CTS thread sizes

DaveEFI · Post by **DaveEFI** » Wed Jul 01, 2015 1:15 pm

As part of changing my SD1 from MegaSquirt batch to sequential ignition, I also want to change to the later high impedance injectors. My SD1 had the factory flapper injection.

However, the different fuel rail fouls the flapper CTS plug. Might be possible to plug it in then fit the fuel rail, but not ideal.

Looking at pics of the later hotwire, the CTS is moved to where the thermotime switch is on the EFI - only a couple of inches or so - and the old CTS position left undrilled.

On my car, I'm not using the cold start injector, so the thermotime switch was removed and blanked off with a screwed in plug.

Sadly, the two threads are different.

A measurement of the threads using callipers into the manifold shows the thermotime one to be 12.4mm (guess at 14 x1.5mm?) while the CTS one measures 10.4mm (could be 3/8" NPT thread?)

What I don't have is a hotwire CTS to see if it fits the thermotime thread.

Be nice to have the same Junior Timer connector - as I've almost finished the new loom.

DaveEFI · Post by **DaveEFI** » Wed Jul 01, 2015 4:11 pm

Got an answer - so it may help others.

The hotwire CTS uses the same thread as the flapper CTS (10x1.5mm), so when they moved it to the thermotime position, the thread was also altered.

Trouble is there are lots of variations of the basic inlet manifold, so I think the easiest way will be to make up an adaptor from 14x1.5 to 10x1.5 to fit the CTS where the thermotime fits, and fit a blank plug where the old CTS went.

Wonder what other gotchas I'll find? It looked ever so simple.

DaveEFI · Post by **DaveEFI** » Thu Jul 02, 2015 9:26 am

Before I make one, does anyone sell a 14/1.5mm to 10/1.5mm adaptor?