C3 General General C3 Corvette Discussion not covered in Tech
Sponsored by:
Sponsored by:

Everybody was wrong!

Thread Tools
 
Search this Thread
 
Old 04-09-2013, 05:35 PM
  #1  
F22
Le Mans Master
Thread Starter
 
F22's Avatar
 
Member Since: Oct 2006
Location: Palmdale CA
Posts: 6,842
Received 275 Likes on 211 Posts

Default Everybody was wrong!

And I mean, everybody! The guys at Cylinder Head Exchange, the local machine shop, local Chevy experts, they were wrong and it's not because they were stupid, it's because we went with an off-the-wall combo, that should work, but didn't (at first).

The whole thing started with pulling the greaseball L-48 out of the 74' and finding that, hey, the bottom end is totally clean on this engine. No dash, but the wear and tear on the car, pointed to about 65K to 75K miles. I mean, even the crank bearings were nearly new looking. Cylinders had no scuffing, the pistons only had a micro layer of carbon on top and it burned clean on all cylinders.

Did the research and found out that the early C4 Corvettes, came with aluminum heads off the L98, with the 113 castings being particularly desirable. This is the same style head as on the Chevrolet ZZ4 350 HO motor. They have 58cc combustion chambers and that matched up with the original dished pistons is good for at least a full point of extra compression.

So I got a set, no rocker arms, just the heads, with the old valves and springs and had them rebuilt and everyone I asked, told me they used standard chevy 1.5 rocker arms, because they had pushrod guides in them.

The initial set up ran like crap. The engine spit and popped and we suspected valvetrain set up, so we adjusted them while running. And did it again, finding the rocker arms loose and misaligned. Did it a third time and it went out of adjustment again! Had the Summit cast rocker arms, with the roller tips and swapped them out for a set of standard Sealed Power stamped rocker arms. Also put in a set of pushrods, because the new set got bent.

Initially, we couldn't turn it a half turn, without the engine totally stalling, now it ran better, but still spit and popped, had no power, wouldn't hold vacuum. We called up our race buddy, who's rebuilt dozens and dozens of engines and he told us to check to see if all the rocker arms were the same. Three were slightly different with just a little lower seating in the ball, but that forced us to look closer.

Looking at them, we could see that there were more than a few rocker arms that were so misaligned, they were either nearly off the tip of the valve stem, or actually tilted sideways, or both! Called up the guys at Cylinder Head Exchange and the local machine shop and they swore, that if it had guide plates, you used standard rocker arms. They were wrong.

It took a crap load of digging, but I found out, that the aluminum L98 head is unique. They used a non-hardened guide plate to aid in the engine assembly at the factory, so some worker, could just drop in the push rods, until the self-aligning rocker arms could be put on! I typed in the head casting number #10185086 and found a blog on CarCraft from PontiacMan.

http://forums.carcraft.com/70/891162...ine/sbc-heads/


10185086 Service 10088113 Aluminum Angled No 163 58 1.94/ Service head for Corvette design
Head 150 350 HO, 300 hp. Supplied
with valves & springs
.

These ARE the 113 castings you want, but wait... See the note at the bottom:


These Corvette-derived aluminum cylinder heads (PN 10185086) are completely assembled with 1.94/1.50-inch intake/exhaust valves, heavy-duty chrome silicon springs, retainers, screw-in studs, and guide plates. They have 58-cc combustion chambers and the intake runners measure 153 cc. These cylinder heads have angled spark plugs, which may not fit some exhaust manifolds and headers. These heads are plentiful and cheap for those working with a budget.

If you decide to use this cylinder head, you may need to make some additional modifications. Because the exhaust ports exit approximately 0.100 inch higher than the stock, headers and exhaust manifolds may require some minor modifications (and this is why I have a slight exhaust leak as well....). In addition, make sure there is adequate clearance around the angled park plugs. AC FR5LS 3/4-inch reach spark plugs with 5/8-inch hex heads are recommended, and late-model rail type rocker arms are required (PN 10089648).


