Amazingly, my 1986 FSM, same page number, 6A1-5, says just the opposite to what yours says. "2. Install gaskets on cylinder heads, blocked openings in gaskets to be positioned at rear of engine".

Jake

 

I appreciate all the responses to my question since Im about to start putting the parts on my engine so I can install it shortly. I think Im going to just use gaskets that are open in the rear. If I do this I should just plug the intake where the bypass hose goes and run a regular heater hose to the core ( is this correct) ?? Also with a different block ( Late 80s truck 4 bolt) and different heads ( 180cc Dart Pro 1) should I have any problems with head gaskets or was this just a problem with the L98 Corvette head design?
Thanks WW

 

It is just my opinion, but I never thought the corvette was prone to blowing headgaskets.
Compared to other similar compression ratio motors of the time, the were probably comparable.
I think the weak link (once you subtract poor cooling system maintenance, old age, overheating etc) was just the head gasket technology of the time.
I don't think anything negative could come from running the open gasket and blocking both ends of the small crossover.

 

Open gasket and block off the hole in the intake for the coolant riser tube. Splice or replace the one heater hose to eliminate the riser "T" from it.


Just curious: Pete did you install the new dart heads for him or is that task on Wayne's own "to do" list?

 

Early OEM aluminum headed motors were prone to head gasket failure due to incompatible materials, but the 113 headed L98 Vette had enough failures to prompt several lawsuits with multiple complaints to the National Highway and Traffic Safety Administration. GM addressed the issue in a November '89 Bulletin ('90 was then in production) linking the problem to galvanic corrosion from coolant leaks due to misaligned intake gaskets. Their solution was to counterbore the front and rear intake mounting bolt holes for gasket retainers that would keep the intake gaskets in perfect alignment and stop the leaks. Though the Bulletin advised that these heads would be available for immediate installation, they only went on the '91 L98's. The design remains on current production 113's which are used on the ZZ4. Whether or not they did anything wasn't really tracked (L98 production ended), but the high incidence of head gasket failure seems to have waned with the '91 - at least around here. These failures are allmost always at #7 and seem to show up at 25,000 to 50,000 miles (a lot just after the warranty pooped out which prompted the litigation). It wasn't a gasket "blowing out", but a weepage of coolant into the combustion chamber with exhaust back into the coolant which worsened the acidic mix. If it went on long enough, it wore a valley into the deck (not easy to repair) and head gasket failure reoccurred. I wouldn't buy a 113 headed Vette without a compression and/or leakdown test and if you're rebuilding one of these blocks, I'd pay attention to the Deck - particularly if the rebuild is due to head gasket failure. If isn't sqaure, you'll be doing it again - and again and again . . .

 

I've almost started a thread several times listing errors and mistakes. It really is a poorly written and poorly organized service manual.

 

It's not perfect, but mine's paid for itself many times over in potential dealer repairs. And, they provide an address for reporting boo-boos, too.

 

Onedef, I completely agree

 

My machinist verified valve guide clearance, reground the brand new valves (just as a precaution) and set up the springs.
I double checked his work, set up pushrod length, checked piston to valve clearance and installed the heads.

 

Well, I just talked to the guy thats helping me install my engine and he's telling me if I use gaskets without the small block off holes I could have a problem with my car running hotter.. According to him these small holes hold back the coolant flow so the coolant in the radiator reaches a lower temp before moving back into the engine, and without these holes the coolant would go through the radiator to fast to cool down enough.. This seems like one of those things that everyone has an opinion on, but no one can say for sure whats correct..WW

 

Nice work Pete.....i'm sure that engine is totally ready to go...looking forward to seeing/hearing it run.

 

Huh??? It isn't used on the F Body L98, it isn't used on the ZZ4 crate (which is about as close as you can get to an L98 these days), and it isn't used on anything I can think of that's built in the US or Asia, Germany, etc, etc. GM abandoned the design with LT1 and has pretty much stop sending coolant through any manifold (they never could get them to seal). The design was a bit of a beta - but a lot about Vettes are. Anyway - GM still figuring out aluminum vs iron (and what to do when they couldn't use asbestos in gaskets anymore) - decided it might be a good idea to keep coolant at the rear of the heads a bit longer and to maintain a sufficient supply (with the restrictors in place), they supplied additional coolant from the heater core outlet. Now the heater core is a small radiator and in the old days, good for a couple of points off of the coolant temp, but I don't know if that was considered. Anyway, if you want to run without the restrictors, you don't need the feed. Coolant temp will remain a function of capacity, thermostat and at low speeds, whatever drives the fans. There are billions of cars out there doing just that and your Vette - though maybe special - isn't any different.