Hi, I have built a ZZ4 clone but used a GM replacement roller short block w/ dished pistons, 8113 L98 heads and ZZ4 cam. I used ARP studs w/ Felpro 1044 head gaskets, torqued to 65# with Permatex teflon thread sealer on ALL studs following the typical GM torque sequence then  I bolted the ZZ3 intake to it.I intially fired it a couple of months ago and found #8 full of water after sitting over night. I pulled it appart, finding a few studs loose. I bought ARP BOLTS for the next round...w/new felpro 1044 head gaskets, cleaned all bolt holes with tap and acetone, thoroughly etched head and block decks, wiped down with acetone and repeated the reassembly. I still have water EVERYWHERE, INCLUDING in the crankcase. Can you help? I can't keep pulling this appart, gaskets are killing me. Everything seems to be true...am I using gaskets that set up this condition?  

Not seeing the engine it's hard to say where and how your problem originates. Some thoughts though:

1) unless these are D dish pistons, you aren't getting all the combustion chamber has to give. Though this is not related to water leaks.

2) L-98 heads are the first generation of heads retuning to configurations pioneered by Sir Harry Ricardo, not that Chevy ever really utilized Recardo's designs the way Ford did for a little bit in the early to mid 1950's then dropped the details. But the Devil or in this case the performance is in those details. The details are a closed, heart shaped combustion chamber with a beak projecting between the in and out valves from the quench side really makes power accepts higher compression and does it on less fuel than anyother design.  These concepts lead to 2nd and 3rd generation improvements found in the more advanced fast burn head; either Vortec or Fastburn from GMPP or similar aftermarket designs would have been a much better choice by some 40-60 horsepower, no other changes.

3) Was the block's head deck milled? Were the heads milled? There's a couple issues with milling or not.

a. The first is to get flat mating surfaces which seal better than those that have warpage.

b. The L-98 head has a pretty thin gasket deck and dosen't take kindly to milling.

c. Whether the block deck, head deck, or both have been milled the intake must also be milled sides and bottom at a specific ratio of the amount removed from the respective deck surfaces or else the intake will not make either air or water tight seals resulting in leaks.

4) Valve lift and springs on L-98 heads. These heads are very weak in the spring pad area, using stiffer springs or a lift that jams the valve's keeper into the top of the valve guide will result in cracks between the oil and water side also often allowing water into the ports.

5) There is also the possibility of other random cracks that allow coolant leaks. One needs to be careful with bolts and studs to insure they are not longer than the thread length of their holes. Running too deep into these holes will result in fractures of the castings. Bolts, or stud nuts pulling down on aluminum such as the head and intake manifold must have a hardened washer under the bolt or nut head, otherwise the aluminum around the hole is crushed and distorted, this can give false torque readings and can also lead to cracking in the bolt hole.

6) It's never a good idea to reuse a head or manifold gasket, especially if the engine's been fired. This begs the obvious question as to whether or not you did.

7) I prefer GM's Michigan gasket to FelPro, seems to have fewer problems. 

The list goes on and on, but these are major things to look for.

Bogie

Thanks Bogie! I did not reuse gaskets, bought new both times. My concern is that I may be using gaskets that were not intended for my application. The heads are new, the short block has about 850 miles and showed no signs of problems sealing the heads that were on it. I really can't afford to remove and disassemble the block....though if all else fails I will. I'm considering buying the GMPP 12557236 head gaskets. It would seem that you found no issue with my assembly practices and that mixed with comments from other sights makes me beleive that it SHOULD be as simple as using tried and true materials. I've been searching other sights to see if the ZZ4 has a history of head sealing problems and it seems that they do. I was hoping to avoid that by using "other" gasket designs. Now I'm not sure. I had one guy comment that he went to 75# on torque and fixed the problem....I'm not a big fan of overtorquing! Your comment about bolt length hit home...maybe the ARPs are too long. That could explain the second round but the first round was with studs and length shouldn't have been an issue there, but???? In reading different forums is sounds like L98 heads have a tendency to "walk around" on the deck and GM has built SO many of these that I'm starting to beleive that I should try the gaskets that they use. Another thought is ditch the L98s since this is a daily driver, change springs in a set of vortecs and motor on....what do you think? Thanks in advance...oh, and sorry about posting under this heading. I didn't intend to do that. Ken

Ken, you used one of many FelPro gaskets listed for your application. Aluminum heads require a composition gasket. Steel shim gaskets don't have enough give for the different expansion rates of aluminum and iron and they tend to eat into the softer aluminum as it moves around, what the rocket scientests call brinneling.

The L-98 head is a bit weak in the deck area and is known to be difficult to seal up. I think another few pounds of torque from 75 to 85 pounds with oil on the threads is a good idea with aluminum heads, even the Ford guys have to do this with SBF GT-40 heads. Really make sure you've got HARDENED washers under the bolt head or nut when you pull 'em down. Go up in 10-15 pound increments, start measuring at 25-30 pounds. Go slow, have a cup of coffee or a smoke between tightening rounds to give the heads some time like 10 minutes to adjust to the forces.

The GMPP gasket 12557236 is specifically made for the L-98 aluminum headed engines and are a good choice not to mention less expensive than the FelPro.

Back in the days before coated gaskets, I've been known to put a thin layer of moly grease on both sides of the gasket to give things a chance to move around as they snuggle down.

Be careful cleaning don't scratch anything.

