Can you guys tell me what spark p.ug to use for a stock 307
Everyone says the AC Delco are junk anymore
Everyone says the AC Delco are junk anymore
Spark plugs
- Thread starter Selene Foster
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The R45TS was used on the 231 V6 and I believe 305 Chevy engines if memory serves.
What year 307? Assuming it's the Olds 307, 5A heads used R46SX with preset gap of 0.080" (and later R46SZ with the smaller gap preset at 0.060") with the old-school gasket. Roller-cammed engines with 7A heads used the long-reach threaded FR3LS6 with gasket and I believe those too, were preset at 0.060" gap. See pics below.
R46SX
R46SZ
FR3LS6
What year 307? Assuming it's the Olds 307, 5A heads used R46SX with preset gap of 0.080" (and later R46SZ with the smaller gap preset at 0.060") with the old-school gasket. Roller-cammed engines with 7A heads used the long-reach threaded FR3LS6 with gasket and I believe those too, were preset at 0.060" gap. See pics below.
R46SX
R46SZ
FR3LS6
Mine calls for FR3LS6 but I can't find them anywhere, can you recommend anything
Yeah, you have the roller engine and would need the FR3LS6 plugs. Check to make sure you have the 6A or 7A heads (easy to see on driver side front on the head just forward of #1 spark plug. GM p/n 5614000 or 5614102 or 5613796. I've heard the newer Delco plugs with the gray lettering suck, but what you want is what I've got pictured above if possible. Either the green stripe versions or if it doesn't have the green stripes, at least if it has the green lettering.
Here's a complete green lettering set for $14.59 plus tax to your door. Depending on your sales tax, you should be able to get these delivered for < $2 per plug.
ACDelco FR3LS6 Spark Plug for sale online | eBay
Find many great new & used options and get the best deals for ACDelco FR3LS6 Spark Plug at the best online prices at eBay! Free shipping for many products!
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A green stripe set of 8 for 15.60 plus tax to your door. Your call. The brown crap you see is dried up old boot lubricant they used to put on the plugs. It can be cleaned off. Edit: They have the wrong part number listed. The box flap says it's part 5613796, just as it should be.
ACDelco FR3LS6 Spark Plug for sale online | eBay
Find many great new & used options and get the best deals for ACDelco FR3LS6 Spark Plug at the best online prices at eBay! Free shipping for many products!
www.ebay.com
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Nope. Cast iron only. They never changed the basic design shape and plug position from 64-90 and never used a tapered seat plug. I think the tapered seat plug was used by Fords in the 50s. GM didn't start using them until the late 60s. Buicks IIRC. As an Olds guy, I always found it weird to use tapered seats on plugs.
Just a note on that. They come pre-gapped at 0.060". However, you ALWAYS check them prior to installation because they could be off due to handling, bumping during shipment, etc. The 0.060" was a reduction from the 0.080" from the earlier HEI plugs because the huge gap was killing the HEI components having to work harder to jump that gap with little gain.
I usually don't advise going against GM specifications, except in this particular instance, I'd go 0.45"-0.050" gap on the plugs and you'll not only gain a healthy spark, you'll also keep your old azz HEI unit from working overtime to jump that gap. Plus, your car will run just fine doing it.
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