487X head work
Thread Starter
Instructor
Joined: Feb 2010
Posts: 118
Likes: 0
From: Ok
487X head work
So I am fixing to take my heads in to the machine shop. I have a few questions befor I go. I am replacing these part due to valves being floated and taken out along with pushrods.
FYI I have a '72 LT1 and keeping stock 487x heads. 2.02 / 1.6's
1. Compression ratio stock is 9.0 I am looking to bump it a bit say 9.5 or 10:1. Stock motor had steel shim head gaskets. Should I stick with steel or mill the heads and go with a permatorque gasket .039? I am looking to still run 91 in the car. Not a daily driver.
If I mill aprox how much should I mill off?
2. Rocker arm ratio. I was told go with the 1.6 and roller tip and should have no issues. Even if I mill the heads?
3. I am ordering new springs and valves, springs rated for .550lift and called a Z28 kit. These springs should hold up to the RPM's correct? 5500rpm ?
4. also plan to do new head bolts and chrome molly pushrods.
Any other tips? Also plan to order a rev box sad to see motor be down due to a mis shift.
FYI I have a '72 LT1 and keeping stock 487x heads. 2.02 / 1.6's
1. Compression ratio stock is 9.0 I am looking to bump it a bit say 9.5 or 10:1. Stock motor had steel shim head gaskets. Should I stick with steel or mill the heads and go with a permatorque gasket .039? I am looking to still run 91 in the car. Not a daily driver.
If I mill aprox how much should I mill off?
2. Rocker arm ratio. I was told go with the 1.6 and roller tip and should have no issues. Even if I mill the heads?
3. I am ordering new springs and valves, springs rated for .550lift and called a Z28 kit. These springs should hold up to the RPM's correct? 5500rpm ?
4. also plan to do new head bolts and chrome molly pushrods.
Any other tips? Also plan to order a rev box sad to see motor be down due to a mis shift.
Race Director
Joined: Jan 2000
Posts: 13,014
Likes: 2,257
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
If you want compression increase...mill them and use a steel shim gasket. Using the composition one just lost everything you gained milling.
No idea what cam you're using so tough to say what springs it needs. The old Z-28 springs are good for basic street performance stuff....but you need to make sure height is set correctly.
Again, rockers depend on cam. Smallblocks typically respond well to 1.6 intakes and 1.5 exhausts.
If heads are apart a couple of hours doing some pocket porting can really pay off!
JIM
No idea what cam you're using so tough to say what springs it needs. The old Z-28 springs are good for basic street performance stuff....but you need to make sure height is set correctly.
Again, rockers depend on cam. Smallblocks typically respond well to 1.6 intakes and 1.5 exhausts.
If heads are apart a couple of hours doing some pocket porting can really pay off!
JIM
Race Director
Joined: Jan 2000
Posts: 13,014
Likes: 2,257
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
If things are flat the shims seal fine. I used them for years spraying nitrous etc and never hurt one. I mean GM used them forever with no issues right?
Don't know how much you're spending on those heads, but don't get upside down in them. Good Small block heads are getting very reasonable these days.
JIM
Don't know how much you're spending on those heads, but don't get upside down in them. Good Small block heads are getting very reasonable these days.
JIM
Instructor
Joined: Mar 2010
Posts: 111
Likes: 0
From: lafayette indiana
i agree on heads u can spend a lot on those stock heads. a new set of RHS cast heads will flow alot better right out of box (assuming u want to stay with a cast head) and they are reasonably priced
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
Buy some RHS Pro Torker 170cc 67cc combustion chamer heads or Pro Action 180cc 64cc chamber heads and enjoy what the LT-1 was meant to feel like, the Pro Torkers will run about $300pr less than the Pro Action heads (why, I don't know the materials and labor are about equal to make either.)
If you want original GM heads, I would look for some 041, 186 or 492 castings from 68-70 era but, these will cost more $$$ to build than the RHS heads.
Link:http://www.compperformancegroupstore...egory_Code=SBC
If you want original GM heads, I would look for some 041, 186 or 492 castings from 68-70 era but, these will cost more $$$ to build than the RHS heads.
Link:http://www.compperformancegroupstore...egory_Code=SBC
Thread Starter
Instructor
Joined: Feb 2010
Posts: 118
Likes: 0
From: Ok
LOL When I first joined the site everyone bombed me about keeping it stock parts... Now you guys are saying to go with different heads. What gives?
I plan to keep original heads on the car but would like to mill them a bit and bump the compression and bring it back to life a lil.
Question is how much do I need to mill...
Putting hardend seat in the heads and have'n valve job done and possibly mill them a bit.
I plan to keep original heads on the car but would like to mill them a bit and bump the compression and bring it back to life a lil.
Question is how much do I need to mill...
Putting hardend seat in the heads and have'n valve job done and possibly mill them a bit.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
If guides are badly worn ... Do NOT install guides ... instead, Do install thinwall guideliners. Your shop can explain why.
If you mill more than about 0.030" from heads, you'll have trouble getting intake to fit & it will require some fiddling to get it to fit.
Forget roller tips ... just get some good quality, long slot plain stamped rockers ... 1.6 if you want ... crane used to make good ones ... so does Howards Cams.
"fixing" to take parts to ... are you a southerner? You & others should complete their profile to include an approximate geographic location so we see about where you're at.
If you shed those heads it'll no longer be an LT1.
-add- 72 heads came with induction-hardened exhaust seats (began MY1971) but it can be cut thru if seats have been ground lots. It really ain't necessary unless you pull heavy loads.
If you mill more than about 0.030" from heads, you'll have trouble getting intake to fit & it will require some fiddling to get it to fit.
