Inliners International Forums General Discussion Electrical Recurve a HEI

I am needing to recurve a HEI unit. What I need is to crank lower in time and still get the full advance need for the engine. I have been researching the subject some. A standard unit has about 20 degrees of advance. I need to crank at about 4 or 5 degrees and still get the 30+ degrees advance. Has anyone done this type of operation on a HEI? Any info. and feedback would be appreciated.

I don't quite understand your definition, except you want more advance. The bent 8 recurve kit will work on your HEI, that will get your advance in earlier. You can also change your vacuum advance. The vacuum advance on my HEI was originally 11 degrees. I changed that to one from a V6 that was 20 degrees. 20 degrees was too much for my 292 and I had to limit the vacuum advance by installing a plate behind the vac advance rod. The problem is that with out the plate the motor would stumble real bad with full throttle. I didn't seem to matter what the initial advance was, with out limiting the vac it would stumble. Hope this helps.

Larry
68 C20 327 daily driver
63 C20 292 Camper truck
65 C10 ? Custom Cab AC,PB,PS,$flasher

Sorry I didn't explain things well. I am not running any vacuum advance on my 292. I am only running the mechanical advance of the HEI unit. The normal advance of a unit is about 20 deg. I am having to crank at 14 to get full advance of 34 deg. at 2500rpm's.I need to crank at a lower deg. it is very had on the starter. If at all possible I would like to crank at O deg. or lower but still get the 34 deg. full advance. I found an article on the net about modifying the weights and center piece of the HEI unit. Don't quiet get the jest of it though. Thanks

Hud MSD makes a nice timing unit to help set all. retard & advance to full timing. Hope this helps.
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I am experimenting with an HEI unit on my 302 GMC. An excellent source you might want to look at is : http://members.aol.com/dvandrews/timing.htm

It is titled "Ignition Timing for Modified Engines". It talks about deternining static advance based on cam duration, establishing maximum advance based on combustion chamber type, it gives a typical advance curve for modified engines, it explains how to modify the advance mechanism range and rate of increase to get to the desired advance curve. I think it will help you.

Hope it helps

I wrote you earlier about your question. After playing around with some spare parts and testing each change, I have the solution to increasing the range of the mechanical advance on your HEI.

You can get more advance by modifying the shape of the fly weights. Here is the process:

You file down the fly weight straight inner surface that rubs against the center plate when the weights expand under rotation.

If you hold a weight in your fingers it kind of looks like the profile of a bird with a long beek. The surface you file is located on the lower part of the bird's beek. That's the straight surface that you file down.

The way to file the straight surface is to slightly taper the outer end and mid range, making the end of the bird's beek slightly more pointed. Be careful not to take too much off. It is amasing how little you have to remove to get the advance range to increase 10 degrees. You can check your progress if you have a spair HEI like I did. The fly weights are hard to file but you only need to taper the bird's beek a few degrees by removing a few thousanths of material.

I used # 106 fly weights but it does not matter what # you use. They all have the same profile, but their weights differ.

Warning: Do not mess with the center plates. I tried and it does not work. The various center plate numbers control the shape of the advance curve but not the range of advance. Changing plates will give you different rates of change (slopes) of the advance curve only.

I hope this works for you.

WANTED TO RECURVE MY MINI HEI ORDERED CRANE CAMS RECURVE KIT SUGESTED BY LANGDON , SPRING ADVANCE CURVES DIDNT MATCH THEIR LIST. MY 200$ TIME LIGHT ALLOWED ME TO FIND GOOD COMBINATION OF SPRINGS. HAD TO CUT OFF CORNER OF VACUUM ADVANCE TAB TO MOUNT VACUUM ADVANCE UNIT[no body told us that]. AFTER INITIAL TIME SETTING TRIED TO SET VACUUM ADVANCE COULDNT ADJUST PINGING OUT.ADJUSTABLE VACUUM ADVANCE WOULDNT ADJUST. YOU CANNOT RETURN MODIFIED PARTS SO I USED SPRINGS & THREW AWAY VACUUM CANISTER...USED ORIGINAL HEI CANISTER WITH LIMITER BLOCK.. TOO MUCH TIME AND MONEY SPENT ON TOO LITTLE GAINS,,,DO YOUR SELF FAVOR KEEP ORIGINAL HEI RECURVE AND VACUUM CANISTER