Topic: Belt length chart

[ruppstang]

I am working on a 1968 S code that I purchased as a basket case. The PO had purchased belts from NPD 18 years ago and they were still in the sleeves. The S code requires 2 alternator belts and there was just one, so I ordered another from NPD using the NPD number from the sleeve. When it arrived it was longer than the original belt that said Autolite on it. The new belt said Ford and was longer. NPD sent me a second belt and it was just like the one that I ordered, too long.

The belt I ordered was a C5 AE-8620-S  NPD # 8620-27 for 68 390 w/o A/C. The original belt that says Autolite is the correct length. All of the belts are from Marti Auto Works. I must either have the wrong belts or a incorrect pulley.

[Bob Gaines]

I am working on a 1968 S code that I purchased as a basket case. The PO had purchased belts from NPD 18 years ago and they were still in the sleeves. The S code requires 2 alternator belts and there was just one, so I ordered another from NPD using the NPD number from the sleeve. When it arrived it was longer than the original belt that said Autolite on it. The new belt said Ford and was longer. NPD sent me a second belt and it was just like the one that I ordered, too long.

The belt I ordered was a C5 AE-8620-S  NPD # 8620-27 for 68 390 w/o A/C. The original belt that says Autolite is the correct length. All of the belts are from Marti Auto Works. I must either have the wrong belts or a incorrect pulley.

The belts Marti uses are typically modern equivalent of the original belts he use's to stamp with the old number. Those modern equivalent belts can sometimes be too long depending on which belt he sources and when . That is why you may get two different length belts both with the same number if each is ordered years apart.

[67gtasanjose]

"Matched Sets" were banded together years ago for dual belt applications

[196667Bob]

Marty : Looks like it depends on which chart you are using. After a quick look, it appears that there is 3/4" to 1" difference between what is shown in the 1960-68 MPC and that shown in the 1965-72 MPC. Also, with or without A/C and with or without Thermactor.
Which are you using and what are the particulars ?

Bob

[preaction]

I just went through this recently everything will be a mismatch untill you buy 2 altenator belts at the same time from Marti autoworks matched sets have gone away long ago and Kevins is the best you can find.

[ruppstang]

Marty : Looks like it depends on which chart you are using. After a quick look, it appears that there is 3/4" to 1" difference between what is shown in the 1960-68 MPC and that shown in the 1965-72 MPC. Also, with or without A/C and with or without Thermactor.
Which are you using and what are the particulars ?

Bob

Bob it is w/o A/C and with thermactor.

[ruppstang]

The belts Marti uses are typically modern equivalent of the original belts he use's to stamp with the old number. Those modern equivalent belts can sometimes be too long depending on which belt he sources and when . That is why you may get two different length belts both with the same number if each is ordered years apart.

I have 2 new belts and they are so long that I am at the end of adjustment and they are not tight enough. The older belt was closer to half way on the
adjustment.

I just went through this recently everything will be a mismatch untill you buy 2 altenator belts at the same time from Marti autoworks matched sets have gone away long ago and Kevins is the best you can find.

Thanks for the heads up on this.

[Bob Gaines]

The belt length on a assemblyline belt is designed to put the proper adjustment typically approximately halfway in the adjustment bracket.

[196667Bob]

Marty : For your application (390, w/o A/C, w,Thermactor), the 1960-68 MPC shows that 2 belts are required, each being Part Number C3TZ-8620-J (ID #C6AE-8620-L). 15/32" wide x 40-3/4" long.

The 1965-72 MPC also shows 2 belts, each being Part Number C9PZ-=8620-GM (ID # JB-414-L), 15/32" wide x 41-1/2" long.

The Alternator pulleys for all of the available Alternators (38, 42 and 55 amp), should be 2.67" O.D.

I personally do not think that 3/4" difference in overall length would prevent you from making adequate adjustment. Therefore, the only only "issue" might be the belt you got from NPD is nut correct. Did you measure its length ? Is it close to the ones I noted ?

I*n looking through the tables, it shows that ID C5AE 8620 S cross references to Part Number B9SZ-8620-A, which has a length of 43-3/4". Looks like this might be your problem.

Hope this helps,

Bob

[ruppstang]

The latter belts from NPD are 44.5 yes I think that is the problem. I am surprised that Kevin Marti has this wrong. I think the correct length would be 41.25.

[196667Bob]

Marty : The ones I noted before are for your specific application. There is a 15/32 x 41.25 shown for several applications, but the one for 1968 is shown for "with A/C". This is Part # C4AZ-8620-A, ID # C4TE-8620-M.

I looked at NPD's belts, and did see one that was 41.2" (JB412), however, it is 1/2" wide.

Interestingly, NPD's listing for the belt you have that is too long, shows that it is for a 390 "with A/C" ?? Seems like there is more than one thing messed up, either with Marti's listing, and/or NPD's.

Bob

[ruppstang]

A friend found this for me.

The correct P/N for a 390 w/o AC and with TE, is C9PZ-8620-S (15/32 x 41.1/4) (2 required). Page 1660 of the 65-72 Master Parts manual.

[196667Bob]

Marty : Yes, I noted that in my Reply #8 ; however, the one from the 1960-68 MPC (40-3/4") is more correct, both part number and length-wise.

Bob