How to tune a 770 Holley Street Avenger?

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myasylum

myasylum

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I have never tuned a carb before. This is a fresh engine and seems to run good as is, but it still needs to be tuned?

I have read about tuning the floats bowls, I haven't checked it yet, but I know your just suppose to see the gas level at the bottle of the sight hole.

What else would I need to know to tune it myself??

If I had someone else do it, what do people charge for something like that, and how would I know that I could even trust it's right from them??

Thanks!
 
If u really wanna tune it, start with the float levels, set'em w/car running and sight holes, make it so the fuel just starts to spill out of the sight holes.

Then set the idle, should only need about 3/4-1 turn out on all, make sure all idle screws are equal when comes to the amount of turns out or in.
Remember you wanna open [counter clockwise] till you get the highest idle rpm then your good. If you go too far the idle speed will be too rich and rpm will drop, so you'll know when that happens.
A dial back/tach style time light will come in real handy.

Get a vacuum gauge and check vac in gear@idle or if 4spd just check what it is at idle then go 2 ratings below example=8 inch gets a 6.5 power valve.[If you found the pv to be rated higher than the vac reading you got, then you'll need to check/reset the idle once the correct rating pv is in place]

Then you could go with a smaller shooter till it stumbles then go back up in size till it doesn't stumble, if it already stumbles, you might need to step up the shooter size.=if it go's a lil then bogs it's too much, if it stumbles/pops/cuts out then go's..it's too lean a shot.

This is assuming you have the timing set or at least real close to what you need.
But now at this point you'll wanna really work on the initial/curve & total timing.
Once the total is at least nailed down you can start jetting accordingly, check plug color and maybe lean the primary out till it slightly surges on the freeway cruise, once it does, pull off and jet it up 2 sizes, then if only running 1 pv in the primary, you'll wanna make sure the secondary jetting is within 7-10 sizes as the primary, in otherwords...you can take the seconday down to the limit of 7 sizes and then work you're way up till it feels good @wot, always check the plugs too.

good luck.
 
I have the same carb, came with a sweet DVD that has all that info in it. I've had real good luck tuning it so far. Pretty simple, the only thing tough to set is a happy medium on the electric choke for all weather situations. Mine came with some secondary springs for tuning and clear sight plugs for setting the float level.

Tom
 
How much tuning the carb will need is dependant on how closely matched the carb is to the engine you are putting it on.

But before you start worrying about anything more that setting up the float level and getting it to idle you need to dial in the timing first. Cams with more duration than stock will require more initial timing and mucking with the idle mixture will just be masking the timing issues.

Get your self a good guide on tuning an engine and read up before diving in is the best advice I can give.
 
dgc333 said:
But before you start worrying about anything more that setting up the float level and getting it to idle you need to dial in the timing first. Cams with more duration than stock will require more initial timing and mucking with the idle mixture will just be masking the timing issues.
Click to expand...

That's great advice right there. Along with wild&crazy's post

Make sure the initial timing is dialed in...
 
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