Need Help:Valve Train upgrade for LT4?
Thread Starter
Melting Slicks
Joined: Jan 2000
Posts: 3,418
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From: NW Chicago Suburbs
Need Help:Valve Train upgrade for LT4?
I'm finally installing my headers. While I'm at it I'll put my Hurst line loc and Harlan shift light. Time for some sub 13 second runs!
I'm also upgrading my valve train, here's what I was thinking:
Comp Cam 26918 bee hive valve springs
Comp Cam 772 Ti valve retainers
Comp Cam 7/16 1.6 Pro Magnum rockers
guide plates
hardened pushrods
7/16 small block rocker studs
What do you think? I want to install a comp cam 305 cam this winter, is this valve train going to work?
Thanks,
Eric
I'm also upgrading my valve train, here's what I was thinking:
Comp Cam 26918 bee hive valve springs
Comp Cam 772 Ti valve retainers
Comp Cam 7/16 1.6 Pro Magnum rockers
guide plates
hardened pushrods
7/16 small block rocker studs
What do you think? I want to install a comp cam 305 cam this winter, is this valve train going to work?
Thanks,
Eric
Large Impressive Member
Joined: Jul 2003
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Since they're all Comp Cam parts, would they have a pretty good idea how it'll all work together?
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Since they're all Comp Cam parts, wouldn't they have a pretty good idea how it'll all work together?
Thread Starter
Melting Slicks
Joined: Jan 2000
Posts: 3,418
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From: NW Chicago Suburbs
Originally Posted by Corvette Kid NC
Since they're all Comp Cam parts, wouldn't they have a pretty good idea how it'll all work together?
Eric
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by silver & red CE
But what about 7/16" rockers, instead of the 3/8", any issues?
Eric
Eric
Race Director
Joined: Apr 2000
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From: Texas
FWIW, the beehive springs won't fit the stock LT4 valve spring seats (ID interference) and the LS1/6 seats won't fit the LT4 heads unless you've machined the valve guide bosses. I would contact CompCams about what seats to use or to find out if you can mod the LS1/6 seats.
Thread Starter
Melting Slicks
Joined: Jan 2000
Posts: 3,418
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From: NW Chicago Suburbs
Originally Posted by 96GS#007
FWIW, the beehive springs won't fit the stock LT4 valve spring seats (ID interference)...
Installed Load: 105 lbs @ 1.800" 130 lbs @ 1.800"
Open Load: 293 lbs @ 1.200" 318 lbs @ 1.200"
Spring Rate: 313 lbs/in 313 lbs/in
Coil Bind Height: 1.085" 1.085"
Outside Diameter: 1.290"/1.060” 1.290"/1.060”
Inside Diameter: .885"/.656” .885"/.656”
Retainer: TI 772/Steel 774 TI 772/Steel 774
Part # 26915-16 26918-16
Description GM LS1 Spring High Load Spring
The ID on the LS1 spring is 0.885", I measure the LT4 springs at 0.900", I thought it was close enough....
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Race Director
Joined: Apr 2000
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From: Texas
FWIW, I just went out to the garage and measured a couple extra LT4 springs and seats I have. I came up with a spring ID of .915 and a seat measurement of .910 Whatever the case, the beehive won't properly fit IMO.
If I were you, I'd talk to Comp. Failing that, I'd buy the beehives and mock one up on the LT4 seat. You'll find they don't seat all the way (close, but not quite). Over time you risk the spring cracking the spring seat and introducing metal particles into the engine.
Lastly, I'd buy an LS1 seat and see what it takes to modify it to fit over the guide. It may be as simple as enlarging the hole in teh seat via drilling on a drill press. I believe forum member "No Go" did something like this for his 381 build up.
If I were you, I'd talk to Comp. Failing that, I'd buy the beehives and mock one up on the LT4 seat. You'll find they don't seat all the way (close, but not quite). Over time you risk the spring cracking the spring seat and introducing metal particles into the engine.
Lastly, I'd buy an LS1 seat and see what it takes to modify it to fit over the guide. It may be as simple as enlarging the hole in teh seat via drilling on a drill press. I believe forum member "No Go" did something like this for his 381 build up.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
Originally Posted by 96GS#007
FWIW, I just went out to the garage and measured a couple extra LT4 springs and seats I have. I came up with a spring ID of .915 and a seat measurement of .910 Whatever the case, the beehive won't properly fit IMO.
If I were you, I'd talk to Comp. Failing that, I'd buy the beehives and mock one up on the LT4 seat. You'll find they don't seat all the way (close, but not quite). Over time you risk the spring cracking the spring seat and introducing metal particles into the engine.
Lastly, I'd buy an LS1 seat and see what it takes to modify it to fit over the guide. It may be as simple as enlarging the hole in teh seat via drilling on a drill press. I believe forum member "No Go" did something like this for his 381 build up.
If I were you, I'd talk to Comp. Failing that, I'd buy the beehives and mock one up on the LT4 seat. You'll find they don't seat all the way (close, but not quite). Over time you risk the spring cracking the spring seat and introducing metal particles into the engine.
