Are valve seats necessary?
Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
Are valve seats necessary?
I am starting the rebuild on a used set of 243 heads i picked up. The specs for the cam I chose are 224/228 .581"/.588" 114lsa
I chose the comp 918 springs good for .600" lift and the 774 steel retainers that go with them.
My question is that while searching and pricing these parts, I kept seeing a valve seat set that seems to match the parts I am after, and I need to know if they are necessary for my mild/medium set up.
It is part # 4705-16.
Full part numbers are as follows: (All are Comp parts) And I will be ordering from Summitracing. You can view all these parts there.
Valve springs --- 26918-16
Retainers ------- 774-12
Seats ---------- 4705-16
I am no expert on valve train geometry and seat pressures etc. How will using the seats effect the spring rate etc??? Will it be like using shims? I haven't built a set of heads in years and I'm getting rusty.
I chose the comp 918 springs good for .600" lift and the 774 steel retainers that go with them.
My question is that while searching and pricing these parts, I kept seeing a valve seat set that seems to match the parts I am after, and I need to know if they are necessary for my mild/medium set up.
It is part # 4705-16.
Full part numbers are as follows: (All are Comp parts) And I will be ordering from Summitracing. You can view all these parts there.
Valve springs --- 26918-16
Retainers ------- 774-12
Seats ---------- 4705-16
I am no expert on valve train geometry and seat pressures etc. How will using the seats effect the spring rate etc??? Will it be like using shims? I haven't built a set of heads in years and I'm getting rusty.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
If you use the later GM valve seals, then the seat is integral with the seal. If you use the older seals, the seat was a separate part. You don't need the new seats unless you don't have either of the above (one piece integral seal/seat or earlier OEM valve spring seat).
You may want to pick up the Comp shims however to ensure an adequate seat force value for the valve springs.
You may want to pick up the Comp shims however to ensure an adequate seat force value for the valve springs.
Team Owner
Joined: May 2001
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Valve seats are only necessary if the heads need them and a competent machine shop can examine them and determine if it's necessary. Many times they do not need to be replaced and the existing seats only get a light grinding to ensure a good seal.
Because of this, it's always a good idea to check installed valve height after any grinding.
SPRING seats are a totally different thing.
4705-16 are valve spring locators (seats)
Use them on aluminum heads.
Because of this, it's always a good idea to check installed valve height after any grinding.
SPRING seats are a totally different thing.
4705-16 are valve spring locators (seats)
Use them on aluminum heads.
Last edited by LoneStarFRC; Sep 10, 2012 at 09:59 PM.
Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
I never got back to you guys. Thanks for clearing that up 
I don't want to buy what I don't need.
I also wanted to make a note for anyone who reads this. The retainers part number for these springs are 774-16 (16 as in a set of 16). Not 774-12 like I had wrote before. That would be a kit with 12 retainers and not 16 which is what an LS engine needs.
Now I have one more question on the valves. Do I need new retainer locks to go with these or will the stock ones be ok? I think they would be fine because the same valves are being used. I cant see them as being bad or unusable.
I don't want to buy what I don't need.I also wanted to make a note for anyone who reads this. The retainers part number for these springs are 774-16 (16 as in a set of 16). Not 774-12 like I had wrote before. That would be a kit with 12 retainers and not 16 which is what an LS engine needs.
Now I have one more question on the valves. Do I need new retainer locks to go with these or will the stock ones be ok? I think they would be fine because the same valves are being used. I cant see them as being bad or unusable.
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
As others said above, just go get a new set of OEM GM 1-piece valve guide seals that have a steel spring seat built into the seal assembly. I think a set of 16 will cost you about $60. The intake and exhaust seals have different part numbers.
Last edited by ZeeOSix; Sep 18, 2012 at 01:23 PM.
Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
Depends if the new retainers are designed to be used with the OEM locks (ie, taper angle, etc). Contact the manufacturer of the new retainers and they should be able to tell you if the OEM locks are compatible.
As others said above, just go get a new set of OEM GM 1-piece valve guide seals that have a steel spring seat built into the seal assembly. I think a set of 16 will cost you about $60. The intake and exhaust seals have different part numbers.
As others said above, just go get a new set of OEM GM 1-piece valve guide seals that have a steel spring seat built into the seal assembly. I think a set of 16 will cost you about $60. The intake and exhaust seals have different part numbers.
Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
Also, I read that stock valve locks are 7 degrees and since the comp retainers are 7 degrees I am fine to use the stock locks. Someone basically asked the same question. As long as the angles are the same, it should be fine.
