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[ROOT]/includes/bbcode.php on line 112: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 4752: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3887) [phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 4754: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3887) [phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 4755: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3887) [phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 4756: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3887) RS Motorsport :: Classic Speed Restored • View topic - Steve's MK2 Sports Sedan
Paul, you know the routine, I gave them all the timing info and everything else they asked for. I dealt with Steve Brown at Quantum, who knows the requirements for these engines. I didn't actually specify valve pocket depths but i still would have expected at least .080"+ extra for the inlets over lift @ TDC and .100" for the exhaust pocket. To have 0 on the inlet and maybe .020" on the exhaust implies that someone miscalculated the cam profile I think.
Warren, they were meant to be custom pistons made for my engine specs so if their not right I wouldn't spend more money to fix them. The delay was caused by ordering at xmas and i was fairly warned not to get too excited till mid march.
What engine are you using now Dave? How many cast iron block modern 2L engines are out there. If I was allowed to run a Duratec I would but the alloy block makes them a no go for sports sedans. And NA Nissan/Honda/Toyota engines are just as cranky as NA YB's.
Mk 2 Escort Sports Sedan 2L N/A YB Cosworth engine rebuild completed. 100% Mongrel FORD...actually Oz block & crank, Yankee pistons, English head & rods, Ozzie cams & valves!
I've always found it easier to not worry about the order sheet and tell them what I need so no one can make a f$$k up with a key stroke.
There is no way in the world you would get anywhere near a reasonable pocket depth with those pistons, they machine the blanks to give the most uniform crown thickness.
You should give them back and ask (demand) nicely for the expedited service.
What is the actual thickness through the valve reliefs on those pistons?
It may well be possible to go deeper. In my experience the critical thickness is between the part of the pocket and where it comes closest to the top ring groove. Some engine builders will say this or that is the minimum crown thickness- the figure is often .200" or 5 mm. They may have a point but I know for a fact that 800 +hp 9500 rpm Nascar engines go down to .140" and probably less, on some pistons.
Maybe i should call CAMS and get a ruling on that front.
This is why I can't use an alloy pinto block:
• it is permitted to use a cylinder block manufactured by a supplier to the aftermarket provided that: (a) it is an identifiable replacement for a permitted, original equipment cylinder block; (b) the centrelines of the crankshaft, camshaft/s and, where applicable, lifter bores are in the same relative positions as the original equipment cylinder block; and (c) it is made from the same material as the original block.
Mk 2 Escort Sports Sedan 2L N/A YB Cosworth engine rebuild completed. 100% Mongrel FORD...actually Oz block & crank, Yankee pistons, English head & rods, Ozzie cams & valves!
Just below is a 2-D model of the modified piston with the correct VP’s to go with his cam & free drop. Int VP @ -.325” and Exh VP @ -.210”.
This model is fully maxed out @ +2.8cc with plunged VP’s. The model also weighs about 386grams which is around 17grams more. It definitely needs undercrown milling on the Exh side as it’s extra thick there.
Compression only figures to a max of 10.9:1. Let me know where you want to go from here.
Attachments
CPpiston attempt 2
CP Piston V2.jpg (41.73 KiB) Viewed 18572 times
Mk 2 Escort Sports Sedan 2L N/A YB Cosworth engine rebuild completed. 100% Mongrel FORD...actually Oz block & crank, Yankee pistons, English head & rods, Ozzie cams & valves!
I never actually bothered because CP have cocked them up and are going to make me new ones. By the looks of the comments from the last email they can be fairly thick which is good for machining a little extra pocket if needed.
Until I get hold of Steve Brown tomorrow not much will happen, as far as CP are concerned I'm not the customer, Quantum Racing are, so they won't reply to my emails.
Mk 2 Escort Sports Sedan 2L N/A YB Cosworth engine rebuild completed. 100% Mongrel FORD...actually Oz block & crank, Yankee pistons, English head & rods, Ozzie cams & valves!
Still no pistons from CP as yet However the gearbox is proceeding well and after getting in a few extra parts from Quaife UK last week it should be ready within a couple of weeks.
Mk 2 Escort Sports Sedan 2L N/A YB Cosworth engine rebuild completed. 100% Mongrel FORD...actually Oz block & crank, Yankee pistons, English head & rods, Ozzie cams & valves!
I really only get them to do specific jobs although they have had substantial input into this engine. I got them to do the last dummy build as Mike Dale was snowed under with work at the time and I needed to know if the CP pistons were made right or not. I wouldnt hesitate to get them to do any specialist machining, cylinder head or block. But for final assembly Mike Dale is the Pinto man and I will be getting him to put it together and do the initial tuning.
Mk 2 Escort Sports Sedan 2L N/A YB Cosworth engine rebuild completed. 100% Mongrel FORD...actually Oz block & crank, Yankee pistons, English head & rods, Ozzie cams & valves!
Good news. New pistons have passed the dummy build with Inlet clearance .150" and 140" on the exhaust. 60" radial clearance around the valves which seem a bit excessive.....
Onwards then!
Mk 2 Escort Sports Sedan 2L N/A YB Cosworth engine rebuild completed. 100% Mongrel FORD...actually Oz block & crank, Yankee pistons, English head & rods, Ozzie cams & valves!