Q Jet chokefast idle operation

[bob_on_this]

"Hey Guys,
I am rebuilding two Q jets from my 305 Crusaders.
I just don't quite get the high idle cam on the Q Jet. It just seems to hang there on the choke pivot. How does this work? I can see where it is disengaged when the choke opens, but what sets it in the first place?

Thanks
Bob"

[bob_on_this]

"This part also keeps the choke from fully opening. This just seems wrong.
Both carbs are the same, so I don't know if they
have been rebuilt or not."

[fastjeff]

"Marine carb don't need a choke high idle cam. (Car engines use them to prevent stalling in gear.) On a boat, you set the throttle where you want it, so anything other then the linkage that opens/ closes it is unnecessary.

I recommend that you remove all of that high idle cam crap and toss it out! The less complications the better, right?

Jeff

PS: Marine Edelbrocks don't have any high idle cam crap."

[makomark]

"Bob:

That the most complicated linkage on the whole carb. Not all the pieces are there to enable the "fast idle" function. It shouldn't hinder the choke plate movement with finger force on the plate.

The big function is to lock out the air valve opening until the choke is open. The other is to provide the vacuum break.

If you start removing pieces, do so at your own risk. removing pieces from the pivot shaft will introduce a lot of play in that axis; thinner pieces may bind and then you are SOL. It can be done but you need to understand all the things that change when you do that.

Digital pictures always help if you have a specific issue in a given area."

[bob_on_this]

"Mark,
Here you can see what I have.
[IMG]http://i38.tinypic.com/n4iknm.jpg"[/IMG]

The part with the rust on it just hangs there, and is called the high idle cam.
[IMG]http://i36.tinypic.com/2qcfjba.jpg"[/IMG]

Here you see the choke hitting this part

[IMG]http://i35.tinypic.com/szx4ic.jpg"[/IMG]

And as you can see the choke opens about half way at best.
[IMG]http://i35.tinypic.com/dhcpc2.jpg"[/IMG]

Also, the choke pull off will only open the choke about 1/64" off closed ???

I think the entire linkage is messed up someplace.

Thanks for the help.
Bob"

[bob_on_this]

"Looking at an Edelbrock site, looks like the small tab on the choke link needs to be BELOW the high idle cam, not under it????"

[bob_on_this]

"I removed the linkage on one of the carbs, and moved the high idle cam on top of the choke and this looks much better. The choke opens now, and if the choke is closed, the high idle cam will swing down (gravity) and rise the idle.
The deal now is, the choke does not close all the way, is this right?

I guess someone has been working on these carbs before I bought it... I don't know how long these ran this way. I was only able to start these engines on a hose before we got it.....

Thanks
Bob"

[diver_dave]

"Bob; I can only say that my chokes need to be fully closed in order to start a cold engine. Others on this board have wired open chokes and that works for them. I can't explain why, but it would be good to do a start test if the choke plates won't close fully."

[makomark]

"Bob:

Your powers of deduction are spot on - someone has messed with your linkage. Sounds like it was not only reassembled incorrectly but the adjustments have been made plain wrong or the adjustable portions of the links have been bent.

I'll have to check later when I have access to my reference material but I believe what you moved is called the fast idle cam follower (lever)...

There are probably about 1/2 a dozen adjustments to those little parts - on an unadulterated carb, only verifying they are correct is the norm.

The choke should have full travel. Mine are setup with about twice the vacuum break opening than that "spec'ed" - another example of customization. Like Dave - mine don't want to start without full closure. Once running a couple seconds, there was no doubt about the richness so customization occurred.

One other suggestion - make yourself a secure carb stand. four bolts thru a piece of plywood, with eight nuts, is super....in a pinch, a large alignment pin clamped vertically in a vise will suffice. it will let you work on the carb and protect some of those linkage adjustments you will be making soon."

[makomark]

"Bob:

That piece you moved is called the vacuum break lever and tang, per doug roe's book. my foobar earlier.

