Timing Help, Any difference Options

[BarberDave]

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I have a 1.7 ,with a Holly 2 bl carb. It was rebuilt last spring. Is there any difference in where you set the timing for a carb. Untill it warms up 15 min. or so it runs like Sh--, after that runs great. Thanks for the help,this is the place to ask. Dave (IMG:style_emoticons/default/confused24.gif)

[Joseph Mills]

Hey Dave!

Right off hand, it doesn't sound like a timing issue. I'm not familiar with your carb, but it sounds like either a carb without a choke, or a carb with a choke that is not functioning.

My webers (no chokes), are a little rough when the engine is cold.

I'm sure someone will chime in that's familiar with your combo.

I guess you've noticed that MUSR6 is coming up.... (IMG:style_emoticons/default/biggrin.gif)

[SLITS]

An engine needs enrichment on a cold start as the fuel is not atomized very well at low airflows until there is some heat in the engine. As the engine warms up, the sprayed fuel from the jets is somewhat vaporized by the heat being generated and burns better.

As far as timing, it is not determined by the type of system introducing the fuel. Timing is a function of the engine design, the time required for complete comustion, and a lot of other things. I have been told that the optimal timing on a T4 is 38 degrees BTDC at 3000 rpm. This is about 5 degrees more than the factory recommends and it will cause a temperature rise in the heads (50+ degrees).

Now, in realtion to your timing that you asked in the other thread, the initial timing (static) point is actually going to be determined by the dizzy you are using. For discussion purposes (I don't know the exact total advance in the distributors), let's say the 009 had 25 degrees total built into it and the 050 has 30 degrees built into it (both are mechanical advance). I will not get into the rate of advance built into them.

If you time your engine at the specified RPM and set 33 degrees, with the 009 the static timing point would be 8 degrees BTDC. If you use the 050 the static would be 3 degrees BTDC. The engine would start easier with the 050 because at low rpm you do not need the advance (time for fuel to burn). Ther more static advance ( igniting prior to TDC), the harder the engine is to start as the "bang" occurs before the piston is all the way up in the cylinder and the explosion wants to push it in the opposite direction of rotation.

Enough?