Cam seal sizes???

[Barraguy]

Planning or replacing cam seals while I do my VC gasket as one is weeping. Rock auto shows 2 different OD seals. 🤔 is there a way to know what size you need before tearing into it?? 84 T1 if that matters
Thanks

[chromguy]

The front cam seal is different than the rear, but I am unsure why the slightly different OD.

http://www.glmwpg.com/ServiceManuals/84p.PDF for OEM part numbers

[135sohc]

The front vs rear OD is different to prevent someone from mixing up the oil seals. On early engines with the smog pump it was mounted on the back end of the head and driven by the camshaft. If the seals were the same OD and got mixed up you would have a oil leak since lip type rotational seals are only going to hold back oil in one direction. Front vs rear being flipped 180* opposite.

For the rear seal one can install a solid 'plug' like later engines had: https://www.rockauto.com/en/moreinfo.php?pk=2589730&cc=1098086&jsn=480&jsn=480

Front seal


https://www.rockauto.com/en/partsearch/?partnum=4105395

[Dr. Johny Dodge]

when you look closely at a shaft seal you'll see several raised ridges in the rubber portion . for argument , looking kinda like,

///////////////////
installation position and direction of shaft turning decide which way the ////'s need to point

these little raised ridges scrape the oil from the shaft and direct it back towards the inside of the engine..
install the wrong way round and those ridges scrape the oil away from the engine and push it outside causing a seal leak due to improper installation

wish I could find the air pump pulley and bolt .. wanna run morosso crankcase evac pump..and forget PVC system

also running 5 liters of oli in a 4 liter 2.5 pan with balance shafts will cause the front cam seal to blow out repeatedly .. didn't know 2.5's were only 4 liters .. at first .. was used to 2.2's lol