Lunati Voodoo hyd roller small block build
 

Has anyone ever tried the 20120711 lunati voodoo hyd. roller in a sbc build? its a 219/227 duration @ .050 with a 112 LSA and a 106 ICL. I built a 385 using it earlier this summer and I'm disappointed so far. Running 183 cc Pro-Maxx Maxx series aluminum heads, Wiseco D-Dish pistons (9.4 static compression) running cam 4 degrees advanced. I just don't feel the torque that I had with a comp 218/224 flat tappet and crappy GM 882 iron heads. The motor never really has a punch to it. It acts like its lazy on timing but I have 34 degrees in it all in. It is the thunderbolt IV 22A module which is a lazy curve not all in till 4500 rpm. I can tell the engine would benefit from more timing around 3000-4000 rpm. If anyone has tried this cam, how did you set it up?

112LSA installed at 106ICL is 6* advanced. Just fixing your math.

Be interesting to see the duration differences at .100" lift and .200" lift between the two cams to see if anything there.

Going from flat tappet to roller and more overall lift the ramp rates have to be higher on the voodoo. SB, I have it advanced 4 degrees additional with my timing set. Actually only 2.5 degrees due to machining errors. So in reality its at a 103.5 ICL. I was trying to bring down the power curve further, but I am wondering with the 6 degree built in if I went to far? Comps XM270HR is a similar grind but with a 110 ICL and slightly less lift. I havent put a small enough prop on it to see where it really dies off, but I've had it up to 5300 rpm and doesn't feel like there's much left.

If you have it (your 112* lsa cam)set at 103.5ICL it's in 8.5* advanced. That's a lot !

For comparitive sakes, in a boat a 218/224 Comp Cams HR on a 112lsa installed at 108ICL (that's 4*advanced) in a 383 usually maxes around 5200 or so rpm. 5400 or so rpm in a 350.

The cam was advertised at 5800 rpm upper end so I figured with the additional cubic inches probably 5500 and then knock off another 200 by advancing an additional 4 degrees. So by that it seems to run to where it should right now. It just doesn't feel as strong as its built. Vacuum is good across the range so I feel I have good valve control. Im thinking about going back to straight up with the lag in my timing would put me about 107.5 and maybe drop 1 prop size and try it.

You have to be very careful setting up that type of lobe. Look on the back of the cam card and it explains how to correctly find the center of the intake lobe. I believe most builders into that type of lobe (Harold Brookshire's), will insist upon an infinitely adjustable timing set to properly degree in the cam. When set up right, that cam should pull really hard for its size and have better idle/vacuum when compared to a symmetrical lobe cam of the same duration. Again, with that style of lobe, you need to correctly find the center of the intake lobe, if you just match up the timing marks, if it ran, it would not run very well. I learned this the hard way on an Ultradyne cam years ago and the Voodoo lobes are just evolved versions of that with the setup being even more critical.

I would add don't underestimate the importance of ignition advance between 2200 and 3200 rpm. Just a few degrees of ignition can make a significant difference between a lazy feeling engine and a torquey one.

Going from the 110 to 112 lsa will kill some bottom and mid range torque, how do the flow numbers compare between the heads

I would think widening lobe sep would help bottom end at the expense of top end.

No, typically the opposite. But of course, it's not the only spec, if you will, that effects rpm range of power.

I've used more 104-106LSA cams on small blocks than I can remember. Not on boats though, obviously.

Not from what I've seen on the dyno, maybe it was just my application.

The 882 GM heads are around 205 cfm @ .500 lift with 165 cc runners. The current heads are 183 cc runners with 255 cfm flow @ .500 I expected less peaky torque with the larger runner but a larger overall gain which just isn't there.

Ok, a couple of questions, is it 385 or 355 cid, what intake are you running and what exhaust.

385: .040 over 350 with 3.75" stroke. Edelbrock performer (not rpm) Cast GLM with stock risers (no extensions) and side exits. I wanted to go Hardin risers and lengthen risers but cant do rear exit and the elbows for side exit all but take up any measurable extension I can add. So far no reversion with this cam. Also considering going to the performer rpm but its not the intake holding this thing back - yet...

1st thing I'd do is make sure you are getting proper fuel delivery.

After that, make sure your tune is on, so many people miss this !

As far as intakes, I always use the RPM or equivalent. Why ? Small light boat I worked on years ago gained 1.5mph with adding a RPM on otherwise stock high hour 260hp Merc 350. did have to add a little fuel to the Quadrajet's secondaries.

