Interesting to know, I'll play around with a bigger gap when I replace my plugs next and see what kind of results I end up with.
I'm going to check mine this weekend... might explain the #2 fouling if they are at .020. Be nice to have a better return on investment of having to run that big, ugly dizzy.
The last one I did was in a SBC, I was changing the plugs anyway and bought a set of plugs prescribed for the HEI donor. Mine went from a .030 gap to a .060 and I did try one on the old .030 gap plug, it looked funky so I got the new set. Bob
OK so here is what I did, First I'll tell you what I have MSD 6AL2 Their coil, the little blaster, An MSD Pro Billet distributor, yeah that word is in there but that is only referring to it's construction, any way its a full on HEI, I have a good set of MSD or Taylor 9 mm race wires and a set of Champions, she was dyno'd with a set of Champs, they oil foul but so far look like they are taking the voltage. She had good power from 2000 to 4000, them a bit of a rumble, I set the timing between 12 and 20, set up an 1/4 mile strip in the forest preserves behind my house. Heres some numbers: Right out of the shop with the pcv capped 17.80 may be off just a bit, set up the course and used a stop watch in the car. Second pass Pcv connected, 16.20 3rd Plugs at 38 timing at 18 16.12 4th Plugs at 38 timing at 20 16.80 5th plugs at 42 timing at 16 14.70 6th plugs at 42 timing at 14 14.20 7th plugs at 50 timing at 14 14.80 and a stumble sound, like lifter roll. 8th plugs at 45 timing at 13 14.60 still a mild roll 9th plugs at 44 timing at 15 14.17 still just a faint stumble roll, I am going to switch out the springs on the distributor. While I was doing this I still had not set up my c6 to where it liked to shift, she was not cooperating much at all, thats the next set of tests, setting up the shift points to be efficient. My tenth pass was open headers, I uncorked the wye, ran a 14.15 with the same numbers as 9, but that was extremely loud and the cops did a drive by and asked me to not do that anymore.I corked her back up and set my brakes a few times. Maybe tomorrow I'll see if she can get the tranny in order. Oh, the last pass I did I set the accelerator pump to full, 9 and 10.
For what its worth, I have 30 plus years dyno tuning, throw away those ramp style, looks like a gay quarter plug gapping tool, and spend a few dollars and buy a WIRE type gauge for gapping your plugs. Just the correct way to do things. BDM
Cool to see some evidence, so I'm not crazy on this plug gap thing. Good to know it did some good for ya, by the looks of things between the PCV valve, opening up the plugs and playing with the timing, looks like you woke up the beast pretty good.
This really shows what the pcv will do to you, it drastically effects the whole fuel air mixture, you can't even get a baseline without it. Once you do set the pcv up correctly you will notice a lot of difference in the vacuum duration. My carb is likely just on the too big cusp, a Holley 750 single pumper would be perfect, the AVS 800 is not just 50 more cfm, it breathes a lot different. With the pcv cap off the idle jumps up 400 rpm just from the added air mixed in. The gas mileage seems to be a hell of a lot better too
While were on the subject, has anyone had a noticeable improvement by indexing your sparkplugs (lining up the gap with the intake valve)?
I'm sure that you would see an improvement, it's done for a reason. Just for shits, the plug temperature I am running was not available as a platinum. It was the recommended temp for the engine so I stuck to it. I bought a set of NGK plugs, they seem to be able to gap out at a larger gap cleaner and straighter. One of the problems I encountered next was a spark knock, this spark knock became more prevalent as I increased the gap. The spark knock is being caused by from what I can decipher is a lean condition at about 4000 rpm, next solution for me is to dilly with some jet sizes and spring rates, if that does not solve it then I am looking at tightening up my distributors timing range, make it curve in quicker at a higher rpm. It seems that a lot of doinking around is required to set up a larger cam. I am logging every aspect of the adventure including temp and barometer. This way I think I can establish a baseline for weather.
another hei tip,theres an empty spade connection on most fuse boxes marked ign,theres your power instead of messing with the harness, also use good gromet through the firewall. now if there was a way to make the monster cap look good let us know
I wondered about this too when I began installing Pertronix in my cars. It sure seems like a wider gap would be called for but Pertronix does not mention it.
Good tip. A lot of guys don't realize that no matter what the output rating is on their "triple-negatron & double-whammo, super-high-voltage" ignition system or their brand new, 'kazilion-plus-volt' rated "J.C. Whitney 'super-double-ionizing, Blast-Fire" coil is, that the ignition will only put out *exactly* the amount of voltage required to jump the existing spark plug gap and nothing more. If the old ignition could produce enough voltage to jump the spark plug gap without misfiring under a given engine load, at a given rpm, than nothing will be be gained by going to a higher potential voltage ignition system. On the other hand, if the output *potential* of your new high-zoot ignition system allows you to open the spark plug gap up, and produce a bigger spark without misfiring, than you may actually see an increase horsepower. Mart3406 ====================
The Jalopy Journal
