Making power out of the 318
I’ll focus on the oil cross over mod alone. I’ll consider all other mods worth it if not necessary for the potential output designed within the modifications being made.
Since the original mod is to block oil and restrict it to keeping the main feed well, then the blocking of the passage is good for the intended high rpm usage it’s being done for.
Now the cross over part. Why is it done? To feed he gallery oil for the Hyd lifter of course. But why? If your going to run a Hyd cam, then is it really the cam you should be running to do the initial mod itself and then circumvent the mod?
To me it does t make sense to do a mod and then work around it to run a hyd cam when at this particular point a solid lifter cam will out power and out rpm the hyd cam.
Drilling the blocks I’ll feed to the head and maybe at best touching up (smoothing out.) the other oil gallery’s passages is all your going to need for a hyd cam. If you need to make more power, go with a solid lifter and cam. The oil coming down from the heads is enough to oil the lifters up top and the splash from down below is enough to do what’s needed.
Big hyd cams may have the goods to operate above 6500 rpm. But why when more power and rpm is available in a solid?
Let’s say that your stock un modified block is good for 6600 rpm. You need more power, the solid cam is the route! It’s just one small plug to have drilled and tapped to fit on the drivers side of the block up front. Done!
The tubing of the lifter bores & gallery should be looked at as a serious build should have this done and this is for the big solids. SFT or roller.
If you can’t make the power with a hyd cam then it’s probably the wrong cam. There also a hassle at high rpm to keep happy and set up. Heavy springs can collapse lifers, not a problem with solids, there not as stable and will not rpm like you want.
That’s what the cross over is for IMO.
IMO, it is an unnecessary modification.
Skip the cross over mod and go straight, directly to a solid cam and go!
That’s my opinion and view as well as what I do & have done & would do on future builds.
I agree and will add this.
The big bearing killer on the SBM is that 3-4 and 5-6 rod bearings are fed by the 2 and 4 main bearings respectively.
So you are feeding those bearings with one feed PLUS the rockers. Every single roller cam I’ve ever seen has a groove around the 2 and 4 cam bearings to get full time oil to the rockers and springs. Which may be good. But, it takes a TON of oil to feed the rockers (and getting enough oil out to the adjusters) and ALL of that oil comes off that one main bearing and I suggest that extra oil going upstairs is a major contributing factor to killing the 3-4 and 5-6 rod bearings.
At this point, I don’t have a good answer of how to fix it, but the crossover doesn’t address the oil going to the rockers.
My gut is telling me to take the 2 and 4 cam bearings and clock them so it blocks the feed hole hole up to the rockers. So NO oil gets to the rockers from the stock holes.
Then to feed the rockers I want to drill and tap into the oil pressure gallery running up the back of the block and run a hose off that to a T or Y and run one hose over to the gallery that feeds the drivers side and another hose over to the passenger side.
Since it will be full time oiling I think a restricter somewhere around .060-.080 would be plenty.
Just rough thinking at this point, but it would stop taking oil from the rod and main bearings.
Thinking about it you could also just pull the oil from the drivers side main feed, but I’m thinking I want to stop taking any oil from the main feed.
I’m going to start putting my junk back together late April or early May. When I get there I may make a video after I get figured out what I want to do.