As a note, I have never ever ever added that much advance to a cam..so I can not even guess what the actual effect is.

SB- I installed an electric fuel pressure gauge with sending unit after filters right before carb because I was seeing some pressure drop after awhile at WOT. ended up going larger needles and seats and tweaking floats to the rich side but now have a consistent 6.5 psi all the time. I've never went this far advance either in anything other than some old flathead go-cart stuff years ago. I'm thinking there's a point where the motor efficiency drops off and I may have found it.

Have you checked with mechanical fuel psi gauge ? Every electric one I've used read lower fuel psi than the mechanical.

this is an autometer one I had originally for a diesel truck build and never used. It reads a little less than 1/4 psi lower than the mechanical gauge I replaced. BTW that was the 3rd mechanical gauge I bought before I found an accurate gauge when tested against a 1% full dial 15 psi lab gauge. (1st and 2nd were both around 1 psi off new out of box) and yes, I checked calibration of the transducer before installing it with the same lab gauge.

you advance a cam and get better low end at the expense of top end. can you get timing cover off without pulling the engine? it would be interesting to see the diff with that cam straight up.

Just an opinion here, I don't think the 183 cc runner is to big for a 385, I think the cam could be larger, if it's in the motor at 103.5 vs 106 it might be costing you 200 rpm on top, I would picture it to be dead about 5000. You could cut the center of the intake down about 5/8 to make it closer to the RPM manifold. I know nothing about the exhaust, but that may be a big part of your problem, the motor just can't breath.

Timing isn't all in til 4500, that's not what I'd do. You could get a V6 module to use more initial timing, they only add 14 degrees. And they do it by 3000 or 3200 as I recall.
So you could have 18 degrees at idle for 32 all in. Before you go get a V6 module you could just try the one you have at 18 and don't rev it high. That way you could see how it idles and picks up off idle. Some say that 32 is the top end for vortec small block timing.
I'd be interested in whether it acts better with the cam straight up too.
Those pistons are the ones I'd have chosen if I hadn't fallen into the flat top forged stuff I found for a bargain.
Is there room for a skinnier head gasket? If you can get your quench distance down below .045" it will benefit you. You could be on the edge of detonation that you can't hear in a moving boat. Maybe give it a drink of premium before resetting anything. High test fights that.
You can set the valve lash very short and get less probability of lifter pump up at higher rpm. I do that but the lifters I have are the short travel type.
Is your carburetor "right"?

Thought I would update this thread. I still haven't pulled the engine to reset the cam to straight up, but have made several other improvements. First, we rechecked timing and we were only at 32 degrees, not 34. After several runs and plug checks I'm at 35 degrees and picked up considerably in the 3-4000 rpm range. Next, replaced the intake with an airgap rpm from edelbrock. After that it seemed to get up to top speed quicker but I didn't gain any rpm, still done at 4950-5000. So the last time out this fall, we pulled out the Hardin Marine" insert silencers from the exhaust hoses. We instantly gained 450 rpm and 6 1/2 mph. We went up 2" of pitch and gained even more speed. I'm still over-revving for how advanced the cam is, so planning to go another 2" up next time out.

WOW ! good job for checking/testing that.

Please recheck your carb jetting ! I have ran into several cars at the track that the exhaust caused same power loss as in your boat. One took 8 sizes more jet. Fact !

Now, that said, I had everything optimized...including jetting...with the previous joke of exhaust. Finally found the bottleneck in it (of course like you thought it was other things) and the car responded right away. Knowing that the exhaust system is one of the bigger influences of carb jetting I went right to it. 2#'s bigger and it responded. #2 more and it responded. So on and so forth. The other car had less of a bottleneck and took 2#'s bigger jets for best 1/4 mile speed.

So, if you where optimized go 2# bigger (frt and rears) and see what happens. If it picks up speed go 2# bigger. If need be. continue. If it doesn't respond, still check your plugs to make sure.

And thanks for posting your results. I've seen those mufflers and I always guessed that they would cut some power. Thus never used them myself and wouldn't know for real. They look almost like what sticking a potato in your exhaust would do.

http://www.hardin-marine.com/images/...410-284401.jpg

I didn't fully realize he had those inserts in. I've personally documented a 500 rpm loss with those inserts as well. Idle dB cut by 6 but top end rpm by 500. If you want inserts that cut 6 dB but don't limit rpm get the GGB inserts. They sound better and the engine will not be restricted. No fuel changes were required (I run full time AFR).