piston slap
#1
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quick question i am just starting to rebuild my cossie engine and want to check if i need to have a rebore and pistons as it slapped quite bad when cold the bore messures at 90.80 and the pistons at 90.60 its a 200 block with 2wd pistons i am aiming for 500 brake the spec of the engine is 7.4.2.1 cr ported polished head 25mm inlet 24 mm exhaust bd14 inlet bd10 exhaust isky valve springs long studded etc running a t4 and 83lb siemens do i need to change the spec and are the pistons ok to reuse?
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#10
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Straight gudgeon pin in the 2wd piston is the cause of slap. 4wd piston uses an offset pin so eliminates slap somewhat. If piston to bore clerances are too large then it will still slap. Not sure on the effect of your bore clearances on the slap side of things.
I would ditch the BD10 exhaust cam and use a standard one though. Your lowering the comp so off boost driveability will be slightly worse than normal and made even worse with the BD10 exhaust cam. That cam is generally regarded as useless in a cossie engine due to it making the engine feel somewhat lifeless at the lower end of the rev range, no matter if its inlet or in your case exhuast. Standard exhaust cam is good for 550bhp anyway
I would ditch the BD10 exhaust cam and use a standard one though. Your lowering the comp so off boost driveability will be slightly worse than normal and made even worse with the BD10 exhaust cam. That cam is generally regarded as useless in a cossie engine due to it making the engine feel somewhat lifeless at the lower end of the rev range, no matter if its inlet or in your case exhuast. Standard exhaust cam is good for 550bhp anyway
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#11
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love the wheels mate got same on mine but in anthrecite best looks mod so far another question mate you've ready seen the head spec but i've just been offered another 1 with 27mm inlets and 26mm exhaust also has leary cams i'm told equivilent to bd16s wat would i be better off with my head with a std ex cam or the 1 ive just mebtioned obviously i'm looking for big power but want to keep some mid range driverbility
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