280zwitha383 Posted May 5, 2007 Share Posted May 5, 2007 The PO said he bought the head and cam off of ebay and the seller claimed the head was shaved but he couldn't tell me how much. I was just wondering if I can mic it somehow? Thanks. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted May 6, 2007 Share Posted May 6, 2007 well... maybe a compression test... metal or paper head gasket? this will make a difference. do you know the cam specs?! anyway.. a shaved head, will increase the Compression Ratio. So depending on the pistons, and cylinder head (p90, n47 etc) this will all vary. tell us some specs Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted May 6, 2007 Share Posted May 6, 2007 Sure me ment shaved and no surfaced? I hear and see alot of people interchange the 2. pro is right though some specs for us and a comp test for you and I'm sure you can get a ball park figure. Quote Link to comment Share on other sites More sharing options...
technicalninja Posted May 6, 2007 Share Posted May 6, 2007 Yes you can, Sort of..... Standard head thickness is 4.248" from what I remember. But you can only tell how much has been taken off totally. Most of time heads are milled because they were warped and a proper job on a Z head mills the block side till it is flat then the top is milled till flat and then top is further milled untill total amount taken from both sides closes on .020 or .040 or .060 and so on as the cam tower shims are .020 thick. To give example. Let's say bottom requires .017 to straighten and top only requires .015. totalled this equals .032. Another .008 should be taken off of top (or bottom if your after compression) to equal .040 and 2 shim kits will be needed. You cannot easily tell exactly how much was taken off bottom if both sides were cut. Good machine shops stamp amount removed so look for markings. Machine shops unfamilure with the L-series only mill the bottom of head and if head was badly warped the top surface will no longer be flat which can result in cam and cam tower issues. You can actually measure a head installed on engine but only at one spot. Directly under the heater hose fitting at rear of head to the valve gasket mounting surface. If I found a head that had been heavily milled but appeared to not have been milled on the top as well I would shy away from it unless the seller started with an un-warped head and was milling for compression alone. A seller who had done this would know EXACTLY how much had been removed. Both sides do not have to be milled as long as both sides are flat and parallel. Hope this helps... Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted May 6, 2007 Author Share Posted May 6, 2007 Monday at work I'll mic the thing if I can get to it and see what I get. P90a head E30 cam (can't find specs for this on the internet but I ASSume it is close to the E31 cam which has 248/248 duration with 10.5/10.4mm lift at valve which is .413/4.09") 150-155psi on all cylinders I would also assume the head was milled for performance because it was completely cleaned, supposedly had new valves and came with the E30 cam when sold on ebay. I would think the seller said how much was milled off but the PO forgot or did't pay any attention. I really couldn't say. The car runs pretty well. Better than the only other thing I have to compare it to which was a completely stock L28 with 200k+ miles on it (came out when the 383 went in). Quote Link to comment Share on other sites More sharing options...
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