Comp Cam's Thumpr Cam

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RustyDusty

RustyDusty

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I've been looking at the Comp Cam Thumpr series for my stock 360 magnum (I am willing to do a LOW cost build if it gets me into one of the slightly larger cams, I'm on a really really REALLY tight budget)... My main goal being a nice lobing choppy idle.

If I went with the hydraulic roller "Mother Thumpr" it says: needs 9:1 CR, 2500+ stall, intake, gears. Which intake, and gears would you go with? Also, the magnum runs at 8.9:1 CR, the Mother Thumpr says it needs 9:1, would stock CR be OK, or does that .1 make a big difference in the scheme of things?

They make it sound oh so simple, then further in the description it says:

Recommended Components:

Complete K-Kit K20-601-4
Cam & Lifter Kit CL-Kit CL20-601-4 [7]
Lifter Kit 822-16 / 867-16 [37]
Timing Set 2103 / 3103
Rocker Arms 1622-16 [23]
Push Rods 7958-16
Valve Springs 995-16 [2] / 26995 [2]
Steel Retainers 740-16 / 795-16
Valve Locks 626-16 [24]
Valve Seals 505-16 [2]
Camshaft Break-In Lube 159

Installation Notes (These notes apply to the above recommended components with the trailing installation note numbers)
Note Description
2 [2] Requires machining on cylinder heads.
7 [7] Stock springs cannot be used.
23 [23] Includes special shafts & spacers.
24 [24] Special 10º 4 Groove Lock. Single Groove use part #612-16.
37 [37] Adjustable valve train required.


How many of these components would you really change? Or would going with their "complete" kit be enough? (includes: • Camshaft • Valve Stem Seals• Lifters • Timing Chain Set• Valve Springs • Assembly Lube• Retainers • Decals• Valve Locks • Instructions)


Here are some links:
"Complete Kit"- http://www.compperformancegroupstor...re_Code=CC&Screen=PROD&Product_Code=K20-601-4

Mother Thumpr Cam- http://www.compperformancegroupstor...C&Product_Code=20-601-4&Category_Code=THMCRS2

Camshaft Specs- http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=638&sb=2


I know this is a bit scatter brained. I tried to get my questions across though. Thanks FABO!
 
I think you're going to end up spending more cash trying to convert to hydraulic flat tappets. You'll need oil tru lifters and I doubt that you can reuse the hollow pushrods since you'll have a different length lifter, by how much I don't know. If someone know's or can go take a measurement, please chime in.

You'll need springs, retainers, etc. That cam is also for 1.5 ratio rockers, not 1.6, you may have to machine the guide seal boss so the retainer doesn't smack the seal at max lift, which is .53 lift - intake. The list goes on and on.

Why not just get a lower duration cam that is compatable with your STOCK engine, stock torque converter, stock c/r, stock gears. The biggest mistake a new engine builder can make is over camming because it sounds cool. Stab in a nice, hughes or comp cam roller that is MADE for your engine and what it needs and can support. Reuse the lifters and pushrods, new springs for the cam, get headers and exhaust, air gap intake. They make good cams out there for your exact setup and you won't be stalling out at the stoplight.

Are you running a carb? You never mentioned your ignition or fuel plans. Or what transmission and gears you have and what you want the car to do besides lope at idle.
 
Thanks! Sorry, it would be a hydraulic roller!

I'll be running a carb. As to fuel plans it doesn't make a difference to me what it ends up needing. I haven't chosen gears or tranny. I will build the drive/powertrain around the 360.

All I want is a good lope, and no loss in power. A 360 mag will give me plenty of speed in a duster for the street.
 
Hey my mistake too. You did mention putting in a roller cam, though the cam link took us to a flat tappet cam. I have comp cams 274HE in my 360 and I like it a lot using stock heads. I can't say it lopes cause I don't have exhaust yet. I'd still stick to a milder cam..
 