Forget roller tips ... just get some good quality, long slot plain stamped rockers ... 1.6 if you want ... crane used to make good ones ... so does Howards Cams.
"fixing" to take parts to ... are you a southerner? You & others should complete their profile to include an approximate geographic location so we see about where you're at.
If you shed those heads it'll no longer be an LT1.
-add- 72 heads came with induction-hardened exhaust seats (began MY1971) but it can be cut thru if seats have been ground lots. It really ain't necessary unless you pull heavy loads.
Last edited by jackson; Apr 26, 2010 at 12:28 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Thread Starter
Instructor
Joined: Feb 2010
Posts: 118
Likes: 0
From: Ok
I am from Oklahoma. Fixing that bad? How about getting ready to see my machinist?
anyways.
You have me curious on the NO roller tip thing.
I plan to keep the Factory heads, and with 66k miles not sure the guides need replaced, and dont worry I never liked the liners. I always did the full guides and machined them down and honed to fit. I once was a auto machinist.
Was not sure on how much would cause a intake issue when milling the heads, been to many years.
I was also unaware of the hardened seats on the '72's. I was told they would not be hardened until later years. Any info or reading material on this? These are virgin heads so maybe if he is nice to them, they should be fine?
So what is your idea on the milling of the heads?
Thanks for the info!
anyways.
You have me curious on the NO roller tip thing.
I plan to keep the Factory heads, and with 66k miles not sure the guides need replaced, and dont worry I never liked the liners. I always did the full guides and machined them down and honed to fit. I once was a auto machinist.
Was not sure on how much would cause a intake issue when milling the heads, been to many years.
I was also unaware of the hardened seats on the '72's. I was told they would not be hardened until later years. Any info or reading material on this? These are virgin heads so maybe if he is nice to them, they should be fine?
So what is your idea on the milling of the heads?
Thanks for the info!
Last edited by RacinJason68; Apr 26, 2010 at 12:41 AM.
Race Director
Joined: Jan 2000
Posts: 13,014
Likes: 2,257
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
I was fixin' to tell ya..... (hey I'm from Tx....that's how we speak!)
I guess it depends on how bad you are determined to keep it stock. If you aren't interested in adding power over the original, then use those. I'd save the $$$ on the new seats and do some port work instead if you just have to keep those. And if you're not changing cams, you aren't going to need a lot in the way of rocker arms.
If they do it correctly and mill the intake face of the head as needed...then intake should fit fine.
But it sure looks like we're about to spend most of the price of a set of much better heads!
JIM
I guess it depends on how bad you are determined to keep it stock. If you aren't interested in adding power over the original, then use those. I'd save the $$$ on the new seats and do some port work instead if you just have to keep those. And if you're not changing cams, you aren't going to need a lot in the way of rocker arms.
If they do it correctly and mill the intake face of the head as needed...then intake should fit fine.
But it sure looks like we're about to spend most of the price of a set of much better heads!
JIM
Last edited by 427Hotrod; Apr 26, 2010 at 12:50 AM.
Thread Starter
Instructor
Joined: Feb 2010
Posts: 118
Likes: 0
From: Ok
Well the stock cam is staying. I see no reason to replace it. I am not going for drag, just a nice driver every now and then.
Port work that big of a issue on these heads? I would think the combustion chambers would be the big issue. They are the X heads and supposed to be a bit bigger on the runners from what I have read on the forum.
Port work that big of a issue on these heads? I would think the combustion chambers would be the big issue. They are the X heads and supposed to be a bit bigger on the runners from what I have read on the forum.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Deo Vindice
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Thicker, more robust, more heat tolerable roof of comb chamber.
Oklahoma ??? Go ask Lance Fenton (OKC) if the fellers in Timmonsville SC know anything about motors... & ask his pal Greg Barnhart at Panelite (OKC).
Like I said ... fixin to go to bed ... gone
Oklahoma ??? Go ask Lance Fenton (OKC) if the fellers in Timmonsville SC know anything about motors... & ask his pal Greg Barnhart at Panelite (OKC).
Like I said ... fixin to go to bed ... gone
Instructor
Joined: Mar 2010
Posts: 111
Likes: 0
From: lafayette indiana
i understand your issue on taking a beating on keeping it stock and untouched by members and then some tell u (like me)to buy new heads.i agree on the rarety on some of these car SOME but in the end its your car and u should do as u please.but us guys that sug. new heads know what road your heading down in cost on your heads yes u can make perfor.gaines w/those heads but it gets ex. by the time u do mach. work,buy good springs,alittle porting etc. my advice and thats all it is is my op. i would take the heads u have rust prevent them and store so u always have the org. heads in a unmolested state to put back on car if u ever want to sell it.buy a set of more mordern heads like RHS and run those u will be money ahead in the end.
Thread Starter
Instructor
Joined: Feb 2010
Posts: 118
Likes: 0
From: Ok
Ok thanks for all the info.
Here is my plan,
1. Do the valve job myself.
2. New springs, keepers, retainers and valves
3. Smooth the ports a bit, sharp edges are no good.
4. Have the heads milled .010 - .015
I will be out parts cost and possibly cost of milling the heads. Sounds like a good deal and I get to keep the stock heads.
Here is my plan,
1. Do the valve job myself.
2. New springs, keepers, retainers and valves
3. Smooth the ports a bit, sharp edges are no good.
4. Have the heads milled .010 - .015
I will be out parts cost and possibly cost of milling the heads. Sounds like a good deal and I get to keep the stock heads.
Last edited by RacinJason68; Apr 27, 2010 at 10:57 AM.
