Valvetrain help AFR 180 Heads
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 16
Likes: 0
From: Niles Ohio
Valvetrain help AFR 180 Heads
I have a set of AFR 180's p/n 0916 that I am working on a rebuild for my L48 motor. Once it goes out to the machine shop it will be a 355 rebuild that is getting splayed caps installed with a scat 9000 cast crank, forged flat top pistons & i-beam rods. Lunati 60111 retrofit hydraulic roller cam 270/278 duration.
The main problem I'm running into is the valve springs that come with the afr heads do not have enough spring rate. I am not comfortable using them after investing this kind of money into a build. Calls to AFR and Lunati have had mixed results, seems like a very grey area to me and not worth the risk over a small amount of money. This car will be mainly a street application not revved past 5,800 rpm.
The valves AFR uses are also 8mm stems and I do not think the lunati retainers and locks will work on them. Will I simply be able to swap the springs out on this and reuse the AFR hardware or will there be an issue?
Cam Specs: http://www.lunatipower.com/CamSpecCa...rtNumber=60111
Stock AFR Spring Info: http://www.summitracing.com/parts/afr-8017
Lunati Suggested Spring Info: http://www.summitracing.com/parts/lun-73943k1
The main problem I'm running into is the valve springs that come with the afr heads do not have enough spring rate. I am not comfortable using them after investing this kind of money into a build. Calls to AFR and Lunati have had mixed results, seems like a very grey area to me and not worth the risk over a small amount of money. This car will be mainly a street application not revved past 5,800 rpm.
The valves AFR uses are also 8mm stems and I do not think the lunati retainers and locks will work on them. Will I simply be able to swap the springs out on this and reuse the AFR hardware or will there be an issue?
Cam Specs: http://www.lunatipower.com/CamSpecCa...rtNumber=60111
Stock AFR Spring Info: http://www.summitracing.com/parts/afr-8017
Lunati Suggested Spring Info: http://www.summitracing.com/parts/lun-73943k1
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
They recommend AFR 8605? if youre running it up over 6. 6200
What pressures do the stock springs have?
Try getting ahold of Jeremy or Tony at AFR they will set you straight. Id bet you could use the retainers etc but double check.
They have good service.
What pressures do the stock springs have?
Try getting ahold of Jeremy or Tony at AFR they will set you straight. Id bet you could use the retainers etc but double check.
They have good service.
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 16
Likes: 0
From: Niles Ohio
I'm more partial to follow what the cam manufacturer calls for because the stock AFR springs seem too light. They may work, but for how long? If they lose any tension at all over time then I think it spells trouble with that cam.
Stock AFR springs are:
Outside Diameter of Outer Spring (in): 1.290 in.
Coil Bind Height (in): 1.050 in.
Damper Spring Included: No
Spring Rate (lbs/in): 360 lbs./in.
Inside Diameter of Inner Spring (in): 0.685 in.
Springs Lunati is calling for their cam:
Outside Diameter of Outer Spring (in): 1.266 in.
Damper Spring Included: Yes
Spring Rate (lbs/in): 462 lbs./in.
Inside Diameter of Outer Spring (in): 0.883 in.
I'm fine with just swapping the springs but the lunati retainers and locks that come with their kit are designed for 11/32 valve stems. AFR uses 8mm valve stems. If the AFR retainers and locks would work with the lunati springs then problem solved, but I have no idea if thats the case or not.
Stock AFR springs are:
Outside Diameter of Outer Spring (in): 1.290 in.
Coil Bind Height (in): 1.050 in.
Damper Spring Included: No
Spring Rate (lbs/in): 360 lbs./in.
Inside Diameter of Inner Spring (in): 0.685 in.
Springs Lunati is calling for their cam:
Outside Diameter of Outer Spring (in): 1.266 in.
Damper Spring Included: Yes
Spring Rate (lbs/in): 462 lbs./in.
Inside Diameter of Outer Spring (in): 0.883 in.
I'm fine with just swapping the springs but the lunati retainers and locks that come with their kit are designed for 11/32 valve stems. AFR uses 8mm valve stems. If the AFR retainers and locks would work with the lunati springs then problem solved, but I have no idea if thats the case or not.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
You have a couple things going on. Less weight valves than stock sbc big stem valve.
Lunati recommends 108# seat because it is such a wimpy low rpm cam.
Our poor oils have caused us to use less spring pressure to keep from flattening out cheap metals used in cam shafts.
