My home inspection of Speedmaster heads

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Sand paper roll on Dremel... rounded the edges

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And if they were corrected how much of a difference would it make? As long as it's not causing a problem.
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I can’t answer that for you since I haven’t done that test.

But I can tell you that 589hp is doable without touching the plug holes.

What 318will has done is what I would do........ if..... I felt like I needed to do something....... which up to this point, I haven’t been compelled to do.
 
What plugs are you thinking? Here's what SM recommends: "SPARK PLUGS
Our heads require the use of 14mm. x 3/4 reach 5/8 hex gasket seat sparkplugs. Some recommended plugs are; NGK BCPR6ES or R5671A-7, Champion RC12YC, Autolite AR3923 or AR3924. Remember these are for mild street engines. Higher compression or boost requires colder sparkplugs!"
 
PRH said:
As has been mentioned...... these are copies of Ede heads.
The plug holes are done that way in the RPM heads, and since that’s the head they copied...... the threads are the same in the SM heads.

My guess is over 95% of the sets in use have not had anything done to the plug holes.
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Yes, at the least or at the most? for most myself included it is just a finish detail, like chamfering edges tidying things up, of minimal performance benefit other than theoretically maybe relating to hot spots? but I’d think at the level PBR is at like he said every little bit helps. I only noticed the difference in finish inspecting the TF’s. Lots of attention to detail on these.
 
PRH said:
I can’t answer that for you since I haven’t done that test.

But I can tell you that 589hp is doable without touching the plug holes.

What 318will has done is what I would do........ if..... I felt like I needed to do something....... which up to this point, I haven’t been compelled to do.
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Agree. It's one of those things that might not make horsepower or cause a problem but just isn't right.
 
MOPAROFFICIAL said:
Would you leave it if the plug sits flush or a hair proud, as then they aren't exposed edges? Do you think removing it could make a tiny bed of carbon around the plug?
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Agree, but I cannot think of one negative in doing it. However, dulling the teeth like edges may result in something positive. I don't think I'm removing enough to really move he CC's of the chamber.
 
318willrun said:
I guess I'll see what some here come up with. I don't think SM is any worse than the Eddies. Not saying it's right, but people have been bolting on OOTB eddies for 25 years ?? Not one issue reported due to plug location to my knowledge
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toolmanmike said:
What plugs are you thinking? Here's what SM recommends: "SPARK PLUGS
Our heads require the use of 14mm. x 3/4 reach 5/8 hex gasket seat sparkplugs. Some recommended plugs are; NGK BCPR6ES or R5671A-7, Champion RC12YC, Autolite AR3923 or AR3924. Remember these are for mild street engines. Higher compression or boost requires colder sparkplugs!"
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The 3924 is the coldest plug I've ever used and man that sucker is down in the hole!!....
 
toolmanmike said:
What plugs are you thinking? Here's what SM recommends: "SPARK PLUGS
Our heads require the use of 14mm. x 3/4 reach 5/8 hex gasket seat sparkplugs. Some recommended plugs are; NGK BCPR6ES or R5671A-7, Champion RC12YC, Autolite AR3923 or AR3924. Remember these are for mild street engines. Higher compression or boost requires colder sparkplugs!"
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RC12YC is what I plan on running. With stock dished 360 pistons and a fel pro gasket, can't imagine I'd run into compression that was challenging.
 
318willrun said:
Agree, but I cannot think of one negative in doing it. However, dulling the teeth like edges may result in something positive. I don't think I'm removing enough to really move he CC's of the chamber.
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Too bad they didn't cut a face into it.
Maybe it would be a good idea to get the grinder out and remove material on each side , open face plug recess, just a enough not too much. But if it ain't broke... dont fix it I guess.
The small recess behind the threads bugs me though.
 
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Ok, one head done..... pretty fast job. Not sure I did anything other than make myself feel better??? LOL...

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What about that terrible 1 angle valve job? How's that going to weigh on your conscience...
 
j par said:
good now you can give yourself some relief from all the guru's buzzing around in your head.... Hey that was a pun!!.. LOL
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Glad they pointed that out. I wouldn't have screwed a plug in till they were bolted on the motor. I just didn't like the hack-saw look around the plug hole. I've got years and years of removing jagged edges in heads with a Dremel, only fitting I should smoothed these out too... :)
j par said:
What about that terrible 1 angle valve job? How's that going to weigh on your conscience...
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I can't fix that at home, so it won't get fixed. I doubt my 360 heads now have a 5 angle valve job... LOL. Just remember, these heads are replacing stock 360 heads.
 
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318willrun said:
Glad they pointed that out. I wouldn't have screwed a plug in till they were bolted on the motor. I just didn't like the hack-saw look around the plug hole. I've got years and years of removing jagged edges in heads with a Dremel, only fitting I smoothed these out too... :)

I can't fix that at home, so it won't get fixed. I doubt my 360 heads now have a 5 angle valve job... LOL. Just remember, these heads are replacing stock 360 heads.
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I'm sure my head's have at least at 3 angle now..
 
j par said:
I'm sure my head's have at least at 3 angle now..
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Years ago, I had a machines shop do a 3 angle valve job, install new bronze guides in a set of factory 2.02 340 "J" heads. I pulled these heads for a set of 596 smoggers with 1.88's that was home ported and just lapped the factory valves. Dropped 3 tenths. Just how things work out sometimes.... :) I guess home porting might pay a little now and then. :D
 
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