Fast90 Woes - Leanness

[Bruce Melton]

Pics...?

I bottomed out on allen button heads and on raised portions of Valley cover.
I tried the perscribed torque and all the recommended install tips but kept losening and leaking. In the end I did apply more than recomended torque but only "short handed" 1/4" drive torque.
The result is below. These are not just casting flaws, they are real stress cracks that can be seen from bottom side. There are more than shown and BTW I do not have milled heads which can worsen the problem.

[joecar]

Hmmm...

seeing that I'm wondering if tightening the bolts any amount is distorting the intake manifold...
manifold hasn't got enough space beneath it...?
leaks if you tighten, leaks if you don't...

Maybe you have to glue it on using RTV and no bolts...?

[TAQuickness]

SHINOLA! I need to double check my valley cover when I pull manifold. Are your heads milled or just ported? Mine are milled 0.024" - might be the problem.

Joe, I like your thinking.

[Bruce Melton]

Sorry, meant milled>Corrected

[TAQuickness]

how much milling, if you don't mind posting that.

[Bruce Melton]

how much milling, if you don't mind posting that.

My current heads are not milled and the problems I had with bottoming out and fit were with unmilled 5.3 heads. We milled a set of LS6 heads .030 and had a similar problem with stock manifold which we finally solved.
If you think about taking say .030 of each head and the effect it has on the angles and depth and width of the "V" the intake sits in, it is fairly major. With a stock manifold it drops the manifold enough cause problems. For the POS FAST it is almost assured it will bottom from the start, then what?

[ringram]

Id have a fast90/90 if they fit properly and wernt so expensive.
Hopefully a competitor enters the market with a decent composite intake.

[joecar]

Is there a way to locate the contact points on the bottom of the FAST and shave those down...?

[joecar]

Would it be possible to use coloured stuff (prussian blue, yellow ring/pinion paint, white lithium grease, etc...) as an indicator to see where the manifold is hitting the valley cover (or vice-versa)...?

[TAQuickness]

Would it be possible to use coloured stuff (prussian blue, yellow ring/pinion paint, white lithium grease, etc...) as an indicator to see where the manifold is hitting the valley cover (or vice-versa)...?

I was thinking about that today. Bruce's latest entry makes me think there is no hope. I have 5.3's milled 0.024"