I ran my car in my first track event this weekend at CMP. Unfortunately, on the second to last HPDE 1 outing it blew a head gasket. It was totally my fault. I should have kept a better eye on the temperature gauge. I think the thermostat (brand new one at that) failed closed causing the engine to overheat. Anyway, my question is; while I have the heads off, is there any other maintenance you guys would suggest I do while I'm at it? This is my first time delving this deep into the engine but I'll have someone much more experienced helping out. I just thought I'd get some opinions on what else to check out while everything is apart.

Thanks in advance guys.

 

How many Miles on the Engine
if above 90K.. since you have the Heads off.. I would bring them to a Machine shop
and test your springs check the guides & valve seats.. install better valve stem seals
If Iron heads why not install Threaded rocker studs.. I would upgrade to 1.6 rockers
and install Trick Flow Push rods... check the roller Lifters as well... JMO!!!!!

 

It has 119k on it. I planned on finding a place to test the springs and such. How pricey can getting threaded rocker studs get? I'm looking more for fairly inexpensive maintenance stuff (as if that exists...) instead of upgrades.

Thanks for the feedback

 

I believe your 87 should have aluminum heads. That is one of the reasons head gaskets blow. The expansion and contraction rates of the cast iron block and the aluminum heads are different. So eventually the gaskets go south .

If you aren't sure about the heads, place a magnet on the head. If it sticks, the heads are cast iron. If it does not stick, they are aluminum. If they are aluminum, you already have screw in rocker studs. 1.6 RR would be a good addition.

I would change out the valve seals, easy to do if you already have the heads off. Suggest Fel-Pro intake seals all the way around. Check springs and replace if needed...again easy if the heads are off...and you have to remove the spring to replace the seals.

Do you have a die grinder? Perhaps now is the time to gasket match the intake runners and runners in the head. Also the intake runners to the runners from the plenum on up. Remove the "bumps" in the plenum behind the TB. You could also do a little grinding on the exhaust manifolds.

I would also suggest that you take a center punch and dimple the "china walls" at the front and rear of the engine. This helps hold the sealant in place. I also dimpled this same area on the intake manifold. I would use the RIGHT STUFF to seal the "china walls".

This will be a good learning experience for you. Good luck. ALSO...label every wire, hose, nut and bolt that you remove. Sounds like overkill...but YOU WILL NOT BE SORRY THAT YOU DID SO. ie there are different size bolts that hold the intake runners to the intake.

 

Learning how to do this stuff is the reason I bought this car...aside from flogging it around the track . They're definately cast iron heads by the way. I'll take a look at the 1.66 rockers. Thanks for the info!

 

You might want to replace the timing set. Here's my 86 before I rebuilt her, nylon broken off and lots of slop.

 

Are the heads after market? The last half of 86, GM switched to aluminum heads for the corvette. I would have thought yours would be aluminum.

 

He's got an 86.

 

Affirmative, it's an early 86 with cast iron heads.

 

I thought only 85's had those crappy nylon timing sprokets.

Replacing the timing chain will require the removal or at least the lowering of the oil pan and also the water pump so you know ahead of time what you're in for. You can't get the lower edge of the timing cover back on without doing this. You must use thread sealant on the head bolts and water pump bolts because they tap into the water jackets of the block.

Threaded rocker studs is a waste of time on a stock motor. You don't need it. I wouldn't even bother.

Rear oil pressure switch will be plainly accessable during this time. If it's leaking replace it now cause it's a pain in the azz to access with motor assembled later on.

Have your heads checked for straightness and resurfaced flat if needed. Also have them vaccum test each valve for leakage. Don't just slap new head gaskets on and bolt them back up without having them checked. It doesn't pay do it half assed.
While you heads are there have them install your new valve stem oil seals that are included in Fel-pro "head gasket kits".

9 out of 10 motors I replace blown head gaskets on due to overheating also warp the heads requiring a resurface and have leaking valves that don't seat and seal all the way. If you bolt a set of warped heads back the block like you're going to have either compression or coolant leakage problems. The same if you fail to check and correct any leaking valves.

