LT4 spark plugs
02-29-2012, 08:32 PM
#1
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Join Date: Jan 2005
Posts: 3
LT4 spark plugs
Hello everyone. I havn't been on here in a while but I have a question for you. My ignition system in my 1996 Corvette LT4 desperately needs to be replaced. It is stumbling pretty bad. I am going to replace the water pump, opti, wires and plugs all at the same time. My question is what plugs to get?
I know that the stock plugs are ACDelco Platinum 41-943 and have a bad reputation of the puck falling off so I would rather stay away from those. I know a lot of people with LT1s really like the NGK TR55s and they have a good reputation but they are only a copper plug and rockauto.com says the LT4 needs a NGK TR5 anyway. Im assuming because it has higher compression? The LT1 had 10.5:1 vs the LT4 having 10.8:1 And this is still only a copper plug. I have heard it is best to replace a plug with the same material it had originally.
Looks like AC-Delco part#14 is a platinum Rapidfire plug that is equivalent to the stock 41-943. Do these have the same problem with the puck falling off?
As far as NGK goes, the platinum version they have available is a 3186 {#TR5GP} G-Power
This is what they recommend for the 5 engine code or LT4
I noticed that Delco does not suggest different model plugs for an LT1 vs an LT4
Does this make a big difference? I need to make a decision pretty soon so please reply with any advice. I have read through a hundred old threads on other message boards and forums but most of the info is several years old and only has to do with LT1s and not the higher compression LT4s.
BTW i have most available blot-ons including CAI, long tube headers, no cats, x pipe, catback, 52mm TB and TB bypass and plan on doing an electric waterpump and taylor full metal jacket wires.
Thanks in advance!
I know that the stock plugs are ACDelco Platinum 41-943 and have a bad reputation of the puck falling off so I would rather stay away from those. I know a lot of people with LT1s really like the NGK TR55s and they have a good reputation but they are only a copper plug and rockauto.com says the LT4 needs a NGK TR5 anyway. Im assuming because it has higher compression? The LT1 had 10.5:1 vs the LT4 having 10.8:1 And this is still only a copper plug. I have heard it is best to replace a plug with the same material it had originally.
Looks like AC-Delco part#14 is a platinum Rapidfire plug that is equivalent to the stock 41-943. Do these have the same problem with the puck falling off?
As far as NGK goes, the platinum version they have available is a 3186 {#TR5GP} G-Power
This is what they recommend for the 5 engine code or LT4
I noticed that Delco does not suggest different model plugs for an LT1 vs an LT4
Does this make a big difference? I need to make a decision pretty soon so please reply with any advice. I have read through a hundred old threads on other message boards and forums but most of the info is several years old and only has to do with LT1s and not the higher compression LT4s.
BTW i have most available blot-ons including CAI, long tube headers, no cats, x pipe, catback, 52mm TB and TB bypass and plan on doing an electric waterpump and taylor full metal jacket wires.
Thanks in advance!
02-29-2012, 10:53 PM
#2
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,825
Re: LT4 spark plugs
The difference between the two plugs is the gap - TR5 - 0.035"; TR55 = 0.050". What gap does your Owner's Manual specify fpr the LT4? The LT1 specifes 0.050".
Is your engine modified in any way? Higher HP may require a colder plug. A power adder (forced induction or nitrous) may require a colder plug.
The TR55-IX is an iridium version of the TR55, with iridium being an alterntive to a platinum plug. The difference between a copper plug and a platinum or iridium plug is resistance to wear. The copper plugs will probably have a life of 20K miles, with the platinum or iridum plugs lasting upwards of 100K miles.
Is your engine modified in any way? Higher HP may require a colder plug. A power adder (forced induction or nitrous) may require a colder plug.
The TR55-IX is an iridium version of the TR55, with iridium being an alterntive to a platinum plug. The difference between a copper plug and a platinum or iridium plug is resistance to wear. The copper plugs will probably have a life of 20K miles, with the platinum or iridum plugs lasting upwards of 100K miles.
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