Thread: tuning and timing questions???

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dont worry about the rambling, im glad you were specific in ur descriptions! this kind of stuff helps, im just a young buck tryin to catch up to my problems.

alright engine, short block is a stock rebuild 283 with 4 valve relief flat tops. other than that for comp, i couldnt help you, *oops*

gm performance vortech iron heads, proform 1.5 self align rockers, 64cc. headers, performer rpm manifold

carb, holley 600 http://holley.com/0-80457S.asp
thats it if you want to know any more about the carb, i just installed a .35 squirter in it *as reccomended by holley and jegs guys*

newley installed cam is lunati voodoo, and yes, sorry advertesed duration is 262/268 and the lift is 468/489.

air to fuel mixture, havent messed with it that much, ive done the basic deal as in turn all the way in, * i didnt tighten them, just till i felt pressure then i stopped* then i turned each side a turn and a half out. all three vaccum ports are used, under the fuel bowl, for advance. one on the metering block used for trans. big one used on brake booster.

**(Also, do you know how your advance curve is? Do you advance more at higher rpm's or did you only check at 2500? You may need to change some springs in the distributor (I don't know the HEI's so I can't help here) )****

this is where i get lost, i read up on a little bit today for the total timing and went from there. i had the idle set all the way up to 3300ish rpm and the mark still didnt go up any further from 2400ish.

and vaccum leaks i havent checked for. i suppose it wouldnt hurt seeing how it is only pulling 11" if i would bring up my idle a little more would that also increase?

trans is a tci streetfighter 700r4 with a stock lockup type converter

umm, anything else you want to know, please pry!!! i want to know! but thank you skids for being so informative!!!

also, it is running alot better after messing around with it all day, but its still not where it should be.

Did you note Skids72 comment about setting the timing with the vacuum advance disconnected?

If you don't you'll end up with retarded timing.

With the cam you have and assuming the timing is retarded 11" vacuum is about right.

If . . . the engine is idling at 600 rpm or so and you increase rpm to about 1500 the vacuum gauge will indicate 17"-19" of vacuum.

I'm asuming your vacuum gauge is connected to full time manifold vacuum.
If it's connected to ported vacuum you'll get readings that are not correct.

Originally Posted by C9x

Did you note Skids72 comment about setting the timing with the vacuum advance disconnected?

If you don't you'll end up with retarded timing.

With the cam you have and assuming the timing is retarded 11" vacuum is about right.

If . . . the engine is idling at 600 rpm or so and you increase rpm to about 1500 the vacuum gauge will indicate 17"-19" of vacuum.

I'm asuming your vacuum gauge is connected to full time manifold vacuum.
If it's connected to ported vacuum you'll get readings that are not correct.

yes, i did all timing with the advanced disconnected. and that is good to know that the 11" of vaccum is alright, less to worry about then.

well thank you all for your help, finally got the purple people eater running good!!

Originally Posted by tim_bo16

yes, i did all timing with the advanced disconnected. and that is good to know that the 11" of vaccum is alright, less to worry about then.

well thank you all for your help, finally got the purple people eater running good!!

Keep in mind that if you don't pick up to 17"-19" vacuum at 1500-2000 rpm with no load on the engine things still aren't correct.
If it does, then everything is probably ok and you just need to pursue the timing the engine wants.

If you can't get the vacuum above 15"-16" you may have the cam a tooth off.