What plugs?

[ezstriper]

just got a sonny's 565 compression about 14.8 and CNC ported 320 heads, have no idea where to start with sparg plugs, usually run accels ? thanks Rob

[want-a-be]

I'd start with the champion 57 heat range plug.

Don

[Awesome Bill]

you can't just ask for a plug when you have not listed what fuel you are running? are you running nitrous? what rpm does this engine work @, etc. etc.

[ezstriper]

cam 2 116, no nitous, single dominator, 7000-7300 ?? hows that..Rob

[want-a-be]

you can't just ask for a plug when you have not listed what fuel you are running? are you running nitrous? what rpm does this engine work @, etc. etc.


Totally true Bill.

I have used the Champ 57s with great sucess in both Drag and Circle track engines. Both gas and alky also. Used them with RPM ranges from 6000 to 9500 rpms and not seen any problems. Make sure your ordering them in the correct reach and gasketed or non-gasketed. lol...I've even used these things in my wifes caddy just cause I had em.

Chamber/dome configuration might make some difference. But I'd think they would be a good start.

JMO

Don

[Awesome Bill]

AR3935, which is a pretty hot plug and your compression and rpm do not warrant this much protection with the fuel. Its pretty much a bracket engine and would only require VP C12 @ best. It would even do very well on 110 purple. So if your going to put fuel that will stand well over 18-1 compression and 8500 rpm, your plugs will need to be a step warmer. I would suggest AR3934 but your over fueling the engine. It will also be done on power with the C16.

[want-a-be]

Just trying to learn some here. I was always under the impression that colder plugs were to be used in race engines. At least engines with higher compression anyways. I see what you're saying about the fuel. It does seem to be a bit of over kill. But once he goes to the proper fuel, shouldn't a colder plug be ran?

Don

[Awesome Bill]

Any fuel even 107 RED vp would work here with the proper timing curve. You should always use the proper fuel for application, ie compression and rpm. Anything under 7500 rpm, you can get away with any race fuel. Once you go over the 15-1 mark, you then have to watch timing and fuel. I have dyno tested 15-1 engine with 107-110-112 and seen very little if any difference as long as we pulled 1-2° timing from the least to the best here. We just dyno tested a Big Chief 572 twin 1150 BBC. This is a jet boat race engine, good solid cam, sheet metal intake, all the good stuff.

The customer wants to run pump gas and make 850 hp under 7000 rpm. So we started the dyno testing with 28° total timing and the engine is right @ 10-1. As soon as I went to open the throttle up to pull back the engine to start the pull, @ 4500 rpm it backfired and cut off. I said to myself what the heck? So I seen the egts were off the chart and over 1550. Does not mean much @ 4500 being fuel was being burnt in the header. So I checked it out and the plugs showed it needed a ton of timing. So I cranked 34° in it.
The engine pulled right down under wot to 4500 rpm and I let her go. EGTs were right there around 1250-1300 and @ 6800 rpm, they were bordering 1400°. The engine made 837hp @ 6800 rpm. So I added 2° more and the engine went 851hp @ 6800 and all egts came right in just under 1400°. Now this was pump gas on a 10-1 big chief 18° 572 with a stout camshaft and twin 1150's.

So if I can pull that hp out of this, what would I get if I put race gas in it? Well we loaded it up with VP107 red and done a pull. First thing we seen was egts way higher and the engine fell off over 40 hp right from the get go. At 6500 rpm the egts were again off the chart. The engines compression did not warrant the fuel being used. It was 2 slow of a burning fuel for the rpm used. We also had the AR3935 plugs in the engine and showed no signs of even making good heat with the 36° timing and pump gas.

We went back to the 93 Exxon pump gas with the engine @ 38° timing and the engine made no more power than it done before @ So if I would of had the spark plug colder, the initial spark being weaker would of made even less.

My engine assembler had a 350 with a 250 shot of nos on his truck. The truck was only running 10.15 and when he came back, the headers were running cherry red. I asked him what fuel he had in it and he said c16. I told him to take that out and put 110 in it, put 34° total timing on it and it would pick up ½ second. He asked me why, and I told him the engine @ 12-5-1 could not burn the C16 quick enough without him making over c16 compression. So it installed the 110, the engine idled better right off the bat he had to lower the base idle rpm setting. He run the truck and it went a 9.55 @ 144. Just by taking the good fuel out.

Spark plugs have to generate enough hot spark to get the fuel burning quickly. Cold sparks are only used for really high compression engines with hot gas. Spark plugs don't burn up, they are burnt up because the ability for the plug to release the heat back into the head in insufficient, thus causing the plug to run hotter and hotter and then become a wick in the cylinder to light off the incoming fuel. Not hot enough and it burns right out the exhaust valve.

Race fuel and spark plugs are a match and very few people understand how that runs together because Tommy or Joey burnt up his plugs, ( for some God only knows crazy thing they were doing) and instantly they say you gotta run colder plugs. Give a monkey a hammer and he will put dents in everything he gets around. Give a monkey a brand new Caddy and the keys, and he will surely wreck it. Monkies!