T56 pretty much nailed it. I was also considering a thumper for my 360 mag but wasnt prepared to spend the money for the other recommended mods(converter, gears etc) If I remember the specs on the one I wanted it would have caused the top of the guide to hit the retainer as it was high enough in lift to cause concern. I installed a lesser cam that was rated at .512 and wound up with about 30 thousandths clearance between the valve guide and retainer. Probably the cheapest way out is a Hughes or Bullet cam, a set of Hughes springs, and Hughes retainers which will allow up to .600 lift without machining the head. I also considered the flat tappet conversion which by the time you are through cost$$$. I had heard from others who did this kit that the pushrods supplied by Comp were problematic and that after you had your setup bolted together that you should carefully measure for actual pushrod length needed. I got out very cheap with a reground new factory core 496/512 lift 276/286 duration 110 centerline
and a set of Hughes springs and reused the factory roller lifter setup which is perfectly acceptable. Total cost 200 bucks. It doesnt have the idle quality of the thumper but sounds pretty dams good.
 
I have a stage 1 thumper flat tappet cam in my 412, I have 1.6 harland sharp rockers and crane standard push rods, It has awesume lope to it even though it is the mildest of the 3 cams in the series, If I am not mistaking the thumper cams are dual profile, they make good low end and midrange probably drop off at 5500, mine is a street car if it sees the strip 2 times in a year thats alot, If you want to talk to a knowledgable guy at Comp Cams Andrew Stroud 901-795-2400 ext 559.
 
Stroker,
What all did you have to swap to get the thumpr to work? Glad to see it will work with 1.6's.

Cheers,
Drake
 
RustyDusty said:
Stroker,
What all did you have to swap to get the thumpr to work? Glad to see it will work with 1.6's.

Cheers,
Drake
Click to expand...
Well apparently I missed the part where you have a Magnum, which means you have a roller cam in there now?? my 360 was out of a 74 charger so I have shaft mounted rockers and so I didn't need anything other then the kit from comp cams, that included the correct Dual springs, although I didnt use them the machine shop that did the work had already set my heads up with a single spring and said that with only having .488 lift I wouldn't need the duals, If I were you and you want to do the "thumper" I would call Andrew @ comp and do what he tells you, I would go roller, first Thumper not mother thumper etc. I like mine I am sure you wont be disapointed. I think youd have to spend to much $$$ to go with the more radical mother or mother humper thumper. IMO
 
Depending on tire height, anywhere from a 3.55-3.91 gear, RPM Air Gap and a 2500 converter would work well with that thumper hyd roller cam (283thr7).

The muther thumpr (291thr7) I'd put 3.91's and a 3000 verter in it.
 
crackedback said:
Depending on tire height, anywhere from a 3.55-3.91 gear, RPM Air Gap and a 2500 converter would work well with that thumper hyd roller cam (283thr7).

The muther thumpr (291thr7) I'd put 3.91's and a 3000 verter in it.
Click to expand...
X2 I have 2500 stall and 3:55's and the thumper
 
412 Stroker said:
Well apparently I missed the part where you have a Magnum, which means you have a roller cam in there now?? my 360 was out of a 74 charger so I have shaft mounted rockers and so I didn't need anything other then the kit from comp cams, that included the correct Dual springs, although I didnt use them the machine shop that did the work had already set my heads up with a single spring and said that with only having .488 lift I wouldn't need the duals, If I were you and you want to do the "thumper" I would call Andrew @ comp and do what he tells you, I would go roller, first Thumper not mother thumper etc. I like mine I am sure you wont be disapointed. I think youd have to spend to much $$$ to go with the more radical mother or mother humper thumper. IMO
Click to expand...

Yes, I've already got 16 good roller lifters in there. I'll call Andrew tomorrow and report back here.
 
From what I've read and heard all I need to do is swap valve springs out for a set of new stock springs to run the Thumpr cam. I'll let you all know how this works out.
 
I don't know the open and seat pressures of stock magnum springs but I doubt they're in a close proximity of what the cam requires. If you're going to buy new spings anyways, why not get the exact ones your cam needs? Don't forget to check valve guide seal to retainer clearance if gross lift is near .5".
 
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