Full top end rebuild...
Discussion
Upon inspection I need a new cam (two of the exhaust lobes considerably warn, with dished followers). I also did a compression check with No. 1 cylinder considerable down (120 psi). I'm hoping that its the head gasket and this is what caused the system to pressurise and blow the timing cover gasket in the first place, however, I'm holding my breath that its not a piston ring as there was a fair amount of oil/burnt oil in the plenum/inlet manifolds which appeared to have come up the breathers (although a friend tells me this could be because the car has been overfilled in the past?).
Also - I laid a straight edge across the top of the valves and three were visibly recessed (inlets curiously - I would have expected exhaust to go first?). These also corresponded to the cyclinders which had slightly lower compression (150-160 ish compared with 190 on the healthy cylinders) so I'm guessing that they're not seating 100% at the heel of the cam.
I'm therefore looking at a new cam, followers, chain and work on the cylinder heads. As everything is in pieces (inlcuding removing the exhaust manifolds which were blowing between the pipes - de cats on order with ACT) I'm thinking of taking the opportunity to upgrade to Stage III heads and a hotter cam (plus other assorted goodies and a remap). I wondered whether anyone had gone down this route and had any views on improvements which can be gained, and which suppliers are recommended?
The extraordinary thing is that although the engine used to pink a ltitle on acceleration (which I'm now putting down to a severly worn chain interferring with the distributor timing) and was quite rough towards the top end of the 4,000 rpm band (cam), the car still used to fly. It goes to show how it can be hard to tell the state of an engine until you have it in bits in your workbench!
Also - I laid a straight edge across the top of the valves and three were visibly recessed (inlets curiously - I would have expected exhaust to go first?). These also corresponded to the cyclinders which had slightly lower compression (150-160 ish compared with 190 on the healthy cylinders) so I'm guessing that they're not seating 100% at the heel of the cam.
I'm therefore looking at a new cam, followers, chain and work on the cylinder heads. As everything is in pieces (inlcuding removing the exhaust manifolds which were blowing between the pipes - de cats on order with ACT) I'm thinking of taking the opportunity to upgrade to Stage III heads and a hotter cam (plus other assorted goodies and a remap). I wondered whether anyone had gone down this route and had any views on improvements which can be gained, and which suppliers are recommended?
The extraordinary thing is that although the engine used to pink a ltitle on acceleration (which I'm now putting down to a severly worn chain interferring with the distributor timing) and was quite rough towards the top end of the 4,000 rpm band (cam), the car still used to fly. It goes to show how it can be hard to tell the state of an engine until you have it in bits in your workbench!
Hi there,
Am having my 500 engine taken apart by v8 specialist at the mo. Having heads cleaned up + reconditioned and can then send digi pics or can be seen at the garage doing the work. Also cam (mild), hi rev lifters and adjustable pushrods (all 10,000 miles). Other bits already sold. Am planning to ebay but always open to offers.
cheers.
Am having my 500 engine taken apart by v8 specialist at the mo. Having heads cleaned up + reconditioned and can then send digi pics or can be seen at the garage doing the work. Also cam (mild), hi rev lifters and adjustable pushrods (all 10,000 miles). Other bits already sold. Am planning to ebay but always open to offers.
cheers.
The numbers are not that important, but they should be pretty even. A hot cam will close later in the compression stroke and will typical give lower values than a mild cam. A leak test is important if you have differences; it can tell you which valve or if piston-rings are leaking. pt
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