Attention: TDR Forum Junkies A week ago the delivery truck arrived despite the previous nights snow storm and left me with a nice looking plywood crate. As excited as a 6 year old on christmas morning I opened the box, an out jumped a nicely ported, back cut valved, o-ringed head. Man what a nice looking casting. For those who read my sob story of overporting my stock head here are some numbers.
I used an ultra sonic tester to determine the exhaust port thickness. I don't have numbers for a stock cummins unported, though. With the head upside down, exhaust ports pointing at you, imagine the valve seat as a clock. The hole I made is at 7:00, but down the throat just before the short side radius. This is where I took the measurements on both heads. After my port job on the first five exhaust ports they measure between . 17 and . 19 of an inch. That is right around 3/16 of an inch or 4. 76 mm (for those friends across the border, reading this). The number six port right around the hole I poked, measures . 09, which is less than 3/32" (2. 38mm). The new Piers head measures 3/8 of and inch in the same area (9. 52mm). I know I didn't hog out that much metal. I also have previously mentioned that the number six port seemed to be a different shape compaired to the other five. --- Less metal to begin with. Poor casting. My finger felt it before I ported... but my brain didn't catch it. Oh well, for the sake of science I march on. I am no machinest or porting expert, these are just my thoughs and findings.
I feel lucky that it turned out the way it has. Had I not poked into the water jacket, and put the head back on, I think it would have cracked and I would have hydro-locked the engine... . to much greater expense than this new Piers head.
I apologize for the fact that this is long winded, but so am I :-laf
Dave
ps. Pastor Bob, my thought is that the Piers head is not a Cummins casting, but a replica, with slightly better designs intergrated into it. Any info???
I used an ultra sonic tester to determine the exhaust port thickness. I don't have numbers for a stock cummins unported, though. With the head upside down, exhaust ports pointing at you, imagine the valve seat as a clock. The hole I made is at 7:00, but down the throat just before the short side radius. This is where I took the measurements on both heads. After my port job on the first five exhaust ports they measure between . 17 and . 19 of an inch. That is right around 3/16 of an inch or 4. 76 mm (for those friends across the border, reading this). The number six port right around the hole I poked, measures . 09, which is less than 3/32" (2. 38mm). The new Piers head measures 3/8 of and inch in the same area (9. 52mm). I know I didn't hog out that much metal. I also have previously mentioned that the number six port seemed to be a different shape compaired to the other five. --- Less metal to begin with. Poor casting. My finger felt it before I ported... but my brain didn't catch it. Oh well, for the sake of science I march on. I am no machinest or porting expert, these are just my thoughs and findings.
I feel lucky that it turned out the way it has. Had I not poked into the water jacket, and put the head back on, I think it would have cracked and I would have hydro-locked the engine... . to much greater expense than this new Piers head.
I apologize for the fact that this is long winded, but so am I :-laf
Dave
ps. Pastor Bob, my thought is that the Piers head is not a Cummins casting, but a replica, with slightly better designs intergrated into it. Any info???
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