425 cam bank angle

Some may argue, or disagree, but this is my way. I`ve talked in length to people that actually understand the principle. It is an accurate way of determining angle. I`ll try and keep the pics in order of 39 vs.45. Make sure your square is square, your straight edge is straight. Using a lifter as a guide won`t work, it`s just too sloppy.

39 block with straight edge snugly laid flat against lifter bore, square laid on block. Square touching bottom, gap INCREASES with rise.



45 block, square stays parallel to straight edge.



Using a protractor set at 90 degrees, set the leg of the protractor down the lifter bore, with the leg seated flat against the lifter bore, note the angle of the protractor in relation to the block deck.
1`st pic 39 block


45 block



Then I made a crude measurement tool. By understanding the design, it makes sense, that since the lifters are laying on different planes, that there has to be a measurable difference. No surprise, there is. I`ve checked several blocks with this tool, 330`s 400`s 425`s 455`s. It`s never lied

The 45 blocks have a wider measurement than the 39`s (lifter bore diameter MUST be taken in to consideration)

39 block with 39 measurement



39 block with 45 measurement



45 block with 45 measurement



45 block with 39 measurement



I hope this makes your task a little easier. Don`t believe all that B.S. about drill spots, lifter size, pixy dust and magic potions.

Thank you , thank you, ill be checkin that as soon as i get home, appreciate the time you spent, and pics are great

I should have paid a little more attention to your pics. I see the lifters are still in, so I`m gonna guess, so is the cam? Pull the cam. on 45 degree blocks, cam lobe centers are in alignment(obviously) 39 blocks no centers align, NONE!
Your only talking a few degrees here, so it`s only obvious when you`ve got a 45 and a 39 cam to compare to each other. Side by side it`s pretty obvious. Laying flat on the bench, front of 45 degree cam facing you, lobes from front to rear #1 thru #16. 5&16 7&14 10&13 12&15. Don`t just eye ball them, use a straight edge. I don`t like this method, centers with this many miles/years on them are tough to determine without having both type cams laid side by each.

I should add, this is Mondellos way of determining angle. Like I said, to me it`s crude, cumbersome, and unless you do it everyday, frustrating. Try laying a straight edge from 5 to 16 on what looks like center of a crusty ol` wore out cam with other lobes in the way. Back in the mid 60`s when they made the break from 45 to 39, and olds builders were doing this everyday, they probably got real good at a visual determination. But today, when the normal guy runs in to just a few blocks in his lifetime that are questionable, it can be confusing.

Excellent info.

if there is a mis-match of block cam angle, will the compression test show the error?

A friend of mine caught some mis-information I gave. I corrected it in "reply #1" above.

The other thing he questioned I won`t correct, as it was purposly written that way for ease of understanding. It has to do with identifying the blocks> I refer to them as 39 and 45 "blocks" If your refering to the actual lifter bore angle to centerline of a particular block, it would be either 42 or 45, if your refering to a cam, it would be 45 or 39. I felt that sticking the 42* in there when refering to a block that takes a 39* cam would just confuse the issue. Most folks only care to know how to distinguish between the two blocks so they know what cam to order, or as in stans case, what he`s selling. No one really cares much about the geometry, unless your getting really anal about max. lift, side load, bla,bla,bla.

BR[], if you would please, change out the perpindicular for parallel. Don`t know what I was thinking, I really do know the difference.

if you just machined a 12" aluminum, brass, or mild steel dowel, the diameter of the lifter bore itself snug, and placed them in the lifter bore, the one that doesn't point parallel to the piston cylinder bore, is the 39 degree. the one that IS parallel to lifter cylinder bore, is 45 degree. I've never seen a message board dedicated to just one model car and year made...that in itself it kind of strange.