390 crank
Thread Starter
|
Senior User
Joined: Dec 2003
Posts: 222
Likes: 0
From: Washington State
390 crank
when I bought my truck I was told it had a 390, like everybody in the world says, I know you can check the stroke. I have my tranny off right now, and I have read that you can tell one from the other by a square notch, or a half moon on the crank flange?. The problem is i have found two posts on here, and one guy says half circle-390, and the other post says square notch-390??? Who is right?? Are these marks on the back side of the crank, where I will be able to see with the tranny out?? Thanx in advance
Laughing Gas
Joined: Aug 2008
Posts: 840
Likes: 8
I've never heard of this method for IDing cranks before, BUT....I just so happen to have 3 cranks sitting around....a 360, 390 and a 428.
Both the 390 and 428 have the square notch...looks close to 3/8" across. The 360 has a larger 1/2 circle cut-out of the flange. At least an inch across.
I can't confirm this is always true, but it's what I have found on my 3 cranks. Hope this helps.
Both the 390 and 428 have the square notch...looks close to 3/8" across. The 360 has a larger 1/2 circle cut-out of the flange. At least an inch across.
I can't confirm this is always true, but it's what I have found on my 3 cranks. Hope this helps.
Needsmorecoffee.
Joined: Oct 2004
Posts: 3,624
Likes: 2
From: CT
61-65 390 3.78 cast cranks can have both the square and half moon cutout. 66 and later 390-428 cranks only the square notch. The longer stroke 3.78 390 and 3.98 428 cranks didn't need the half moon cutout to hollow the rear crank throw like the shorter 352-360 cranks. This info from Dave S on the net54 forum. Dave said it wasn't till the 428 cranks were machined that Ford discovered the half moon cutout wasn't needed to machine the rear throws. Thus why it was dropped from 66 and later 390 and 428 cranks. It's really not the best way to ID a crank but guess in some cases it can be used to compare. You'd need to remove your flexplate/flywheel-clutch assy to see the rear crank flange. I think measuring stroke with the dowel trick would be easier unless you need to R&R the flexplate or flywheel while the trans is out. Then you can see what cutouts it has anyway. FWIW.....
Reps for Argess for doing the leg work and checking it out. My 69 1UB 428 crank has the single square cutout as well.
Reps for Argess for doing the leg work and checking it out. My 69 1UB 428 crank has the single square cutout as well.
Thread
Thread Starter
Forum
Replies
Last Post
Robert Lund
1967 - 1972 F-100 & Larger F-Series Trucks
15
Oct 15, 2016 02:19 PM
thomasstemmle
1948 - 1956 F1, F100 & Larger F-Series Trucks
20
May 7, 2016 10:00 PM
efrntzl
1968-Present E-Series Van/Cutaway/Chassis
5
Sep 19, 2015 10:12 PM
BigB6958
1961 - 1966 F-100 & Larger F-Series Trucks
42
Aug 31, 2015 11:51 AM