99% of Chevy heads, come with either guide plates or self-aligned rocker arms, but not both, but these heads come with BOTH and there's a special guide plate, just for these heads! There are two standard guide plates, one for iron heads, one for aluminum, but there's a THIRD guide plate for the L98 head and that's the one that's installed in my head. PN 10111771.

http://www.gmpartsdirect.com/perform...CATID=817.html

Then, from my local Chevy dealer, yesterday, I ordered a set of of the factory, GM Performance rocker arms #12495490, this is the same rocker arm that's used on the ZZ4 and it is self-aligning. I picked them up at lunch and compared them to the regular Chevy rocker arms, and they're a 1/4" shorter!!! No wonder I bent two sets of push rods!.

So today, I first go to the machine shop to pick up a fresh set of standard length pushrods (my third set...) and the old pro behind the counter swears there's no such thing and everything must be true on the Internet. Again, no such thing as guideplates AND self-aligning rockers.

Go to the GM dealer at 10:30 and pick up my rocker arms. Go directly to the shop, I'm still dressed in business attire, slacks and a polo shirt and start putting assembly lube on the tips of the pushrods and get them in the lifters. Get the paint brush, squeeze some lube and get all the rocker arms, ***** and the top of the pushrods and get them in. It's almost lunch, but I'm on vacation time now. Everything looks exactly lined up, this is good.

We adjust the entire valve train in something like twenty minutes. Put in the backsplash pieces we made out of cardboard. Start the 74' up and no $hit, it's running perfect. No loud tapping, no misalignment, no binding, no loose rocker arms, no tight rocker arms. No spitting, popping, no nothing. Just running smooth and quiet. Unbelievable....! Three weeks of hell getting this right and now we know. I'm gonna make sure the Cylinder Head guys and the machine shop knows too and mail them a copy of what I found. I'm stoked that it's not running like a POS. Tonight, put on the valve covers, drop it down and drive it around and see if it still feels like a 97 pound weakling or is it going to run better? So far, so good.
F22 is offline  
The following 4 users liked this post by F22:
210ken (09-26-2020), doorgunner (09-26-2020), Fredric Björnefält (09-26-2020), Rescue Rogers (12-22-2020)
Old 04-09-2013, 05:39 PM
  #2  
MrJlr
Race Director
 
MrJlr's Avatar
 
Member Since: Feb 2006
Location: Chino CA
Posts: 12,239
Received 13 Likes on 10 Posts

Default

Originally Posted by F22
And I mean, everybody! The guys at Cylinder Head Exchange, the local machine shop, local Chevy experts, they were wrong and it's not because they were stupid, it's because we went with an off-the-wall combo, that should work, but didn't (at first).

The whole thing started with pulling the greaseball L-48 out of the 74' and finding that, hey, the bottom end is totally clean on this engine. No dash, but the wear and tear on the car, pointed to about 65K to 75K miles. I mean, even the crank bearings were nearly new looking. Cylinders had no scuffing, the pistons only had a micro layer of carbon on top and it burned clean on all cylinders.

Did the research and found out that the early C4 Corvettes, came with aluminum heads off the L98, with the 113 castings being particularly desirable. This is the same style head as on the Chevrolet ZZ4 350 HO motor. They have 58cc combustion chambers and that matched up with the original dished pistons is good for at least a full point of extra compression.

So I got a set, no rocker arms, just the heads, with the old valves and springs and had them rebuilt and everyone I asked, told me they used standard chevy 1.5 rocker arms, because they had pushrod guides in them.

The initial set up ran like crap. The engine spit and popped and we suspected valvetrain set up, so we adjusted them while running. And did it again, finding the rocker arms loose and misaligned. Did it a third time and it went out of adjustment again! Had the Summit cast rocker arms, with the roller tips and swapped them out for a set of standard Sealed Power stamped rocker arms. Also put in a set of pushrods, because the new set got bent.

