Quadrajet carb spacer on a 69 472 any suggestions?

[dirtycustom40]

Im thinking about trying an aluminum or phenolic  carb spacer on my 69 eldorado.Motor is stock.Car does not run hot but has an irratating hot start problem after about 15 minutes of sitting and also blubbers (for lack of a better word) sitting at idle for a few minutes on a warm day.Float is set to specs and i really would like to leave it where it is rather than lower float level.As i will be up and down in altitudes.I use premium,lead additive and have tried sea foam and marine stabil to combat enthaol content in gas.Both seem to help but not cure problem.I live at 5600 feet in elevation and i have read pressure and ethanol content in gas isnt helping my problem.Gas cap is venting properly.I thought about trying a carb spacer to help keep heat away from carb.Not worried about needing heat from intake crossover here.I dont really know what spacer might be compatible with this carb.I know i need to lengthen choke rod and raise linkage and things like that but unsure about trans vacuum modulator hook up.Right now it is running to back of carb.I dont know if i can hook it up direct to intake and have it shift properly.Havent tried yet.Any suggestions on spacers,material,thickness,brand etc. or about this in general will be appreciated.Figured this might be worth a try.

[TJ Hopland]

I tried one on my 73 and it did not help.  Also did not help things that I never did quite get the choke to quite work right again.  What I ended up doing before I ultimately went EFI was mounted an electric fan behind the grill hooked up to a mechanical timer.  I just wound the timer to about 10 mins anytime I shut off the engine.  Worked great for about 8 years. 

[TJ Hopland]

I should add that before I did the fan if I found gas with no ethanol it would only do it on 90+days.  With ethanol it did it pretty much any time it was over about 75.   

[Gene Beaird]

Does the 69 still have the manifold heat control valve?  If so, is it functioning properly?  You may want to wire it open, to make sure it's not moving too much exhaust heat through the intake.  Additionally, you may want to block off the heat cross over in the intake.  With the new alcohol-enriched fuels of today, that may be almost necessary to control fuel boil.  It's a bit more work than adding a spacer on the carb, but probably help the issue a lot, and other than modifying the intake manifold gasket, everything on the intake manifold should bolt back on in it's original position.

["Cadillac Kid" Greg Surfas 15364]

Mr. Dirt,
The '69 Quadrajet should have a "hot idle compensator" on the top, front of the air horn.  It's purpose is to vent the bowl when the gasoline temperature rises due to heat soak. This car should have a vapor return line from the fuel pump.
I would check these things first.  These engines do run hot and because of the "nestled" position of the carb in the manifold do tend to boil the gas when heat soaked.  You might try one of the 1/4 inch thick "isolator" gaskets available.
Greg Surfas

[dirtycustom40]

Heat control valve works perfectly.The vent on top of carb seems to be ok though its hard to tell if its 100%.I dont really know how to test that.I have checked fuel lines and replaced the rubber ones from passenger fender to fuel pump.Its more irratating than an actual problem.Its a cadillac,a tap of the key is all it should take.I gotta keep reminding myself things change and get old.I have had 7 of theses old eldorados but the last one was almost 25 years ago and i lived in the midwest then.Fuels were different and i never gave a thought about altitude till i moved to albuquerque.This car has just over 70,000 original miles and runs nice especially on the highway.The spacer idea really seems like more trouble than it would be worth.Blocking the intake crossover would probably do more good than anything else,just not crazy about pulling intake again.I purchased this car about 4 months ago and havent driven it much.Actually i rarely drive a car as i ride year round here.When i do drive this car it will mostly be a 1000 mile plus round trip down to sea level and usually in the fall or spring when its cooler out here.I do need to get it out on the road more before i go back to chicago in october.Maybe im just a little too picky and this may be something i will have to live with.This is the LAST car i ever plan to buy.I have thought about some sort of injection system but dont know what oem later model parts could be used and aftermarket stuff i saw was pretty pricey.

[dirtycustom40]

Im gonna assume that i could check the hot idle compensator by pusing down on it when car is good and hot at an idle.I would think the spring would contarct at high temp allowing plunger to drop and vent bowl.

["Cadillac Kid" Greg Surfas 15364]

Mr.Dirt,
For those of us that have current model cars (I just had a "company car" for work), the disparity between new cars and 40+ year old cars regarding starting, idling and noise reduction is quite apparent.  The older cars don't and never did, start with the flick of a key, hot, cold, Winter, Summer, nor idle seamlessly without a burble.  For its day the Cadillac was the best, and the Eldorados were the best of the best.  I know, i bought a new Eldo in '72, and it was head and shoulders above my 1970 Malibu.  Today, however, the Impala I was driving for work (when its electronics have not failed) makes my Eldo seem "Klunky".
The hot idle compensator is just as you describe, a bimetalic element that when hot allows the rubber "stopper" on its end to release pressure from the bowl, should it occur.
Your suggestion about just acceptance of the car's characteristics is most likely the best.
Greg Surfas

[dirtycustom40]

Im getting ac charged on thursday and the car will be good and hot by the time i get it to my friends shop so i will poke at that valve more out of curiosity than anything else.Other than that ive learned theres times to leave well enough alone and quit while your ahead.Thanks for the input guys.

