Lunati Voo Doo Cam.

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hux340

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G'day All,
Wanted my 71 340 Demon to go faster. Couldn't afford a strip down, so I went bolt on stuff.
Did the following -
750 Holley DP
Elderbrock dual plane air gap performer inlet manifold.
Bigger cam, (see cam card below).
Doug's ceramic coated full length headers.
Will be in the near future adding Elderbrock alloy heads & MSD dist.
Opinions appreciated.

IMG_0696.JPG
 
I have the same cam and basically everything else. I have had a slight tick since the install. I recentlly found a bad lifter. The cam sounds great. I may have some other issues as well.The car is not performing as it should. Now I know why. My advice to you is to seek a knowlegeable person you can trust to make sure everything will work together. I thought my pushrods were to short. They are not. Lunatis tech people are no help at all. Border line rude. I bought the entire kit. Cam,lifters,valve springs. It is very frustrating. Hope you have better luck than me. Next I will be checking the valve springs yo make sure they are not bottoming out. Good luck.
 
Hi m8, that sux. My 340's running sweet as & I also agree with the cam, it sounds tough as.
 
Did you use your stock push rods and rocker arm assembly?
 
I have the same cam and basically everything else. I have had a slight tick since the install. I recentlly found a bad lifter. The cam sounds great. I may have some other issues as well.The car is not performing as it should. Now I know why. My advice to you is to seek a knowlegeable person you can trust to make sure everything will work together. I thought my pushrods were to short. They are not. Lunatis tech people are no help at all. Border line rude. I bought the entire kit. Cam,lifters,valve springs. It is very frustrating. Hope you have better luck than me. Next I will be checking the valve springs yo make sure they are not bottoming out. Good luck.

Hydraulic lifters these days suck! Had a 408 with lifter issues. Brand new engine and the lifters would clatter on start up.

Are you running adjustable rockers?

Hi m8, that sux. My 340's running sweet as & I also agree with the cam, it sounds tough as.

What compression are you running?
 
The noise doesnt go away. No. Stock rockers.
 
The noise doesnt go away. No. Stock rockers.

Have you checked for valve retainer to valve guide clearance? I've read on here that .520 is just about max for uncut LA heads. You have .533 lift on the exhaust side... might want to check clearance. Not saying for sure but might be the noise you're hearing.

Guessing it's according who you talk too...LOL... but with the lift you're running... if it was me I would definitely go adjustable roller rockers. I had a push rod bust straight through two of my stock rocker arms running a .474 lift cam. After that I went adjustable roller rockers.
 
G'day All,
Wanted my 71 340 Demon to go faster. Couldn't afford a strip down, so I went bolt on stuff.
Did the following -
750 Holley DP
Elderbrock dual plane air gap performer inlet manifold.
Bigger cam, (see cam card below).
Doug's ceramic coated full length headers.
Will be in the near future adding Elderbrock alloy heads & MSD dist.
Opinions appreciated.

That cam likes 10:1 to 11:1 compression
You're heading in the right direction with your build
 
Also if your running a automatic you'll want a higher stall converter to match that camshaft
 
Do you have a automatic or 4 speed? Rear gear and tire size? Like stated before, You will need a high stall converter and/or steeper rear gears to make a bigger cam work.
 
Hydraulic lifters these days suck! Had a 408 with lifter issues. Brand new engine and the lifters would clatter on start up.

Are you running adjustable rockers?



What compression are you running?
Hey Mulley. Long time no see.
 
I've been for a little while now...LOL
And with a new Avatar I might add......
G'day All,
Wanted my 71 340 Demon to go faster. Couldn't afford a strip down, so I went bolt on stuff.
Did the following -
750 Holley DP
Elderbrock dual plane air gap performer inlet manifold.
Bigger cam, (see cam card below).
Doug's ceramic coated full length headers.
Will be in the near future adding Elderbrock alloy heads & MSD dist.
Opinions appreciated.

View attachment 1715195967
Classic cam size for a good strong street engine.
As long as your converter and gears match up, you’ll be in good shape.
 
Cam is right between Comps 274 and 284 HL hyd cams
did you check your geometry retainer to lifter interference
you will have to check your geometry with roller tip rockers and raise your shafts and new pushrods to make the roller tip rockers work right- no nearly so much with iron adjustables figure the costs- roller rockers are not cheap and should not be necessary with that lift
 
OP, if the engine has never been touched, let's assume that your 340 has the early high compression pistons. If it has ever been rebuilt, then we don't know what pistons you have in there, and CR in that situation will be a pure guess.

The early 340 pistons protrude about .018" above deck. So, there are 2 options on the heads:
  • If you select the closed chamber versions (PN 60779), you will have to use a thicker head gasket to make sure those pistons do not come too close to 'closed-off', flat areas on the new heads. A standard Felpro 8553PT head gasket at .051" thick would do that with a bit over .033" nominal piston to head clearance, AND give you the bonus of a tight quench gap between pistons' tops and the flat 'closed' areas on the new heads. BUT you'll need to measure each piston above deck and make sure you don't get much less piston-to-head clearance on any one cylinder. Running down in the low 30's for piston-to-head clearance is about the minimum safe limit for the street and with unknown parts, and any variations in parts, like a longer than standard rod length, will make the piston-to-valve clearance too tight. You don't want to risk a piston-to-head collision. You could run a slightly thicker custom head gasket if you want to bear the expense.
  • The other option is to use the 60179 Edelbrock heads with the milled 'open' chambers. That head with the Felpro 1008 head gaskets will put your at about the same CR numbers. You won't have a quench gap in that setup but it will be safe from any piston-to-head collisions.

Static CR for the 2 setups above and stock early 340 pistons will be right around 10:1. Dynamic CR will be right at 8 with that cam, installed with the timing dot-to-dot. So that actually works out pretty well.

