I have been struggling with finding any double roller timing chain/gear sets for my brand new L31 crate engine from Summit racing. I have ordered 3 different timing sets now, all with different fitment issues. The latest is the Comp Cams #2136 which states that it fits "87-present factory roller equiped blocks". That is not the case. When I bolt it up and torque it down, the back of the top gear touches the block casting from the top oil galley plug end. Looks like slight grinding down of that block casting would work, but I dont feel I should have to modify a block to make a double roller fit. (is it possible the block castings vary?)

As for the cover, no issue there, I have an aluminum old style 10-bolt cover ready to go.

Anyone else run into these issues? I'm ready to throw in the towel and go with a single roller despite the slack I've seen in them after 50K miles or so. I am aiming for heavy duty as I did the LT4 hot cam swap and machined my heads for the LT4 springs. Aiming for 400(ish) HP and want a decent chain for the over 5500 RPM ranges.

 

Grinding the block above the cam area for double roller chains is a fairly common thing. I don't have enough experience to say exactly how common, but you may want to look into it.

 

i am going to bebuilding a 99 l31 soon. i think i am going to go with one of the name brand single roller timing chains. prolly a comp set. from what i hear they last long enough.

 

Thanks for the feedback guys! I called Summit Racing back and inquired about this. Apparently this is very common and you simply need to die grind a bit behind the top of the upper gear. Turns out the parts I have are correct and his only concern was grinding it away without introducing metal grindings all over the internals. The guy seemed to know what he was talking about in the brief 5 minute convo I had with him, so Im going for it. he indicated leaving about .020 clearance to be safe.

 

I'm running a L31 block with a Cloyes double roller timing chain. I had to do a good amount of grinding to get it to work.

 

Its normal to grind that spot, its even in the manufactures installation notes.