75 edo carb upgd - vacuume and fuel canister questions

[nphoenix]

I replaced my quadrajet with an edelbrock 1411 750cfm. Good news it passed emissions flawlessly and engine runs great - but shifts require laying off gas.

I have the distributor vacuum connected to the 3/16 manifold vaccum port an the carb. The carbs Timed Vacuum port is plugged with a cap.

I have 2 hanging vaccum hoses i need to connect in. One comes from the EGR valve. I think its the EGR valve - back center top of manifold near firewall.

The other was on the back of the carb and went to the cruise control thingy (w speedometer cables feeding it) and it tees off to other stuff too.

With these 2 hoses hanging is it reducing vaccum so to cause the tranny shift issue? I did add a new kickdown electrical switch by the carb - i wired to the normally open contacts so throttle needs to be about 3/4 to close the contacts... Normaly Open is correct?

There is a tap off the manifold for vaccum near the EGR - should i tap both feeds into that source???


Also right now the Charcoal canister is only connected back to the tank. There are two hoses (i think 5/8 and a smaller) ... Can I just leave the canister hanging?? Plug these 2 hoses?

[steelybill]

Where is your transmission modulator getting it's vacuum?? It should be manifold vacuum. I doubt if the vacuum could change much with things disconnected like you say. The big Caddy engine has plenty of vacuum. The kick-down switch shouldn't have anything to do with normal up-shifts. The modulator does though.

BILL

[nphoenix]

Thanks - i bought some tee adapters and couple of feet of hose and will try tonight. Also i found a vacuum diagram to help out.

So basically i will restore vacuum feeds to the trans modulator and power brake release.

My 2 questions remain are on the EGR - should this get a full time vacuum feed or get the "timed" output.

On the charcoal vapor canister i was going to cap the old feed from the carb.. and splice in vacuum - hope that's correct - it's labeled as "canister purge hose" .. i dont wnt to create a vacuum in from the tank.. unless that's what is needed.

[steelybill]

The EGR is supposed to be operated by ported vacuum. It opens the valve between 2 and 7 inches of vacuum, and stays open with 7 and more.

The charcoal canister is also ported vacuum. The other items are manifold vacuum, according to my manual.

[nphoenix]

Thanks for all your replies. I also received a response from Edelbrock.

I ended up with the following retrofit on my 1975 Eldorado from quadrajet to edelbrock 1411 750cfm.

Physical mods:
- I needed an adapter plate to go from the quadrajet manifold to the "square bore" on the carb. (bought an off name adapter at Checker auto parts)
- I needed new bolts - qty 3 2 1/2" and one 3" where the throttle cable mounts
- I had to fabricate a new throttle linkage mount to offset the bracket about an inch towards the fender and about 3/4 inch back towards the firewall
- Fabricated a levered microswitch for the electrical tranny downshift.
- Removed/cut/remounted the throttle linkage post off the quadrajet and bolted over the same location on the Edelbrock so my cruise control would still attach as it used to.

Vacuum:
- On the carb the "timed port" (left hand) is capped and all vacuum is tied into either the front right port, the large backcenter port , or a manifold tap (near the EGR). The large backcenter port got a barbed connector from Lowes - it mostly feeds direct to the brake booster but has one tap to the tranny modulator.

[steelybill]

Sounds like you are getting it under control OK, with the mods etc.
Edelbrock also has a plate the goes under a square bore carb, on a spread-bore manifold, to adapt that carb to in. I use one on WEIAND manifolds, for the same combo.