Head Question
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
Head Question
I am getting a set of vortec heads from summit. The gm performece web site says that The maximum camshaft lift is .475. I am going with the lunati voodoo 60101 cam here are the specs
Duration at 050 inch Lift: 213 int./219 exh.
Advertised Intake Duration: 256
Advertised Exhaust Duration: 262
Advertised Duration: 256 int./262 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.454
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.468
Valve Lift with Factory Rocker Arm Ratio: 0.454 int./0.468 exh. lift
My question is this cam going to work with these heads.
Duration at 050 inch Lift: 213 int./219 exh.
Advertised Intake Duration: 256
Advertised Exhaust Duration: 262
Advertised Duration: 256 int./262 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.454
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.468
Valve Lift with Factory Rocker Arm Ratio: 0.454 int./0.468 exh. lift
My question is this cam going to work with these heads.
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
I guess part of the reason for posting is that the cam lift is approaching the max lift of the stock vortec springs. I would believe that the cam will be pretty much on the money. The max lift on the heads may be worse case senario or perhaps an average lift.
The cam I choose for my vortec heads has .458 lift. Close but should work. I decided at the last minute to change valve springs just to be on the safe side. I'm now good for .525 or .550 lift. Should I decide to go with a bigger cam, I won't have to worry about the springs. Don't ask me why but the springs are somewhat pricey, list for about $150 a set and made by Crane. I feel that anytime a componet is used at it maximum rating, a problem down the road may occur sooner than later. I don't understan why GM doesn't provide springs for .500" lift cams for the stock Vortec heads.
Perhaps Lunati has some data that they could share with you.
The cam I choose for my vortec heads has .458 lift. Close but should work. I decided at the last minute to change valve springs just to be on the safe side. I'm now good for .525 or .550 lift. Should I decide to go with a bigger cam, I won't have to worry about the springs. Don't ask me why but the springs are somewhat pricey, list for about $150 a set and made by Crane. I feel that anytime a componet is used at it maximum rating, a problem down the road may occur sooner than later. I don't understan why GM doesn't provide springs for .500" lift cams for the stock Vortec heads.
Perhaps Lunati has some data that they could share with you.
Pro
Joined: Aug 2003
Posts: 530
Likes: 0
From: Victoria Texas
The thing to look out for is the retainers hitting the top of the valve guides. You have to cut the top of the guide down if you go over .480 lift, no matter what spring you run.
My friend thought he would be OK with a .485/.490 lift cam, he got the engine started and once the lifters pumped up he bent several push rods and shoved several push rods through the top of the rocker arms before he got it cut off, he had the guides cut down and has had no problems with it so far.
Bad part of the story is he told the machine shop the cam he was using and to set the haeds up for it.
The good part is the shop made good on all the parts to fix it and repair the heads, he did loose his labor for the tear down.
Good point to always check things and not assume it is ok.
My friend thought he would be OK with a .485/.490 lift cam, he got the engine started and once the lifters pumped up he bent several push rods and shoved several push rods through the top of the rocker arms before he got it cut off, he had the guides cut down and has had no problems with it so far.
Bad part of the story is he told the machine shop the cam he was using and to set the haeds up for it.
The good part is the shop made good on all the parts to fix it and repair the heads, he did loose his labor for the tear down.
Good point to always check things and not assume it is ok.
Last edited by Skid*MARK; Oct 11, 2005 at 01:56 AM.
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
Originally Posted by Skid*MARK
The thing to look out for is the retainers hitting the top of the valve guides. You have to cut the top of the guide down if you go over .480 lift, no matter what spring you run.
The Crane kit is more than the springs. It also had new retainers.
Last edited by mandm1200; Oct 11, 2005 at 11:09 AM.
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Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
Are you saying the Lunati kit is coming with new springs (and retainers)? Many cam kits only come with cam, lifters, and lube. If so, they may have already addressed the potential problem of the factory springs/retainers.
The Crane kit I was referring to was springs and retainers made for vortec heads for cams with higher lift that the stock setup supports. http://store.summitracing.com/defaul....asp&x=36&y=10
The Crane kit I was referring to was springs and retainers made for vortec heads for cams with higher lift that the stock setup supports. http://store.summitracing.com/defaul....asp&x=36&y=10
