Dreaded cam question....

[Slammed70]

Not only is the gear on my dist stripped out, but the gear on the cam is all chewed up aswell. Not to mention it being a little flat and worn out. So naturally I wanna upgrade. And get away from that solid cam bull****.

Im assuming to swap to hydraulic flat tappet I just need to get the right cam and drop in some new lifters, maybe some new pushrods...I dont know.

But heres my question...bewarned its a cam question.

Is there a cam that will make my truck sound mean? I still want it to be street able with some power increase, still is gonna be my DD once I make it happy again. I just want it to sound mean and scare people when its idling.
Is there such a cam?

[kxmotox247]

I think Compcams is making some new "thumper" series that is supposed to be street friendly. I don't know anyone who has run them though.
The chewed up gear deal... where did your distributor come from? I bought a crate motor distributor from a guy and it had a hardened gear on it. The machinist who built my engine swapped gears since he said it would tear up the cam gear. I don't know if this is related to your problem...

[chev74]

GRRRRRRRRR!!!!!!!!!!! FIND A CAM THAT WILL LOPE

its awesome to hear a cam that almost make your engine die at a stop while idling!

[Billla]

The CompCams "Thumpr" cams have streetable lift but more overlap so you get that lope. It's a great way to waste gas and driveability for no more power

http://www.compcams.com/Thumpr/default.asp

[70rs/ss]

Wow, I think I just found my new cam!! I doubt there is any loss of power and or Fuel economy, but then again who spends $500 on a roller cam with a choppy idle to get MPG?!!

[Billla]

Originally Posted by 70rs/ss

I doubt there is any loss of power and or Fuel economy

Don't doubt; it's a certainty. High overlap with low lift will absolutely cost you both. You're getting the "sound" of a hotter cam without the performanc e (lift) that would normally come from that cam.

Up to you, but be clear what you're buying...

[Slammed70]

Originally Posted by Billla

Don't doubt; it's a certainty. High overlap with low lift will absolutely cost you both. You're getting the "sound" of a hotter cam without the performanc e (lift) that would normally come from that cam.

Up to you, but be clear what you're buying...

Can you clear that up abit....Im getting from you that its gonna cost us power and reliability just for the sound?

[Billla]

Originally Posted by Slammed70

Can you clear that up abit....Im getting from you that its gonna cost us power and reliability just for the sound?

Yep - power, fuel economy, driveability and maybe some reliability - that's my point from my very first post

The reason hot cams sound "nasty" is because they have a ton of overlap - time when both the intake and exhaust valves are open. This is required for very high-RPM engines for two reasons; first, we want the outrushing exhaust gasses to "pull in" the intake charge...so much so that we're willing to let a little intake charge go out with the exhaust. This is why we see flames in drag race engines...this is intake charge catching fire in the exhaust Second, on the SBC, the exhaust valve and runner is smaller than the intake. This isn't the level of problem people think, as we're only getting rid of the burnt gasses from the power stroke...the air and fuel we pulled in the (larger) intake runner/valve is gone - destroyed in the explosion that made the power. But at higher RPM we do reach a point where there's not enough time to get all of the exhaust gasses out, so our only choice is to leave the exhaust valve open longer. Long duration is also typically matched with higher lift, as it's all about moving the intake charge in and the exhaust out...so we use every trick we have. All this makes the engine run lousy at idle-3000 RPM , but great at 6000+ RPM...which is where we need the power. Note also that high overlap cams typically are paired with expensive valvetrains as the lobe profile now slams the valves open and closed more agressively - which is harder on the valves, seats and springs.

The Thumpr cams are made with lots of overlap but streetable lift, so we end up with that nasty sound of a high duration, long overlap, high-lift cam but with an overall profile that's more streetable. But as I've said (3 times now ) you're making the same or less power of another cam with equal lift, you're wasting fuel and driveability at idle - 3000 RPM and you're slamming around your vavletrain.

To net it out, Thumpr cams are for folks that want to make noise, not power. IMHO it's the same as the ricers that cut off their muffler and put a SuperTrapp on their tailpipe. Sounds nasty, means nothing. For CompCams, it's a smart deal because they end up with people breaking engines by putting in too much cam - now they have a product to sell for those that want noise but not power. If you're buying a cam because of the sound clips on the website, you're not really interested in making power. I will kick the butt of your "nasty sounding" car every time with my properly matched cam.

To use a phrase I heard in Texas for "cowboys" that dress up but have never actually been on a ranch: "Big Hat. No Cattle".

I'm not going after anyone - what's important to you is important to you and I respect that - but just be clear what you're buying: sound, not power.

[dave3156]

Great description on how it all fits together. I don't think I have seen it stated as well before. I looked at cam specs alot when doing my recent build. I went with the cam that had the highest lift, but was still streetable without much lope. It was an extreme energy 268 grind with 515 lift.

[cdowns]

lots of people that just want to make noise go the blowmaster route

[ridin98ci]

I have had good luck with the Lunati Voodoo cams.....in my Mopars....Larger bore lifter means you can get more lift less duration and they still sound BAD

[Myself]

I used to like Comp Cams until the XE268 in my wife's truck lost 7 lobes and ruined the lower end at 6500 miles. Comp WOULD NOT stand behind it. In fact over the phone they talked to me like I was an idiot and there must have been something else that caused it. I also know of 2 performance engine shops that quit using Comp because of all the problems (I'll be glad to give those names). Northern Auto Parts was very helpful and did all the warranty stuff for me (unlike Comp). And the warranty guy said mine was one of the worst cams he'd ever seen. It had air bubbles in the cam core and the lobes were not hardened properly. I went back with Crane Powermax. I WILL NEVER BUY ANOTHER COMP PRODUCT AGAIN!!

[Ole Blue 68]

Originally Posted by ridin98ci

I have had good luck with the Lunati Voodoo cams.....in my Mopars....Larger bore lifter means you can get more lift less duration and they still sound BAD

I'm running a Voodoo in my truck and I'm a fan.

[Scott68-93-97]

Bronze dizzy gear will keep from chewin up the gear on the cam, get something that has as much lift as possible with the lowest duration and a high degree of lobe seperation thats what you want for the street anything over 220 degrees of duration at .050 lift will require a torque converter swap so stay a way stay there or under with the most lift and you should have a wide powerband. if you want it to idle without knocking your teeth out then get something with 110 degrees of seperation or more stock cams are way up there at 116, overlap can also be an issue the longer the 2 valves are open together the choppier it will run