Thumper

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12many said:
Anyone play electric guitar here? I like a Les Paul through a British amp, think Marshall or Orange. Anyone can buy both, tune things up, crank it up and make some spine tingling sounds once in a while. Might still suck, can’t hang with the real deals but a nice power chord or two, some single notes put together is all it takes to get “that” from the sound. Best comparison I can make. Just cause you can’t really play doesn’t mean you forfeit or forgo the pursuit of aural pleasure!
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I do.…..and after reading this thread, and comparing cams to musical notes I think some can identify...….so do you want peter paul and mary? or deep purple. I don't know about you but i'll take highway star or lazy over michael row your boat ashore. all are quality songs just different in character.
I ran an ssi .509/292 in my car since about 1995 for performance reasons because I wanted a street/bracket cam. didn't give a **** about gas mileage, wasn't what I was looking for. the sound of the cam was just an added plus....and was not a consideration in me picking that grind, but my mopar buddies loved the way it loped....me too.
3/4 cam, is that what the .509 is? could be....old school.

currently i'm building a stroker with a comp. cams roller close to .600 lift. do I care what it will sound like? not really as long as it hauls ***.
higgs
 
hollywood hig said:
you might get what your asking for.....lol.
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That's just it. I'm not askin. lol It's a nice little guitar. It has the original finish and very complete, but it has battle scars. Plays out of this world.
 
so thumper is lumpy
some like choppy

the crate magnum 380hp version cam with a 288* / 292* roller. .501"/.513" lift (230*/234* @ .050) M.P. P4876348 (380 & 435 HP Crate Motor
HR nothing to do with a Thumper look at the durations spread
 
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PRH said:
There’s tons of videos on line of cars with those cams idling.
It’s not the type of busy racy idle I like myself....... it’s just “choppy”...... but they’re apparently pretty popular.
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Yup.
 
12many said:
Anyone play electric guitar here? I like a Les Paul through a British amp, think Marshall or Orange. Anyone can buy both, tune things up, crank it up and make some spine tingling sounds once in a while. Might still suck, can’t hang with the real deals but a nice power chord or two, some single notes put together is all it takes to get “that” from the sound. Best comparison I can make. Just cause you can’t really play doesn’t mean you forfeit or forgo the pursuit of aural pleasure!
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Marshall JCM 800 100 w lead series.
 
Wyrmrider said:
Sound
I've done builds for absolute quiet so a stereo with classical music can be heard but still run well
and I've done stealth builds that sound stock until you really get on it
and then there are builds where you go for the most power
Want a performance sound get a 60's Howards or Clay Smith open the exhaust early and vibrate the headers
but then they (and many others) were quite brutal on the springs of the Day- Want something really brutal try an Ak Miller grind
Crane with his "computer smoothing "marketing really shook up the cam business

The lunati Bootleggers "Note: Custom grinds available for Chrysler" but why seems like a Voodoo would be better in any case
I stuck them and the Lunati Bracket master II in the list for reference

I just read in one of PRH's links that Comp's Billy Godbout learned from Harvey Crane- Well so did the owner of Camcraft- me I'd rather deal with Camcraft
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So how about some tricks n' tips?
 
some larger cams
XE285HL 285/297 242/247 .545/545 110
Howard 285/289 238/242 .555/562 108 in at 104
Voodoo 287 242 . ..........533

Thumper 287/305 235/249 158/165 .507/494

Purple Plus 287 240 153 .316 .474
MP 280 287...................... .474 .474 [email protected] my est for MP 280 cam

Howards HR 290 237 162 .373 .580
Howards HR 291 .......241 159 .367 .550

Howards 291 244 165 .566
PP292H 292/299 257/354 .508/508 108
440 HP ..292 ........213 ................447 115LCA
BradH measured an original 440 HP cam: 292/309 @ .006 lifter
note that it takes 10 degrees to rise from .004 to .006 on the intake but 15 on the exhaust
Lunati ....... ?? 216 ................455 Luniti's version of 440 Magnum

XE295HL 295/307 251/257 564/564 110
Howard 295/301 248/254 .578/590 109 in st 204
Voodoo ....297...... 252 ................552 intake lobe
 
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12many said:
Anyone play electric guitar here? I like a Les Paul through a British amp, think Marshall or Orange. Anyone can buy both, tune things up, crank it up and make some spine tingling sounds once in a while. Might still suck, can’t hang with the real deals but a nice power chord or two, some single notes put together is all it takes to get “that” from the sound. Best comparison I can make. Just cause you can’t really play doesn’t mean you forfeit or forgo the pursuit of aural pleasure!
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Sounds like me :) I got a bunch of Les Pauls and Strats, played through Bassman & Bandmaster stacks and a 50's Magnatone.
 
Take and advance most 280 and bigger about 8-10 degrees and the you'll have a real nice crackle of an idle.
 