Initially, we couldn't turn it a half turn, without the engine totally stalling, now it ran better, but still spit and popped, had no power, wouldn't hold vacuum. We called up our race buddy, who's rebuilt dozens and dozens of engines and he told us to check to see if all the rocker arms were the same. Three were slightly different with just a little lower seating in the ball, but that forced us to look closer.

Looking at them, we could see that there were more than a few rocker arms that were so misaligned, they were either nearly off the tip of the valve stem, or actually tilted sideways, or both! Called up the guys at Cylinder Head Exchange and the local machine shop and they swore, that if it had guide plates, you used standard rocker arms. They were wrong.

It took a crap load of digging, but I found out, that the aluminum L98 head is unique. They used a non-hardened guide plate to aid in the engine assembly at the factory, so some worker, could just drop in the push rods, until the self-aligning rocker arms could be put on! I typed in the head casting number #10185086 and found a blog on CarCraft from PontiacMan.

http://forums.carcraft.com/70/891162...ine/sbc-heads/


10185086 Service 10088113 Aluminum Angled No 163 58 1.94/ Service head for Corvette design
Head 150 350 HO, 300 hp. Supplied
with valves & springs
.

These ARE the 113 castings you want, but wait... See the note at the bottom:


These Corvette-derived aluminum cylinder heads (PN 10185086) are completely assembled with 1.94/1.50-inch intake/exhaust valves, heavy-duty chrome silicon springs, retainers, screw-in studs, and guide plates. They have 58-cc combustion chambers and the intake runners measure 153 cc. These cylinder heads have angled spark plugs, which may not fit some exhaust manifolds and headers. These heads are plentiful and cheap for those working with a budget.

If you decide to use this cylinder head, you may need to make some additional modifications. Because the exhaust ports exit approximately 0.100 inch higher than the stock, headers and exhaust manifolds may require some minor modifications (and this is why I have a slight exhaust leak as well....). In addition, make sure there is adequate clearance around the angled park plugs. AC FR5LS 3/4-inch reach spark plugs with 5/8-inch hex heads are recommended, and late-model rail type rocker arms are required (PN 10089648).


99% of Chevy heads, come with either guide plates or self-aligned rocker arms, but not both, but these heads come with BOTH and there's a special guide plate, just for these heads! There are two standard guide plates, one for iron heads, one for aluminum, but there's a THIRD guide plate for the L98 head and that's the one that's installed in my head. PN 10111771.

http://www.gmpartsdirect.com/perform...CATID=817.html

Then, from my local Chevy dealer, yesterday, I ordered a set of of the factory, GM Performance rocker arms #12495490, this is the same rocker arm that's used on the ZZ4 and it is self-aligning. I picked them up at lunch and compared them to the regular Chevy rocker arms, and they're a 1/4" shorter!!! No wonder I bent two sets of push rods!.

So today, I first go to the machine shop to pick up a fresh set of standard length pushrods (my third set...) and the old pro behind the counter swears there's no such thing and everything must be true on the Internet. Again, no such thing as guideplates AND self-aligning rockers.

Go to the GM dealer at 10:30 and pick up my rocker arms. Go directly to the shop, I'm still dressed in business attire, slacks and a polo shirt and start putting assembly lube on the tips of the pushrods and get them in the lifters. Get the paint brush, squeeze some lube and get all the rocker arms, ***** and the top of the pushrods and get them in. It's almost lunch, but I'm on vacation time now. Everything looks exactly lined up, this is good.

We adjust the entire valve train in something like twenty minutes. Put in the backsplash pieces we made out of cardboard. Start the 74' up and no $hit, it's running perfect. No loud tapping, no misalignment, no binding, no loose rocker arms, no tight rocker arms. No spitting, popping, no nothing. Just running smooth and quiet. Unbelievable....! Three weeks of hell getting this right and now we know. I'm gonna make sure the Cylinder Head guys and the machine shop knows too and mail them a copy of what I found. I'm stoked that it's not running like a POS. Tonight, put on the valve covers, drop it down and drive it around and see if it still feels like a 97 pound weakling or is it going to run better? So far, so good.
Wow.....what a PITA!
Get 'er done before the cruise !

