Lunati 704
- Thread starter moparker
- Start date
-
OldmanRick
Well-Known Member
If you've got the recommended springs, i doubt that's the problem.
Has this been a ongoing issue, or a recent development? What are the symptoms that lead you to think this?
Are you getting noise upstairs, or is the car bucking/surging near the shift points? Do you have stock rockers or adj. and what are your shift points.
My first thought was you may have too much preload, but it could be several things and some more info would only help.
Has this been a ongoing issue, or a recent development? What are the symptoms that lead you to think this?
Are you getting noise upstairs, or is the car bucking/surging near the shift points? Do you have stock rockers or adj. and what are your shift points.
My first thought was you may have too much preload, but it could be several things and some more info would only help.
So I run the Lunati 704 in the 340 in my Duster. I’m not some engine guru, so take all of this knowing I’ve only built a few engines and my 340 definitely had some hiccups. Initially I tried to run it with single springs on the advice of the guy that did the machine work on my heads. I wiped out a set of Harland Sharp rockers that way. Not enough spring for that cam. Maybe it’s possible, but it didn’t work for me.
I had my heads cut for doubles and run the recommended Lunati springs now. Not sure what you’re running for lifters, but the Lunati lifters that come with the 704 are their “performance replacement” lifters with the wire clip retainer. They worked fine for quite awhile, but then I started having issues with them collapsing. I replaced them with the Lunati Micro-trol lifters, they have a c-clip style retainer and are their higher performance lifter. So far those have been holding up well.
Lunati’s have pretty fast ramps, and the 704 in particular seems to be pretty tough of valve train parts. Now that I’m running it with the micro-trol lifters, Smith brothers push rods and Crane ductile iron rockers it seems to be happy.
These are the lifters I’m running now. Unfortunately it looks like they’re not available anymore…
Lunati 71977-16 Lunati Micro-Trol Hydraulic Lifters | Summit Racing
I had my heads cut for doubles and run the recommended Lunati springs now. Not sure what you’re running for lifters, but the Lunati lifters that come with the 704 are their “performance replacement” lifters with the wire clip retainer. They worked fine for quite awhile, but then I started having issues with them collapsing. I replaced them with the Lunati Micro-trol lifters, they have a c-clip style retainer and are their higher performance lifter. So far those have been holding up well.
Lunati’s have pretty fast ramps, and the 704 in particular seems to be pretty tough of valve train parts. Now that I’m running it with the micro-trol lifters, Smith brothers push rods and Crane ductile iron rockers it seems to be happy.
These are the lifters I’m running now. Unfortunately it looks like they’re not available anymore…
Lunati 71977-16 Lunati Micro-Trol Hydraulic Lifters | Summit Racing
High rate springs will not collapse lifters at high rpm; they could collapse lifters at low rpm because there is more time. You should use dual springs or singles with a damper, both are designed to reduce spring surge which can cause lifter pump up at high rpm. Beehive or conical springs are another alternative [ & a very good one ] because their lighter weight & design allows for less tension, reducing valve train wear & stress.
moparker
Well-Known Member
- Joined
- May 25, 2008
- Messages
- 2,492
- Reaction score
- 663
I have had valve train noise since install. Not on break in with the singles. At 2200rpm I get ticking .It sounds like the valves. Not a lifter tick. Many others with this cam have complained of the same issue with this cam. Car is quiet on start up. After warm up it starts. Runs fine. However the other day I put my foot in it and seemed like I lost power. It seems runs stronger with not full throttle. Motor was rebuilt 2 years ago. Did 800 mile easy break in. I am running comp cam lifters, factory rocker arms. The lunati lifters failed. Thats why I switched lifters. Tried adjustable rockers. No change. I dont race my car. Like to drive it and occasionally put my foot in it. 71 340, .30 over, Holley 750dp, 2800 stall, 3.91 gears, headers.
moparker
Well-Known Member
- Joined
- May 25, 2008
- Messages
- 2,492
- Reaction score
- 663
Maybe I could get them from Lunati. Summit quit handling Lunati products.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 24,922
- Reaction score
- 12,274
That sounds more like carburation....
unless the cam is dropping lobes.....
or your imagination is working overtime,lol.
Advertised Duration (Int/Exh): 276/284;
Duration @ .050 (Int/Exh): 234/242;
Gross Valve Lift (Int/Exh): .513/.533;
LSA: 110
So my 340 is .060” over, 9.8:1 compression, 308 heads ported and flowing 264 cfm at .500”. Originally a 4 speed with 3.55’s and now a T56 with 4.30’s, the 3.55’s just weren’t enough for the cam. 750 DP. Street car that’s getting pretty close to 40k miles now, the original Lunati PR lifters lasted until around 30k miles or so when I had a couple collapse and just never pump up again.
