Took a photo of a head that Ed Peters did for me 20 years ago and a stock head.
Ed's on the left.
Took a photo of a head that Ed Peters did for me 20 years ago and a stock head.
Ed's on the left.
Last edited by Johnny; 12-04-2016 at 07:01 PM.
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My "presumed" FM head looks a lot like it.
Last edited by tryingbe; 12-19-2017 at 11:50 AM.
Back cut from the valves...right. I think also he softened the edge on the ridge on the lower side.
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Looks the same as my FM head, I recognize the exhaust valve. Should also have the little wear caps that go on the valve tip.
Ian Adams Function>Form 1990 shadow scrapped, too rusty:( 1991 Spirit R/T Scrapped, parts sold:( 1989 Turbo Caravan Daily beater with built-[I]ish [/I]engine slowly evolving into weekend turbo beater.
That is exactly how I cleaned up the chamber on both of my heads. Great minds think alike!!
Bryan
86 GLHS #161, 2016 Impala
SDAC National Member, SDAC Buckeye Chapter Member
A man has got to know his limitations.....
Thanks for these pics, i don't think I've seen them all side by side before. That helps, understand what is done to the swirl head chambers anyway.
Wayne H.
'91 Dodge Spirit ES 2.5L turbo 5spd
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Sharp angles = hot spots. Get rid of them. What is everyone else seeing?
Dont push the red button.You hear me?
That, plus un-shrouding the valves.
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"laying back" the chamber softens the pressure rise inherent in the fast burn head making it more resistant to knock.
Working on clearing the decks.
Wouldn't it also open up the area for the gases to get in and out?
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I'm not sure if the 'quench pad' area of a 782 pad actually does any quenching with the stock piston-to-head clearance being so large?Wouldn't the smaller quench pad do the opposite?
Dont push the red button.You hear me?
Looks like something is going on next to the spark plug (6 O'clockish) to the intake valve on the FM head... or is it just me /the angle?
Mike
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A few thoughts...
Correct.
The long side corner (as the intake charge exits from the bowl into the chamber) is too sharp of a turn.
At that point, the charge becomes disrupted and is a significant contributor to fuel washing on the cylinder wall.
Additionally, it is lacks any contribution to squish for knock suppression and/or centralized burn within the chamber.
So the left side should kind of match the right side.... right? (lower part of the photo)
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Somewhat - yes.
Here's a decent reference chamber.
Also worth noting... The intake valve is flat which is indicative of a 'nail-head' valve - great for intake flow but horrific for the exhaust.
On the other hand, the exhaust valve is relieved in support of a high tulip - great for the exhaust but horrific for the intake.
Also notice the exhaust valve sits higher relative to the intake valve - low margin is needed for the intake while a wider than normal margin is appreciated on the exhaust.
In fact, the MP exhaust valves fall far shy of what's needed regarding a high tulip valve - this alone is worth 12-15cfm @ 25" on the exhaust side.
This along with serious porting effort on the exhaust is the only way to achieve 200cfm @25" flow through the exhaust vs the typical 170-175cfm on most ported heads.
nice info...Somewhat - yes.
Here's a decent reference chamber.
Also worth noting... The intake valve is flat which is indicative of a 'nail-head' valve - great for intake flow but horrific for the exhaust.
On the other hand, the exhaust valve is relieved in support of a high tulip - great for the exhaust but horrific for the intake.
In fact, the MP exhaust valves fall far shy of what's needed regarding a high tulip valve - this alone is worth 12-15cfm @ 25" on the exhaust side.
This along with serious porting effort on the exhaust is the only way to achieve 200cfm @25" flow through the exhaust vs the typical 170-175cfm on most ported heads.
^I believe this, plus the shape of both 2.2 and 2.5 "turbo" pistons have very little area to work with the quench pad (is this what you meant, or are you talking about "squish" distance from top of piston to quench pad?)I'm not sure if the 'quench pad' area of a 782 pad actually does any quenching with the stock piston-to-head clearance being so large?