Quote:
Originally Posted by enaberif
Spark plug gap on a HEI Chevy should be .045 as .030 was for a points system. Yes using the wrong gap will make a vehicle run like absolute crap. When I put plugs in my truck they were gapped for .030 and I could not get it to run properly no matter what.
Also doing vac gauge measurements I am pretty sure it should be on manifold vacuum not ported vacuum as should your distributors vacuum advance to get optimal performance.
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I used to run .060 gap with a Jacobs Mileage Master multi spark setup on my 1985 5.0L C10. She ran nice and smooth. That or an MSD6AL is about the only aftermarket coil system I would use because it doesn't bork the stock ignition module. The mileage gains were not enough to make the price worthwhile.
Run the gaps as wide as you can get away with it lights the fuel better. .045 is a good number for stock HEI with a new Delco coil and Ignition module.
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8
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