Threejdsolds

I have a 1967 Toronado 425 which , upon cleaning and measuring , is very clean.Don't know anything about nickel content but the machinist said the block had almost "no wear". Crank and pistons are good. Had to explain the .921 lifter issue to the machinist . SO, here's the question : is a 39 degree 425 Toro .921 lifter cam interchangeable with a 39 degree 455 cam? I have available a 455 W-30 cam and cannot find in any of the threads if it will work in the 425. Thanks for the help. John

Oldsmaniac

Yes, any 39 degree cam will work in a 425 toro block.

Threejdsolds

Oldsmaniac, thanks for your reply. Was reading the Tech article on valve geometry - math was not my best subject . My buddy and I were comparing engines last night . He is rebuilding a 455 and I the 425. The pushrod lengths are different. Why ,if a "C" head will fit a 455 and a 425,are the pushrod lengths different ? Is there a difference in the blocks between a 39 degree 425 and a 39 degree 455 that affects the pushrod length ? Which pushrod (425 or 455) would be used with a 455 cam in the 425? By the way, when I ordered the lifters from Egge , the rep (after putting me on hold for 5 minutes to ask someone else) said I could not use a 455 cam in the 425. Trying to make this "add up".

2blu442

John, can you compare the old pushrods in both the 425 and 455? I would have expected them to be the same length too.

Oldsmaniac

Yes in general you cannot use a 455 cam in a 1966 425 UNLESS it is a toro engine with the larger lifters. I dont know what to say about the pushrods but if in good condition you may want to use the 425 units. Be sure to check lifter preload...too much is no good for performance and none will create a noisy valvetrain. If the pushrods are too short you wont have any preload. If they are too long you may have too much.

gmrocket

pushrod lengths are different because of a few things,,the .921 lifter is taller at the pushrod cup, some 425's had different height valve stem tips, the rocker bridges are also a little different in height. if your using all factory stuff just make sure your not overcompressing the lifter plunger, or not preloading enough. i like to see 1/2 to 3/4 turn on the bridge bolt. cams can be interchanged

Oldsmaniac

Just to be clear , the stock valvetrain is not adjustable by the bridge bolt. Rockers are bolted down tight.

gmrocket

maybe i should have said 1/2 to 3/4(compressing the plunger) turn,when on the base circle, before the bridge contacts the head. clear enough?

joe_padavano

Note that the larger lifter diameter will make the cam act slightly "bigger", since the valves will open slightly earlier and will close slightly later. The difference will only be a few degrees.