Wyrmrider said:
WEll I've been wrong before so I'll try again
I first thought the thumper style cams were a fix for low compression motors
but now I think just for those that want a lopey idle and are not aware of the torque they leave behind.
An Oxymoron
Comp lists their thumper lobes on page 12 of their lobe catlogue
surprising they have different lobes for .842, .875, .904 all good- but why, comp turning over a new leaf? Here's the two basic thumps for .842 and Mopar size lifters at 1.5 rocker
........................006.........050......,200........lift w/ 1.5
Thumper SBC 279/297 227/241 138/148 479/465 107 PONTIAC

Thumper SBM 279/296 227/241 142/149 .486/473 107 BBM AMC CRS lobes int & ex/
note with the same seat timing the Mopar version has enough additional duration @.200 to make a difference (AMC and Magnum will have more lift with 1.6 rockers)
Neither has a lot of lift at those durations, either .006 or .050
Why?
not having to trim the guides? springs? target "poser" market?
any ideas on why the large spread between intake and exhaust durations?
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My basic 10:1 318 with J heads ended up making well over 350hp with the thumpr. The 107lsa made for a nice wide torque curve and yes, it sounded good.

Could a a different cam make 10hp more at the top end with the same idle/driveability characteristics? Almost certainly.

Does it matter to me? Not in the slightest.
 
For a streeter, that's what I keep preaching.
With 350hp;
10hp more/even 20, at 5200 in first gear means nothing except tirespin.
10hp more/even 20, at 5200 in second gear means almost nothing because it comes after 80/85 mph with typical street gears.
But 20/30 extra footpounds at 30/35 mph, or in passing gear, is very noticeable.
 
frosty
was that measured 10:1? that's more than recommmended
post up your cranking compression pleasw
any port work?
headers?
have to figure where that cam might work and where not
 
Furthermore;
If you have to sacrifice those 20/30 ftlbs at stall, to get the 10/20hp at 5200,that is often a bad trade,
but not always.
But 20/30 ftlbs at 32 mph, with street gears, is rarely unappreciated,lol.
 
ProStocker273 said:
I've been running the middle sized Comp Thumpr in a 273. With 1.75 headers 3in collectors with street tunnel ram and pair of 450 cfm Holly's. My car is around 2600lbs with a 4speed with 4.56 gears and currently 29in tall tires.
That Comp Thumpr has been a good cam for my only 9:1 tween. Car idles awesome, right at 700rpm, sounds great, and pulls to 6000rpm quickly. Motor is only 9:1 and heads have minor porting.
I choose the Thumpr because I didn't want to machine the heads for more than .500 lift. I wanted a more radical cam that would work with my only 9:1 compression. I have 155psi cranking compression with this cam.

Specs for the Comp Thumpr is a
Operating range 2,200-6100
Adv duration (IN 287) (EX 304)
Duration @ .05 (IN 235) (EXH 249)
Valve lift (IN .497) (EXH .483) with 106 LSA

I'm now building a 318 with 10:1 compression and ported 360 heads and was considering running my old cam but felt I'd be leaving to much on the table. I've been looking at the
Comp XE 285HL Hyd flat tappet or the
Comp XS 282S Solid flat tappet.

I'd be curious AJ with your math if it would show which would be better cam for a small cube manual trans combo like mine. Im doing oiling mods and prep to get this motor to rev to 7 to 7500 for peak power. Been trying to read up on adv or retarding cam timing to shift the power band up.

The XE285HL specs are 2500-6500
Adv dur (IN 285) (EX 297)
Dur @ .05 (IN 241) (EX 247) with (IN.545/EX.544 lift) on a 110 LSa

The XS282S 2500-6500
ADV Dur (IN 282) (EX 290)
Dur @ .050 (IN 244) (EX 252) (IN.520/EX.540 lift)
on a 110 LSA

I'm not sure on the intake center line of those 2 cams. Not sure how much to retard cam for the RPM range I want. The motor may be small enough that peak power will move up to the 7000rpm range with the larger cam without needing to retard cam. Either way I plan to call call luntai and comp and see what they recommend. I may go custom grind but would appreciate any further cam info. This isn't a daily driver but does need to run on pump 93.
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Mr Prostoker273...can you post a video of your 273/ Comp Thumper idling and revving a bit please? I have a basically stock 273 in my '67 Dart and like a bit more sound out of it. Thanks!
 
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RustyRatRod said:
They do work well.

And I just love how these gurus always talk about "not" using what a cam might sound like as a precursor to making a decision. LOL nobody goes cam shopping without thinking about how something will sound. Nobody.
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I don’t. Honestly. I recently shopped around for a solid roller for my stroker and spoke with a few reputable grinders. Told them all that I could care less how it sounds, just want it to maximize my combo.
Sure, I was 18 once and wanted everything to idle like a fuel car but I learned my lesson. My dad always teased me and said “All roar and no go!”
 
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