Technical > Matt Shaff's Engine Shop
Time for a rebuild?
JrFuel Hayden:
Dude, I assume you run on alky, what is your compression ratio ?
I wonder if your 6AL ign is not enough.
Ask some other racers that are running your alum heads, and burn alky what timing they run.
Jon
gasserx:
They are running blown alky, but as far as i could understand they ran injected alky in earlier years.
I will take the advice of changing one plug for each run, smart way to keep track on things and as you said, i will always have "new" plugs.
The worst part now is that my racing season is over as i have already pulled the engine out, and i will do a complete teardown and rebuild. Last race here in Norway is just 1.5 week away, so im not going to make it. I have learned so many things now that i would like to try out, but i have to wait for the spring to come.
Well... at the next race my 12year old daughter is going to get here license for alky junior dragster, and that might take some of my time anyway.
I only have a stock 350 block, but forged crank and pistons, Brodix heads ... with my so far bad 60 foots at 1.300 (best so far), i really think i can push it way more when i get the correct tune in it.
--- Quote from: JrFuel Hayden on August 26, 2015, 01:09:55 PM ---You are welcome Gass, it is a bit disappointing when I give, asked for advice, and they don't take my advice.
Is your alcohol dragster buddy racing NHRA Top Alcohol racing blown alky or injected nitro ? Blown alky is a different game. i agree with his advice to put one new plug in your motor with any tune-up change, matter-a-fact I suggest a new plug every round. As an example, Q-1 could be early in the morning, at 1200 DA, and Q-2 could be around noon, which could have a density altitude of 3000', well your tune-up just changed because you will have less good air going in your motor, it just got fatter. So I suggest in Q-1 new plug in #1 cylinder , Q-2 new plug # 2, etc, that way it's a little easier to keep track where your new plugs are, plus after 8 runs [ ya I know that might be more than 2 events] you will have a new set of plugs in your motor with only a few runs. At $3.00 each it's not allot of money.
When I 1'st started helping my partner, Bud Hammer he was indexing plugs also, but that goal was to keep the high piston dome [ 16;1] from smashing the plug ground strap closed. When I was doing that I kept trying different plugs until the strap was between 10;00 and 2;00, without using plug washers, I think the washers changes the heat range. But when I built my 1'st RR SBC we cut with a porting tool a "fire slot" in the dome, with the idea it would help the flame front go over the dome, but also not have to index the plugs. I always try to keep our car simple, less likely to have a crew member put the wrong plug in the wrong hole. Also when I ran my motor in a Comp elim [ B/ND] and he had help from the Autolite rep, I asked him now that I cut the fire slot, would it be any advantage to index the plugs 180° from what I was doing, he said Autolite tried that and the dyno test didn't show any difference.
You are right it costs more to go fast , "speed cost money, how fast do you want to go ?" But I know allot of SBC injected alky racers running 8.60's,[NE-2] and 7.60's [NE-1] with bowtie blocks, OEM forged cranks, off the shelf pistons, shifting at no higher than 8500.
Your Vertex is fine until you up your combustion pressure with higher compression and higher fuel flow, and even then you can have Spud hop-up your Vertex, or go to a Mallory Mag. I run 20 amp MSD, because i run around 16;1 compression, 220-230 fuel flow and 10,000 rpm. Your 38° timing looks about right for a non-raised runner heads, but I have helped some JrFuel cars at the Bowling Green Reunion when they had a ton of water grains in the air, you can't burn water, so we kept leaning the fuel and upping the timing to as high as 42° to try to get some heat in the plugs. He would have won, except he red-lighted.
Jon
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