soo i bought these and was wonder if iverpaid or not

[overdrivex]

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=230330280439&_trksid=p2759.l1259

never heard of the brand before. But 2oo cheaper than used triple weber side draft setup. and 700cheaper than new triple webers

bah its suppose to be "overpaid"

Edited March 17, 2009 by overdrivex

[Carl Beck]

I don't know if you overpaid or not. If you got what you wanted, in the condition you wanted, when you wanted them - then a couple hundred one way or the other really doesn't matter that much.

The Dellortos are basically the same as the Webers, but I think you have a wrong price comparison. The Webers being more common, usually sell for between $450.00 and $550.00 {at least several that I've seen go though E-Bay that actually sold}.

At any rate - I don't believe that you can use manifold vacuum for the distributor advance. When you go to wide open throttle - manifold vacuum drops; while a vacuum signal taken at the carb venturi increases. It an increased vacuum signal that is used by the vacuum advance on the distributor.

So the seller may have screwed up the intake.. Hard to tell from the pictures, but the intake runners look like the shorter version - good for constant high speed use, but not so good for a street driven car.

FWIW

Carl B.

[overdrivex]

well the last set i saw sold for 800 and 60 shipping. and right now theres a set going for 650 with 90ship but still not near end. but at the end of the day your right price is a mute point.

didnt know i wouldnt be able to use the distributor advance though. i thought it was small part that is actually attached to the distributor itself. kinda looks like a FPR. i guess ill find out when i get them ill post closer and clearer pictures.

[doradox]

well the last set i saw sold for 800 and 60 shipping. and right now theres a set going for 650 with 90ship but still not near end. but at the end of the day your right price is a mute point.

didnt know i wouldnt be able to use the distributor advance though. i thought it was small part that is actually attached to the distributor itself. kinda looks like a FPR. i guess ill find out when i get them ill post closer and clearer pictures.

You can use manifold vacuum just fine. The only difference between ported ( which is what you would have with stock SU carbs) and manifold vacuum is that ported vacuum is unavailable when the throttle is closed, otherwise they are the same. I don't believe the SU uses venturi vacuum for the distributor vacuum advance as that would over advance the timing at full throttle and lead to detonation. Also the vacuum port is in the wrong place for venturi vacuum.

http://www.jetlink.net/~okayfine/su/troubleshooting.html

Go to the bottom of the page at that link for a better explanation.

Steve

[overdrivex]

it pretty much said what all the other articles i read about vacuum advance said except this was more specific to datsun which helps. end of day i'm still hands on guy. i wont fully grasp the concept until i install them and tinker with it. thanks for everyone's responses and as always, very helpful.

[26th-Z]

It appears as though you have purchased the Interpart carburetor selection from the 1973 Interpart catalog - part numbers 2102032 for the manifold and 2102033 for the linkage. The Dellorato twin-choke sidedraft carburetors were part number 1106310 for the DHLA 40 type recommended for street use.

Personally, I think you got a good deal on the price.

[overdrivex]

wow you actually had part no. for every thing. guess you have the original interpart catalogs. thanks.

he said hes sending them today. probably waited for pp to clear his bank. doesn't look like ill have them over the weekend oh well.

[Carl Beck]

You can use manifold vacuum just fine. The only difference between ported ( which is what you would have with stock SU carbs) and manifold vacuum is that ported vacuum is unavailable when the throttle is closed, otherwise they are the same. I don't believe the SU uses venturi vacuum for the distributor vacuum advance as that would over advance the timing at full throttle and lead to detonation. Also the vacuum port is in the wrong place for venturi vacuum.

At any rate - I don't believe that you can use manifold vacuum for the distributor advance. When you go to wide open throttle - manifold vacuum drops; while a vacuum signal taken at the carb venturi increases. It an increased vacuum signal that is used by the vacuum advance on the distributor.

Hi Steve / everyone:

I agree that I should not have said "at the carb venturi"... that should have said "just past the carb venturi"... better still I should have used the term "ported vacuum".

After reading countless articles related to manifold vs ported vacume and finding widely differing views, I begain to realize that in most cases the individual views were dependant upon a limited number of engines, or a limited number of "hot setups" for specific cars.

All, focused almost entirely on what happens to manifold and/or ported vacuum signals at different throttle positions or engine loads. Only one considered the entire timing advance system. The entire timing advance system includes the technical spec.'s of the vacuum advance mechanism being used, and the signal strength range it covers.

So I do not agree that you can use manifold vacuum just fine. Unless one also makes the stipulation that the vacuum advance mechanism, as well as possibly the distributor timing curve are then matched to the manifold vacuum signal.

The vacuum advance mechanism on the Z is designed to work with the ported vacuum signal of the S.U.'s. Depending on the configuration of your engine, the intake manifold used the stock vacuum advance mechanism may or may not pull in all the advance at idle when hooked to manifold vacuum. It may or may not allow the timing to retard enough at cruise either.

In that case - the safe thing to do, might be to use no vacuum advance with the triple carbs and the associated intake manifold - and make adjustments to the static timing and distributor timing curve - that you can control.

FWIW,

Carl B.

[doradox]

Hi Steve / everyone:

I agree that I should not have said "at the carb venturi"... that should have said "just past the carb venturi"... better still I should have used the term "ported vacuum".

The vacuum advance mechanism on the Z is designed to work with the ported vacuum signal of the S.U.'s. Depending on the configuration of your engine, the intake manifold used the stock vacuum advance mechanism may or may not pull in all the advance at idle when hooked to manifold vacuum. It may or may not allow the timing to retard enough at cruise either.

In that case - the safe thing to do, might be to use no vacuum advance with the triple carbs and the associated intake manifold - and make adjustments to the static timing and distributor timing curve - that you can control.

FWIW,

Carl B.

Since the only difference between ported and manifold vacuum is when the throttle is closed one might say that by using manifold vacuum the only time the timing curve would differ from stock is at idle or any other time the throttle is closed. So during a large majority of the time the engine is running it is using the stock timing regime.

If using no vacuum advance then the only time the timing curve is the same as stock is when the engine is under a high load or at idle. Arguably a small percentage of the total time the engine runs.

I would suggest that the former is the "safer" way to go.

However, when you are on the gas hard both no vacuum advance or manifold vacuum advance behave exactly the same way. The whole point of vacuum advance is to advance the timing during cruising and other light loads. That's why race distributors don't use a vacuum advance.

Anyway if the manifold he has won't let the vacuum advance work then he essentially has none. Which is what you suggest. So no harm done.

Steve

[conedodger]

If the DHLA is anything like the DRLA they will have an extra circuit. idles, transition, and power. Chokes are nice. These are probably better carbs than my triple Webers.

Dellortos were mostly OEM carbs for Italian cars. Mine, on my 914 are from a Fiat. They also made lots of motorcycle carbs.