Quote:
Originally Posted by AZKen
I thought you were asleep and was re writing my post when you posted, that's why it's gone. But you have it quoted. I see it's 5:30PM there, sorry.
It is possible that you have a tapered head with non tapered plugs that "seems" to fit. That is what we are both thinking. That's what Turbobill said way back. If that is possible, you don't want that. Others will chime in tomorrow. BigBlockV6 has a post talking about tapered for larger motors. D10 plug.
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AZKen has already brought up the fact that 73-74 379, 432 and 478M V6 engines use a short tapered plug which was originally the AC R43T plug superseded by the AC 10 plug which I have a set of and will probably never use. Other factors to consider is the newer big cubic inch head has larger valves than the stock 305D head. 379's share the same intake valves with later 305E engines(305D have smaller valves) and have the larger Magnum Sodium filled exhaust valves, while the 432 and 478 heads have the larger Magnum intake valves over the 379. To find out which later model head you have a look at the intake and exhaust port sizes will determine that. 379 heads have the smaller ports like the 305. 432 & 478 are the big port Magnum heads, I think your best bet is to find a matching set of heads. I would also like to mention that not all 73-74 478M engines used the short tapered plugs. A replacement crate engine built in 73-74 could have the 3/4 long reach plugs for older applications. I have a late 73 478 that came out of tilt cab TM7500 series with the short tapered plug while the 74 478M in my 68 was a new replacement crate engine that came out of a 63 6500 series tilt cab and came with the 3/4 long reach plugs.