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Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
Now this one I don't expect anyone to know, but I will ask anyway. What is the difference between these two retainers? 774-16 and 787-16.
Both are 7 degree angle, with a 1.055" Outside Diameter, and a .640"inside diameter. Both are steel etc.
The guys on LS1tech seem to use 787-16 as the set to go with. But when I compare the two on Summitracing the 774-16 set has a note that specifically says its for the GenIII engines. Everything about them is the same though from what I can tell. Furthermore it says that the 787-16 is meant for non-LS applications. So Im not sure what to get. I have 774-16 in my parts list as of now.
The 774's sound like the way to go. But the fact that many use 787's confuses me...
Both are 7 degree angle, with a 1.055" Outside Diameter, and a .640"inside diameter. Both are steel etc.
The guys on LS1tech seem to use 787-16 as the set to go with. But when I compare the two on Summitracing the 774-16 set has a note that specifically says its for the GenIII engines. Everything about them is the same though from what I can tell. Furthermore it says that the 787-16 is meant for non-LS applications. So Im not sure what to get. I have 774-16 in my parts list as of now.
The 774's sound like the way to go. But the fact that many use 787's confuses me...
Last edited by NukeC5; Sep 18, 2012 at 02:30 PM.
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
I'd recommend contacting Comp Cams to be sure.
http://www.compcams.com/tech-help/Support.aspx
COMP Cams®
800-999-0853
Local: 901-795-2400
If I had to choose, I'd go with the Gen III type (774-16). Don't know what the difference really is, but like suggested you should call Comp Cams Tech Dept to get the real answer.
774-16
http://www.compperformancegroupstore...Category_Code=
787-16
http://www.compperformancegroupstore...Category_Code=
http://www.compcams.com/tech-help/Support.aspx
COMP Cams®
800-999-0853
Local: 901-795-2400
If I had to choose, I'd go with the Gen III type (774-16). Don't know what the difference really is, but like suggested you should call Comp Cams Tech Dept to get the real answer.
774-16
http://www.compperformancegroupstore...Category_Code=
787-16
http://www.compperformancegroupstore...Category_Code=
Last edited by ZeeOSix; Sep 18, 2012 at 05:00 PM.
Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
Ya I think I will. I also need to ask them which valve locks to use. I am going to do a set because its like 10 bucks for a set of 16 hardened-steel locks. But there are 15 to 20 sets of 7 degree angle locks to chose from 
Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
Well I just found out that comp makes an LS specific valve lock. Because LS1/LS6 Valves are 8mm (A metric, not standard measurement) they take a special valve lock part# 623-16. Of course they cost quadruple the amount normal hardened steel retainers cost. But they are a 1 groove 8mm 7-degree angle valve locks, so they are what I will be going with.
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
When I replaced my valve springs, I just reused the OEM retainers and locks. Still running the stock cam in my LS6. They only had 21K miles on them so I saw no reason to replace them.
Not sure if better quality retainers and locks gets you anything over the OEM parts. Maybe if you're going with some insane cam and stiff springs they would be a worthwhile upgrade.
Not sure if better quality retainers and locks gets you anything over the OEM parts. Maybe if you're going with some insane cam and stiff springs they would be a worthwhile upgrade.
Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
When I replaced my valve springs, I just reused the OEM retainers and locks. Still running the stock cam in my LS6. They only had 21K miles on them so I saw no reason to replace them.
Not sure if better quality retainers and locks gets you anything over the OEM parts. Maybe if you're going with some insane cam and stiff springs they would be a worthwhile upgrade.
Not sure if better quality retainers and locks gets you anything over the OEM parts. Maybe if you're going with some insane cam and stiff springs they would be a worthwhile upgrade.
Also the beehive springs require the smaller beehive retainers. So since I'm changing springs and retainers, I am willing to throw down 30 more bucks for their matched locks.
Last edited by NukeC5; Sep 18, 2012 at 07:25 PM.
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
So the used 243 heads you're rebuilding didn't come with stock beehive springs and retainers/locks?
Thread Starter
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
Hmm I don't know what they are.. Matter of fact they probably are. I didn't even think about it. I knew I was changing everything out. Never even considered that the beehive style came on the cars. Is that unique to 243 heads? Or do all LS1/2/6 have them?
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
On my first build in this car, I used new locks because the machined locks are stronger than the stock stamped locks. They were also $30 at the time. The AFR heads that I now run have their own retainer/lock setup.