MrJlr is offline  
Old 04-09-2013, 06:22 PM
  #3  
zwede
Race Director
 
zwede's Avatar
 
Member Since: Sep 1999
Location: Plano TX
Posts: 11,301
Received 333 Likes on 255 Posts

Default

Wow! Good info! I've been around Chevy V8's for 25 years and had never heard of this.
zwede is offline  
Old 04-09-2013, 07:21 PM
  #4  
ezobens
Drifting
 
ezobens's Avatar
 
Member Since: Aug 2005
Location: Wauconda IL
Posts: 1,443
Received 64 Likes on 56 Posts

Default

The self-aligning rockers and guide plates on the L-98 has been well documented in any write-up I've read regarding these heads.
Worst case, always refer to GM's own documentation vs listening to some Bubba at the machine shop to avoid any issues.


I do find it odd that you couldn't get standard rockers and hardened guide plates to work as the valve position on these heads are no different than any standard SBC head. Did you actually measure for proper length pushrods or just stick in standard length ones and hope for the best? With all the pushrod bending you had going on, pushrod length with proper guide plates would have been my first place to check.
Just my .02

Last edited by ezobens; 04-09-2013 at 07:25 PM.
ezobens is offline  
Old 04-09-2013, 10:51 PM
  #5  
F22
Le Mans Master
Thread Starter
 
F22's Avatar
 
Member Since: Oct 2006
Location: Palmdale CA
Posts: 6,842
Received 275 Likes on 211 Posts

Default

Originally Posted by ezobens
The self-aligning rockers and guide plates on the L-98 has been well documented in any write-up I've read regarding these heads.
Worst case, always refer to GM's own documentation vs listening to some Bubba at the machine shop to avoid any issues.


I do find it odd that you couldn't get standard rockers and hardened guide plates to work as the valve position on these heads are no different than any standard SBC head. Did you actually measure for proper length pushrods or just stick in standard length ones and hope for the best? With all the pushrod bending you had going on, pushrod length with proper guide plates would have been my first place to check.
Just my .02
Thanks and if I had to, I'd have gone the route you recommended. The little-known combo works fine (as long as you have the right parts!)
F22 is offline  
Old 04-09-2013, 11:02 PM
  #6  
crf311
Melting Slicks
 
crf311's Avatar
 
Member Since: Jan 2003
Location: meraux LA
Posts: 2,938
Received 83 Likes on 74 Posts

Default

Don't know why you had problems. I put a set of these heads on a gm crate motor short block, a few years ago. when I got my heads they were complete with the self-aligning rockers all I had to do was measure for the push rods. No problems in over 4 years.
crf311 is offline  
Old 04-09-2013, 11:02 PM
  #7  
F22
Le Mans Master
Thread Starter
 
F22's Avatar
 
Member Since: Oct 2006
Location: Palmdale CA
Posts: 6,842
Received 275 Likes on 211 Posts

Default

Took two hours off to install the valve train and then left an hour early to boot! We started it, no noise, tweaked it and backed it out of the shop into a nearly deserted industrial center. Rolling back, healthy idle, crisp throttle response, so what's it gonna do?

Put the stick in first gear, stabbed it and dropped the clutch. The engine snarled, tires broke loose and the *** end came around. Grabbed second and the back end squatted hard. OMG!!! Every expectation was exceeded! RPM's rising hard and the nose still coming up. Stoked, stoked, stoked. This thing would slay my 95' C4....After three weeks, three valvetrains and nights at the shop, we're rewarded.

