Hello im Danny from holland i have restored a cad coupe deville and overhaul tehe engine.
I have made a dual exhaust 2.5 inch and the egr pull off the engine.
Im drinving on propane and i will more hp, cant i take the 76cc heads from a 472-500 cid and i think i have compression 10:1 and the intake.
Off will broke the crank:rant2:

thanks for your reply
Danny

Crank should not be a problem, as the 472 crank is basically the same. You might want to get an MSD coil to ensure you have sufficient spark, new plugs, wires. Check your lower end ( rod end to crank throw fit ) with scrutiny. I'm sure that the only bearings you can get are aluminum, Federal Moguls. If Clevites are available, I'd go with them, but I doubt they are. One trick you might want to try, a Total Seal top ring. You can find them at totalseal.com.

My inglisch is not so goo but i think you not understand my question.
Ihave overhaul the engine with new crankshaft bearings camshaft bearings moly piston rings etc only the camshaft en the flat top pistons are originel.
distributor everythng is new ihave already drive now 3000 mile whit the engine.
Im driving on propane and a compression 10:1 its better I want more hp and the early 76 cc heads have bigger valves and more compression but fit the 76cc heads a 1979 425 engine.
Ands i heard that the 425 engine its not so strong iwant no dammage the engine after a few mile.
ps all the bearings are clevitte 77.

thanks for your openion .

greetings danny