C8 heads on a D3 block.

I have a bone stock D3 460 in a 68 Galaxie. I also have a (blown up) C8 460. The C8 heads are max effort 2.25I/1.76E, 72 cc., fully adjustable. Would the big valves hit the stock dish pistons in the stock block with a .564/.588 cam ? Thinking of swapping heads to raise compression.

my cam is .562" I and .586" E lift, and the valves don't come anywhere close to hitting my dished pistons (SpeedPro/TRW L2404 aftermarket but stock configuration with a 22cc dish).
Heads are TFS 290 (2.20" I and 1.76" E with 74cc chambers). Block is C9. Similkar to what your describing. I hope this info helps.

jss227 wrote:I have a bone stock D3 460 in a 68 Galaxie. I also have a (blown up) C8 460. The C8 heads are max effort 2.25I/1.76E, 72 cc., fully adjustable. Would the big valves hit the stock dish pistons in the stock block with a .564/.588 cam ? Thinking of swapping heads to raise compression.

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Your valves will probably hit the piston notches on the radial edge if the pistons are O.E.M. 1973 or later. The notches are plenty deep but, not large enough for that size valve to fit into them and with that size camshaft I do envision a clearance problem.

Pistons are oem, thought there might be a problem, but wishfull thinking. Was trying to be cheap and save money for other motor. Rod through the pan sucks.

You can notch the pistons for very cheap with a piston notching tool / cutter. Take the same amount off each one (depth) to keep the pistons in balance.
Clean out the shavings, re-check clearance, assemble, and go have fun.

jss227 wrote:I have a bone stock D3 460 in a 68 Galaxie. I also have a (blown up) C8 460. The C8 heads are max effort 2.25I/1.76E, 72 cc., fully adjustable. Would the big valves hit the stock dish pistons in the stock block with a .564/.588 cam ? Thinking of swapping heads to raise compression.

______Hickory Dickory dock
He put C8s on a late engine block
______The clock struck 2
______The valves hit and went through
______You can't always mix parts that come stock*

*(Unless you fully evaluate, correct and adjust as needed.)