Last edited by F22; 04-09-2013 at 11:09 PM.
F22 is offline  
The following 2 users liked this post by F22:
210ken (09-26-2020), Eddie 70 (09-26-2020)
Old 04-09-2013, 11:07 PM
  #8  
F22
Le Mans Master
Thread Starter
 
F22's Avatar
 
Member Since: Oct 2006
Location: Palmdale CA
Posts: 6,842
Received 275 Likes on 211 Posts

Default

Originally Posted by crf311
Don't know why you had problems. I put a set of these heads on a gm crate motor short block, a few years ago. when I got my heads they were complete with the self-aligning rockers all I had to do was measure for the push rods. No problems in over 4 years.
Didn!t come with the rockers, as I planned on new rockers anyways. If you dontknow, ya don't know and glad to hear your combo works well, good to know. Most people are just skipping the L98 heads and just going with the AFR's, etc.
F22 is offline  
Old 04-09-2013, 11:28 PM
  #9  
SuperBuickGuy
Melting Slicks
 
SuperBuickGuy's Avatar
 
Member Since: Aug 2012
Location: Woodinville WA
Posts: 2,544
Received 380 Likes on 267 Posts

Default

Originally Posted by crf311
Don't know why you had problems. I put a set of these heads on a gm crate motor short block, a few years ago. when I got my heads they were complete with the self-aligning rockers all I had to do was measure for the push rods. No problems in over 4 years.
I ran those heads with no trouble either.... used roller tip rocker arms... weird, sounds like I got lucky... (which, if I had a choice, I'll take lucky over good every time)
SuperBuickGuy is offline  
Old 04-09-2013, 11:37 PM
  #10  
F22
Le Mans Master
Thread Starter
 
F22's Avatar
 
Member Since: Oct 2006
Location: Palmdale CA
Posts: 6,842
Received 275 Likes on 211 Posts

Default

PS: Did my best to research this, beforehand. Even purchased "The Chevy Small Block Interchange Manual, by David Lewis, The L98 heads are coverd, but no mention of the DUAL use of inert guide plates AND self-aligning rockers, but yet it was helpful, because they showed in another pic, the two style rocker arms, early (standard) and the now common place, self aligning rocker arm. The author stated they started using these in the mid-80's.... Hmmm.

That tickled the memory cells kicked in. I had done the top-end on my third ex-wife's 87' Corvette and I didn't remember seeing hard contact between the rocker arms and the guides. The next day, went on my Photobucket account, where I still had hundreds of photos of the process and sure enough, tbey were self-aligning. Fixed! And even online, it took a lot of searches. I'm posting this, so somebody who does this, doesn't have to go through the same experience I did.

Last edited by F22; 04-09-2013 at 11:40 PM.
F22 is offline  
The following users liked this post:
210ken (09-26-2020)
Old 04-10-2013, 12:02 AM
  #11  
ramair_bryan
Melting Slicks
 
ramair_bryan's Avatar
 
Member Since: Jan 2009
Posts: 3,301
Likes: 0
Received 22 Likes on 20 Posts

Default

Well written. Theres few that can keep my attenion for long. But I noticed that I read the whole thing, and didn't even blink. Well done..... Also..........I once bent and broke a bunch on our pontiac the same way. So better put an old speaker magnet on the side of your oil pan to catch the particles. After that, I also glued some on the oil drain backs before it can even get to the pan. ......... Now go smoke the tires w/video..................
ramair_bryan is offline  
Old 04-10-2013, 01:29 AM
  #12  
F22
Le Mans Master
Thread Starter
 
F22's Avatar
 
Member Since: Oct 2006
Location: Palmdale CA
Posts: 6,842
Received 275 Likes on 211 Posts

Default

Originally Posted by ramair_bryan
Well written. Theres few that can keep my attenion for long. But I noticed that I read the whole thing, and didn't even blink. Well done..... Also..........I once bent and broke a bunch on our pontiac the same way. So better put an old speaker magnet on the side of your oil pan to catch the particles. After that, I also glued some on the oil drain backs before it can even get to the pan. ......... Now go smoke the tires w/video..................
The magnet idea is good and thinking just now, the Milodon oil pan comes with a magnetic plug. Yep, it doesn't always go together as planned. As Super Buick Guy said, you can be lucky or good, but sometimes, you're just screwed and you have to work through it and it can be tough.

