Lunati Voodoo hyd roller small block build
08-03-2017, 07:46 PM
#21
Registered
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"?
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"?
Last edited by NHGuy; 08-03-2017 at 08:25 PM.
10-12-2017, 05:02 PM
#22
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.
10-12-2017, 05:58 PM
#23
Registered
iTrader: (1)
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.
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.
10-14-2017, 03:15 PM
#24
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).
