I put bolts in my back holes of my newly installed 57 ford intake, Ted mentioned not to install too long of bolts because they could make contact with the push rods so I started with 3/4 bolts and went up, the first size that would reach the threads was I-1/2 " with a flat washer so I feel safe as I snugged them , not overly tight.

The bolts he is talking about will be much shorter than 1 1/2".  Where are you putting those bolts?


Lawrenceville, GA

1-1/2 sounds too long to me, I used 5/8"

I'm talking about the bolts at the rear of the intake before you reach the bolt holes that actually hold down the manifold, looking from front of car to rear, the right one is underneath the gas linkage plate , the one on the left is below the far end hole where the coil mounts, if i'm wrong tell me before I try to start my car but I went from 3/4" up to 1-1/2" and 1-1/2" was the first bolt to thread 

sounds like you are trying to put a straight threaded bolt into a taper pipe thread which would explain why it takes so long for the thread to engage.
 probably need a 1/4 or 3/8  National Pipe Thread ( Taper) plug.
stuey
 

Greetings to all:  If it's the bolt below the throttle linkage bell crank assemble and the other is under the rear coil bracket mounting hole, those bolts would be the rear intake mounting bolts.  It would take about 1 1/2 inches to reach the first couple threads also. If these are indeed the bolts you are referring to, my concern would be 1 1/2" is too short, not engaging enough threads for reliable clamping or worse.      I measured 1 3/4" on some old intake bolts so would say that's the shortest length for that location. Especially for the coil side as that hole in the intake manifold is a little deeper. Perhaps someone could chime in who may have an engine on the stand to verify this. Hope this helps, JEFF.......................


64F100 57FAIRLANE500

3/8-16 X 1¾” is what’s listed in the Ford parts manual.  This reaffirms what Jeff has also come up with.

Lorena, Texas (South of Waco)

Thank you Ted, I was going to a schematic on my next attempt to get the right bolt. Thank you and God Bless, you are so much help to us all.