spark plug question
Registered User
Joined: Jul 1999
Posts: 312
From: Tucson, Arizona USA
I used to use 3923's gapped to 0.035" with an MSD-6AL producing 14-psig boost. I will be making significantly more boost with my new setup (>20-psig). I am now using NGK's R5671A-7 (stock #4091) plug. It is two heat ranges colder than the FR-1LS, which I believe is two ranges colder than the 3923 (please correct if I am mistaken). I know Larry at ASSC Racing uses these plugs gapped to 0.032", which is what I've gapped mine to. He is making 26-psig boost (F1) on his L98 (runs 9's and he drives it daily). And if you feel these NGK's are not cold enough, the following is a list of even colder plugs w/stock numbers:
R5671A-8 (7173)
R5671A-9 (7405)
R5671A-10 (7942)
R5671A-8 (7173)
R5671A-9 (7405)
R5671A-10 (7942)
Registered User
Joined: Jul 1999
Posts: 312
From: Tucson, Arizona USA
rskrause what plug would you sudgest for a 355 with afr 210 F.A.S.T msd digital 6 about 20-25 psi form a 88mm turbo?
I'm not Rich, but Larry's car I talked about above is a 355 with AFR's, MSD-6AL, FAST system with 72-lb injectors, running 26-psig with an F1. He uses the plugs I mentioned, gapped to 0.032".
Willie
I'm not Rich, but Larry's car I talked about above is a 355 with AFR's, MSD-6AL, FAST system with 72-lb injectors, running 26-psig with an F1. He uses the plugs I mentioned, gapped to 0.032".
Willie
Registered User
Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
SMOKNZ, using the wrong plug style could cause two problems (that I can think of).
1. The gasket seat head doesn't have a tapered seat cut into it, so the sealing surface. I'm not saying that they all leak, but I could see how a leak would be more likely.
2. Since there is not a seating surface, the reach of the plug may be incorrect. The seating surface is what determines how far into the chamber the plug extends. So, mis-matched parts could lead to a problem with reach.
I'm not quite sure why I'm having to justify using the correct parts, though, since AFR's instructions clearly state what style plug to use.
Mike
1. The gasket seat head doesn't have a tapered seat cut into it, so the sealing surface. I'm not saying that they all leak, but I could see how a leak would be more likely.
2. Since there is not a seating surface, the reach of the plug may be incorrect. The seating surface is what determines how far into the chamber the plug extends. So, mis-matched parts could lead to a problem with reach.
I'm not quite sure why I'm having to justify using the correct parts, though, since AFR's instructions clearly state what style plug to use.
Mike
Registered User
Joined: Oct 1999
Posts: 448
From: DAPHNE,AL USA
Originally posted by engineermike
SMOKNZ, using the wrong plug style could cause two problems (that I can think of).
1. The gasket seat head doesn't have a tapered seat cut into it, so the sealing surface. I'm not saying that they all leak, but I could see how a leak would be more likely.
2. Since there is not a seating surface, the reach of the plug may be incorrect. The seating surface is what determines how far into the chamber the plug extends. So, mis-matched parts could lead to a problem with reach.
I'm not quite sure why I'm having to justify using the correct parts, though, since AFR's instructions clearly state what style plug to use.
Mike
SMOKNZ, using the wrong plug style could cause two problems (that I can think of).
1. The gasket seat head doesn't have a tapered seat cut into it, so the sealing surface. I'm not saying that they all leak, but I could see how a leak would be more likely.
2. Since there is not a seating surface, the reach of the plug may be incorrect. The seating surface is what determines how far into the chamber the plug extends. So, mis-matched parts could lead to a problem with reach.
I'm not quite sure why I'm having to justify using the correct parts, though, since AFR's instructions clearly state what style plug to use.
Mike
Mike the plugs will work either way. tapered or gasket. They both also extend into the chambers the same and will not leak if tight . I think what some people are thinking is should they change their plugs if they are running the tapered style on the AFR heads. No need until you need new plugs for some reason because you not going to gain anything. Unless it will make you sleep easier..
Registered User
Joined: Jun 2002
Posts: 251
Originally posted by Willie
rskrause what plug would you sudgest for a 355 with afr 210 F.A.S.T msd digital 6 about 20-25 psi form a 88mm turbo?
I'm not Rich, but Larry's car I talked about above is a 355 with AFR's, MSD-6AL, FAST system with 72-lb injectors, running 26-psig with an F1. He uses the plugs I mentioned, gapped to 0.032".
Willie
rskrause what plug would you sudgest for a 355 with afr 210 F.A.S.T msd digital 6 about 20-25 psi form a 88mm turbo?
I'm not Rich, but Larry's car I talked about above is a 355 with AFR's, MSD-6AL, FAST system with 72-lb injectors, running 26-psig with an F1. He uses the plugs I mentioned, gapped to 0.032".
Willie
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