badone07

The carb originally ran rich prior to me acquiring it with the motor. It's a 1984 355 non-computerized setup. The motor is rebuilt with 0 miles. It's only been broken in, as of this past Saturday. It's bore is .030 over and crank cut .010/.020. -12cc 4 valve relief speed pro pistons, moly rings and 9.3 to1 compression. 193 heads with swirls cut out and remainder of ramps opened up to 1/2" width, 3 angle valve job, new seals, springs and guides. Screw in studs, gasket matched intakes, ported and polished. summit hydraulic 1102 cam, older performer intake with altered middle bolt holes. I rebuilt the non-cc HEI and it has an advance kit and adjustable vacuum advance.

It's then topped off with the original rochester quadrajet (17080213) with hot air choke. I used Walker kit #5501A, to rebuild it. Now it's been about 18 years since I last rebuilt a quadrajet, so I'm pretty sure I probably screwed something up. Since the carb was pretty gunked up, I stupidly removed the power piston stop, before I soaked the assmblies. I researched online and found that "2 full turns out, was the factory setting." So that's where I placed it. I also epoxied the caps in the body, that could possibly leak. The placement of the float wasn't listed in the kit for my particular carb, so I set it at 3/8" by the toe of the float, to housing. I did have to bend it up, it was previously lower. The carb to intake gasket is slightly cutout different than the original gasket, so figured I would mention it. The butterflies don't appear to be hanging up.

Now after getting the motor running for break in, the choke works fine and pulls off correctly. However, it's like the carb is stuck at fast idle. I have a strong return spring. The idle speed screw is backed all the way out and I released the chokespring tension to fully open. I have checked for vacuum leaks and didn't find any, anyplace. It idles at 1250 rpms and refuses to go any lower. Mixture screws nor timing have any effect on the idle speed. I did get the mixture to run rich and lean though. The motor runs great, no bogging etc. I ran it up to 4000 rpms without a problem, except not being able to get the rpms low enough to set timing and idle mixture. Anyone have any suggestions? I'd rather keep the rochester on it, but I getting tempted to rebuild a Holley 4160 I have laying around and be done with it.

***Maybe one more thing I should mention, although I doubt it is effecting anything... To keep the quench down and instead of using felpro 7733pt-2's I had laying around, I stupidly used these head gaskets...

http://cgi.ebay.com/ebaymotors/ws/eB...category=33665

Well I have slight seepage of coolant on the outter cylinder heads to block. No oil leaks and doesn't appear to have coolant in combustion, nor combustion in the coolant. Hopefully a retorque will help it. Just want to get the carb/idle problem sorted out first.

Thanks,
John

Damon

Maybe the fast idle cam IS sticking, or you put the (complicated) choke linkage together improperly and it's hanging the throttle open. One sure way to tell- yank the carb, open up the choke fully, back the curb idle speed screw all the way out and see if the primary throttle plates are wedged tightly in their bores- not being held open by something, even slightly. If so, figure out what's holding up the show and fix it.

Also, check your secondary throttle plates to make sure they are seated FULLY in their bores. They have beveled edges and should close so snugly in their bores that you can barely see any light around them when they're closed (if you take off the lower throttle body part of the carb and hold them up against the light). Check to make sure the linkage from the primary to secondary side is not holding them open (adjustement is done by bending- yes, BENDING- the metal arm). If that's not it, loosen the secondary throttle plate screws slightly, seat the secondary throttle plates in their bores, and hold them firmly so while you re-tighten the screws.

badone07

I just got home and took it back off. After comparing the original carb to intake gasket to the replacement, it appears to be hanging up the right primary plate. After comparing the impressions, that one with a few others I have laying around, looks like a bad cutout on the new gasket. I'll try another gasket. Which might be part of the problem.

The other appears to be the placement of the fast idle cam. I loosened the screw up and everything snapped back to where it belongs. If I place the fast idle follower on the highest step(notch), the primaries open slightly. If I place the follower just touching the cam above the notch, it seems to work properly. Please correct me if I'm wrong, but I only see 1 notch.

I'm not sure what I'll do with the front vacuum break. I don't have an angle gauge that small. I'm sure I can fool with it later. While I have the carb off, I'm thinking of pulling the top cover and checking my float level again. While I'm at it, I'll probably knock out the plug and tap it, for access to the power piston stop. This way after it's back on, I can make any necessary adjustments without dismantling. I know it's set at "2 out" but might try 1 3/4 or 1 1/2 out. By the way it's positioned now, I'm pretty sure it's not exactly like it was before I removed it. I'll post back tomorrow if I made any progress or got it working properly.

Thanks,
John

Damon

The fast idle cam basically has only 2 steps on it. Fast, slightly over normal idle, and then nothing (falls off the fast idle cam and relies on the normal idle speed screw on the driver's side of the carb). Leave the fast idle screw backed out quite a ways so it's not doing anything while you're figuring this problem out- then screw it back in and play around with it until you get an acceptable cold-engine idle speed out of it. Yes, the fast idle cam will hold the primaries open if you are on one of the notches- that's it's job. That's how it speeds up the idle on a cold engine- it hold the primary throttle open slightly above normal idle speed.

The adjustement of the choke break (vacuum can) doesn't require any special tools. Take a 1/8" drill bit and make it so that when the vacuum can pops the choke plate open slightly that you can JUST SQUEAK the drill bit between the choke plate and the rear of the choke tower (hold the drill bit vertially against the inside of the choke tower). That will get you in the ballpark on that adjustement. Note that your carb has a REAR vacuum break as well, which ALSO pops the choke plate even further open than the front one (but takes more time). I recommend you remove the linkage from the rear vacuum break to the choke linkage. This stuff is difficult enough without having to deal with 2 competing vacuum breaks each doing their own thing.

The power piston adjusting screw (APT) you can set anywhere you want between 0 (screwed all the way down) and 4 turns up. I hate that little thing, frankly, and I just install the size rods in the primary that will work correctly in the first place, screw the thing all the way down and forget about it.

badone07

I really appreciate you taking the time to respond. I've had my full of these POS quadrajunks. All this did was bring back memories of all the other GM products I've owned, that immediately got a holley put on them, whether the rochester was good or not. I know the linkage is right now. It ran better with the linkage screwed up. At this point, the only thing I'm about to accomplish is washing out my rings. I'll take the rochester off just one time to replace it with a new holley 4175 and be done with it. Then it gets hurled into the trash, where it belongs.

Thanks again,
John

Damon

Ouch. That hurts. I've been working on these things for about 20 years now. I know them inside and out. They're good carbs, but they have their own quirks, just like any carb. I haven't found one yet I couldn't get working and working well. If you want to send it to me I can get it working for you. No charge except shipping (unless I find something really hosed up requiring buying parts which I only charge my cost on). Pay me when you get it back and like the results.

I don't do this for money, obviously. I just enjoy the challenge. Shoot me an email if you want to give it a shot.

badone07

Damon, I emailed you last night.

badone07

The carb is right back to being a typical POS. 0 miles on it. Just started once a week with fresh gas, while working on other areas. Choke wouldn't pull off. Leaned out choke some and junk. I should've known better, than leave one of these on one of my motors. Time to just use a Holley and be done with it. Man I hate Rochesters. Thanks for trying to help.

John