Pelican Parts Forums - is it possible to add vacuum adv port to IDF's (that dont have them already)?

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is it possible to add vacuum adv port to IDF's (that dont have them already)?

Hi Folks

Got a pair of 40 IDF's for a 73 2 litre on the car now. Actually they came with the car.

I can't help but thinking that putting the
original vacuum advance distributor back in in place of the 050 would be a good thing given that
this car is used for street driving. Problem is, is that this particular pair of carbs does not have the port.

I have heard that you can add the port but its not for the squemish.

Anyone know anything about this?

Thanks much in advance.

Curt

They can be drilled. The bosses are located on the mixture/air adjustment side of the carb. You drill and put a 1/8" pipe in. Where you drill otherwise will determine the type of vaccum you get (ported, etc)

Hi Pappy

Thanks for the info, though I see that I may be a bit confused.

Check me on this:

I am driving along doing 60 mph in 4th and at some point I stomp on the throttle. I want the distributor to advance the timing in response to this sudden demand for more power.

Therefore I believe that I need add the port to the carb above the throttle plate and then run this to the correct port on the distributor.

But, it sounds like from what you are saying, I add the port to the mixture side of the throttle plate (in other words, below the throttle plate).

Can you straighten me out on this?

Thnks again

Curt

Vacuum advance is used under part-load conditions, as the density of the air/fuel mixture is low, and flame propagation is slower, hence the need for advancement.

But what you describe seems to be more of a near wide-open-throttle need for advancement - something that will likely lead to knock. Are you sure that your accelerator pump system on the IDF's is working properly? A good carb guy (which I'm not) like Jake Raby could probably help you diagnose this problem.

Vacuum advance ports are typically put just above the level of the closed throttle plate. There is a boss on some/most Webers for the port, and it is on the side somewhere.

--DD

Brad is exactly right. Here's some more info.

http://www3.telus.net/public/alpine65/VA66.jpg

Hey Everyone

Thanks for all the great replies

I realize I misunderstood Pappy's post, he was telling me which SIDE of the carb the ports go on, not whether they are above or below the throttle plate.

I guess I am just looking for better response from the engine as driven in the varied daily situations on the highway and around town. I find that as I try to get the car up to speed, the slow shifting gearbox (till I fix it) cause the revs to drop to the point that the engine is under a fair load as it confronts the next gear. Otherwise, the carb setup works fine.

For a steet car under these conditions, is there any advantage to a centrifical advance only distributor? I note that Jake loves the Mallory centrifical advance for his engines.

Thanks Alfred for the great tutorial. Good reading for all.

Sooner or later I would like to get the Mallory vacuum adv dist from Aircooled.net for all the reasons John has mentioned in the past here on this BBS.

BTW, anyone live on the central coast of CA? You know, Santa Barbara, Buellton, Santa Maria, Lompoc!!

Thnaks guys

Curt
Lompoc, Ca

MikeZ lives in SB. There are a few others around who are in the area. John Larson over on the Rennlist 914 email list runs West Coast Garage in Santa Maria. And there are others...

--DD