[nickydags]

http://www.jegs.com/i/Comp+Cams/249/08-601-8K/10002/-1

Mutha Thumpr Camshaft Kit
287T H-107
Adv/Dur: 287/305
RPM Range: 2200 to 6100
Intake/Exhaust Lift: .489/.476


anybody know anything about this package and/or anyone who has it.....? Thinking about it for my ZZ4

any input would be greatly appreciated.....thanks...nick

 

[ALLT4]

You have 1.5 rockers in a ZZ4 is that cam with 1.5 or 1.6 rockers? A good cam for use with 1.5 rockers is a GM 846, it's just me but that cam you have listed seems like a poser more than a runner. You know, just all for that lumpity lump idle.

Otherwise if you have 1.6 rockers you're changing to, the Hot Cam is proven performer time and time again.

The GM 12370846 would be a slide in affair, but as always, check spring clearance! A GM 846 is similar to the Hot Cam but uses 1.5 rockers.

Personally I would keep more lift on the exhaust just like most of GM's cams for the Vortec heads. There's reason they do that, the exhaust ports on the Vortec heads aren't that great.

 

[nickydags]

I am assuming it is 1.5 as the kit is specifically for the ZZ4 SBC.... I dont really know much about what to look for so....thought I'd reach out to those better educated to give me a few things to look for and/or stay away from.... the car is just a basic street cruiser, not looking to set any land speed records or insane 1/4 mile times... Im doing a long overdue Auburn posi in the rear with some Motive 3.73's ...it has a TH350 with a pretty high stall
(dont know exact stall speed) with headers and a 3 inch X-pipe Magnaflow ...just looking to make it a little lumpier and perform a little better than a stock ZZ4.....I checked out some past posts..found this video

http://www.youtube.com/watch?v=ZNe9inCP_OQ

here was the post it was from
http://www.stevesnovasite.com/forums/showthread.php?t=105121&highlight=mutha+thumper

I read in the thread somewhere that it was kind of more show than go as far as performance cams go in some opinions but like I said, Im new as far as cams go, and....Im not trying to be the fastest....just a little something performance wise...a little noise and lope is good too.... it states that it should add roughly 60+ HP but you know how those numbers are (and I see they used a diff intake too, but I have a similar one so who knows) I appreciate the replies....keep em coming....they are very helpful...thanks..Nick

 

[batman09]

I've heard bad things about that mutha thumpa cam

 

[6NOVA4]

I thought the ZZ4 heads were alums modeled after the corvette L98 D port heads and not the vortecs? just curious. I looked at the GM performance parts website they say nothing about the ZZ4 having vortec heads? I know they aren't as good as the fast burn heads right? I would look into using the GM "hot cam" kit before I'd go with that Comp Cams setup IMO.

 

[ALLT4]

Yeah they are, sorry my mistake.

 

[nickydags]

hey Batman...what have you heard....dont leave me hanging...lol Im sure there are good and bad opinions out there...(if you read these forums long enough you'll lose your mind) I wish someone out there had this kit installed so I could get some hard facts..............anybody?

 

[6NOVA4]

Yeah they are, sorry my mistake.

oh no worries bro...I just wanted to be sure I didn't want to be telling people the wrong info. I like the vortecs and the L98 heads I think they're good for mild street performance and truck engines. Use 'em if ya got em!!!:beer1:

 

[lktna]

The only problem with the L98 production heads is they can only handle a .480 lift without having the valve guides cut down to clear the valve locks. Other than that they flow just as good if not better than vortecs. The 083's are the cast heads and the 113's are the aluminum Corvette heads. The 113's will handle a little more lift but not much more.

 

[nickydags]

so with the specs listed above with the aluminum heads that are on my car...I'd be cutting it pretty close with the 489 intake and 476 exhaust lift....

 

[ALLT4]

Here's the stock cam in a ZZ4 for reference...

10185071
Hydraulic roller tappet:

Duration @ .050
I: 208
E: 221

Lift:
I: .474
E: .510

The heads use 12551483 Single spring, 1.78 installed height, 1.22 coil bind. 1996 LT4 Corvette, ZZ4, CT350/400 and ZZ383 engines.

The stock lift is already well over .480 lift on the exhaust side, with the LT4 springs a Hot Cam is usually right on the edge of what the springs can take with 1.6 rockers. .525 .525 respectively. It's done everyday though without problems. The caveat is to always check the retainer to guide clearance, never assume because "it's done everyday"

1.78 installed height - 1.22 coil bind = .560 gross lift - .525 Hot Cam lift = .035 Safety margin. Getting a little close for comfort but like I said people are out there doing it everyday with no trouble.

FWIW the ZZ383 uses the same springs, uses the GM 846 cam with .528 lift on exhaust side .509 on the intake. 112 Lobe centerline BUT with 1.5 rockers. If you ask me that's the cam you need to use unless you REALLY want that lumpity lump idle.

You can get a more lumpity idle by disconnecting the vacuum advance if you have one with the GM 846, I did it for a while in my ZZ383, it sounded tough but didn't run as well cruising. Hooked it back up and am enjoying the good life, my wallet thanks me.

Here's what the 846 sounds like....

 

[nickydags]

OK...so I ending up buying the kit from Jegs....installed it this weekend...cam, beehive springs, and retainers...... and.........................


awesome.........it runs strong, seems like night and day from the previous performance numbers according to the seat of the pants dyno.....sounds mean as hell.......pretty much exactly what I was looking for.......a decent performance upgrade for the money with a big stick sound.......

totally satisfied with my purchase...and got to bust open the ZZ4 and make sure everything was A-OK with the rest of the engine components.

Im giving it a thumbs up...we'll see what happens when the posi -unit and the 3.73's go in , in the next week or so...should be one fun little 400 horsepower street machine............thanks everyone for your inputs and helpful advice, It is/was much appreciated.....Nick:beer1: