Building a 496 RB 440. 11.5-1, Holley Super Sniper 440 SEZ heads, 0.051" head gaskets. Looking at different cam and cam profiles. I've talked to Dwayne, and he said Comp's are kinda hard to get at this time. I'm looking for mid-range HP and torque.
Looking on the Comp site, I see the Mutha Thumpr is available but not sure if it would work for my needs. So much info to digest! Thumpr has a LSA of 107 where most of the others are 110-112 LSA. Timing events are confusing too. Example: The Mutha Thumpr exhaust closes at 49 ATDC opens at 82 BBDC, intake
opens 42 BTDC, closes at 69 ABDC whereas the XR286HR-10 exhaust closes at 2 ATDC, opens at 55 BBDC, intake opens 12 BTDC closes at 44 ABDC. duration @ 0.050 is about the same on both, but lift is a bit different. What does all that mean and do? Also looked at the Trick Flow Track Max and it has a lift of
0.600. Quite a bit higher than either Comp. I've never talked with anyone that has used the Mutha Thumpr, so no idea about that one. You guy's that understand all this are a genius if you ask me! So much confusion. Could anyone shed some light for me? This is mainly a street driven, but driven hard vehicle. (1970 Challenger)
Thanks in advance! Jeff

Instead of diving right into cam specs how about saying what it is that you're trying to accomplish? Sounds like you want a hyd roller cam for a street driven hot rod. Maybe a 600 hp engine? You said mid range hp and torque so you must have some gear and converter in the car? Do you want a smooth idle or are you comfortable with a rough idle and some bad manners at low speed? The thumper cams are designed to have a rough idle for people who want that sound. They don't necessarily make more power but they sound like they do. I'm sure you can find some dyno tests on the thumper cams if you search around a little bit.

With those cubic inches, that compression, and those cylinder heads, I think you’ll be better off with a cam 10 degrees bigger than what you’re looking at.
I don’t believe there’s any reason a comp cam would be hard to get right now. Have Duane custom order you a cam for your specific needs.

Yea, forgot some info! 5 speed Tremec, 4.10 Dana. Shooting for 550-600 HP. I usually run 97 with a mix of 110 fuel. I don't care if it has a rougher idle, but I do want to drive it on the street too. I am interested in a hydraulic roller. I've scoured the interweb and have found so many builds, dyno runs etc from all different cams I know the duration plays into idle quality, but why so many variations of degrees of opening and closing? Andy, I watch closely the ones you build and notice you stay close to the 240-242 duration range and have good idle quality, yet produce great power. That's what I'm looking for, Thanks for the response! Jeff

Dwayne did the cam that I have in the 496 RB that is in my Coronet and I think it is just about perfect. It is 239/245 hyd roller and it made 610 hp and 630 torque. The engine runs super smooth with a big fat torque curve down low. I had a slightly larger cam in there before and I didn't think it drove very well on the street so we redid the whole combination.

With the Trick Flow heads you don't need a lot of duration to make really good torque. The EZ heads might require a slightly different lobe since they typically don't have as much low lift flow. Best to chat with Dwayne on the subject.

But in general if that was my car I'd avoid the Thumper stuff and go with something like the 286HR. Or dive into the Comp catalog with some guided help. Comp has the XFI lobes for EFI engines so those might be a good choice. I like using a beehive or conical valve spring with the hyd roller lobes but it costs more money.

Brian at IMM is also a good guy to chat with about HR cams and EFI. If it was my engine I'd also go with the Gaterman lifters, a high quality set of rocker arms, and some stiff pushrods. It costs more money to put the good parts in the engine but they seem to run better.

With the Super Sniper you aren't going to be able to mix race gas or else you'll kill the O2 sensor. So you'll need to use something like Hot Rod 102 unleaded or whatever is available in your area.

I assume you have headers on the car and a performance exhaust system? Since you have more compression than my engine and a better exhaust system you could step up the cam a notch or two. The problem is that even with 4.10 gears once you stick it in OD your engine won't be turning all that high going down the freeway. If you want it to run smooth going down the freeway then you need to keep the timing on the small side.

Are you going to install a Hyperspark distributor too so you can use the Sniper to control timing? I highly recommend doing that since then you'll be able to fully control the timing curve. That way you can build in extra advance for cruise and pull timing at WOT along with a start retard and launch control and all fun stuff.

Andy, Yes I do have the Hyperspark ignition system. Thanks for the heads-up on the O2 sensor with 110. Hadn't thought of that. I do have TTI headers, 2 1/2" Magnaflow exhaust on the car.

Okay, with those headers you should be in pretty good shape. Is the car running now or are you building it? Do you have room to run a Trick Flow intake? If so, get it deep port matched by Hughes (or someone else if you prefer). You have the standard port EZ heads correct? Which Super Sniper do you have? The Super Sniper 650 is all you need so hopefully you don't have the 8 injector one. If you're planning to use the extra inputs for oil pressure and fuel pressure you'll need a harness. I had some harnesses built since nobody else has them. With the harness you can hook up three sensors to the Sniper and measure fuel pressure, oil pressure and one other. Maybe trans pressure, brake pressure, PS line pressure, etc.

The thumper series cams were ground with the notion of creating a lumpy idle sound.
If that is a priority , have at it.
But there are better cams out there that address specific performance objectives.
And some of them sound pretty lumpy too.

Andy, I do have the Super Sniper 650. Why do you say not to use the 8 injector unit? A friend of mine has purchased one, I haven't had time to install it for him tho. I do want to be able to tune by a laptop. I have a couple of the Holley gauges that hook together by can-bus. I've been told the oil pressure gauge doesn't work with the can-bus on the Sniper. What sending unit are you using for oil pressure?

The Super Sniper at the moment is only half finished, not sure when Holley will finish the software. The Super Sniper will data log fuel pressure and oil pressure and you can view them on a digital dash but you can't view them on the hand held. I have a digital dash in my car so I'm set but it costs a bunch of money to buy the Super Sniper + sending units + digital dash. I'm not sure it is worth it but it does work if you go that way. It would be a lot cheaper if Holley would update the software for the handheld so you can view fuel pressure and oil pressure but they haven't done it yet. Maybe when they do that the CAN bus gauges will also work. The CAN bus gauges are a cool idea but most people are going to want an oil pressure gauge if they have a gauge panel.

According to the little I have learned from friends more into FI than I will ever be.....I feel the 107 is probably not a good idea.

Not only the 107, but the whole bunch of extra ex duration providing even more overlap........ doesn’t sound like a real EFI friendly choice.

Someone might have one of those cams on the shelf somewhere....... but I wouldn’t be too confident Comp does.

I used a thumpr cam, hr 235/249/107 in a 408 stroker smallblock. The EQ iron heads flowed 272 @ .600, with great midrange numbers. The motor has an airgap intake, 850 Quickfuel carb, 10.1 compression, and the cam is at 105, rather than the recomended 102. It made 504 hp at 5700 rpm, and 519 tq at 4700. I use a true 4,000 stall converter, and in a 65 dart the thing is a beast. Properly set up with slicks, i have a good idea of it being able to run hi 10s.
If you look at circle track cams, the LSAs are very narrow in a lot of cases, because they don't need to worry a rats butt about manners below a certain rpm, like 3,000 rpm for instance. That is pretty much what you get with a thumpr cam. It is best to use the max compression you can though, to help offset the early exhaust opening of the thumpr cams. Also, matching the converter or running more gear ratio in a stick car will work much better given the extra overlap these cams have.