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  • BBC Sparkplug help

    I'm working on an unknown year BBC with head casting #353049, don't know original application. I want to put new plugs in it, it has 3/4" reach gasket plugs that I started to replace 'in kind' but I don't like how they feel. I get to a plug where I can see up in there and I swear it is a tapered seat. I've looked over the internet and can't find anything, do any of you guys have experience here? The head is an Oval Port that is supposed to be one of the better ones.
    The tapered plug is the UR5 short thread, can the long thread of the gasketed plug extend into the chamber that far without hitting the piston? Know what I mean?
    Thanks for you help, OJ
    A Carter Carb Shop, sales and service

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    If the car ran before you need to make sure the new plugs are just as long. Some plugs have gaskets and some dont, so its comparing the length from the bottom of the gasket or end of the tapered plug.

    If you are not sure or never ran this before you need to take a piston to TDC and either run caliper in there or some straight rod to see how deep it goes before hitting the piston and take away at least .060 to make sure you have no interference.

    We had the problem with our first set of aluminum heads. Never realized the plug was halfway into the head and the electrode was being shielded by almost 3/8 of an inch of remaining threads. So if we started out using the aluminum head length plugs in the cast iron heads without that extra decks material, we would have had a problem.

    That lesson taught me to never install the heads until I check the plug length.

    Found a head. There are about 7/16ths worth of threads in that head, so I would think that 3/4 plug will stick in quite a bit.
    Last edited by anotheridiot; July 13, 2017, 12:12 PM.

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