heads and cam experts, need help with milled heads
12-27-2010, 12:25 AM
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heads and cam experts, need help with milled heads So I just picked up a set of 243 heads for a good deal with a fresh valve job ready to go. Only problem is that he can't remember exactly how much they've been milled but he thinks 0.025. I'm worried about compression and what size cam I can fit without ptv problems? I tried cc'ing them myself using a dropped and water and filling the combustion chamber with plexi glass over it(filling through a hole) but its hard to get a true measure. I would get between 60-61.5cc
12-27-2010, 01:20 AM
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12-27-2010, 01:29 AM
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I've got some tips regarding CCing cylinder heads.
First drill 2 holes in your cc plate. The "fill" hole is centered and the much smaller "bleed" hole is at 1 end of the combustion chamber. I usually set it to far one side laterally and put a 1/4 peice of plywood under one of my cylinder head stands. this makes it far easier to get the resulting "bubble" out of the chamber.
Another trick is to use straight antifreeze instead of water as the CCing fluid. Antifreeze has a much lower surface tension than water and bubbles at the edges are less likely to form.
I use Sta-lube blue boat wheel bearing grease to seal the plate to the cylinder head. Due to the blue color you can really see the "print" of your seal after pressing the plate onto the head. You can also see if you have excess grease in the chamber. These two things are very hard to see if your using vasoline or another clear sealant agent.
I have found that a selection of hypodermic sryinges work pretty good for me as a measuring device. The fancy burets are a bit of a pain to use IMO. I"ve got cattle sryinges that are 60CC total that work pretty good for most of the cylinder heads I've worked. I've drilled the center hole in my plate specifically to fit the tip of this syringe (no needle-end of hypo flush with bottom of plate fully installed) and I use a 10 cc syringe (finer garduations) to fill the rest up through the bleed hole using a fine needle.
So the process is as follows: Seal plate down with blue grease. Carefully measure 60 CC in big hypo, plug hypo into plate, and inject antifreeze. Do not remove big hypo; the 60 cc should have covered up its tip and if removed liquid might come out. Carefully measure up 10 cc of antifreeze in little hypo and fill the remaining void to botom of cc plate. Subtract what's left in small hypo from 70 CC and your there. You can get pretty quick with it after a bit of practice.
I can produce consistant results using this method. I have checked my 60 cc hypos with a lab buret and it was dead on. Brand on all my hypos (just checked in tool box) is Monoject.
Good Luck
Rick
First drill 2 holes in your cc plate. The "fill" hole is centered and the much smaller "bleed" hole is at 1 end of the combustion chamber. I usually set it to far one side laterally and put a 1/4 peice of plywood under one of my cylinder head stands. this makes it far easier to get the resulting "bubble" out of the chamber.
Another trick is to use straight antifreeze instead of water as the CCing fluid. Antifreeze has a much lower surface tension than water and bubbles at the edges are less likely to form.
I use Sta-lube blue boat wheel bearing grease to seal the plate to the cylinder head. Due to the blue color you can really see the "print" of your seal after pressing the plate onto the head. You can also see if you have excess grease in the chamber. These two things are very hard to see if your using vasoline or another clear sealant agent.
I have found that a selection of hypodermic sryinges work pretty good for me as a measuring device. The fancy burets are a bit of a pain to use IMO. I"ve got cattle sryinges that are 60CC total that work pretty good for most of the cylinder heads I've worked. I've drilled the center hole in my plate specifically to fit the tip of this syringe (no needle-end of hypo flush with bottom of plate fully installed) and I use a 10 cc syringe (finer garduations) to fill the rest up through the bleed hole using a fine needle.
So the process is as follows: Seal plate down with blue grease. Carefully measure 60 CC in big hypo, plug hypo into plate, and inject antifreeze. Do not remove big hypo; the 60 cc should have covered up its tip and if removed liquid might come out. Carefully measure up 10 cc of antifreeze in little hypo and fill the remaining void to botom of cc plate. Subtract what's left in small hypo from 70 CC and your there. You can get pretty quick with it after a bit of practice.
I can produce consistant results using this method. I have checked my 60 cc hypos with a lab buret and it was dead on. Brand on all my hypos (just checked in tool box) is Monoject.
Good Luck
Rick
12-27-2010, 09:59 AM
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Ok thanks for the help guys. I've just been using a dropper for babies that I bought at a local pharmacy. So if the mill ends up being .025 how big of a cam can I run with that?
12-27-2010, 10:05 AM
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I have 62cc 243's and was recommended not to go over mid 230's. So with even more milled off I wouldn't exceed that without measuring, and even a smaller cam may be required if you're not flycutting, such as a 224 or 228r.
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12-27-2010, 11:33 AM
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The cam im looking at is 226/230 .598 .600 116+1 im hoping the wider lsa will give me a bit more ptv clearance. But the car is my dd so i cant take it all apart just too find out the cam wont work haha.
