FYI on cam lobe identification, hydraulic grind will have sharp up ramp the flatten off with longer hold or duration timing then sharp down ramp. Combo grind will have softer up/down ramp with a gradual smoothed out peak roll over, quieter valve train solid or hyd. Solid grinds tend to have a sharper on/off peak, less hold time.

 

I looked up the Vtunder SHV-4001 and it is listed for earlier shovel, up to 1977. Then they have cams listed for late shovels, '78-'84 but not with the specs of the SHV-4001. I would think with different specs it is more than just the cam gear.

 

They are very good - I got them for a Hot Rod Panhead years ago - still running them - The Pan is not so much of a Hot Rod these days

 

Specs are the same 70 to 84 on any cam, the part number split is the early or late gear on it. You are WAY overthinking a lot of this stuff and confusing yourself in the process.

 

As @TwiZted Biker said above, the later cam has a different cam gear, the cam is the same otherwise. The late gear can be identified by the ring on the outer surface of the cam gear. Which cam be pressed off and replaced with the original or at least one with the correct tooth pitch to match the drive gear on the pinion shaft (also changed on later models).

Paul

 

Late to the party… love threads like these. So Everyone is going to lose their mind and say without measuring themselves that I’m wrong but I’ll throw this tid bit in here…. The stock published shovelhead rocker arm ratio of 1.43 is wrong. I don’t care what a box label or Harley manual says… measure them. Somewhere around 76-77 best I can tell the moco gradually increased this ratio. Go measure for yourself. You’ll find many about 1.45 all the way STOCK OEM to 1.5… from the factory although I realize they are all published at 1.43. (Not aftermarket.. OEM)

Chew on that and randomly go measure a few known to be early and late. I measured too many back in the day to be able to think I’m wrong.


With that said, I’ll throw my 2 cents into the hat on EVO valvetrain vs Shovel… If you need all new parts by all means go ahead and buy a bunch of evo parts and spend days measuring and checking and confirming.. you’ll broaden your cam selection… maybe a few more modern cam choices to choose from.. but that’s it.

A valve is not some genius brain powered creature that knows it’s getting a magical evo cam instead.. nope a valve knows I’m off the seat.. and 550 lift is 550 lift. Your valve doesn’t care how or what you use to bring it off 550. You can have ground whatever specs you want to lift the valve off the seat and it won’t care.

‘’My ok… 3 cents then, is just run shovel stuff and pic a cam to meet your expectation.

If after all your math is done, if your matching valve timing, duration, overlap, separation, lift… they will make the same power. In the end your not going to make more power with a magic evo labeled grid over a shovel grind.

I went down two expensive rabbit holes with big names. I have heads and parts done from each big name.. Mackie, Baisley… what I know is with both I spent a fortune and did all I was told to do… and in the end after all that money, they both made about the same power as my cheap carefully selected stock style shovel stuff. The ported heads from both following each path made the same power and ET’s as my messaged stock stuff.

I spent like $3k to have my Baisley top end run high 11 second ET’s and that was about the same ET as my own port work with a Stock set of 81 heads, solid sifton lifters, crane 1.5 roller rockers and Andrew’s M grind or Redshift 550 cams.

When guys brought me Shovels to build.. (lots of 88”, 86”, 93” & 98”) I’d usually set them up to run pump gas but high compression… I had one big trick to really increase efficiency and run considerably more compression than most builders did.. I ran the lowest dome piston possible to make the highest mechanical compression. Often the early 1800 S&S piston before they changed the dome shape. NEVER run dual plug. That’s for total drag motors with masssive domes. The dual plug increased the chamber and ruined your chance at a lighter piston with a lower dome. I could get almost 12:1 with a low dome 1800 series piston and with careful chamber machining run on pump 93 octane with no detonation. Chamber messaging was important.. you wanted to remove anywhere carbon wanted to build. That fire ring was a pain. I’d mock assemble a billion to]imes with a crushed, torqued copper head gasket to ensure no more no less than 1 thou all around from top of the ring to recess in the head while torqued with the gasket height I’d use. Pain in the but but Necessary.

little motors.. I like running the lightest Valve train parts I could get. The shortest lifters I could find and the minimal spring pressure possible with a measure of cushion for high rpm. The Andrew’s B with light springs, aluminum push rods, about 10:1 was a beautiful fun little motor. Quick revs, zippy little combo. 84” under that was a fav of mine. Anything over 88” I liked the 4030, Redshift 580S, over 93 street, I liked The Andrew’s M or the 4050. Anything more performance focused where fast wear and tare was acceptable.. I loved the Sifton 118, S82. For 103’s I liked the Redshift 631 or still that 118 Sifton.

No cam installation was more challenging than that 118.. but man did it make awesome power in the 11.5 to 13:1 range. It was the nastiest sounding cam ever. It was intimidating with how it sounded mechanically too… darn near sounded like bolts being shaken in a paint mixer. It was really hard on the valve train. But oh so rewarding.

OP… after all my rambling.. Pick a nice hydraulic cam in the 24-250 duration. To me… lift is a secret weapon that you can’t use if your looking for bolt in. So as Spanner said, most any of the bolt in variety will make more power than stock. Without serious compression above 9.7:1 it really doesn’t matter. They’ll all make similar power.

 

the key we found road racing using fuel dye strong red color - reason i knew every port on a Harley head was bigger then a Z28 302 engine so Hello

the dye and alluminum ports on the buell engine did this for me the light color was the hi speed air and fuel stains dark color was the air slowing down - staining the area that needed finesse - 12 races and heads in hand after - with the same combo improved lap times just a bit over a second 2 1/2 mike road corse

if you ever watch road racing at a pro level 20 bikes on the track 8 to 12 are in the same second around the track - porting shops is a scam it makes it worse 90 percent of the time as a flow bench is just blowing air using a number that has nothing at all do do with the engine they are going on yea sometimes a squirrel finds a nut - double a Harley engine size drag racing only then it helps but street riding even road racing it’s awfully mistake

 

I do not think I am over thinking in this case, going to their site I do not see a late version of this cam like I said above. Other grinds I see early and late. If you see a late version on this cam show me and I will eat crow.

https://www.compcams.com/products/co...-davidson.html

 

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Thanks Paul, I all ready knew this. LIKE I SAID ABOVE Looks to me that comp cams does not sell a late version of the SHV 4001. Could I buy that cam and change the gear? Probably but I am not going to pay for a cam with the wrong gear for my application.