I’ve had adjustable rockers on it the whole time. The valve train has always been loud, it’s not a specific noise or tick at any speed it’s just louder than your typical hydraulic cam. Honestly sounds more like a solid lifter set up than it does hydraulic. And I’ve played around with the lifter preload (within reason), loose or tight doesn’t seem to change the noise significantly.
I didn’t trust the stock stamped rockers for that much spring, which is the reason I run the adjustables.
I like the cam, it’s a little too much for how much I use my car on the street but power hasn’t ever been an issue. It’s a rocket ship above 3k rpm, although it drops off pretty fast under 2,500 rpm. But between the cam, head porting and large carb it’s not surprising.
Huh. I know they’d been having supply issues, I didn’t know Summit had dropped them.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 24,922
- Reaction score
- 12,274
It kindof depends on if there have been changes to; your operating elevation, or the ambient temperature. Lemmee see if I can remember this right; A change of 2000ft or 30*F, is one jet size.
I have a Hughes cam advertised at 276/286@ .008 tappet rise =230/237 @.050 on a 110, with a lil more lift, in a 367+.040=367 so similar to your 340=.030=345. At 930 ft elevation, I run 78/86 Holley jets in an ancient 750DP on an Airgap with TTIs and a dual 3" system.
As to the noise, don't forget that the pushrods can occasionally rub on the tunnels. AND, with stock 318/360 rockers it is possible for the rockers to rub on the retainers; not so much with the clearanced 340 rockers...... but with the lift over .500 you gotta check.
moparker
Well-Known Member
- Joined
- May 25, 2008
- Messages
- 2,492
- Reaction score
- 663
It does sound like a solid lift. I played around with preload also. Well, at least I know running singles isn't a good idea. I will keep observing and keep you guys posted. They way I understood it, Summit just dropped them due to some quality issues.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 24,922
- Reaction score
- 12,274
On My Hughes HE3038AL cam; Cam specs were;
276/286/110advertised (.008 tappet lift), and 230/[email protected] , and lifts of .549/[email protected] arms
The recommended springs were HUG1129, and these have been working fine on the Hughes supplied HDlifters since 2004@ preload of 1/2 turn. I regularly shift at anywhere between 6000 and 7000, and up to 7200 on the limiter. I reset the preload about every Second year, and they are dead-quiet again.
Sorry, I do not recall the lifter number other than it was NOT the 5001. At that time (2004), Hughes only sold the two small-block lifters; namely standard and HD. Mine have the circlip retainers and are NOT variable duration. They were only a little more expensive than the standards. Hope this helps;
HUG 1129 DUAL VALVE SPRING SB ,
145# @ 1.800" / 358# @ .550" LIFT (PAC SPRING)
Like I say, I take mine to 7000 and beyond just because it sounds so great.
276/286/110advertised (.008 tappet lift), and 230/[email protected] , and lifts of .549/[email protected] arms
The recommended springs were HUG1129, and these have been working fine on the Hughes supplied HDlifters since 2004@ preload of 1/2 turn. I regularly shift at anywhere between 6000 and 7000, and up to 7200 on the limiter. I reset the preload about every Second year, and they are dead-quiet again.
Sorry, I do not recall the lifter number other than it was NOT the 5001. At that time (2004), Hughes only sold the two small-block lifters; namely standard and HD. Mine have the circlip retainers and are NOT variable duration. They were only a little more expensive than the standards. Hope this helps;
HUG 1129 DUAL VALVE SPRING SB ,
145# @ 1.800" / 358# @ .550" LIFT (PAC SPRING)
- Installed Height/Pressure: 1.800"--145#
- Pressure @ .550" lift: 358#
- Pressure @ .600" lift: 375#
- Coil Bind: @ .750" lift
- Outer Spring ID/OD: 1.085" /1.459"
- Inner Spring ID/OD: .800" / 1.078"
- Type of Spring: Dual
Like I say, I take mine to 7000 and beyond just because it sounds so great.
Last edited:
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 24,922
- Reaction score
- 12,274
IDK man; 234/242/110 is pretty big for street in an iron-headed 345. But you got most of it covered with the 2800/3.91s.
Yup, the 704 is a lot for a street car. It’s street manners are very much “drive it like you stole it”. Doesn’t like to take off slowly, not real big on idle vacuum. But it really comes alive once you go past 3k.
moparker
Well-Known Member
- Joined
- May 25, 2008
- Messages
- 2,492
- Reaction score
- 663
-
