Inliners International Forums General Discussion Engines Tuning HEI/Carb on 292

Now that I've fixed the loose flywheel issue I'm working to get my 292 tuned on my 66 C10. Approx 9.4 comp with lump head and 214/218 dual pattern cam and 500 Edelbrock, Clifford intake, Langdon exhaust, true 2.25 duals, stock HEI from Langdon.

Vacuum is ~14 inches at idle with vacuum advance plugged. I've also installed Crane blue/silver HEI springs and adjustable vacuum can with adjustment full clockwise. Initial advance is 10 deg. I haven't been able to take the truck out after making these adjustments due to work/time constraints but truck seems to be running well in the driveway. I am not really sure what the vacuum can adjust really does but assume it changes vacuum sensitivity. Crane instruction sheet doesn't really go into that. Also want to add that I am using full manifold vacuum and Crane vacuum canister lockout at its highest (notch) setting.

Am I in the ballpark to start or any suggested changes?

The carb settings jets, springs are stock. Any suggestions there? I am learning as I go. Thanks !

My suggestion....Drive it...then tune it....drive again...see how it cruises...see how it performs. There's an old way to check if your running lean or rich...while the engine is cold you quickly run onto the road and Hammer on it...I'm talking full throttle through all the gears...then shut the engine off and come to a stop...pull a plug...if its black your running to rich...if its a clean burn..your fine...if it looks like things got really hot...then your lean or you may need to back your timing down a bit. Haven't done it myself, but I heard it works from the older guys I have talked with. I'd leave the carb as is...turn the A/F screws in until the engine struggles to run...then back out until max RPM is achieved. The reset your idle if need be and drive the heck out of it.

What a topic.

Much can be discussed on the need of timing, here are some basics. I like to use manifold vacuum hooked up.

8-10 degrees idle with no vac line hooked up

20-25 with vacuum line at idle

36 full load no vacuum

40-50 with no load on highway with vac

Best to use a adjustable timing light. These cost around 75.00. Your engine will thank You.

Thanks for the info and suggestions. I know there are many variables but wanted to make sure I was in the ballpark to start with the HEI springs and vacuum canister setting.

I've used a regular timing light and can use timing tape. Does the adjustable timing light bring any advantages besides convenience in not needing a tape?

The adjustable is just better for convenience.

Can you post a pic of your distributor? Maybe with the cap off.

Tom,

I bought a digital timing light today and trying to troubleshoot my results.

I set idle advance to 11deg btdc at ~650 engine rpm. I can run the engine up past 3000 and get ~32 deg mechanical w/ vacuum disconnected. However when I ease off the throttle the idle advance does not return to 11 deg. Instead it stays around ~20 deg. Bringing idle back to 650 or so doesn't help. Checking the weights and springs I see nothing that would cause this and after shutting down, remove, reinstall cap the idle advance goes back to where it should be until I push rpm again. I thought maybe the advance springs were weak and switched to the 2 silver ones in the Crane kit- same results. I also checked my timing light against another with same results at idle.
Any ideas?

And this is what I'm trying to get back on the road...

Liking that truck! I have a 66 I'm restoring with a 292 as well. Are you apart of the 67-72 chevy trucks forum? If not, We'd love for your to join on the 60-66 side of things there.

Thank you. I lurk over there at the 67-72 chevy trucks forum from time to time. Lots of great info.

If you pull the springs and weights, how smooth does it rotate? The timing advance portion.
You may need to pull the distributor and clean/ relube it. Pay close attention to the advance plate and it's movement on the shaft.

Thanks. I'll take a look at that.

HEI's are notorious for their mechanical advances to stick or completely freeze up on the shaft over the years. It may be time to pull the distributor and have it rebuilt professionally. We did thousands of them over the years for racing and street performance guys and always had to tear them down completely and polish the distributor shafts and de-gunk the advance plate to remove years of varnish and other stuff to free them up. Once you do this, it will be good to go from now on.

I found the problem (or at least a solution). The advance without the rotor moved fine. When I installed the rotor it seemed to bind. It looks as though the structural ribs on the bottom of the rotor impinged on the weights ever so slightly. Added a thin washer under the rotor attachment screws and the problem went away. Manufacturing tolerences?

So playing with the advance now.

-12 degrees idle with no vac line hooked up
~25 with full manifold vacuum at idle
~34 with no load no vacuum
~48 with no load with vac

Thanks for all the help and suggestions!

Now to figure out the carb. The truck accelerates very well to ~3000 then slows up a bit. I don't have a frame of reference as this is my first inline 6. Not sure if that is just normal or some carb tuning is in order. So far the Edel 500 is as received - stock settings.

Mine went up to 4000 no problem...you might have to richen up the secondaries a bit. I had a 600 on my 292...ran fine out of the box with no issues. Remember though that the stock cam makes torque at low RPM so if it slows down a little at the top end its cause your losing torque.