Thread: Weird thing done to 305, what cam is it?

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Young man, that's one fine looking El Camino. I've owned a few of them myself and always regretted it when I sold one.

The idle is a little low to tell what's really going on. Maybe you idled the motor down to hear the cam lope because it doesn't lope with the idle set higher. Am I close to the truth? My best guess would be a flat tappet hydraulic cam something like the Comp cam here.....
http://www.summitracing.com/parts/cc...make/chevrolet
The reason I'm saying that is because I have used this cam many times in an otherwise stock SCR motor and it works really well for a street cam. It had a little rumble to it at a high idle, but if you idled the motor down, it would have a little lope to it like the video you posted.

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Thanks guys, I totally understand!

Techinspector1: no, not at all, it is idled at 750rpm if I don't set the choke, 1250ish if I set the choke and 850rpm warm. I had a screwdriver because the drivers side was running richer (pass side 2.5 turns out, driver side 4.5 turns out on idle mix screws) if I go any higher it will occasionally diesel if I shut it off when it idles say 1,200rpm. It will "choke" as I can describe.

I can see why you would say this but it idles that way if I don't have choke on. It was a warm day just a cold start.

Did you notice how the idle was uneven the first couple seconds? Because it wasn't warm

This engine should idle well at 650-700 RPM.

The picture of the carburetor on the towel looks to me to be an Edelbrock 1910 Performer. Is that a familiar number that you were able to see on the carburetor? If so, it's an 850 cfm replacement for a BBC and that would definitely account for the gas mileage as well as potentially impact the idle circuit.

As a drill - warm the engine up and re-time to 8 degrees initial and 32-34 degrees all in. hook vacuum line back up to the distributor and starting with the driver side, gently bottom the idle screw. Turn out until the idle smooths and peaks - you'll be able to hear the change. It should be between 2 and 2-1/2 turns. Repeat the process on the passenger side. If there's more than 1/2 turn difference, I'd look for a vacuum leak.

Glenn

Both sides are 2.5 turns out. My dad adjusted them last and I assumed he forgot he already did 2 turns? They didn't back out on thier own, he probably made a mistake.

It will die if I put it in the 650-700. It will ONLY idle in park, the second I put it in gear it runs for a couple seconds. It idles 450-550 if I have it set that low I have to rev it at stop lights so I keep it safe and idle it at 850, then in gear its about 650rpm.

That is NOT and edelbrock! That is a Brand new performer quadrajet that I had professionally built. It sucks the gas I need instead of dumping more and wasting it.

I didn't ever do total timing? I did idle timig of 8.5*BTDC @ 850rpm. I tried all over the board and I found 8.5* and a mechanic went over it and said its just right. He said if I wanted to I could try 9* but said it was just fine as it was.

850 RPM is okay - sounds like the stock converter is nice and tight!

As to the carburetor, the "Performer" is an Edelbrock name - Edelbrock made several Q-Jet replacements – all of which are out of production but can be occasionally found at speed shops or rebuilders. The 1904 and 1906 were replacements for the M4M QuadraJet and rated at 795 cfm. Edelbrock made a Performer Q-Jet replacement for Thermo-Quad (Chrysler) part number 1905.

You refer to the carburetor as a “performer quadrajet” which would make it in fact an Edelbrock unit. The Performer RPM Q-jet was an aftermarket high-performance QuadraJet produced by Edelbrock. The part number for the RPM Q-jet is 1910 (which was why I asked if you recognized that number). These carburetors were based on the late-style large primary bore Chevrolet castings and came with an electric choke and were known for their generous idle-fuel calibration circuits. They were only available in 850 cfm versions.

Several other rebuilders have made “high performance” versions of the (Rochester) QuadraJet but most are merely rebuilds of the original - and in my opinion one of the best carburetors made.

Best,
Glenn

I thought it was a Rochester? I had an old Rochester before that the float keeped getting stuck and wouldn't start. It would flood with just one pump of the pedal. I was stranded once because it keeped flooding. So I had a quad built. It had some upgrades in it such as the jets but that's what it was referred to as a performance carburetor? I don't know the carb numbers. I didn't even check.

This site has informed me so much, I want to thank you ALL so much

Your pic loaded on my screen after I posted it.

Maybe it is an edelbrock rpm? That is the same carb??

Go back and answer my post #34---------------it might explain why you are so far off on the idle mixture screws and a couple other idle/low rpm thingies-----------

No, the drivers side does! On the drivers side is where my PVC is.

Ignore the unplugged ports, it was more for a documentary of steps and things I have replaced on the car.






I know its opposite but that's how the car came.

something I just caught in those pics of the carb. You said it will diesel when you shut it down ? Replace that broken electric solenoid on the front of the carb and set your idle speed with it, it is designed to kick the plunger out with key on and retrack ( or drop the idle speed)with key off, thus fixing the diesel effect.

Originally Posted by HWORRELL

something I just caught in those pics of the carb. You said it will diesel when you shut it down ? Replace that broken electric solenoid on the front of the carb and set your idle speed with it, it is designed to kick the plunger out with key on and retrack ( or drop the idle speed)with key off, thus fixing the diesel effect.

Good eye! And I think what Jerry's saying about your PCV is that it doesn't appear to be sitting straight on your valve cover, like maybe that SS braided hose is a bit short, and it's pulling your PCV cockeyed in the valve cover? If it's cocked it might be a vacuum leak?

Originally Posted by HWORRELL

something I just caught in those pics of the carb. You said it will diesel when you shut it down ? Replace that broken electric solenoid on the front of the carb and set your idle speed with it, it is designed to kick the plunger out with key on and retrack ( or drop the idle speed)with key off, thus fixing the diesel effect.

Good catch.
The motor cannot run-on or "diesel" if the throttle blades are closed completely. An anti-dieseling solenoid is an electro-mechanical device that allows the throttle blades to seat fully closed in the throttle bore so that the motor cannot continue to run when the ignition key is turned off. When the key is turned to the power on position, the solenoid is re-energized and positions the throttle blades so that the motor can idle. Look for an anti-dieseling solenoid that will fit in your bracket or re-engineer the system with a boneyard find. Here's an example of a new unit for a Chevy truck, '68 to '74. A search through a boneyard would likely yield a bracket to mount it to your carb.
1968-1974 Chevrolet K20 Pickup Carburetor Idle Stop Solenoid - Standard Motor Products ES9 - - PartsGeek.com

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Is that on the drivers side in front of the linkage?

Originally Posted by Littlechevy

Is that on the drivers side in front of the linkage?

yes..............

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In your last picture it appears to be connected, if so with the throttle blades should be completely closed with the engine not running. If that's not the case you should be able to adjust it.