Quote:
Originally Posted by Dead Parrot
Fuel grade(s) being used?
I see TBI heads mentioned, are you running a carb or some version of FI?
Are you running rich or lean on air fuel mix? (rich burns faster - needs less advance, lean burns slower - need more advance).
How does the motor run? If it runs just fine with less timing, quit arguing with it and enjoy. You adjust timing to match the motor and usage, not the motor to meet some arbitrary timing specification.
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Running a Q-Jet, The sparkplugs read like my AF is pretty spot on.
It sounds like some motors like less advance, I guess.
Quote:
Originally Posted by Greasey Harley
Fine, I give up.
I bought a set of heads. smaller 1.72" valves, bigger 70cc chambers.
I know I said I didn't want to swap heads, but that was mostly a money thing.
A buddy of mine had these setting on a shelf, freshly rebuilt and sold them to me for $200.
IF my calculations are correct, it should drop my compression down around 10:1 and still make good torque.
A lot of good information here. I appreciate all the help. I'll update this post after I swap them out.
-R
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Okay, I
may have jumped the gun a little on that one.
Quote:
Originally Posted by 68post
Those TBI heads get a bad rap that's usually undeserved. They use less timing than vortecs do, and the reason those TBI engines run out of air is because of the puny 187* @ .050 intake duration cam they were teamed with.
They have around a 185cc intake port.
They should be perfect for a truck build, and I am sorry but I don't have a link to the timing thread that would tell you where to start tuning the timing correctly for them. They are very fast burn heads.
(If you'd like the info I'd be happy to find it again. The gentleman that had posted the info has used them successfully on more than a few builds)
I specifically sought-out a set of 305 TBI heads for a 307 build that I will likely angle mill to achieve an approx 10-1 compression or slightly more (small cam - approx 207* to 192* intake duration @ .050), and I'd rather use them for my goal than vortecs or 305 HO heads.
If I were you I'd do more adjusting first, you very likely have too much advance at 2,800+ rpm !
EDIT:
"ThirdGen.org" is where you'll find great swirlport head info, and "FAST355" is the gentleman with the info & alot experience with them, and it's his thread with great timing info also!
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I'm getting an edumication here.
Quote:
Originally Posted by cadillac_al
Interesting read. I guess the OP has some timing to back off.
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...Yep looks like it
I was ALWAYS taught that Small block Chevys like [Need] between 32 and 36 degrees total timing or you're giving up power.
I will play with the timing and see what happens.
I'll keep this post updated.