A coworker of mine, good bud races the NMRA series with a six second 92' Camaro and I asked him if he threw hundreds of dollars at stuff that didn't work and that he never used again and he immediately agreed and summed it up, saying it can be "hit and miss". I didn't feel so bad after that. Thank you all and this is why I love this forum!

Last edited by F22; 04-10-2013 at 01:43 AM.
F22 is offline  
Old 04-10-2013, 01:52 AM
  #13  
F22
Le Mans Master
Thread Starter
 
F22's Avatar
 
Member Since: Oct 2006
Location: Palmdale CA
Posts: 6,842
Received 275 Likes on 211 Posts

Default

PPS. The Lunati Voodoo cam is a 272 grind, for RV's, 4x4's and Marine applications, or where bottom end torque counts. I had reservations about the cam Lunati recommended for a daily driver, wanting to go with the 268, higher lift cam, like many others. Top end is nice, but that hard pull and torque is good for some giggles too!
F22 is offline  
Old 04-10-2013, 08:36 AM
  #14  
David Mc
Racer
 
David Mc's Avatar
 
Member Since: Mar 2003
Location: Klein Texas
Posts: 448
Received 20 Likes on 19 Posts

Default

Some of us are not "Everybody"



David Mc is offline  
Old 04-10-2013, 09:02 AM
  #15  
BOSTONCAMARO
Melting Slicks
 
BOSTONCAMARO's Avatar
 
Member Since: May 2006
Location: Lynn MA
Posts: 3,292
Likes: 0
Received 14 Likes on 9 Posts

Default

I knew all about this actually....but then again like David Mc I am not everybody hehe

glad to hear you got it sorted out!
BOSTONCAMARO is offline  
Old 04-10-2013, 09:48 AM
  #16  
oldschoolvette
Le Mans Master
 
oldschoolvette's Avatar
 
Member Since: Nov 2006
Location: Orlando FL
Posts: 7,215
Likes: 0
Received 1 Like on 1 Post
Default

wow good info..glad you got it
oldschoolvette is offline  
Old 09-26-2020, 12:10 PM
  #17  
pabutler17
Cruising
 
pabutler17's Avatar
 
Member Since: Jun 2020
Location: NYC Metro - Long Island
Posts: 12
Received 1 Like on 1 Post
Default

Thanks for this info, I have a few questions, I am looking to put these 113 heads on my 81 is it possible to give you call? My cell is 917-449-1700
pabutler17 is offline  

Get notified of new replies

To Everybody was wrong!

Old 09-26-2020, 02:07 PM
  #18  
pabutler17
Cruising
 
pabutler17's Avatar
 
Member Since: Jun 2020
Location: NYC Metro - Long Island
Posts: 12
Received 1 Like on 1 Post
Default

When you did the heads did you replace the cam? Is so what did you use?
pabutler17 is offline  
Old 09-26-2020, 02:14 PM
  #19  
210ken
Pro
 
210ken's Avatar
 
Member Since: Aug 2010
Location: Napa, CA
Posts: 517
Received 344 Likes on 183 Posts

Default

Guide plate pn 10111771 is not a valid number on GM Partsdirect. Was that a typo?

thanks ,

ken
OOPS, THIS IS A SEVEN YEAR OLD THREAD!!

Last edited by 210ken; 09-26-2020 at 02:42 PM.
210ken is offline  
Old 12-21-2020, 01:03 PM
  #20  
JJBlack95
1st Gear
 
JJBlack95's Avatar
 
Member Since: Dec 2020
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
Default

I have these heads on a ZZ1 HO 350. I’m looking for replacement rocker studs. I’m having trouble finding adequate technical assistance from GM. Does anyone have a suggestion for a dealer with direct knowledge of these heads?

Thanks
JJBlack95 is offline  


Quick Reply: Everybody was wrong!



All times are GMT -4. The time now is 02:16 PM.