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393 stroker kit advice

7K views 8 replies 5 participants last post by  davis 
#1 ·
Wondering if this is a simple swap for stock crank or do,s it require work on block for clearances of longer stroke.
 
#3 ·
russxr67 said:
block mods are not needed for clearancing. Unfortunately its not quite as simple as swapping in a crank. Custom rods and pistons are usually part of the equation.

As Russ notes, you likely need custom pistons, however, there are stroker combinations that can use off-the-shelf Chevy rods, which tend to be moderately cheaper than most Cleveland-specific rods. Clearancing may be necessary depending on your exact combination, but generally it is not required. A 4.000" stroke crank with H-beam rods usually needs some block clearancing performed.

Nearly all aluminium rod combinations require clearancing due to the thickness of the big end/caps, though they are not very practical in a street application nor for many strip applications.

There are other details that make it more work to swap in a stroker crank. Most of the crankshaft manufacturers' stroker cranks are really 351W cranks with Cleveland main bearing sizes, which is what I call an "SVO" style crank. That is, they are designed for the Ford Motorsports SVO blocks that are basically a Windsor block with Cleveland main bearing diameters. Nobody, it seems, has anything to do with "real" Clevelands these days. In some ways it is even worse here in the US due to the short production life of the engine.

:davis:
 
#7 ·
My understanding is that if it's a real high revver big dollar strip orienated motor then the advantage of Ali rods is for their lightness to keep recipricatating mass down so motor can live at big revs.

But all Ali rods stretch and get metal fatigue at a much lesser time interval than steel rods, not a problem for a drag/race only operation that scedules a routine strip down and freshen up at regular intervals.

So is it is an all out 8 second clevo your doing? Go the Ali rods, otherwise steel ones would be better.
 
#8 ·
gtjim said:
im building my engine for steet strip application, minimal time on street, mainly a cruise run, the rest down the strip.surely the rods would last a while,, max revs would be bout 7300-7500 rpm.
Another point with aluminium rods is to build the engine with about 60 thou deck height clearance as ally rods can stretch this much during high rpm,s. Aluminium rods tend to fatigue much quicker than steel pieces and hence they have a limited lifespan and are usually turfed after a set number of passes before they have exceeded their modulus of elasticity (some big fancy words ,eh?).7300-7500 rpm is still steel rod territory.
 
#9 ·
STROKEXD said:
My understanding is that if it's a real high revver big dollar strip orienated motor then the advantage of Ali rods is for their lightness to keep recipricatating mass down so motor can live at big revs.

But all Ali rods stretch and get metal fatigue at a much lesser time interval than steel rods, not a problem for a drag/race only operation that scedules a routine strip down and freshen up at regular intervals.

So is it is an all out 8 second clevo your doing? Go the Ali rods, otherwise steel ones would be better.
The added bulk of the aluminum rods diminishes their weight savings advantage. You have to use a large chunk of the alloy to be strong enough to take the abuse. The best deal going for aluminum rods is really for blown alky cars. The aluminum absorbs some of the pounding produced when lighting off the mixture with a giant 14:71 lung atop it. Otherwise, with steel rods, the crank is beat to death and is oftentimes not worth 3 passes.

For everyone else, steel rods are the only way to go. Titanium is great if you can afford it, but you can easily drop 5K US on a good set of them, so few people use them for their hotted up street cars.

My "semi" all out 8 (maybe a high 7 in it?) second Clevo uses nothing special Scat H beams. For drag racing, a good I beam rod is usually all that one needs unless running nitrous. With the price of the H beams being very reasonable these days, a good H beam is cheap insurance.

:davis:
 
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