Re: Spark Plug Heat Range
i on a whim am trying that e 3 spark plug . i have about 2k miles on them but seem to get about 1.5 mpg better milage on the freeway and dont have as many knock events .could be just that they are new plugs . i could be nuts but these things just might work. just thought id throw it out for ya :hello:
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Re: Spark Plug Heat Range
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This is a tapered seat plug, which is not correct for the early LT5. However, if it's already in there, I wonder if you'll need to use tapered plugs from now on? |
Re: Spark Plug Heat Range
Pete,
I'm positive its a 41-630. But I will look again when I get home. One other possibility is that if I do have heads with tapered seats, it would give more evidence that the motor had in fact been replaced as I was told. Supposedly, original motor had cam seize issue and GM replaced it with a new one. Sepaking with Ron Kreigh at BG, he said that the service engines were all 4 bolt, 93+ motors. Curiouser and curiouser. |
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Lastly, if I understand right, te Motor if replaced for warranty was a complete motor right? so if a 92 got a replacement 93 then it should have the IH and plenum for the 93 model right? would that then mean that the early cars were fitted with EGR if using a later motor? I am curious more then anything one how that was all settled.. Dominic do you know what mileage your motor was swapped at? |
Re: Spark Plug Heat Range
Guys,
A couple of clarifications. The car is a 92 #474. It was built in June of 92 so it was built in the last few days of that MY. The information I had received was that the motor had been replaced at 16K due to camshaft seizing. The owner (unknown) insisted and supposedly GM showed him a motor with a good dyno sheet. Wouldn't mind having that myself. I'll need to check out the heads and see what numbers are stamped on the back. According to Graham Behan, GM had decided to phase out the LT-5 during the 92 MY. Mercury Marine could build motors economically ONLY at a 1500units/annum pace. So they basically built all the motors that were going to be used for the next 3 MY in 1 year plus whatever would be needed as service engines. I have the same question as =Jeff= regarding the top end. OTOH, IH were definitely 90-92 as was plenum. When I port matched the cylinder heads this past winter, the primaries were smaller than the secondaries. Secondaries were about 37mm. Primaries needed basically a crescent moon cut to match with 36mm IH. As for the spark plugs, I pulled several and they were 41-602s. My mistake because I still had 41-630s in the cabinet. Those I had used with the 84. However, the ground strap still indicates that I could go with a colder plug and lean out WOT fuel. Currently running .040" gap. |
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