I’ve been slowly working on a LQ4 build to go in a 1967 Skylark. Two jobs and two kids is making for very slow progress. I’ve bought a M295 oil pump, cloyt timing chain, BTR stage 2 Truck Cam with BTR Valve Springs and a Holley Swap oilpan. I was going to leave the 317 heads on and not break head gasket. However when I went to install the valve springs I found out the rings were not sealing. I have since pulled the heads and once I manage to get the crank pulley off will finish breaking the block all the way down.

This is my first project car ever and I feel like it is getting beyond my knowledge base. I plan on getting the block cleaned, checked and possibly a new home/bore. I’m this far so it seems silly to not get new bearings installed while I’m here. The issue I’m having is what to do with the pistons/connecting rods. The simplest and cheapest route appears to be to put LQ9 factory parts in and move on with life. However I’m reading that factory pistons are “weak” and cause catastrophic failure if they let go. I’m also hunting for a pair of 799 heads to replace the 317’s. Although I have seen a few spots where the 706 heads are cheaper and work well on 6.0 engines. I’m not sure if the cam I have will cause issues with the lq9 pistons and upgraded heads? Should I just keep the 317’s, do the lq9 pistons, and call it good? I’ve tried researching things but sometimes my lack of knowledge makes understanding what I’m reading difficult.

The purpose of the engine is for a cruiser and maybe an autocross event. The plan is for it to get paired with a 4L80E(still to be bought). I want to run pump gas and will be sticking with EFI. The truck intake will be going back on. I’m not looking to drag race this car and I don’t want to build something that is un-drivable on the street. I’m getting ready to deploy for a bit so I can save up for new parts and wait for online sales but I see no reason to drop $700 when $300 will work for my purpose. Can I get an azimuth check?

 

The factory pistons are actually pretty stout. If they need replacing, just get some LQ9 pieces as you mentioned. For a lot of your questions, give WS6Store a call. They are a vendor/sponsor here, and appear to treat people right. They will give sound recommendations, good customer service and nice prices.

 

you sure the rings were not sealing? How much was blowing passed them? If they were all leaking the same amount it was probably just normal blowby passed the rings. Especially if it has been sitting and most of the oil would have ran down off the cylinder walls.
these engines will go 300-400k with proper oil changes and the compression will still be good!

 

LS7 CO,

I was using compressed air to keep the valves shut so I could do a spring swap. The cylinder would completely decompress in about a minute. All the hissing was coming from the front cam opening in the valley. I tried using a rubber mallet to reseat the valves and would get a pop at first but then it went away after the hissing stopped. I pulled the heads on the advise of a coworker who stated that all the air shouldn’t leak out if the rings were sealing.

 

Not quite a leak down test but enough to know there was too much air getting past the rings. How do the bores look? Can you still see any crosshatch? I'd probably just have everything checked out and come back in with a re-hone, new bearings and rings.

 

It is likely that you can spend less on a better condition motor than "fixing" what you have.

Sux to throw stuff in the trash but sometimes it's the best way to go.

 

RB,

Really I think it is my fault for taking so long to work on the motor. There is still cross hatching in the cylinders but a small line where the pistons sat at. I bought this motor well over a year ago but I’m just very busy and working a couple hours where I can spare them here and there which is hard when you don’t know much as I get stumped easy.

While it sucks to spend the money, nothing about building this car will be cheap. Honestly I like the idea of building a motor from the ground up. It just would have been easier to do a SBC than an LS but I’ll be happy in the end. I don’t mind spending money but wasting it buying more expensive parts that don’t fit my need is just silly. It is easy to do when reading magazines that are trying to get you to buy the latest and greatest parts. Happens in the gun world all the time. I appreciate the help here.

 

did you keep the air hooked up or were you shutting air off to the cylinder before trying to remove the springs?

 

I did shut the air off but that seemed to be what the person who told me to do it this way indicated. Not that it matters now as the heads are off but was that incorrect procedure?

 

Yes the air will leak out of the cylinders, you have to keep air pressure going.
Honest mistake though, the first set of springs I did years ago I also thought I had a major problem because of the amount of air escaping. But it ended up being completely normal.

Needless to say I personally wouldn't tear it down any further other than pulling the camshaft out. And as everyone else will say, when you do that do NOT look at the cam bearings because they always look like crap.
These are the headgaskets from WS6 store I have used http://www.ws6project.com/user_stor/...oducts_id=6485

 

Edit:..... previous poster removed his comment ?

 

If there's still cross-hatch marks in the cylinders, probably best then to just leave it alone and run it. The short blocks in these motors are pretty stout to begin with; much tougher than older motors. Doesn't sound like you're doing anything that will really stress it out too much.

Bearings might be worthwhile but if the thing doesn't show signs of that sort of distress inside (black smelly gunk in the crankcase and so forth) they're probably OK as well.

Compare prices of things though. Look REAL HARD at what a bunch of pistons, machine work, etc. will end up costing you; and compare to the cost of just picking up a low-mileage, relatively cherry sort block at the buzzard nest. Just doesn't make sense to spend $2000 to get the same results you could get for $1000. But if you don't need it at all in the first place, don't spend it.

But seriously, your best choice might just be to leave it alone, get the heads worked maybe, use a C-clamp spring compressor instead of the air (which personally I've NEVER found to work for me), and run it. If the heads were still on it, I'd tell you to try the rope method; that's what I've done on countless motors, with FAR more success than air. And yes, that air procedure you describe was incorrect; the air will ALWAYS leak down within a matter of a few seconds.