On a production block, I can see truing and bushing the lifter bores, but on an aftermarket block with better quality control (hopefully), is it really that important?

I had my LT1 block bushed, but I can't see a reason to have the Motown short block lifter bores bushed, especially for $300. Is the few horsepower you'd pick up from having absolutely perfect valvetrain geometry really worth it?

While we're on the subject of finding every last horsepower, what about lifter valley breathers and oil restrictors? Is it really beneficial to run restrictors in a street engine, even if it is solid roller? I know the idea is to limit the amount of oil in the top end, and eliminate drain back past the cam, but if you run a pan with an extra quart of capacity, does it really matter how much oil is being run upstairs?

The lifter breathers aren't really possible because of the additional lifter valley bracing in the aluminum Motown block, but I'm debating on whether I should run restrictors with my solid roller setup and use valve spring oilers in the valve covers, or just leave out the restrictors and call it good.

Thanks!

 

Yeap, it's mostly for correcting what the factory did wrong. A aftermarket CNC machined block is not going to gain much from this.

IMHO restrictors in a street motor = busted lifters.

I do agree that you want to control the drain back and where it drains back to the pan. I do some odd things here but I want all the oil to go back either down by the timing chain or down thru the back drain back holes if I have a wet sump... even a good external drainback is a good idea but most guys dont need it.

Bret

 

I'm still running stock bores on my LT1 block but one thing I did do was have them grooved on the top side to retain a little extra oil. I have a solid roller set up and running with out restrictors because as Ace stated, I drive mine a lot on the street and oil is my friend.


P

 

I plan on running a Canton oil accumulator, a 7 quart pan, and I have a 25-row Mocal oil cooler that will increase the capacity of the system as well. I don't see "running dry" as a realistic problem if I'm pumping a lot of oil upstairs. I'll trade a few horsepower for better longevity.

As you can see in the picture of the Motown Lite aluminum block, lifter valley breathers aren't an option because oil that gets into each section of the valley needs a path back to the pan.
http://www.worldcastings.com/docs/05_cat_pg6.pdf

Would you run spring oilers in addition to unrestricted oil delivery in the block? We're fabbing my valve covers now and I'd rather not waste the time and expense of adding spring oilers if they're not really needed.

 

Unless you're endurance racing... you probably don't need the oilers. Every little bit helps but the gains you see in spring life are going to be even more noticable with more "radical" setups. I like the extra security myself.

And no... no oil restrictors, even on your aluminum block. Just use a common sense approach in trying to aid oil drainback.

-Mindgame

 

i learned first hand about oil restrictors in a street car. i had a solid cam adn full roller rockers, and ran oil restrictors. i broke it in to the cam recommenders specs and it still starved the lifters for oil. i ended up ruining a cam a set of lifters, an oil pump, all the bearings and broke a few pushrods becasue of the added clearance in a brand new motor. luckily i only put about 20 miles on it and got it apart and fixed before it ruined more things (like the brand new forged crank) i from personal experience dont recommend them.


*Eric

 

You could paint the lifter valley with that paint...

I think it's called Glyptal or some such thing. Smooths it on out and promotes faster drainback.

You can also polish the valley if you want to get really crazy.

 

^ Yeah, my old gen 1 SB was coated with teflon within the lifter valley and
oil returns. Cool little trick I thought.

More on oiling - I have a related issue with lack of oil to the valve train.

How much oil is supposed to splash onto the valve train during cold start up
and idle to ~ 2000 RPM?

I removed my valve covers to check for a strange noise. I didn't see any oil
spraying from the rocker oiling holes.

Is this normal?

More info here and video here:
http://web.camaross.com/forums/showthread.php?t=369614

 

Jim,

Yeah I'm a big fan of accusumps and good pans, but oil restrictors stop the top of the motor from getting more oil to help feed the bottom end. If you have the right main clearances then you should be good to go in terms of oil pressure and volume for them, so pump the rest where you are worried about low RPM oil starvation... the LIFTERS!

The Comp and Isky lifters I have used and I love them, have always worked well for me.

Bret

 

I just had a 454 put together by Mike Blackstone at Watsons Racing. I am running a solid roller with bushed lifter bores and 426 Hemi lifters. Mike used restrickters to control the oil up top but opened the hole up a little to make sure the lifters didn't starve as the engine will see alot of street use. This was new to me but sounds like the right move.

 

Ran resrictors in my solid roller, but i opened them up to .100 from .060, and it ran fine for about 5k miles, until a failed Mez pump cost me the head gaskets, and warped heads.

P

 

Hey you guys do whatever you want, but you just don't need them in a street car if you have the right clearances on the bottom end.

Bret

 

The only argument that i have to that is for every one person that says you dont need them, there will be one that says you should. I think just do what you want.

P

 

That's my point, if you feel like you need .0035 clearance on the mains, you probably need them. I've run into way to many people who have beat up solid roller lifters on street motors. As I said do what you want, but I'm not going to recommend doing this.

Bret