Lastly, I'd buy an LS1 seat and see what it takes to modify it to fit over the guide. It may be as simple as enlarging the hole in teh seat via drilling on a drill press. I believe forum member "No Go" did something like this for his 381 build up.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
07-503-8 Cam
1318-16 1.6 ratio, 3/8" rocker arms
26918-16 Springs
4505-16 Hi-tech studs-7/16 base, 3/8
787-16 Spring Retainer
7940-16 5/15 7.200 pushrods
Can't remember why, but 7/16 studs wouldn't work...used high strength 3/8"..
Remember never trust compcams hot line!!!!!! Call them over and over until you get something resembling a consistent answer, different tech reps will give you varying answers, often criticizing another reps recommendation!!!!!!
BTW, my last call to CompCams was to get a Max RPM for this setup...their answer is why would I ever want to rev above 5900, since this would be above the power band of this cam....car dynos 365rwhp at 6400 rpm!!!!
IMHO don't believe anything Comp Cams has to say!!!!!!!
1318-16 1.6 ratio, 3/8" rocker arms
26918-16 Springs
4505-16 Hi-tech studs-7/16 base, 3/8
787-16 Spring Retainer
7940-16 5/15 7.200 pushrods
Can't remember why, but 7/16 studs wouldn't work...used high strength 3/8"..
Remember never trust compcams hot line!!!!!! Call them over and over until you get something resembling a consistent answer, different tech reps will give you varying answers, often criticizing another reps recommendation!!!!!!
BTW, my last call to CompCams was to get a Max RPM for this setup...their answer is why would I ever want to rev above 5900, since this would be above the power band of this cam....car dynos 365rwhp at 6400 rpm!!!!
IMHO don't believe anything Comp Cams has to say!!!!!!!
Last edited by LT4BUD; Sep 1, 2004 at 12:19 PM.
Thread Starter
Melting Slicks
Joined: Jan 2000
Posts: 3,418
Likes: 1
From: NW Chicago Suburbs
Originally Posted by LT4BUD
Can't remember why, but 7/16 studs wouldn't work...used high strength 3/8"..
LT4Bud, what did you do for the cups?
Eric
Le Mans Master
Joined: Jul 2000
Posts: 5,012
Likes: 5
From: OKC OK
Originally Posted by silver & red CE
Anyone else have issues installing the 7/16" rockers on an LT4? I know several folks have run the 7/16" rockers on 113 L98 heads...
Eric
Eric
Thread Starter
Melting Slicks
Joined: Jan 2000
Posts: 3,418
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From: NW Chicago Suburbs
Originally Posted by LT4POWR
I'm running 7/16" studs & rockers without any issues.
I call CC about the cups. No kidding about the "TECH" line. I kept pushing for an answer on the spring cups, the tech rep finally went back to engineering and asked, there's a new part number for spring cups for the 26918 springs on GEN1/2 SBC heads:
cc 4706-16
JEGS doesn't have them, ordered a set from CC, 2nd day air comes to $47.00, nothing is easy.
Eric
Thread Starter
Melting Slicks
Joined: Jan 2000
Posts: 3,418
Likes: 1
From: NW Chicago Suburbs
Originally Posted by LT4POWR
I'm running 7/16" studs & rockers without any issues.
I called CC about the cups. No kidding about the "TECH" line. I kept pushing for an answer on the spring cups, the tech rep finally went back to engineering and asked, there's a new part number for spring cups for the 26918 springs on GEN1/2 SBC heads:
cc 4706-16
JEGS doesn't have them, ordered a set from CC, 2nd day air comes to $47.00, nothing is easy.
Eric
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
I think the 7/16 issue was related to the rocker arms.....the "right" rocker arms weren't availiable in 7/16????
Have you picked out your rocker arms......again sorry I don't remember for sure, but some were too wide as I recall..
Like many other things you have to look at the whole package..
The people who did my heads didn't like my selections......they specifically do not like self aligning......they like guide plates.....but then they build race engines
Have you picked out your rocker arms......again sorry I don't remember for sure, but some were too wide as I recall..
Like many other things you have to look at the whole package..
The people who did my heads didn't like my selections......they specifically do not like self aligning......they like guide plates.....but then they build race engines
Last edited by LT4BUD; Sep 1, 2004 at 01:54 PM.
Thread Starter
Melting Slicks
Joined: Jan 2000
Posts: 3,418
Likes: 1
From: NW Chicago Suburbs
Originally Posted by LT4BUD
they specifically do not like self aligning......they like guide plates.....but then they build race engines
I'm going with the Comp Cam ProMagnum stainless steel rocker, they need guideplates...my engine's not a race engine by any means, but I do race it. I want to gt those LT4 springs out of there and go with some Ti retainers.Thx for the help,
Eric
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
I run the 7/16 inch studs-thread right in. Also the CC Pro Magnum non selfaligning with guide plates.
Only catch with the guide plates is the LT1/4 head supposedly uses a special Chevy guideplate otherwise if you use a CC supplied one, the pushrods/rockers won't be 'perfect' ie slight crows foot angle to them. Now I have been running this combination for ~27,000 hard miles with no ill effects, but I will probably look at a different guide plate this winter.
You will like the 26918 springs...IM on the way.
Only catch with the guide plates is the LT1/4 head supposedly uses a special Chevy guideplate otherwise if you use a CC supplied one, the pushrods/rockers won't be 'perfect' ie slight crows foot angle to them. Now I have been running this combination for ~27,000 hard miles with no ill effects, but I will probably look at a different guide plate this winter.
You will like the 26918 springs...IM on the way.
