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Stock throttle body question

Started by Adam76, March 18, 2023, 07:01:53 PM

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Adam76

Hello,

Just a few questions as I'm finishing my M8 softail build.

1. In the picture of the throttle body, what are the 2 threaded parts, and do I need to block them off with a bolt?

2. Before first start up after cam change, new lifters installed "dry" and top end rebuild, what's the best way to prime the oil system?

Spark plug cables disconnected and fuel line disconnected?

Is it really necessary to prime, or should I just fire it up with everything hooked up?

Thanks.
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Ohio HD

Shouldn't there be a support bracket attached to the throttle body there?

Crank the motor over without plugs, plug wires grounded. Do short bursts of maybe 15 seconds at a time till you have oil pressure. At least you have oil to the pressure switch.

It would have been a good idea to pump the lifters before installation. But they'll pump up.

les

I think it should be ok to not ground the plug wires.  The ignition should detect that the plugs are out (no deceleration of the piston on the compression stroke) and neglect sending current to the plug wires.

Hossamania

For my peace of mind I would ground them, just because if I did wreck something, I have no one to blame but myself. And I do plenty of things for that to happen. Easy enough to ground them.
If the government gives you everything you want,
it can take everything you have.

rigidthumper

The S&S backing plate bolts to the heads, and supports the TB/manifold directly, so no need for the factory support that was using those holes originally. I crank the engine over a few times in 5-10 second bursts, with the primary side plugs out, just to listen for clatter and get the oil moving through the passageways before start up.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Adam76

Thanks guys, appreciate the advice.  :up:

Adam76

Quote from: rigidthumper on March 18, 2023, 08:19:03 PMI crank the engine over a few times in 5-10 second bursts, with the primary side plugs out, just to listen for clatter and get the oil moving through the passageways before start up.

Just a question about the fuel injectors. While I'm cranking it over to get oil pressure, will they be spraying fuel in to the combustion chamber even though there's no spark?

rigidthumper

Not if you hold the throttle wide open while cranking-this is known at the "clear flood mode", and disables fuel while cranking. With the plugs out, no compression, so no spark.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

hrdtail78

Quote from: Adam76 on March 21, 2023, 05:26:06 AMJust a question about the fuel injectors. While I'm cranking it over to get oil pressure, will they be spraying fuel in to the combustion chamber even though there's no spark?


If the engine isn't in sync.  It will not provide spark or fuel.  For same reason.  The engine has no idea what part of the engine cycle it is in.
Semper Fi

Adam76

Thanks gents, much appreciated 👍