Take precautions with that new distributor and the new heads, and watch the total mechanical + initial ignition timing advance. It will likely not be happy if you push the total much past the low 30's; and it does need to be any more with that higher CR. Your overall tuning needs to be better with that level of DCR.

Depending on where you rev the engine, the standard Edelbrock valve springs are going to marginal IMHO with this cam and the lift.

Make sure you check piston to valve clearances; it will probably be just fine but don't take any chances.
 
G'day All,
Wanted my 71 340 Demon to go faster. Couldn't afford a strip down, so I went bolt on stuff.
Did the following -
750 Holley DP
Elderbrock dual plane air gap performer inlet manifold.
Bigger cam, (see cam card below).
Doug's ceramic coated full length headers.
Will be in the near future adding Elderbrock alloy heads & MSD dist.
Opinions appreciated.

View attachment 1715195967

That’s the same cam I run in the 340 in my Duster. My set up is a ‘68 340 that’s .060”, 9.8:1 compression, eddy rpm air gap intake, 750 double pumper, Doug’s headers, and ported 308 heads flowing 264cfm @.500” in front of an 833 with 3.55 gears and 26” tall tires out back. Some observations

- the cam is noisy. Lunati’s have fast ramps, and they can make for a noisy valve train. Also, the lunati lifters aren’t great. I also use crane adjustable ductile rockers and Smith Bros push rods, and at some point I will ditch the lunati lifters

-3.55 gears with 26” tall tires is probably the minimum gearing for the cam. Even with a 3.09 1st gear it’ll lug if you’re not on the throttle quick at take off. It really wants a 3.73 or 3.91, but I can’t do the freeways around here with those gears

-there isn’t a ton of idle vacuum, so if you have power accessories you may need a reservoir. I only have about 10” of vacuum at idle, but everything is manual on my car

-above 3,000 rpm it’s a rocket ship. Below 2,000 rpm there isn’t much there. When I go T56 I’ve got 4.30’s for it, you don’t want to set up your cruise RPM much below 2,500. It won’t cruise below 2k without lugging it

Now, I’m not some engine builder or tuning master, that’s just what I’ve found with mine and I won’t claim to have the best set up. I do have a wideband on it, so it is tuned decently well because I can see the air/fuel ratio all the time. Honestly, for what I do with my car the 10200703 would probably br easier to drive. I would have to lower the compression a smidge with a thicker head gasket though if I did that, as I’m already on the verge of detonation with the 91 octane fuel here.
 
Na your compression with a 1020073 cam would be fine. That's the cam I run on the street and I sure would not go any bigger for a street car. 360 (.30 over) 2400 stall, 3.55 gear, P/S P/B and A/C all work fine. I do run 93 octane but can get away with 91.
 
Na your compression with a 1020073 cam would be fine. That's the cam I run on the street and I sure would not go any bigger for a street car. 360 (.30 over) 2400 stall, 3.55 gear, P/S P/B and A/C all work fine. I do run 93 octane but can get away with 91.

No, it wouldn’t. I’ve already pulled a few degrees of timing out of my current set up because of detonation. Maybe with aluminum heads I could pull it off, but I know for sure it wouldn’t work with the iron heads I have now, because even with the 10200704 I get detonation unless I pull timing.
 
Some chamber polishing might help. I'll venture to guess that no quench and the slower overall burn rate in the open chamber are probably what is limiting the CR for you. (I also wonder if a manual trans set-up will be less forgiving.)

I was gonna ask about ignition timing but you have addressed that. Have you slowed the rate of adding in the mechanical advance? (I.e., heavier springs...)
 
Some chamber polishing might help. I'll venture to guess that no quench and the slower overall burn rate in the open chamber are probably what is limiting the CR for you. (I also wonder if a manual trans set-up will be less forgiving.)

I was gonna ask about ignition timing but you have addressed that. Have you slowed the rate of adding in the mechanical advance? (I.e., heavier springs...)

Chambers were cleaned up some when the larger 2.02/1.60 valves were added and the porting was done. They're not polished, but they aren't exactly stock either. I run KB243's that are .018" over the deck, which is why I run the open chambers, so the quench is not ideal. The manual transmission doesn't help, and the 3.55 rear gears add to that. If I had 3.91's it would probably be less of an issue. Timing is set up at 20* initial, it's at 34* all in mechanical with no vacuum advance. I pulled it back from 36* all in. I use a Mallory Unilite distributor, I forget the exact spring combination because I ordered a few different spring kits to play with, but I set it up to start advancing about as late as I could. All in mechanical is about 2,800. Cranking pressures on my 340 are 175-180 psi.

I've messed around with the tune quite a bit. Again, I'm not saying it's perfect or anything. It doesn't detonate the way it's set up now, but, there isn't a whole lot of "wiggle room". I'm pretty sure I couldn't step down on the cam without dropping the compression a little, say 9.5:1. But that's just what I've encountered with my engine, I'm sure it's possible to get away with more. I just don't think I can with my engine.
 
It's a 4 spd car so that's good, no auto/converter issues. Put plenty of initial timing on it and tailor the curve to hit a decent total number.

Good camshaft. Make sure the springs and rockers are OK with it.
 
Im running 3.91 gears, 15 inch tires. Not 100% sure on converter. I think its 3000. Gonna check that also. I used brad penn break in oil. Trust me, I tried to do everything by the book.
 
Do you have a automatic or 4 speed? Rear gear and tire size? Like stated before, You will need a high stall converter and/or steeper rear gears to make a bigger cam work.
Got a A833 with 3.23 rear gears as I live in the country & half my driving is doing 65 mp/h. I know the 3.23's are letting me down. Rear tyres are 255/60/15's.
 
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