The spring pressure at max lift determines whether the valve will float based on the weight of the valve trains inertia.
So to figure it out,,..... Just simple math for an example. 360# per inch spring Installed height of 1.800 inches and you have a cam that lifts the valve .500 inches Your installe 1.800 has 100# seat pressure at .500 lift it gains 1/2 of the 360 = 180 So you have 280 #@ .500 lift
do some thinking on your own and look at the spring pages on Comp cams web sight. around page 300
It is not rocket science.
Lunati recommends 108# seat because it is such a wimpy low rpm cam.
Our poor oils have caused us to use less spring pressure to keep from flattening out cheap metals used in cam shafts.
The spring pressure at max lift determines whether the valve will float based on the weight of the valve trains inertia.
So to figure it out,,..... Just simple math for an example. 360# per inch spring Installed height of 1.800 inches and you have a cam that lifts the valve .500 inches Your installe 1.800 has 100# seat pressure at .500 lift it gains 1/2 of the 360 = 180 So you have 280 #@ .500 lift
do some thinking on your own and look at the spring pages on Comp cams web sight. around page 300
It is not rocket science.
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
Your using high quality parts in your build which is outstanding! Double check if that cam is ground on a billet core.When I did my retro roller swap I found most cams are cast..I went with a Crane Cams billet core with a pressed on iron distributor gear.Also running a Howards polymer fuel pump pushrod because I heard the bronze tip ones don't last...You can't run a regular fuel pump pushrod on a billet cam.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I just put in a Howard's retro HR cam, 280* advertised duration with AFR 195's. I contacted AFR and asked if their springs would work with the cam. As the recommended spring rate from Howards was close to the spring rate on the 195's I used the already installed springs. 462 lbs/in seems to be overkill for your cam.
Pro
Joined: Jun 2010
Posts: 535
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From: CA
I just put in a Howard's retro HR cam, 280* advertised duration with AFR 195's. I contacted AFR and asked if their springs would work with the cam. As the recommended spring rate from Howards was close to the spring rate on the 195's I used the already installed springs. 462 lbs/in seems to be overkill for your cam.
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Melting Slicks
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From: Sacramento California
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2018 C2 of Year Finalist
Had a 1976 L-82, 4-sp
Joined: Mar 2011
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Le Mans Master
Joined: Aug 2010
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From: Central Texas
Tiger80,
I like that combination. I'm going with something similar for my build. What rear axle ratio and transmission are you running? Give me a heads up when you get it running. I'd love to know how it turned out.
I like that combination. I'm going with something similar for my build. What rear axle ratio and transmission are you running? Give me a heads up when you get it running. I'd love to know how it turned out.
Race Director
Joined: May 2005
Posts: 10,674
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From: Millington Illinois
St. Jude Donor '08-'09
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 16
Likes: 0
From: Niles Ohio
Street Rat, I have a 4 speed manual with the 3.07 rear end. I'm thinking a lower rear end might be needed next but I want to see how it runs first because this car is still used to cruise around on the highway and make 500 mi trips on occassion. Don't want to totally ruin mileage and have it turning 3,500 rpm at 70mph or something.
63mako, That's a good point on the 8019 springs. Very close to the lunati recommended springs specs. I would be comfortable running those. I will call AFR for pricing on that route. I don't think places like summit even offer a spring upgrade anymore. Would probably have to come straight from AFR. Anyone have any experience with that?
63mako, That's a good point on the 8019 springs. Very close to the lunati recommended springs specs. I would be comfortable running those. I will call AFR for pricing on that route. I don't think places like summit even offer a spring upgrade anymore. Would probably have to come straight from AFR. Anyone have any experience with that?
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Street Rat, I have a 4 speed manual with the 3.07 rear end. I'm thinking a lower rear end might be needed next but I want to see how it runs first because this car is still used to cruise around on the highway and make 500 mi trips on occassion. Don't want to totally ruin mileage and have it turning 3,500 rpm at 70mph or something.
63mako, That's a good point on the 8019 springs. Very close to the lunati recommended springs specs. I would be comfortable running those. I will call AFR for pricing on that route. I don't think places like summit even offer a spring upgrade anymore. Would probably have to come straight from AFR. Anyone have any experience with that?
63mako, That's a good point on the 8019 springs. Very close to the lunati recommended springs specs. I would be comfortable running those. I will call AFR for pricing on that route. I don't think places like summit even offer a spring upgrade anymore. Would probably have to come straight from AFR. Anyone have any experience with that?
