Doug1964

Update on my high rpm idle problem. I spoke at length with edelbrock on three occasions. The problem turned out to be a vacuum leak. However, not a vacuum leak in the ordinary sense of the word. I had no external vacuum leak. However, the new carburetor as assembled from the factory had one of the secondary throttle plates installed crooked and it was not sealing well in the throttle body and allowed an internal vacuum leak to occur in the carb. I loosened the throttle plates and adjusted them for best possible fit. They still allow some leak by and do not seal perfectly, but they are better than they were. A flashlight test shows that none of them seal perfectly. Prior to the correction of the throttle plate problem, the small 283 was getting too much air from the pcv and the non-sealing throttle plate to ever idle at a low rpm. With the throttle plates adjusted to best possible sealing (it's still not perfect) with the pcv still connected, I can get down to about 600 rpm. If I disconnect the pcv, the engine will idle all the way down to stalling out below 400 rpm. I also talked to edelbrock re open vs four hole spacer. Edelbrock stated definitely go with the four hole spacer and not the open spacer. Once I got the crooked throttle plate adjusted, I tested the engine with the open and four hole spacers. Definitely got better idle and low end torque with the four hole spacer and less offensive exhaust fumes. The reason my car was running better initially with the open spacer, the open spacer was allowing the other side of the carb to compensate for the vacuum leak from the one side of the secondary plates. Now all is running much better (but not perfect). I will say that I am a little disappointed with the quality of the throttle plate sealing ability in the brand new edelbrock 1403 500 cfm carb. No amount of adjusting will get a really good air tight seal in any of the throttle bodies. I ended up really just making sure all the throttle plates were as even as possible. However, if you perform a flashlight test, none of the throttle plates will actually make a near perfect seal. (And this is without any linkage problems or binding or set screw problems. The edelbrock plates just don't fit perfectly in the throttle bodies) The only question I have now is that common to all edelbrock carbs or do I have one that for some reason the plates or throttle bodies are not perfect. Also will the throttle plates and bodies wear-in to one another after some use and constant opening and closing to where any tolerances will eventually close up and seal tighter? I am trying to decide if what I have now is as good as it gets with an edelbrock throttle plate seal or should I send my carb back for a new one expecting to obtain perfect seals in each throttle body? Should I expect to see a perfect throttle plate seal from the factory or is an even razor thin are gap equally around all plates to be expected when performing a flashlight test?

Frankie the Fink

I don't know what PCV system you are running but you have to be VERY careful with this addition. The run of the mill PCV S-100, FV-100 valve has too much 'draw' for our little 283ci. I had to put a restrictor in the vacuum line to the PCV valve to tweak things to get the optimum crankcase ventilation vs vacuum drop.

Also interesting is that Edelbrock sells an open spacer for their square bore carb to square bore intake adapter (#2732), and shows it in their online tech videos, but recommends the 4 hole on the phone ?

I don't know how 'perfectly' any throttle plates fit in any carb but it appears you got a bum carb - I do know several dozen folks that run Edelbrock Performers and Thunder carbs with no problems.

I am going to test fit an Edelbrock on my 396ci after screwing with a Holley 4150. I'm thinking of posting a video of me doing a discus type throw of the Holley into the lake that I live on to express my opinion on that cantankerous POS. After days of 'dialing' it in and having it run near perfect it mysteriously floods on me and stalls out randomly for no reason. Not a lot of fun having your motor 'dump' with power steering and power brakes.

I think somebody should start re-manufacturing the WCFBs.... I have two dual quad setups that run like bandits and that a human being can actually understand.

Doug1964

What kind of apperatus did you install in the vacuum line to choke down the pcv flow? I think I am running a fv-100 or similar flowing pcv.

Matt Gruber

Doug
Kudos for fixing it. Was not an easy problem to solve
Many parts are not "perfect" when u really study them. No need to send back the carb, but i share your disappointment with the quality. It could wear in over time.
Frankie
they sell open spacers for drag racers, and they are cheaper to make(don't have to worry that bore size matches the carb).

MikeM

The very early systems used a simple valve to replace the road draft tube. That's all. The factory left in place the vented oil fill cap and the unsealed dipstick tube.

