5 bolt/6 bolt

markg · 09-06-07, 10:22 AM

What is the significance of a 6 bolt belhousing vs. 5 bolts on a 1966 289 block?

Big-Foot · 09-06-07, 10:39 AM

I thought that all the 66 and later blocks were 6 bolt.

Not sure of what you mean in terms of significance but the bellhousing for a 5 bolt block will not properly bolt up to a 6 bolt block..

John Fitzpatrick · 09-06-07, 04:18 PM

Quote:

Originally Posted by markg

What is the significance of a 6 bolt belhousing vs. 5 bolts on a 1966 289 block?

I'm pretty sure Ford made the change from 5 to 6 bolt bellhousings in August of 64. The 5 bolt blocks came with a 160 tooth flywheel and 10.5 clutch and the bellhousing was smaller. The 5-bolt bellhousing also used 3/8" bolts while 6-bolt units use 7/16". The timing chain cover bolt pattern, and therefore the water pump’s, also changed about that time, but I don’t remember exactly when.
John

John Fitzpatrick · 09-06-07, 04:19 PM

Oops, double click.

Doc Watson · 09-06-07, 04:55 PM

all 289 blocks up to the end of 64 had 5 bolt bellhousing patterns. Block numbers will be...

C3AE-N
C40E-C
C40E-F
C4AE
C4DE

As of 1965 all 289's have a 6 bolt bellhousing.

C5-AE-N
C50E-A
C6AE-C

The 289 hipo block is exactly the same block as the standard 289 with the difference being thicker main-bearing caps. Although the block numbers are not all the same...

289 hipo 5 bolt

C30E-B
C40e-B

289 hipo 6 bolt

C5AE-E

I need to get out more.....

Jac Mac · 09-06-07, 05:06 PM

I think it was in mid 65 that change was made from 5 to 6 bolt, going by HP part numbers, C40Z-6010-C for 5 bolt-- C5OZ-6010-C for 6 bolt.

Timing bolt cover pattern on block is same , but design of cover in pump attach area is different to accept later pumps with sandwich plate ( early cover had direct contact with coolant in impeller cavity & was subject to erosion- also provision was made for oil fillertube to intersect with cavity from timing chain area to valley.)

So if your block cast number is C6--- then you have a 6 bolt 289.

Jac Mac

John Fitzpatrick · 09-06-07, 06:13 PM

Quote:

Originally Posted by jac mac

I think it was in mid 65 that change was made from 5 to 6 bolt, going by HP part numbers, C40Z-6010-C for 5 bolt-- C5OZ-6010-C for 6 bolt.

Jac Mac

Yep, I was wrong. It was '65 for the 6 bolt. I should have done a little Googling. My 6 bolt 289 had the old style timing chain cover with no water pump backing plate. And they did erode!
John

markg · 09-06-07, 11:25 PM

Thanks guys..