Topic: 68 AC idler pulley

[68Metuchen390GT]

I’ve read the previous posts on the 390 GT idler pulleys but I have two idler pulleys and need some expertise identifying them. The one on the left I believe is a 68 390 idler with “SPC” on it. I’ve seen Jeff and Bob say early 68 and late 68, my car was built June 68 in Metuchen so I think the one on the left is correct for it. If some clarity on the rough estimate when early and late would be for the AC set up would be appreciated.

The pulley on the right is I believe a 1970 390 AC idler pulley it’s much flatter and has even bend lines on the back. What say you?

The first three photos after the pairing of parts is the left one.

[Bob Gaines]

I’ve read the previous posts on the 390 GT idler pulleys but I have two idler pulleys and need some expertise identifying them. The one on the left I believe is a 68 390 idler with “SPC” on it. I’ve seen Jeff and Bob say early 68 and late 68, my car was built June 68 in Metuchen so I think the one on the left is correct for it. If some clarity on the rough estimate when early and late would be for the AC set up would be appreciated.

The pulley on the right is I believe a 1970 390 AC idler pulley it’s much flatter and has even bend lines on the back. What say you?

The first three photos after the pairing of parts is the left one.

Image 5 is of a FE fixed idler pulley . The other style is not. 

[Bob Gaines]

I am not sure of the application of the one with "spec" on it but it is not a Mustang FE pulley .Most likely a smallblock version IMO. I can say that the "spec" one is a 1970 or later version of whatever based on the front bearing cover. The one I identified as a FE pulley looks to be of a later 68 /69 version of FE pulley. The early before March of 68 versions are completely different in appearance.

[krelboyne]

Correct, the idler on the left is mid-1968-69, all small block V-8's.

The one on the right is for an FE aka 390/428CJ. It looks like the small bearing variety, which is 1968-69. The large bearing FE idler should have a D0.. part number stamped. It would have been used starting in 1970. Used until roughly 1971, when the 390 was discontinued in the LTD / Galaxie.

[68Metuchen390GT]

Perfect thanks for the help, now if I can locate a 68 390 idler pulley I will be all set

[68Metuchen390GT]

Perfect thanks for the help, now if I can locate a 68 390 idler pulley I will be all set

So I found this one on eBay, it looks very similar to the one that you said is a 70 pulley, is this one correct

[krelboyne]

I think that you have a 1968 390 idler. Compare the cap diameter of your small block idler marked SPC. That one does have a small bearing. The photos make them look equal.

See this thread: http://www.concoursmustang.com/forum/index.php?topic=19404.msg122678#msg122678

[Bob Gaines]

I think that you have a 1968 390 idler. Compare the cap diameter of your small block idler marked SPC. That one does have a small bearing. The photos make them look equal.

See this thread: http://www.concoursmustang.com/forum/index.php?topic=19404.msg122678#msg122678

+1 . I said as much in my reply #2.

[68Metuchen390GT]

Thanks Bob and Scott that was very helpful, I have seen the 70 pulleys and they do have a D0 part number on them, the one that Bob said was an FE pulley on the right does appear to be the same as the NOS one I found on eBay. I some how had them reversed and after much review I agree. It even appears the same as one in Jeff’s 68 390 AC kit below. So it does appear I do have a late 68 pulley after all. Thanks all.

[J_Speegle]

....... It even appears the same as one in Jeff’s 68 390 AC kit below. .......

Just to keep the record straight that is a picture of a 69 kit I have. Hopefully I didn't mislabel it in another thread