You can find an original rochester drawing by going to googlebooks and searching <doug roe quadrajet 4mv choke> it should take you to page 54 of the book and it will be the bottom drawing. It is a side view. It will also show the fast idle parts and I think you'll be at least two short."

[joeld98]

"Bob, I had a similar problem after rebuilding mine. Can you spot the mistake in the before and after pictures? It took me a couple tries before I got it back together (First carb rebuild) correctly. First I had the fast idle cam on upside down and backwards. Once I fixed that, I had the vacuum break lever tang over the cam instead of under it. Looks like yours is that way also.
Before"">
After

[bob_on_this]

"Thanks guys,
Lots of help, and Mark, thanks for the link.
I will work on them today."

[makomark]

Joel - do you have a correct "After" picture?

[makomark]

bob - there another shot on page 82. search google books with this string and it will get you close:

doug roe quadrajet fast idle cam

[bob_on_this]

"Thanks Mark,
I think I have it in right now. I also have the choke closing. I think the PO that messed with these carbs, when trying to get the chokes to open, had bent the arm (that the pull off pulls on) out of whack.

New question;
Both my Crusader 220 are freshly rebuilt with flat cam followers. My engine guy wants me to run the engines at 1800 RPM or so for 20 to 30 minutes to break in the cam. (will also use a diesel engine oil with high zinc).
Anyway, sounds like he wants the engine at this speed very quickly, with little to no idle.
My plan in to remove the distributor and pre lubing the engine prior to starting, also the cooling system, as best I can.
How can I prime the fuel system (safely)?
I really don't want to be down there with a cup of fuel to keep the engines running while the fuel pump fills everything.
Any ideas?

Thanks
Bob"

[fastjeff]

"Can you borrow an outboard fuel tank? If so, pipe it to your fuel pump and pump the bulb until the carb is full.

Jeff"

[diver_dave]

"Bob; that's all a good process, but do add GM EOS or some aftermarket cam break-in juice. Crane, ZDDP, etc. I don't think even that diesel oil is good enough for that first 30 minutes. Yes, even cranking puts more load on the cam than 1900 rpm."

[makomark]

"Bob:

If you are doing it in the driveway, Jeff's recommendation is the cleanest - just don't overfill the carb's fuel bowl. if the outboard tank isn't available, pour about four ounces of fuel into the forward vent tube - it will go straight into the bowl area. You can use a coffee stirrer in the vent tube over the float. When it stops rising as you add fuel, the bowl is full.

check with your engine guy - sounds likely that he used a cam lube during assembly and he may have already primed the oiling system. I'd also get his written list of oils he finds acceptable if he is providing any type of warranty.

When I did mine, I left the raw water pump off and used the garden hose straight into the oil cooler (FWC). We also added ~ 12" of exhaust hose to the elbows when we did the second engine - the first one ws a bit wet once done.

The other good ideas are oil pressure gauge and temp gauge. An IR gun can substitue for the temp gauge.

That "start and go right to 1800-2200 RPMs" is no BS on a flat tappet. That initial hour spent doing the first start correctly should give you a couple thousand hours of service life on your rebuilds.

If you need the instruction sheet for the rest of the carb adjustments, they are easy to email."

[bob_on_this]

"Thanks Mark, any and all info would be great.
I should have my email on my profile.

Thanks
Bob"

[makomark]

Bob:

How are you doing on this project? Any data shortage(s)?

[bob_on_this]

"Hey Mark,
Seem to have all the data I need, now I just need my back to heal, and the weather to get warm again.
Starters, alt, pumps all done and painted.
I think I have decided to buy a small fuel tank, a cheap gage set (three gages and tach for 80 bucks on ebay). Mount the engines (one at a time) on a flat bed trailer and let my engine builder run the engines at his shop.
Hope to reinstall in the boat around March.

Bob"

[makomark]

"Glad you are making progress.

plan sound ok - I ran mine in the back of the truck. bolted them to a custom made 'stringer frame'.

Best thing for the back is rest...with the detail work done, you should be good by march."