I'm ready to try some NGK spark plugs in my 455 after a recommendation (thanks Jim Rodgers!) and review of archives on the site. From review of those old posts, I see where there are two NGK plugs talked about for the 455; one a UR series and the other the BPR4ES. Can anyone explain the differences between the two differnt NGK plugs? Is either a projected nose plug? On the info on the UR's, I see that the 4 is the stock replacement, 5 one step colder, and 6 two steps colder. When is the BPR4ES warranted? I'm having some detenation problems with my combo and have been using the Champion extended nose plugs which might be enhancing what I don't want here? Pics and detailed explanations of these two different NGK plugs would be most helpful! Thanks!
Evans, the BPR plug is a gasket seat plug while the UR plug is a taper seat. so unless you have aluminum heads go with the UR5 or even UR6 plug. Especially since yo uare trying to help with detonation troubles. Do you have good quench and what compression ratio are you running? WOW, that's a lot of cam for the rear gear you are running.
Stock steel heads on the car (converted to larger S1 valves) so will go with the UR5 or UR6. The cam I have is very mild and is said to be just a tad hotter than a stock Stage 1 cam. It's really pretty civil and docile. I'm not sure of the CR? Is the UR plug a standard nose? I'm not sure what a tapered seat is? Detenation is mostly off idle during mild to moderate acceleration. Gas is 92 octane. Car even pinged with a gallon of xylene/ toluene actane booster mix. Timing is set a 34 degrees all in at 2400 RPM. My thought is that the extended nose plugs I'm using are putting the spark closer/ deeper in combustion chamber. I could back/ retard the timing a degree or two more but thought I'd give the NGK plugs a try first at this setting.
Good thinking on the plug if it works. It is a protruding plug, but too many of us have had good lock with it to be responsible for detonation by itself. I was thinking the cam you had was the one Poston did that was the old Kenne-Bell "window rattler" on a 112 LCA. Did you degree your cam when it went in? How about polished combustion chambers? Tapered seat is like your iron Buick heads have. There is no plug gasket, just the tapered fit between the plug and the head. You could also try an adjustable vacuum advance and hook it to manifold vacuum. It will retard some when you put that little bit of load on the engine. Check your tach when it is pinging and then put a timing light on it and figure where the advance is at that RPM.
you may be pinging because you have dead gears back there,these cars are heavy and need gearing to get up and go. Thanks
Evans, I'm using the UR-5. It is a projected nose plug, like the Champions you are using, but a colder plug. Projected nose plugs put the spark deeper into the combustion chamber, and have an effect similar to advancing the timing. Therefore you can run less timing, and get the same performance. I find that my car likes 32*, anymore and it will ping on me, but the car feels great. Also remember a small cam with little or no overlap, will build higher cylinder pressures, and lower numerical rear gearing will load the engine more, both increasing the chance of ping. Don't fall into the trap of running timing that someone else is running, thinking that will work in your combo also. You need to find what your engine likes through experimentation. If you get the car to a track, try different timing until your trap speed maxes out. When I spoke with John Osborne at the GSCA nats, he told me he uses 30* total because that's all the BBB wants. Maybe, but I think everyone's motor is different. What works for one guy may not be best for you. Good luck. BTW, the BPR NGK plugs have a flat seat, and are the type of plug used in the TA aluminum heads. I think if you go to www.sparkplugs.com they may have a picture of the plugs so you can compare.
Larry The guy in he last issue of either MCE or MM made more power with stock stage 1 build up as measured on a dyno all the way to 36-38 degrees. So I agree with you that a universal number cannot be assumed to be correct.
Jim, I saw that article. Very interesting. I was quite surprised. I think a dyno pull is somewhat different from the real world load in an actual vehicle. How long does a dyno pull last? I think the article said something like 15 seconds? 38* :eek2: I'd have to see that in a full weight GS.
I'll try the UR-5's. Sounds like I'll need to retard the timing a couple more degrees or more until the pinging goes away. I do have the Crane vacuum advance unit set up per Dave Ray's (IgnitionMan) way hooked up to manifold vacuum. I know it is set up right. 3.08's will have to remain for now. I really like that ratio for all around gearing on my car. Thanks everyone for the help!
I had pinging problems with mine until I finally pulled the heads and smoothed out the chambers and it went away. Tom
Maybe talk to Dave R. about tightening your vacuum advance cannister spring a bit. If you are working with him with his product, I'm sure he'll help you make sure that's set up right for your car and engine combo.
