Bolt sizes/ threads: Intake/ VC

[P72Ford]

What size are the bolts for the intake on my 1990 351 P72? Summit tells me they can be 5/16"-18, or 3/8"-16. My Ford service manual doesn't say.

I am thinking 5/16"-18, but I'm not sure.


Also, are the valve cover bolts just regular old 1/4"-20?

[DuceAnAHalf]

yes vc's are 1/4-20
im pretty sure that the intake is 5/16-18

[gadget73]

5/16-18 sounds right to me as well.

[1987cp]

Drive to your local Ace Hardware, pull an intake bolt at random, and go in and match it up. Then you'll know for sure!
Just make sure to re-torque the bolt before you drive home.

[P72Ford]

Thanks guys. They're 5/16-18

[85crownHPP]

will that be the same as the bolts holding the upper to the lower as well? I wanna make a set of those stud-guides to ease re-installation.
I made some 1/4 20 for the valve covers when I did the Bronco II, but its a damn metric motor, lol... I can use em next time for a box though.

[1987cp]

will that be the same as the bolts holding the upper to the lower as well?

Pretty sure it is, yeah. I don't have an EFI intake handy, but I seem to remember them being the same size.

[gadget73]

yes, upper to lower bolts are the same thread, and size as the lower manifold to head bolts. If you're careful with your length selection you can use the same guide bolts for both. Just use them in the outer corners of the upper where the short bolts are.