colonel Posted April 23, 2014 Share Posted April 23, 2014 Tried to search but don't appear to know how to do it effectively as I get everything with any of the words in it and using quotes comes up empty so I will ask directly. Putting a new 489 together with aluminum heads and am wondering if they will require something different than the NGK UR5 plugs that were in it. Brodix info suggests Champion RN12YC for pump gas which in NGK terms equates to BPR5ES, among others according to some lists, which is the same heat range as the UR5 I had in there. Thought about those Bosch Platinum plus 4 plugs with the 4 ground lugs on the side. Any advise/experience with playing with heat ranges and types of plugs would be appreciated. Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted April 23, 2014 Share Posted April 23, 2014 Hard to help with heat range with out knowing your combo. I guess I would start out with a FR5, it is a 5/8th hex 3/4 inch reach plug. There is a lot better header clearance with that plug. I run Autolite AR3933 but have run NGK R5671A-9 might be cold for your setup. Quote Link to comment Share on other sites More sharing options...
waupachino Posted April 23, 2014 Share Posted April 23, 2014 If you're not running a power adder like NOS, NGK R5671A-7 would probably be the best, it's part # is NGK 4091. Rock Auto has the cheepest prices on these by far at $1.55 each. Quote Link to comment Share on other sites More sharing options...
colonel Posted April 24, 2014 Author Share Posted April 24, 2014 No power adders other than the right foot. As I said a 489 with aluminum heads, edelbrock fuel injection, MSD Igniton, 4l60E trans, 3:90 gear, no A/C. Car is 99% street 1% track to see if et went down with new modifications. I see now where you guys are getting those NGK #'s as Brodix suggests a R5671A-8 for race gas which this car will never see as it is a street car not a race car. Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted April 24, 2014 Share Posted April 24, 2014 FR5 is a street type plug that has the same heat range as your UR5 just a modern smaller 5/8 hex that is easier on installation. You can cross that number to Bosch if you want. I use a lower cost plug until I decide the best heat range. Quote Link to comment Share on other sites More sharing options...
colonel Posted April 26, 2014 Author Share Posted April 26, 2014 Thanks, I guess I will start with those fr5. I can't use the ur5 as it is a .490 reach and taper seat plugs for the stock heads and I gather these aluminum heads use a .75 reach with a gasket seat. Any thoughts about using a FR5 projected insulator vs FR5-1 non projected insulator?? FR5-1 looks like it has more space around the tip to allow more air fuel to immediate area?? How will I know if I have the right heat range....insulator will be light brown color???? If I was ahead of the curve I would have looked into plugs before I put the heads on so I could see just how they fit in the combustion chamber. I certainly don't want any 13/16 size plugs as I can see those being hard to deal with with headers. I have gone to a 1 7/8 primary tube header and the 5/8 ur5 plugs were not a problem to get in and out Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.