Sojer

Inform me every time I see a high hp street build they use retros on a already roller block. Why not use the spider (stock style lifters?

vetteoz

iTrader: (13)

In a magazine engine build writeup?
They are probably promoting their advertisers products

GMMP LS7 lifters are good to 7K @ $135
Link bar lifters start @ $350

I know what I would use in a factory roller block.

Sojer

Thats another thing ls7 lifters I knew they were cheap but 7k rpm that's sweet.

novaderrik

i don't know about the newer LS engine lifters, but the gen 1 roller lifters were only good for about valve .530 lift before the oil holes got covered. there is also an issue with the dogbone retainers in the gen 1 engines above that much lift, but i think they took care of that when they came out with the retrofit LS style lifter retainers for the gen 1 blocks.

vetteoz

iTrader: (13)

http://forums.corvetteforum.com/1579707959-post17.html

sofakingdom

iTrader: (1)

THIMK about how a cam works:

To make a cam "bigger", they don't make the lobes TALLER. The peak of the lobe of a peanut cam is basically already as tall as it can be, and the cam still be able to be installed.

"Lift" is THE DIFFERENCE IN HEIGHT BETWEEN the peak of the lobe and the "heel". Remember that: DIFFERENCE IN HEIGHT.

So since the peak of the lobe is always already about as tall as it can be and it still slide through the bearings, then to make a cam "bigger", the zero lift side of the lobe is made progressively SMALLER. Which is why it's EASY to grind material off of a cam and make it "bigger", as is commonly done in racing.

Therefore as cam lift gets HIGHER, the lifters retract farther and farther into their bore at zero lift; and eventually they slide below the surface and come out of the figure-8 retainer. VERY BAD things happen when they do that. This becomes a potential problem at around .550" or so of lift, typically; sooner for a small base circle cam.

The original roller system isn't subject to that problem.

It does however have a different problem that comes into play. Since the block in the late model system is taller around the lifter bores, then eventually as you make the cam bigger, the original style lifter eventually sinks so far down in the bore that the link bars come to rest on top of the bores and keep the lifter from following the cam. They make "special" extra tall ones for that situation.

FRMULA88

Stock parts are just fine for stock aka street applications especially when you are within the design parameters of those stock parts.


The instant you cross those parameters it is no longer a stock application.

Hi-performance aftermarket parts exist for this reason; they pick up where the OEM parts leave off.

My engine has a Dart block, roller cam with solid lifters, shaft mounted rockers. 18 degree heads & JE 18 degree forged piston. These are hardly parts that would have come or even been necessary on a stock 225 hp 350.


BUT a max effort drag strip 421 SBC making 680 HP NA is another matter.

stock parts would have a VERY short life in such an application.

So take articles for what they are, they are meant to show what the aftermarket has to offer.

As with any project if you are unsure, rely on the experience of a reputable engine builder in your area, and NOT some magazine article.


If you plan to build a motor get to know a builder... you will be far better off in the long run.

Sojer

I have a flat tap motor so I would have to use retros. I know they make aftmk roller lifters (stock style) but to much cam and they may fall in the bore.