TonyJ
Newbie
First thing, spray them with some penetrating oil. I'd do that for a while and see how they rub down. I'd probably go over it lightly with some oily emery cloth, but not be too aggressive.
L31 head gasket job tips?
- Thread starter onspeed
- Start date
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Finally going to get around to finishing it this week. Got the heads on and torqued, just need to get the rest reassembled. Largest thing I'm worried about is the fuel spider and the distributor. Didn't mark the distributor since I figured I'd be rotating the engine to torque the rockers... sort of regret not doing so after reading all the frustations people have with getting it back in right. Someone mentioend on page 1 that I'd need to get the timing electronically set? Regardless of whether I put it back in the same orientation or not? It turns out my HPTuners doesn't work with the '97 PCMs, so anybody know how much a dealer will charge for this?
Also, fuel spiders. I have the old one with the poppet valve. The car was running a little rough, but I'm not sure if that's because of the cracked head or some other issue. Worth it to go ahead and upgrade to the ones with injectors, or put all back together and give it a shot?
Also, fuel spiders. I have the old one with the poppet valve. The car was running a little rough, but I'm not sure if that's because of the cracked head or some other issue. Worth it to go ahead and upgrade to the ones with injectors, or put all back together and give it a shot?
Any dealer and most independent shops worth their salt will have the scanner that can read and set the timing. The problem is that is has to be @ 0 degrees plus or minus 2, which is a rather narrow window to hit off of dead reckoning. The engine will run with it being at least 15 degrees out, but won't run well and should set a P1345, though not always. If you mark the distributor body relative to the rotor and the rotor relative to the firewall, you can usually put it back in on the money if you don't rotate the engine. In your case, you'll have to roll it to TDC and stab the distributor with the rotor pointing as close to cylinder 1 as possible. Then you can take it to get the timing set properly.
Given the amount of rust and corrosion that I saw in the pics of your cracked head, I would say that the poppets are the least of your worries. I would be far more concerned about ring seal and compression issues arising from it. As far as the poppets go, though, I would clean them up as best you can and see what happens. If it runs well, then you're fine. If not, then you can make sure it's the poppets and not compression or ignition issues before you drop $300 on the upgrade.
Given the amount of rust and corrosion that I saw in the pics of your cracked head, I would say that the poppets are the least of your worries. I would be far more concerned about ring seal and compression issues arising from it. As far as the poppets go, though, I would clean them up as best you can and see what happens. If it runs well, then you're fine. If not, then you can make sure it's the poppets and not compression or ignition issues before you drop $300 on the upgrade.
Yes. 
dkennedy
I'm Awesome
I just went through this head buying thing, and from all my research I stayed away from the heads mentioned in the quoted section above. These are imported castings built with generic parts. They might work out just fine, but then again who knows.
After several weeks of reviewing options, I settled on THESE heads from Summit @ $309.50 each with no core. After looking at the serial numbers on the castings I determined that they are manufactured by Dart for Summit. They do have the funky looking ports on the intake side, but stock intake manifold gaskets will work just fine.
EDIT: For whatever reason page 3 of this thread wasn't showing up before I made this post, so it's pretty much past due, but maybe some food for thought for others that might be in search of information.
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Yes.
Oh well. I would have marked it, but the procedure in the service manual for installing a distributor without marking it made it sound pretty easy to install and easy to see if it wasn't in the proper alignment.
Anything else I should know for reassembly? The LS motors are considerably easier to work on IMO. The instructions for setting the rockers given in the service manual is to get zero lash and 1 additional rotation clockwise with the valves closed. That sounds about right?
Also, the torque spec for the head bolts is 22 lb-ft + 55-75 degrees (depending on the bolt)? I searched around a bit and it seemed like people were doing that or ~60 lb-ft. Either way, that seems a bit loose for a cylinder head, although I've never worked on a SBC before. LS head for instance is 22lb ft + 90 deg + 90 deg.
The marking procedure is primarily so you don't have to roll the motor to #1 TDC before pulling the distributor, and also to put it back as close to being in time as possible. I always recommend setting the crank retard offset again after intake jobs on Vortecs, just to be sure. Installing a distributor is pretty easy in a SBC, but marking things saves time for techs, where time is money. The only thing that can be a pain is getting the oil pump drive shaft to line up with the drive in the distributor gear, as the distributor shaft will rotate a bit when it meshes into the cam gear. You will need a long flat blade screwdriver and some patience since you are doing it from scratch, so to speak.
The lash setting sounds right, as you are setting zero lash first, then the one full turn to preload the lifter.
LS engines use torque to yield headbolts, where SBC's do not. This means that the LS head bolts permanently stretch by entering the plastic deformation range on their stress/strain curve, whereas SBC bolts only reach elastic deformation, meaning that they return to their original length after being removed. That is why SBC headbolts can ( but not necessarily should) be reused, and LS headbolts cannot. Clamping force on a fastener is a function of design, torque angle, and material strength so that a change in torque angle alone does not directly reflect a difference in clamping force.
Had a brain fart today as I was reinstalling the rockers, rods, and new lifters. Was torquing down the rocker arms to 22 ft-lb for some reason. They were like that for maybe 10-15 minutes before I noticed my mistake... any chance I damaged anything?
Did you run it?
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