New Cam For Ram Air Heads
 

I have a Pontiac 400 with standard block. L2262 pistons, 60599 round port Edelbrock aluminum heads.
Upgrading from 2157 Edelbrock cam to a Lunati Voodoo 703 cam.
What kind of problems could I run into with this swap.
Thanks for helpful advice.
Ready To Rumble!!!!!

Should be a hot rod. The 204/214 cam that’s in it is woefully small.

Valve spring wise the E heads will have no problem with the lift of the 703 Cam with 1.5 factory ratio rockers, but you will need to play with factory Q-jet a bit in terms of that Cams idle vacuum.

I have the Edelbrock 1411. 1.5 roller rockers. The heads are the 72cc.

"Valve spring wise the E heads will have no problem with the lift of the 703 Cam with 1.5 factory ratio rockers..."

How about the catalog stated 120 lbs spring pressure ? If that is in fact where they are at.
And the 0.181" away from coil bind ?
Your opinion on those.

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I'd probably be asking Paul what kind of pressure he likes to see on those voodoo cams, he's setup more of those and has more dyno time on them than anyone I know.

X2


Personally I would not trust what a cam salesman would dictate, nor any general spring pressures listed on the Lunati website.

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Right. Called Lunati tech. They said the cam would work with the heads however I have had problems with tech advice from companies over the phone.

That may get you in the ball park and be fine for what you're doing but I tend to want to listen to the guys that build and dyno these things for a living as to what works best. I know Paul taylors the spring pressures to what controls the valves the best based on his testing and experience, and it's not always what the cam manufacture recommends.

He probably even has experience with these heads. What's the best way to contact him?

Best way to contact him may be a PM through the site here. GTOfreek.

He runs a shop in Tucson and he's extremely busy so might take some time for a response.

Thanks. PM sent.

So there out of the box spec state that the springs are good for .575" lift and granted they not the best springs in the world, also I have never kept track of how there pressure drops off after a given number of rev's to 6K , but they should live for 20'000 miles I would hope if your not smaking them with over .500" lift

The Edelbrock head experts are saying that they have no problem (not having problems) with the springs Edelbrock installs in their preassembled heads.

The only way to know for sure is to remove a spring and retainer and check them. Everything else is an assumption that things will work fine.

When I build engines here, even if the heads are supplied from the owner or we get heads from another source, I take a couple of springs off and check some things out. First you need to make sure there is adequate clearance between the top of the seals and the bottom of the retainers.

Check the springs at the installed height for seat pressure, then compress them to the intended lift and check open pressure. Continue to compress them until the "stack" solid, then back them up apprx .080". This tells you the maximum running room for the springs and it should be greater than the lift at the valve from the cam you are using.

I don't run a "butt-load" of spring pressure on my street engines as a general rule, but pay very close attention to geometry and the items mentioned above.

I'm sure Edelbrock set those heads up with enough spring pressure and room for a .500" lift flat hydraulic cam, but I'd still check everything to make sure.........Cliff

For those who may be curious I just dug out a near virgin set ( like 15'000 miles ) of 6X-4 heads and here's the spring spec.
Intake seat pressure = 115
Exh seat= 110
Intake coil bind=.490"
Exh coil bind= .520"

I noticed on the question and answer section on the cam sales page that someone asked about using the cam with those heads. The answer from Lunati was they needed to change the springs and gave a part number.
These ram air heads are so different than original D ports though. I don't think much cross references.
I specifically asked the Lunati tech on the phone about it and he said there wouldn't be a problem.
I'm hearing enough positive reports to try them out.

I ran a Crower solid flat cam that had near .550” lift with 1.65 rockers with the stock Edelbrock springs with no problem. I only shifted at 5500-5700 though.

Like others said they aren’t the best springs but they work ok for a broad range of mostly street applications. They are a single spring with a flat damper. At least the ones that came with my heads were.

If you want a decent upgrade the Lunati 73100 springs work well. They are the same OD and when installed at Edelbrock’s standard 1.8” height gave around 135# seat pressure on my heads.

Great info, thanks.
These;
https://www.jegs.com/i/Lunati/638/73...RoCW0QQAvD_BwE

Yep, those are the ones. I used the Edelbrock retainers and spring cups.

Anything to update?

Stan

It's cam break in day.

Break in procedure completed. There is some lifter noise. Small tick.

Lunati says to check lift and see if it lost any.

Started it up again to see what it sounds like. Not really a tick. More like just a little more valve noise than I'm used to with the small cam that was in it. Could this be normal? Do big cams make the valves make more noise? Would there be a sound change after moving to a bigger cam?

Can you post a video?

Video link;

https://share.icloud.com/photos/05b1...r_Township,_MI

Are you push Rods all spinning well by 1200 rpm?

