I currently have the XE256H10 in my L69 w/3.73 gears. At some point later on I'd like to go with TPI with either the 3.73's or 3.42's. Will the H10 version work well with the TPI or is the H12 a better match? The specs aren't that different from one to the other other than the LSA:
Lift Duration @ 0.05 Lobe separation
H10 0.447/0.454 212/218 110
H12 0.449/0.456 212/218 112

The TPI would just be a stock setup.
Thanks, Larry.

 

TPI would probably like the increase in vacuum from the wider LSA.

 

I'm looking at the XE256H-12 myself for my 85 TPI shown in sig. The Comp catalog recomends this to work well with 305/350 TPI's. I'm asuming stock chip, since it makes no mention of aftermarket chips or mods at all. Mine is a auto, I was told by a reliable source that this cam in a 305 with auto "might" need to have the idle speed raised in the chip, but that it also could be fine as is. He also told me since its an 85 that the stock fuel and spark tables would work well with this cam. I don't know if this is true for the 86+ programs, but I do know the 85 are their own animal. What year ECM and TPI unit are you planning to use?

If I were you, I'd "almost" be tempted to leave the cam you have in there since its there and they are close, and see how it runs as is. You could change it later if it runs bad, but that would be lots of extra hassle. BTW, how do you like the H-10 cam, and how much difference did you notice between it and the stock "L69" cam? Is the idle 'noticeable', and did you have to mess with the carb to get it to idle well? This would be a good indication . If it idled lumpy/rich with a Q-Jet, it probably would idle horrible with the TPI, unless you got chip work.

 

I like the cam there's a noteable difference from the stock L69 cam. It's not a lot but I can feel more HP and Torque with it, when I get on it it'll chirp 2nd gear. It only did that when the weather was just right and then not always. I still need to take it to the mountains here to see how much it really changed the power. The engine's still tight (about 500 miles on the rebuild) but it gets a little better as I put on more miles. The throttle response is better. I had my mechanic set the engine up due to the guy who reinstalled the motor not doing it right but as far as I know there weren't any idle problems other than having to raise it up about 100 RPM's. It's got a little more "lumpy" idle but not by much. You can tell it more listening to the exhaust at idle. I'd recommend it. When / if I do go to TPI I'll use the '87 version (less wiring )
Thanks all for the feedback.
Larry.