Timing cover new vs old
 

I was talking to my machinist and I mentioned I was putting on tri power and had to go back to older timing cover with bumpout for thermostat cover.

He said he thought the newer ones had a different design and ran cooler.

Does anyone have any info on that.

Thanks

Greg

There are 11 bolts out there with the dimple for a tripower.I run a 4 bolt,a 8 bolt and a 11 bolt on my current cars and I see no diff in any of them.If I have a choice I would find a 11 bolt with the dimple.Tom

here ya go!
https://www.ebay.com/itm/Pontiac-400...QAAOSwnk1dryhw

I’ve seen covers with the dimple to clear the Tri-Power thermostat housing made by the factory as late as 1974.

The later covers will need a little work on the backside of the upper bolt boss to provide clearance for the thermostat housing, just a file the boss down by about an eighth of an inch and you’re good.

The three coolest running cars in our club have the 8-bolt water pumps. On paper the 11-bolt sure looks to have the advantage, but we haven't seen that to be true. This is after tightening up the plates in both styles.

Another option is finding an aluminum thermostat housing and weld/building it up on the inside so you can grind the clearance on the outside of the thermostat housing.