I haven't taken it back apart. Trying to decide if this is normal or not. Thanks for the great suggestion. It will be my first stop if I take it back apart.

Here is a link to a video where I put my phone right on the valve cover. Normal, not normal, any thoughts? https://share.icloud.com/photos/00pa...r_Township,_MI

Now I'm getting a backfire out the intake. Video link to that below;

https://share.icloud.com/photos/0rvT...r_Township,_MI

Took the covers off and everything looks normal. No lock nuts backed off. All the nuts have pools of oil in them.

An intake pop like that just about has to be springs.

From the video I don't hear excessive valve train noise.

Intake pop could be ignition timing off, lean A/F or poor valve adjustment.

I tried changing the timing and the intake backfire did not change.

The valves are adjusted properly. Not that hard and I took my time.

Doesn't seem like a carb adjustment. Seems like the valves are not getting held on their seats since the cam change. Didn't backfire before the cam change.

The springs are an unknown.

What would be the best springs for this application?

"The springs are an unknown"

I thought it was stated at the very start of all this they were the valve springs as delivered from Edelbrock !

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Pull the plugs and check them all,double check all of plug wires for tightness on distributor and plugs. What is your timing set at ?

This is a hydraulic cam?
Adjustable locking nuts on rockers?


I'd back each intake adjuster nut off by 1/2 turn and see what it does?


:confused:

Regarding the valve springs. You stated the cylinder heads were, quote.... "The heads are pre-assembled ones"

And weeks ago I suggested they were the single valve springs with no damper, p/n 5767.

If in fact they are installed at 1.800" then Edelbrock rates them at 120 lbs on the seat. And as already suggested they should of been tested.


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I checked all the easy stuff.

The heads were bought back in 2003 by the previous owner who is deceased. I can't ask him if the springs were changed. Even if they are original they are unknown.

What I would like to do is change the springs to something that works with these heads and the cam. Something better than what was on these heads originally.

I have one recommendation earlier in the thread. Can I get some confirmation on that? Thanks.

I don't have a tester and the shops around here are busy until summer, maybe fall.

So what springs do you recommend? Thanks

Good info on the spring upgrade. Can anyone see why the Lunati 73100 springs wouldn't be the best for this application?

You need to know what the installed height is for the valves to figure out the springs needed.
Then need to know the lift of the cam, the manufacturer's recommended seat/open pressures for it.
Then check for coil bind then retainer to valve guide clearance.


:)

I was hoping that someone had done this with these heads by now and had the springs all figured out. They have been out a long time now. These were purchased 15 years ago.
Thanks for your help.

"Can anyone see why the Lunati 73100 springs wouldn't be the best for this application?"

Evaluate that spring installed at 1.800 with 0.489" valve lift. How far is it away from coil bind ?


Potential for spring surge ? Is it only a race thing? ..... from Comp Cams, "Anything more than 0.150 inch may cause spring surge, which can greatly reduce the available spring load needed to close the valve."

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You are saying I need a spring that is closer to coil bind. Between .150 and .060 to be just right, not have coil bind or spring surge.

What springs are out there that fit that range with the 1.800 installed height? Needing one with around a 1.150 coil bind.

How about Comp Cams 986

1.430 Dual Spring 120 @ 1.780, 280 @ 1.250, Coil Bind @ 1.150 (Set)

http://knuckledraggin.com/wp-content...he-popcorn.gif



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Springs are not your problem. Distributor and carburetor are. You have a lean intake backfire when opening the throttle and probably too much advance. In your videos, you are not revving high enough to enough consider valve float.

I am still running the same Crane springs I installed in in the late 90's. Last rebuild I checked a spring and they were within 5% of new. Your Edelbrock springs have never even been run and you are only revving to around 3,000 RPM in the vid and your back fire occurs off idle.

When you whack the throttle, your carb is gulping air and doesn't have enough fuel to compensate. It pre-ignites and backfires through the carb. If there is any kind of accelerator pump or power valve/piston adjustment on that Edelbrock carb, you need to sort that out.

Important! I noticed valve train noise in the first place. It didn't sound right. You might not be able to hear it in the video but I could hear it. Something is wrong.

The carb; works perfect on another vehicle.

The timing; Tried moving the timing and the backfire out the carb is the same.

The springs; They can go bad for various reasons. We drove the car for 10 years now with the timing chain two teeth off because of how the previous owner installed it. About 10 tanks of gas a year. Plus the single springs on there were set up too far from coil bind. They could have easily gotten hot an annealed, lost their seat pressure.

There's no reason not to change the springs. None.

I would like to move forward with some new springs and would like some help getting just the right ones. Valve springs are one of the most important things in an engine for performance and the ones I have in these heads right now are far from optimum, especially with the new cam.

Thanks for your ideas.