The spacers are actually an emission device and as they restrict airflow into the engine if you get them turned out so that they're the same diameter all the way through you'll increase your airflow & therefore power. :thumbsup:

Share this post


Link to post
Share on other sites

The spacers are actually an emission device and as they restrict airflow into the engine if you get them turned out so that they're the same diameter all the way through you'll increase your airflow & therefore power. :thumbsup:

Oh you don't want to do that! They are not an emission item.

http://www.cididit.com/anti_spacer_info.htm

http://www.magnafuel.com/products/accessories/revPlates/index.htm

http://www.popularhotrodding.com/buyersguide/0601phr_best_carb_spacers_cheap_horsepower/index.html

Buddsy

Share this post


Link to post
Share on other sites

They're different though, they don't actually reduce in diameter. If you look carefully at the second picture, the nice purple coloured ones, you can see that while there is a lip it's the same diameter throughout.

The guy who told me they were fitted by Lotus to reduce emissions, and who sold me a set with the restrictions removed, was Ken Snailham of QED. As he put it, what's the point of fitting a 45mm carburetor onto a 40mm inlet throat??

Share this post


Link to post
Share on other sites

I do see where you are coming from. A reduction in dia could be seen a reducing flow but the lip has to be smaller as it needs to sit within inlet manifold so the lip can do its job as an anti reversion. Not all restrictions are bad as sometimes they increase velocity. Isn't that why my turbo has the 40 DHLA with the smaller chokes with gives better performance than the 45 DHLA with the larger chokes?

I just don't believe Lotus would have added anything to strangle performance.

Buddsy :welcome:

Share this post


Link to post
Share on other sites

Isn't that why my turbo has the 40 DHLA with the smaller chokes with gives better performance than the 45 DHLA with the larger chokes?

Buddsy :welcome:

Yeah, I must admit that there was no detectable increase in performance after fitting the QED spacers to my S3 & I've never seen an explanation as to why Lotus fitted 40mm Dellortos to the turbo when they'd fitted 45s to the NA.

I just don't believe Lotus would have added anything to strangle performance.

Buddsy :welcome:

They fit cats don't they??

Share this post


Link to post
Share on other sites

But cats are fitted as a requirement by law.

Surely, the cats are there to get the emissions down to the levels required by law. If they could get the levels down by using cheaper/freer-er less power sapping methods they would??

Share this post


Link to post
Share on other sites

I thought they were introduced along with the unleaded fuel to reduce the amount of lead that was pumped out onto the streets?

Buddsy

Share this post


Link to post
Share on other sites

I thought they were introduced along with the unleaded fuel to reduce the amount of lead that was pumped out onto the streets?

No, it converts carbon monoxide, unburnt hydrocarbons & oxides of nitrogen into carbon dioxide, nitrogen & water.

From Wikipedia:

Share this post


Link to post
Share on other sites

OK but still it was a thing that was forced to be fitted by gov not by Lotus I think?

Buddsy

Share this post


Link to post
Share on other sites

OK but still it was a thing that was forced to be fitted by gov not by Lotus I think?

Yes, it was the only way Lotus could get the emissions down to the required levels after all other methods had failed.

Share this post


Link to post
Share on other sites
Guest

My 2p, the ones with the springs in are oil seals. If it is a top end gasket kit them I'll side with the cam shaft oil seal camp. Spring bit generally goes oil side - be careful fitting them, any forcing, stretching or abuse and they will leak.

The spacers go in with the lip into the manifold, away from the carbs. My guess is that they are there for no other reason than to help centralise/align them and more improtantly to provide a nice smooth passage for the air flow (so as not to upset flow).

Hope this helps!

Ron T.

Share this post


Link to post
Share on other sites

Yes, it was the only way Lotus could get the emissions down to the required levels after all other methods had failed.

In Europe they are required, it's not just a thing of meeting the emissions specs it's law to have to fit cats. It's stupid but that's how it is. Manufacturers could have met the same emissions targets via lean-burn or possibly other methods but they were ruled out by the requirement to have catalytic converters.

Regarding 45s Vs 40s, it's the same as to why engines which are naturally aspirated have a lot more effort spent on them in trying to improve the flow of the air when compared to that of forced inductions.

In a standard atmosphere situation the highest possible air pressure difference between the cylinder is a compete vacuum in the engine and 1 bar outside it, pushing the air through the cars and into the engine. You'll never get to a complete vacuum in the cylinder, so with a compression ratio of 10':1 you'd at best get a pressure differential of 0.9 bar. Now allow for restrictions in the air filter system and other such things, you get a lot less air flow than a 45mm hole would normally allow.

Compare that to a forced induction, you could get as much as 6bar pressure differential, again you loose a bit due to the pressure in the cylinder being greater than 0, and loose a bit due to air flow restrictions, but some are near constant or not directly proportional to the amount of air flowing. That way, the restrictions don't have anywhere near the same impact on the amount of air that eventually gets into the cylinder. Any restriction which means you get less fuel & air than the cylinder could cope with (before melting pistons etc), you can dial up the pressure.

On the basis of the above, for a naturally aspirated engine you spend the extra money on larger carbs, better head flow work, cam shaft profiles that keep valves open as long as you dare, it's how you get as much air in the cylinder for the burn. For a supercharged engine (including turbo) you don't have to be as fussy, you can still get the maximum amount of air & fuel in even with a few things being less than the best case scenario.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  


×