Finishing a hot 1800 build

[jon8christine]

I'll dig into it more thoroughly this weekend after archery. I never measured cranking torque, but it turned pretty easily with a standard ratchet before putting the spark plugs in. Nothing like Eldest Builds video when he had the wrong main seals in.

[Nut124]

Also, check the engine ground cable. The starter motor current flows thru it.

[jon8christine]

Everything checked good so I bought a new gear reduction starter (was only a little more than a new OEM style starter) and now she starts like a new car.

Now that I've worked through the new engine startup issues I'm starting the measuring, tuning and adjusting phase. Even though I have a 32/36 DFEV carb I was reading on setting up dual idfs (may want to try them eventually), and they talked about fuel pressure so I checked mine ( electric fuel pump in the trunk). It reads 4.1psi just before the carb without the engine running (just teed in to the fuel line) and 4.5 at idle and all the way up to 4,500 rpm was steady. So the pump is good, but do I need to get a fuel pressure regulator to drop it down to 3psi?

If so, is the Holley 12-804 a good one? The Inglese NG1081, 1-4 psi regulator that is mentioned in the IDF post looks like it's out of production.

Thx

[jon8christine]

Did the unthinkable and reread the redline instructions that it came with... They say 3psi Max.

[jon8christine]

Did the unthinkable and reread the redline instructions that it came with... They say 3psi Max.

[18Fiatsandcounting]

A max of 3psi sounds too low to me. I thought the spec was 3 to 5 psi? The only issues with higher pressure would be overcoming the needle valve on the float bowl, and 4.1 psi doesn't sound too high to me. I don't know anything about the Holley regulator.

What say others?

-Bryan

[Nut124]

I would be ok with 4.5psig. I run my IDFs at 4 to 4.5.

As long as you do not have flooding of the carbs it should be OK. I see that some needle valves are all brass and some others have a synthetic rubber (?) tip. Perhaps the all brass ones are early and needed lower pressure. My IDFs have the rubber needles. I have also heard there was some concern about the fuel foaming as it flows past the needle valve if pressure is too high.

I'd drive it.

IIRC, your build has a high CR. Go easy early on and listen to pinging, knock. Lean makes detonation more likely. Running a bit rich is safer for the engine and provides cooling. If you are running NGK6, I'd switch to NGK7.

[jon8christine]

Yeah there are no symptoms of fuel problems, so I guess I'll run it.

I've been listening for knock but so far so good. Only have 91 octane available, but I'm at 6,200', so that helps a little. I'm currently running NGK 9s (I think I read a recommendation on the Guy Croft forum for them). I know you said they were for racing before, but will running "too cold" cause any issues so that I should switch to a 7? My understanding is the "temperature" of a spark plug is an indication of how fast it disappates heat to the head so that the tip stays in the right temperature range.

Just installed an AEM air/fuel gauge, so after I get the carb tuned I'll be watching / learning how to use it. Thx

[18Fiatsandcounting]

My understanding is the "temperature" of a spark plug is an indication of how fast it disappates heat to the head so that the tip stays in the right temperature range.

That's my understanding as well. Colder plugs have less of the center insulator tip exposed to the combustion gases so they stay cooler.

I'm no Guy Croft in terms of expertise, but NGK 9s would seem to be too cold unless you're running a serious race engine.

-Bryan

[Nut124]

The NGK7 is the GC recommendation for Fast Road, what ever that means. Running a plug too cold could result in persistent fouling of plugs and subsequent misfiring. Big carbs tend to foul plugs. A plug in the correct heat range for the application is self cleaning and will not build up carbon deposits on the center that could eventually result in miss fire.

A plug too hot can contribute to detonation as the center electrode gets way too hot.

I used to run NGK6 but after a 3x20min track session the plugs looked like they had overheated. Now run NGK7.

Where is the AEM O2 sensor located? It should be in the common section of the exhaust not in a single cylinder runner. In would target 12.5 to 13.0 at WOT. Perhaps a bit higher at light cruise, just for fuel economy. I would accept 11.0 and above at low speed. I'd avoid anything over 13 at WOT.