After running thru a few cold to hot to cold cycles, retorque 'em when the engine is cold. Yeah the gasket guys say this is unnecessary with these new perma torque what-ever gaskets and if you believe that I've got a bridge in Tacoma I'll sell you.

Bogie 

Hi Bogie...and thanks! You've just supported some of my thinking. Wasn't too sure on the high torque numbers but...I'll do it cuzz YOU said so. I'm headin' for the Chevy store tommorow! Can't wait to seal her up. Thanks again,  Ken   

Hi Bogie...It's me again. I'm going with all GMPP gaskets this time, found good info on Sallie's sight. I have a quick question on drilling the accessory holes on the L98 heads. I'm using a serpentine set up off of a Camaro. These heads only have two accessory mounting hole drilled in the passenger side. I'm a little leary of running with just two bolts in the serp set up. What are your thoughts on drilling and tapping for the third bolt? Again THANKS for all your help! Ken  

If you’re drilling where the machined pad is on the front of the head there's no structural problem, just keep in mind the bolt will penetrate into the coolant jacket and have to be sealed.

Frankly I'm not a fan of serpentine belts. Where I'm doing a simple installation of water pump and alternator, I take the GM serpentine stuff off and put V-belts back on. To me it's a cleaner and simpler look that gets rid of all those gompy castings hanging on the front of the engine. If however you're running air conditioning, smog pumps, power steering and the like, I guess serpentine provides better structural mounting for these accessories, though I just don't like the look.

I almost forgot, again! Put a squirt of oil on the heads where the hardened washers sit and do the same under the bolt heads. Check the depth of the long head bolt holes, some blocks used slightly different length bolts in different places.

Bogie

Thanks again Bogie...I will be drilling on the machined surface...just enough to get 4-5 threads I think. Was planning on stuffing a stud in there with sealer. I always poor plenty of oil under, over and around all washers/bolts and I already checked the bolt lengths so I'm ok there too. I'm pretty confident that the gaskets are the culprets! Thanks for all your help....btw, this is in a 93 C-1500  700r4, 3:42 posi, will add TPI over the winter. Should be a tire roaster/daily driver!  Ken  

When you say the heads were thoroughly etched do you mean they have machine hash marks? If so there's your problem, aluminum and cast iron have different expansion rates if the head can't slide that little bit it'll tear the gasket and cause a leak. The head surface must be almost dead smooth.   

Hi Bogie! I've found an interesting little nick that starts at the rear lower cooling passage and extends up just beyond the fire ring "brinneling" mark on #8 cylinder. Yup after the last start-up they now have brinneling marks....very very light but it is there. I'm sure this is the source of my leak! Can't beleive how much different the GMPP gaskets are! My new question is...two fold....any problem with welding the nick full...filling flush and then have the surface slightly milled? Just enough the clear the brinneling? Thanks in advance! Ken  

Ken, yeah the brinneling marks are not a good thing, it shows the head and gasket are not moving together. This has been my experience with FelPro gaskets on the L98, LT-1 and 4, GMPP Fastburn, and a the few aftermarket Al heads I've used.

If the nicks are deep say .010 inch or more welding before milling is probably a good idea. As long as the welding doesn't get close to the valve seats to where heat could require R&Ring the seats. If you have to go through that a new set of heads may prove cheaper.

The decks on both the heads and the block need to have a good finish, no machine marks. Sometimes when you look at GM's machinging you have to wonder if they just cut the part off with a chain saw instead of a mill. These aluminum heads need the block deck and the head deck each to be flat within .005 inch. Any places that exceed that should indicate that milling is required to restore the surface. The L98 head is especially sensitive as it just is a bit shy on thickness, so it bends and warps eaisily. On the other hand one would think that it does a better job of conforming to surface contours, but real life just doesn't seem to work like that.

Bogie 

Hi Bogie ...and thanks. I've just purchased a set of Dart Iron Eagles...my new question is.....what valve spring set up will be BEST for the ZZ4 hyd roller? I don't want to rob the L98s but just might....are the GM LT4 as good as they need to be? Thanks in advance...again! Ken  

The LT4 springs are good stuff with the ZZ4 cam.

So what's with the L98s? Did you just tire of chasing problems?

Bogie 

Well....it isn't quite like that, but close. The Darts are going to do a couple of things the L98s won't. I can make use of the extra chamber volume...drops me into 87 oct range which is desirable for a daily driver...and makes a little boost attractive(later), they flow a little better, they're cast iron....and they have that warming effect from the cross-over for that Michigan winter thats comming up! AND....since I've decided to take the early retirement from FORD, I may have to use my BABY for more than just fun. I kinda figured the LT4s were my best bet, just wanted your opinion. I think I'll have a little more peace of mind with this package PLUS........now I get to port up the L98s for a future project. THANKS AGAIN! I hope you won't mind hearing from me when I seal her up again.  Ken  

Early retirement, wow! I just got back from a hiring trip to Detroit, picked up a bunch of engineers and am now training them how to design airplanes. Lots of really good Ford and GM people out there, unfortunately we can't take more than a few.

I live in what has become an upscale yuppie and gen-x neighbor hood where Beemers, Lexus, and Benz are the vehicles of choice. They all meet at Starbucks and Tully's to explain to each other what good American's and Republican's they are; they really get annoyed by my GMC pickup with the bumper sticker that reads "If you didn't buy American, you ain't much of one." So they explain to me how their Nazi car was built in America, I explain to them the difference between some assembly required in America and Made in America. They're F'ing clueless. Most take the time to tell me “ain’t” isn’t in the dictionary, like I ain’t got no education.

Bogie