I like to use all new head bolts. These tap into the water passages of the block so they come out with a lot of buildup on the threads which is a time consuming pain in the azz to clean off. Just toss them and go with a new set. Fel-Pro carries a reliable and affordable set. No need for expensive wild ARP bolts or studs for the heads.

How hot did you get the engine?

 

Thanks for all of the advice. It pegged out at 260 *F before i noticed steam coming from the hood....

 

Okay, then that opens another can of worms. Press-in studs and limited pushrod clearance in the heads just to name two.

If you plan to ever move to 1.6 RRs, which would call for a spring replacement, you're looking at addressing both of them.

New springs will most often call for increased pressures. Press-in studs tend to pull out, a little at a time, due to the increased spring pressure. Not all at once and maybe not even all of them, but the incidence of it happening is well documented over the years.

The holes in the heads through which the pushrods travel is small. Adequate for a stock setup up, but the increase in rocker arm ratio often makes the pushrod ride against the head, bind and bend. So you'll end up with a hand full of bent pushrods.

I know all that from personal experience on a pair of early 86 L98 iron heads on a 86 Vette engine.

There's a fix for both of those: Drilling and tapping the stud holes for replacement screw-in studs for #1 and elongating the holes in the heads using something like the Louis Tool for the needed clearance for #2.

All this, naturally, adds to the over-all cost of the re-build, so at some point it would cheaper and, yes, better to just move to a pair of aftermarket heads or a pair of stock replacement heads from a Forum member (Parts For Sale) board.

Jake

 

If they are cast iron, have them magnafluxed. Iron heads can crack. It's somewhat common depending on how hot it got. And you want them checked for warpage as mentioned, and check the valve springs. Over heating can ruin the valve springs. I would also replace the thermostat. Overheating can ruin them too, and a new thermostat is only $5. When the heads are off, check the cylinder walls for scoring. It's possible to ruin the pistons if it gets hot enough. But you want to cover all your bases so you don't have problems when putting it back together. I have seen alot of overheated engines that about EVERYTHING is junk. But hopefully your didn't get that hot.

 

[QUOTE=86PACER;1575882665]I thought only 85's had those crappy nylon timing sprokets.

Replacing the timing chain will require the removal or at least the lowering of the oil pan


No need to remove or lower the pan on a SBC. Never once in over 30 years have I had to do either...

 

I've seen guys have to lower the front of the pan to get the cover back on right. Even the shop manual calls for the removal of the oil pan when removing/installing the timing cover. But I'm certainly not going to question someone who's got more experience than I've been alive.

 

BBs have the same issue. After fooling with both race and street engines for decades too, I found that for ME, the most leak-free way is to, at least, lower the front of the oil pan. That way pretty much guarantees no leak.

There's a work-around though that, from personal experience, is a toss-up. Involves cutting the gasket then filling the gap with sensor safe silicone on re-assembly.

Worked about half the time for me but, eventually, I scratched if off my "How to Do Stuff" list and bit the bullet and became a pan dropper. CONGRATS to those who've had better results.

Choose your poison.

Jake

 

86Pacer. All that is needed to be done is take dikes and trim the conners of the timing cover where it meets the pan. This process has been going on probley from 55 when they started using this block platform. Trim the conners like I said put some GMS in the conners tilt in the bottom take 2 phillips screw drivers one each side put threw screw holes in cover and in to the screw holes in the block pry down push in to alain pins start screws and complete. Old chilton manuals and even some of the timing sets we would recive showed this.

 

if he wants a little more lift Installing 1.6 Rockers.. I would absolutely
have them converted to threaded studs!!! or at least drilled and pinned

 

PS a new thermostat.. is a must drop in a 180 Deg to lower the
manifold temp and give a little extra power!!!!

 

Notice I said stock. Threaded studs come into play with stiff valve springs.