Spark Plugs

[WildWilly]

Hello all, need some advice. My engine is back together and my guy is asking about which plugs. I know nothing about spark plugs. Can you guys offer some advice?? Including gap would be great. As always many thanks.

From Steve C's write up, here is basically what I have.

Willy (Bill) has chosen the 'best' stock parts...so to the 75hp euro 1300 engine (in theory) he has 'added'...

1500 euro cam (24/68 64/28 9.9 lift) (a tiny bit more lift than that 1300 euro cam... but they are almost identical)

H/C OE pistons 35.3 CH and 1.6 dome (ends up with 9.9:1 static compression,up from the 9.2:1 of the euro 1300 and the 8.5:1 of the USA spec)

1500 euro cylinder head (no decompression recess like all the USA spec heads) and a bigger exhaust valve, bigger port size, bigger valve seat throat sizes on both valves compared to any 1300 x19 head

1500 twin out exhaust manifold, custom exhaust system of his design.

Inlet manifold modified for DCNF/DCNVA (euro 1500 intake manifold to start with, so biggest stock ports)

Carby upped to 36DCNVA which uses twin 28 chokes (simultaneous opening) compared to the 34DMTR (24/26 choke progressive) of the stock 85hp 1500, or the 22/22 of the 32DMTR variants found on the 1300 X19's.

 

[zonker]

Accepted practice when adding a cam and compression is to go down one heat range and keep the gap to oem specs assuming you're not running a more modern ignition system, like distributorless or/and trigger fire coil on plug.

If you've upgraded the ignition to distributorless, then you might be able to add another .010"-.020" gap depending on the coil output.

 

[WildWilly]

thanks

this is great, I'll pass it along. We are going to electronic ignition and a new Bosch coil, so that extra gap info is also great, Many thanks.