Starting in 1963, both the oil fill cap and the dipstick tube were sealed to allow the PCV valve circuit to maintain a constant 1"-2" vacuum on the crankcase. When the PCV valve was disconnected from the crankcase, engine rpm should go up by 50 rpm as described in the shop manual.

If you are picking up 200 rpm with the PCV as the only variable, I'd guess you have a serious mis-match of components here as that's not the way it's supposed to work. PCV valves are calibrated per application.

Frankie the Fink

Well - you had to ask - one of my more Bubba solutions...but it's invisible and it WORKS !

MikeM is right...the original RPO-242 used just a PCV valve but I have yet to find one...everybody will point you to the 327 PCV valve - the 283 was different and I suspect it was calibrated for less draw than the modern S-100, FV-100 versions (that's my theory at least).

Remember I have an original 270HP, solid lifter, Duntov 097 dual quad car. It pulls about 16" of vacuum at idle. With the FV-100 PCV valve I stuck a brass fitting in the PCV's crankcase hose with a 3/16" orifice in it. This eliminates a rough idle due to too much vacuum leaching, prevents oil "pullover" and the car runs superbly with no blowby and the PCV still "sucks" just fine.

Believe it or not AC-Delco sold an aftermarket kit to install the RPO-242 option. I've only ever seen one and I was outbid for it in an auction (somebody paid silly money for it). Pic attached.

The goal is to pull out the corrosive (and explosive!) crankcase fumes at a rate that does the job with the least amount of suction. I feel I've accomplished that.

Doug1964

I am pulling 19.5 inches of vacuum at idle so my pcv valve really sucks. So much air goes through the pcv you have very little margin of error when trying to balance air fuel mixture and idle speed through the carb. i will try placing a fitting in my pcv line as well with a sized orifice. My 53 ****** cj 3a has a similar pcv system. Lot of folks don't know it but ****** had one of the first patents on the pcv system in the forties for their jeeps. It was hi tech for the times. Thanks frank.

Frankie the Fink

I bought a brass fitting with a VERY small hole in it and started out by drilling a tiny hole in it and worked my way up to the 3/16". Before the PCV addition my car pulled 18+" of vacuum. I think you can go until you get a little over a 2" vacuum drop and you should be OK. If you try this approach make DARN SURE you blow out the newly drilled orifice before installation so you don't get shavings in your crankcase !

Snipescastle2

Hello everyone! I have a friend at work whose late father, owned a few older C-1's, '57, '60 and a '61. he found an air cleaner (single four barrel) chrome AC air cleaner(Louvered on the sides and flat across the top, except for air cleaner nut dimple), the base had been painted by his father, but the silk screened instructions are visible after cleaning off some of the paint. the wire mesh arrester is missing, as is the original element, but the Chrome lid is in perfect shape. He also has a Delco-Remy dual point distributer from a dual quad hipo 283 pn-1110891 I'll have to get the date code from the tag for you later. I just wanted to let everyone know he has these available for someone in need of some original parts to complete a resto or to replace a worn/ bad part. pictures to follow tomorrow.
Thanks!
Ben
Moderators, I'll find out how much he is asking for these parts and update this tomorrrow, or you can move this thread to the parts for sale area if you deem necessary.
Thanks!
Ben

Frankie the Fink

I mounted my Edelbrock AVS Thunder carb on the Chevelle 396 today and the throttle plates looked as good as any carb I've seen...you don't want too perfect a fit or you'll have sticking throttles. I've got everything hooked up but the fuel line and I'm having to fabricate some things for that to get it looking like I want.

Doug1964

That's a nice looking Chevelle.

mickatbp

Sorry to resurrect this thread but my email is down and this will help me track the thread down later. I have the same problem with fast idle, I have the after market PCV valve, a vac advance distributor and the phenolic spacer under my wcfb 2x4 carbs. I can't get my idle down and my timing is okay ... this will give me a few more fault finding options to consider.

I know Frankie will be thinking 'this guy still hasn't fixed this' ... sorry time gets away ... work ... injured children ... redundancy announcement ... and working on the body (C1 that is).