84 Bird, was 305 carb. Now 350 aluminum RHS heads, air gap intake, quick fuel 650 four corner idle. Currently trying to use long plug Champion c57yc. In cooler weather, Plugs foul and I am told are cold heat range. I am on my second set of plugs, it will not start now due to fouled plugs (wet, black) Engine builder says to use champ 71 plugs (new numbers from champion) in researching 71's, from research it appears they are a short plug for small engines. (Short plug, hot range). Does anyone have experience with these plugs, or do you have an excel short plug with a warm heat range that you have used? Need 14mm, 3/4" reach. Thanks, Byron

 

Those are race plugs 9-10 heat range in a ngk plug.

I like ngk plugs. You need something like a bkr6e. Ngk-6364 or 6962 or equal

 

Orr89Rocz, thank you for your response... When you say heat range 9-10, what does that specifically mean? Or, what are the heat ranges for these plugs? 1-20? Are these plugs in the middle or lower range - upper? For future reference - I am unable to find any info on heat ranges - kinda like heat ranges for dummies... Thx byron

 

I am most familiar with ngk plugs. So i use their heat ranges and then look at online spark plug cross reference charts to determine what other manufacturers plugs are rated at.

Ngk typically ranges from 4-10. 4 being hot and 10 being cold.

4 is typically stock oem engine. Think factory 305/350 with 9:1 comp, small cam, somewhat restrictive type heads/intake. Low overall power.
5-6 are for mild modded motors, most typical head cam street deals. Stock ls motors run around 5, heads and cam motors a 6. Medium to fairly powerful hp levels. 300-550 whp stuff. My 11:1 383 all motor sbc ran 6's. 400 whp car pump gas

7-8 are boost/small nitrous shot plugs. Alot colder, safer for higher compression higher cylinder pressure builds found in most boost and nitrous motors. Some racey all motor compression deals may also find these useful. I run 8 heat range in my 1200 hp+ turbo car

9-10 to me are serious race plugs. High nitrous and boost use, higher compression still. 14-16:1 comp motor cars, ultra high hp shots etc. these arent street plugs imo

 

Orr89RocZ.. So the plug you mentioned is a heat range 6. Bkr6e.. There are listed bkr6es, is that for a short plug. Further, is a bkre7e one step hotter. Thx b

 

Yeah its a 6. 7 in the number is a 7.

S is for standard plug. Nothing special. The bkr6e is the v power line. It has a notch cut in the electrode. Both are about the same

6364 is standard 6962 is v power

 

Orr89RocZ - I think I have it.. I did look for a short plug, could not find one in the NGK - interesting, I have a 70 Buick Stage 1 in my stable that I have run the same NGK plug for a few years. I don't even think about them... I guess that says something about the plug.. Thank you very much - very helpful - if you are aware of a short plug number I would appreciate it. best regards, byron

 

That i am not sure. I know my 305 car i just changed plugs on this past fall used ngk ur5 plugs. They were shorter than the champions that car came with so depends on brands.

 

Thank you, I will go with the ngk.. You were/are kind to help me through with this. Regards, b