Anyone else notice this???

[85maro]

Anyone with an iron head motor considering a 3x00 swap should consider this. I can't imagine I'm the first to notice this, but only 1/2 the lifters are recieving oil with the way oil drainback is set up on these heads. Surgery required.

[pocket-rocket]

Well luckily the lifters recieve their oil supply from an oil gallery inside the engine that fills their bores (and the lifters themselves because of the hole in the side of them) which then oils the pushrods (why they have holes in the ends) which oils part of the rocker arm.

Notice the arrows in the center of the pushrods.

[NFSINSANE]

Yeah there are oval like holes on each side of each lifter bore

[85maro]

I'm not talking about internal tappet oiling, I'm talking about tappet face oiling. Cam lobe & tappet face oiling is primarily drainback, unless the tappet has direct lubrication via a hole in the tappet face which these don't. It's a simple fix regardless, just plug the second oil drainback hole for the middle tappets and drill another on the other side of the resivoir. As long as there's a stream of oil directed to each pair of tappets oil should reach both lobes because of how sticky oil is. When it's flowing over the valley drain hole it forms a 'ribbon' like stream that covers both lobes.

[pocket-rocket]

In the lifters I have taken apart, I think I remember seeing a hole in the bottom of the hydraulic chamber that should lube the roller in turn oiling the cam lobes. I have a few old ones in the garage (where I am headed in a few minutes). I will pop one apart and see/take pics if my camera batteries aren't being finicky. I see what you mean now that you explain it though, and yeah, if I were doing this same thing I would be concerned as well.

[pocket-rocket]

There is for sure an indentation in the bottom of the inside of the lifter. I can't be 100% certain it does oil the roller though. Right now my camera batteries are being a pain (old Ni-Cads), so I can't snap a pic of it right now, but maybe someone else on here who has taken pics of their lifters while doing a spring swap can post up. If I didn't have anything on my list of stuff to get hot on I would run down to Meijer and buy some batteries.

[3400-95-Modified]

He's not using roller lifters, he's using flat tappet one's, hence the issue of a Iron head motor with 3x00 top end.

[pocket-rocket]

Duh (that is pointed at me). As you can tell, I am not much into pushrods. :P So flat tappets only get their oil from what's draining back from above huh? That seems kinda silly and you would think there would be somewhere else for it to get oil from (like from somewhere at the bottom of the lifter bore or something). Oh well, at least I try to help regardless.

[turboD]

On the flat tappet lifters from the General, there was a flat spot ground on the side of the lifter to aid in the lubrication the cam/lifter contact area.

[geoffinbc]

There is still plenty of oil on the cam lobes. Ever lifter bore has oil clearance so oil seeps out the top and bottom of the lifter bore to oil the lifter body and it gets on to the face. Plus the drain back oil hits the spinning cam and it gets tossed around the cam tunnel. Also the cam bearings have oil clearance which adds more oil into the cam tunnel which also gets tossed about by the spinning cam.

If you really worried put stand pipes in the drain back holes of the cam tunnel which will not allow any oil to drain back to the crankcase until the oil level in the cam tunnel is just high enough to contact the cam lobes. I have never checked if doing this will interfere with the cam lobes so you will have to experiment. You could even switch to lifters with pressurized face oiling.

But honestly it is nothing to worry about since flat cam lobes never seem to be a problem

[AaronGTR]

^That's what I was thinking but I wasn't sure. I knew he didn't have the roller lifters in his car (they were never offered in the rwd iron head motors), but it's been ages since I worked on one of the flat tappet lifter engines. Last one was the carb'd 2.8 in my '84 pontiac 6000. Ironically I was rebuilding it because the cam had some lobes that were completely worn down and had several cylinders not working. Engine over heated and seized on me. Was probably because of that very oiling issue... and the fact the previous owners didn't change the oil often enough and my lifter valley drip channels were all gunked up.

[geoffinbc]

Yes flat cam lobes did happen. But typically on high mileage motors with poor maintainance records. Also Iron heads do not have the same drain back holes as aluminum heads. They drain down the face of the head between the intake ports so all those little oil channels get drain back oil. But if you look at a Small Block as an example you will only see 1 drain back hole between each lifter pair which means drain back oil would hit the cam body between lobes and the lobes would only get splash oil which seems to have been working fine since the mid 50's

[85maro]

Actually I'm building a 3.4/3400 hybrid that'll have a roller cam. I took the roller off a lifter and there's no hole underneath. I haven't tried it yet (obviously) but I'm trying to dispel the idea that rollers can't be used in a flat tappet block. How did this idea start in the first place? Anyway back to the reason I started the thread which is to point out where return oil is going. Maybe this is why we hear of more tappet failures on gen 1 & 2 blocks with a hybrid conversion? If I'm not mistaken the cam is exposed to oil flung off the crank in sbc's whereas 60* v6's have a second divider in the lifter valley between the crank & cam.

[SappySE107]

The gen 2 heads have the same oil return holes as the gen 3.

[ForcedFirebird]

Interesting. The even pattern on the ports was changed in the Gen 3 along with the lifter valley design.

Who's wiping lobes? I only know of one, and he found a used Crane 272-2 and didn't put the lifters back in order.