["Cadillac Kid" Greg Surfas 15364]

"If it ain't broke, don't fix it"

[Viator Trudeau]

r
e::  hot idle comp.   I recently installed a carb kit in my 68 eldo because of lumpy idle after a 3 month no drive period.   After the kit, no change.   I gave no thought to the cork ring under the idle comp. valve.   Took it apart again and noticed the cork ring (in the kit) was not at the top of the bowl.  Found it in the kit box, installed it and the idle was very good at any time.   The cork ring must have went bad during the no drive period, as it always idled well after the previous kit was installed 12 years ago.     Viator Trudeau

[dirtycustom40]

My idle compensator was gone and the hole was plugged.I pulled the plug and found a bi-metal strip at a local yard with several old caddys and bought another carb kit for the cork seal,picked up a 1/4 inch phenolic spacer and removed the check valve from the fuel filter.I am also using marine sta-bil in fuel.Im not sure which one of these helped but i have noticed a definate difference.The few times i have had a chance to drive the car it has been over 100 degrees and it starts much easier.

[Scot Minesinger]

Guys,

This has been very helpful.  I have the same problem with my 1970 and it is annoying only really.  After about 15 minutes when it is over 75'F it takes too many cranks to start.  I will check out the hot idle compensator.  Not sure if that is the problem, because my car idles smoothly when hot, and OK until hot.  This DC summer with 105'F temperatures and stuck in traffic jams in the afternoon certainly tested the cooling system.  Also, will consider the fan behind grille with timer-that seems like a good idea. 

Thanks,

Scot

[TJ Hopland]

That electric fan really did the trick.  You still leave the original fan in place so that is still your cooling system when the engine is running.  The electric fan just needs to run for about 10 mins when you shut down.   Thats all it takes to keep the overall under hood temps below the threshold where the gas boils out of the carb.   Opening the hood also does the trick but that is only really practical when you pull into your own garage.  I never had issues with the battery running down from this.  I ran an inline fuse to the back of the alternator to pick up the positive power for the fan.   I then ran the ground for the fan into the car to hook to the timer.   Figured this way if the wire was damaged worst case the fan just turns on.

For those that are still looking for a spacer one thing to be aware of is many of the spacers are for the Edelbrock spread bore carb which did not have as large of bores as the Q-jet did so they wont work. 

I dont remember on these is the kickdown switch for the transmission mounted to the intake?  IF so that is another thing that will haev to be adjusted if you change the carb height.       

[dirtycustom40]

I bought  a 1/3 inch quadrajet phenolic spacer and just spaced up the return/kickdown bracket a 1/4 inch and ran the modulator vacuum line to manifold vacuum and it all worked out fine.I will need to lengthen choke rod a bit but will wait till it starts to get cooler here.The more i thought about it the less i wanted to use a big aluminum spacer.

[Scot Minesinger]

Thanks for the idea of the additional electric fan.  That theory is easy to test, next hot day after coming home will open hood in garage and direct fan on engine.  Then in 20 minutes if it starts nice, I know how to solve it.  Plus it is always good to have additional cooling capacity on hand.

[Viator Trudeau]

RE: Q-jet spacer,  for carb. spacer and/or any Q-jet part go to Quadrajet parts,com 

PH.  908 362 7692   The web site lists hundreds of parts.
Viator Trudeau   CLC # 8697

[disturbo]

Does anybody have ,69 Deville vac diagram

[Scot Minesinger]

The 69 vacuum diagram is different than the 1970 Cadillac, so no sense in sending you that.  The factory published comprehensive diagrams but did not include them in shop manual, and I found one for a 1970 on e-bay.  Try looking on e-bay or other sources for classic Cadillac literature.  The 1970 has a timing retard solenoid that only advances timing in R, 3rd, or under heavy throttle, plus storage tanks the 69 does not have. 

You can get the entire diagram from the shop manual in pieces.  Go to engine cooling(or electric) for that switch screwed into block by power steering pump and dist to get that diagram.  Go to climate control to get the power servo diagram and dash.  Go to brakes to get the brake release vacuum diagram.  The brake booster and trans vac modulator are piped directly to back of carb.  Another way is to go to car shows as their are still unmolested 1969 Cadillacs out there.

[disturbo]

Ya at the show last week there was a 70 but they had an edlebrock carb and manifold so it didn't help.  Iknow I am missing something in the vac advance and I think that why she runs hot