Inliners International Forums General Discussion Engines jets on a edelbrock 500

i finally got title/plates/registration on my 63 pickup. i built a 292 for it and have been starting it every week and the engine got broke in with the original manifolds and rochester. after that i switched out to the clifford intake, headers and edelbrock. i now want to start driving it on the road. i thought i had a small vac leak since the vacum was slightly under the green area on the gauge. well i tested it today with propane thru a hose and no difference when i traced the intake and base of carb. is there a better way to check for vac leak? also i feel this is running rich by the smell too. i do find after adjusting the carb with the air screws turned almost all the way in it seems to run better (less smell). i tried using the book that came with the carb but it talks about a drop of 20 rpms and my gauge won't measure that small. i wonder if i need to rejet. it has the clifford 264 cam and .060 over. any suggestions would be apriciated. thanks, hoggyrubber

I seem to recall that my 250 is .030 over and I'm using the stock jetting on my 1403. I tried all sorts of different jets thinking I needed to lean it down only to come to the conclusion that the stock jetting works the best by far. I've got Clifford intake and dual exhaust. Hope that helps.

I have an EDL 1404 on a '68 292 L6 bored @ .030 over, Crane 260H cam, Offy intake, Clifford headers. I'm running the carb at stock jets [#1423(.086)] with #1452 [.070x.047] metering rods. "Position 13" on the calibration Reference chart. I think we also went to yellow springs.
Best way to tune the carb is by hooking a handheld Vacuum guage inline with the full-time vacuum port. You want to go for the highest number of "inches of Mercury" [ "Hg] while at a smooth strong idle. 15" to 17" Hg is a nominal goal.
I also have a Carter AFB 9605s [much like an EDL 1405] (600 CFM) on the V8 350 in a '71 GMC. On that carb we went thru a number of combinations to try and pass AZ emissions, last summer. The winning combo was two stages lean in both power mode and cruise mode. That truck now runs well with .070x.052 meter rods, .098 primary jets, .095 secondary jets, and Orange springs. It's "Position 24" on the Cal Ref chart.
Hoping this helps.

I had a 1405 on my six and tried about every jet and rod combo also float levels while monitoring with an A/F ratio guage and it ran rich all the time. switched to a Q-jet and increased performance and gas mileage. I was able to tune it to run almost perfect. I say almost because no carb will keep ratio exact like a digital fuel system. This is quite a statement comeing from a guy who always hated Q-jets on V8s, but they seem to be the answer on a six with a carb.

What Q-jet are you using Big Bill? What model?

We have on occasion removed the four barrels and replaced them with a Holley 500 2bl. Another good card is the Rocjestor 2 bbl that showed up on some 455 Olds in the early days.A huge carb with good manners and flow. A two barrel seems to run much better on the 6cyl 4bbl manfolds. Now that is espcially true where the carb sits with the primarys forward and the secondaries rearward. IE the Slant six four barrel set up. The difference in drivablilty is remarkable and power is also. No noticeble drop any way. I did this mod first in the 1970s but have recently since seen several chev sixes with it done and for the same reason. Of course the mind goes instantly then (since EFI was mentioned ) how would a Holly Throttle body injection work installed this way. I suspect really good, but I dont really know (yet) The two barrel works better because of the more symetical placement. With the fourbarrel it seeemd one half of the engines run good and the other o so except for full throttle.With the two barrel that is gone comletely and it runs as intended. Course this idea may not suit and that is fine. One should always have what they want on their car , I beleive that. I just offer it from experience. It may not suit you, I understand that especially if your heart wants a four barrel. .

Run a Q-jet setup to run on a 4.3 V6 or A 5.0 V8 and always mount it side ways. The q-jet was brought out by the factory to replace the AFB/Edelbrock style carbs mainly because they ran to rich for most engines. Although I used to race Pontiacs with daytona series AFBs and loved the way they performed on the track. Also ran them on the street, but gas was cheap,six to eight mpg didn't matter and who knew what air pollution was.

thanks everyone. i seemed to have to set the idle a little higher than the 500 rpms on the rocherster. it was pulling 17" of hg at idle. i forgot i still have to run the "heat to the bottom of the intake. it has been warm enough here i didn't think it would make too much difference. sorry i forgot to mention it has the clifford intake and headers. it is running pretty good i just wanted it to be just right before i started to drive it. the guy that inspected it barked the tires pulling out of the garage. i thought running it a little too rich might not bee good for the engine. thanks again, hoggyrubber

My 292 idles at 900 RPM. Higher if I have my foot touching the accelerator pedal. [I have a "hare trigger" throttle cable set up.] I live in Tucson, where it's hot much of the time. I use no carb heat on an Offy intake. But I will admit the engine runs better in the summer.

Dear HR;

There are 2 (or more) screws used in the idle adjustment. :rolleyes:

The speed adjustment screw (moves throtle plate)and the air/fuel screw(s) (change mixture).

It doesn't matter who makes the Carb. as It's the same for ALL.

First make a rough speed adjustment. Then; turn a mixture screw in till it 'misfires' (to lean) then back out 3/4 of a turn.

That's all folks.

PS: Jets, rods, springs & other parts are NOT involved with/in the idle circuit.

thanks john and everyone, i am pretty used to adjusting the rochesters on the other inline sixes i have but i am no pro. this edelbrock has one speed screw and two mixture screws. the speed screw isn't a problem i can oviously set it wherever but i was using the stock setting for the 292 which was 500 rpms. it didn't seem like adjusting the mixture screws brought up the vacum like i figured it would and it didn't idle smooth at 500 rpm's like the stock inlines i have. it does have a higher lift cam so that may affect it aswell. since this carb wasn't made for this engine and i don't have any experience with 4 barrels i was just "rootin" around for answers. i am just tryin to work out every kink before i start driving it a lot. i need to hook up the "heat to manifold and mabey try bumping up the rpm's a hair. thanks again, hoggyrubber

Hr;

The higher lift cam will require a slightly higher idle speed to 'smooth it out'.

Try it at 750 RPM.

Good luck.

thanks john,i wasn't sure if i needed to leave it around 750 or not. i will leave it there and try it on the road soon and see how it does since i've messed with it a little more.

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