Doing a top end/upgrade. couple questions, heads, rings and deckheight extremes. Options

[Aaron Cox]

motor ate a head gasket. pulled it apart before it could flame cut a cylinder or head.

so its apart. 71 x 94, with LARGE cam. has mahle euro '8:1 pistons" in it.
deck was setup at .031 but was running a head gasket.

heads have never been decked/surfaced. pulled em and cleaned em, 2 chambers have a sparkplug crack starting - so they need to be welded.

while its apart, i plan to re-ring it, hone the barrels, get the heads done, and???

questions - what rings do you recommend for mahle pistons?
certain rings justify certain hone finishes right?

heads need welding.
valves are sealing great to the seats. guides are good. (motor has 35 k on it since full rebuild.) when the head gets welded, will this require new seats/guides and a resurface?
what is the proper welding setup- my machinist may want to weld em cold, but i was told to pre heat em first - your thoughts?

when reassembling - how tight can i go on deckheight? the euro pistons have a .034" dish to em. should i trim the pistons .034 to make them flat, and trim the cylinders accordingly also?

trying to get as much CR with these 94mm pistons as i can, and running 91 gas.

last question- cam. how does the cam affect deck height? how tight can i go?

going to CC my heads tomorrow - before machining.... what is the range for a stock 2L head? 55-65cc's?

*on reassembly - head gasket will be omitted, and cylinders will be lapped into the head. valves will also be lapped into their seats again.

[Dave_Darling]

Welding the heads is not a simple process; you do have to do pre-heating and so on.

Welding on the heads will make them move around enough that you will need another valve job to make sure the valves and seats are still concentric.

Heads would originally have had "about" 56cc volume, IIRC. But small differences in the volume can have relatively large effects on the CR, so measure measure measure!!

--DD

[Aaron Cox]

Welding the heads is not a simple process; you do have to do pre-heating and so on.

Welding on the heads will make them move around enough that you will need another valve job to make sure the valves and seats are still concentric.

Heads would originally have had "about" 56cc volume, IIRC. But small differences in the volume can have relatively large effects on the CR, so measure measure measure!!

--DD

i pickup the syringe and discs tomorrow..... will measure.

so a valve job would be required again (simple), but the seats would have no risk of getting loose in the pre-heating or welding phase?