When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Forgot to say, this is without rocker arms on yet. So nothing to do with timing. And yes, stock pistons, valves.
your pistons are hitting the head. like already said use your old gaskets if you have them. If not yes buy some.
your valves are not opening they are not hitting. To check ptv clearance the valve train needs to be mocked up on at least # 1 hole.
This isn’t a good situation for the parts dartboard, lol…. First thing I would check is if the timing chain is installed correctly. Could be out of phase.
Are these stock valves and pistons?
I agree. One thing I'd never do is install the head with no head gasket-UNLESS-You install it with no bolts/studs holding it to the block. Installed with no gasket, if you turn the engine over too hard, with an 18" breaker bar (how hard is "hard?") could be a great way to bend valves, or worse!! I'm just guessing here but I would think any cam with 112° LSA, or tighter, and .600" lift, or more, would never clear without a head gasket. With no bolts/studs, what would you do? Use a second indicator to measure how far the head lifted, then try doing all the math without getting confused? Too much monkeying around for me. Put the head gasket you'll be using on the block, tighten the head down with a 3/8 drive ratchet until you feel resistance, say just a bit over finger tight, and push down then pull up on the head to ensure the head is all the way against the gasket. If you feel movement, or hear a metallic sound, its not all the way down. Then start measuring. If you must use the clay method, don't use playdoh, use real modeling clay. Playdoh can spring back slightly, giving erroneous readings. My .02, and best of luck......
really? cause i see everybody saying you have to have an RA of like 30ish. On mine theres no gouges or anything, but from what Ive read everybody says they have to be super smooth.
I had my LS7 heads "fixed" a couple of years ago. All I did is use a flat honing stone (Norton brand) to hone off the heads. Then I cleaned the block deck surface well, and torqued the heads down. This was 26,000 miles ago. No issues. Yes, I've been doing this stuff a long time. So I know what I'm looking at. I agree with vette4fl, in that stains mean nothing. In most cases, if you know the engines history, as in no overheats to cause warping, etc., you'll be fine with the finish thats on the heads and deck now. Unless you've gouged up the aluminum to where it looks like a dog has chewed them up, you'll be fine. If you go to a Surgeon, expect him to cut you. If you take parts to a machine shop to be machined, expect them to machine them, whether needed or not. Again, my opinion.......
When I’m checking PTV as you are 65gmc, I use .030 valve spring shims on the block deck, in place of a headgasket. I hand tighten the bolts. I check my clearance numbers in the clay, and do the math for the difference between the .030 shims and whatever headgasket I am using for the particular build that I’m working on. I make sure I know the COMPRESSED thickness of that headgasket being used. It’s a simple and quick way to check ptv. I’ll use 6 shims scattered about the head to keep the head square to the deck. Make sure that your head dowels are in place, to ensure the head is in the right place. The shims have holes in the center of them…run your headbolts though the holes.
your pistons are hitting the head. like already said use your old gaskets if you have them. If not yes buy some.
your valves are not opening they are not hitting. To check ptv clearance the valve train needs to be mocked up on at least # 1 hole.
When I’m checking PTV as you are 65gmc, I use .030 valve spring shims on the block deck, in place of a headgasket. I hand tighten the bolts. I check my clearance numbers in the clay, and do the math for the difference between the .030 shims and whatever headgasket I am using for the particular build that I’m working on. I make sure I know the COMPRESSED thickness of that headgasket being used. It’s a simple and quick way to check ptv. I’ll use 6 shims scattered about the head to keep the head square to the deck. Make sure that your head dowels are in place, to ensure the head is in the right place. The shims have holes in the center of them…run your headbolts though the holes.
Thats a good idea. Most guys working on this stuff have some cheap measuring tools, which is fine. Like a 0-1" micrometer, which can be had at estate sales, flea markets, garage sales, etc. A 0-1" mic and a dial caliper, and an indicator would be all most people need. Anyway, hard washers could also work. But its all personal preference. Most important is to get accurate measurements without any damages.....
Ok, so to address all the answers. I unfortunately do not have my old gaskets to check clearance. Yes, obviously I will need to mock up the valve train to check ptv, I just was turning it over to check everything. When putting the head on, i only used a few bolts, not torqued by any means. And turned over gently, with a small ratchet, so no bent stuff. Im also using modeling clay, instead of playdough. Now im left with either using shims, or washers of some sort in place of the gasket, or just buying a head gasket to check. The thing is, I really cant afford to buy the gasket, realize I either have room, or not, then buy another accordingly. Im honestly considering just going with the stocks that compress to .053, rather that a cometic 0.45 or something. The only reason I haven't bought stocks in the first place is because I would like to bump compression as much as I can. So here we are.
Ok, so to address all the answers. I unfortunately do not have my old gaskets to check clearance. Yes, obviously I will need to mock up the valve train to check ptv, I just was turning it over to check everything. When putting the head on, i only used a few bolts, not torqued by any means. And turned over gently, with a small ratchet, so no bent stuff. Im also using modeling clay, instead of playdough. Now im left with either using shims, or washers of some sort in place of the gasket, or just buying a head gasket to check. The thing is, I really cant afford to buy the gasket, realize I either have room, or not, then buy another accordingly. Im honestly considering just going with the stocks that compress to .053, rather that a cometic 0.45 or something. The only reason I haven't bought stocks in the first place is because I would like to bump compression as much as I can. So here we are.
I have several used GM mls gaskets hanging on the garage wall. Would you like me to send you one? You pay shipping.
GM gaskets are only $59 a set on Summit. You can reuse the one you use for your test fitting. All you need is a cheap digital caliper for measurements, which you probably already have…
The gasket should provide the minimum amount to clear the piston and the intake valve, but not necessarily the exhaust valve. Then with the clay make sure you have at least 0.080” clearance on intake and 0.100” clearance on exhaust.
thanks for the vids! that guy did a nice job explaining. I'm leaning towards just getting the stocks, and going from there. I have a hunch that ptv may be close with the stocks, considering my cam size. Ill probably end up running the stocks but I guess if I have so much clearance that I feel confident with using a thinner one, then Ill go down that road.
Agree again with vette4fl. As I said earlier, if you're going to use a head gasket, I recommended using the gasket you intend on running. I've heard of guys even torquing MLS gaskets down to spec for checking, and they work fine when retorqued. Just don't run the engine/heat cycle it. Don't think I'd do that with composite gaskets, but??? Anyway, as we've said, just tighten head down finger tight, as long as threads are good on both nuts/bolts/studs, or just 1/4 turn tighter.
NOTE!! Be careful about getting any crap between the MLS layers, which could cause problems.......
Alright guys, so here's where I'm at. similar to that shim method mentioned by @Che70velle, I used a bunch of small washers, 12 to be exact, spread out around the head surface to replicate the thickness of a head gasket. Funny enough all of the washers measured out to in and around .045". With the thinnest of the bunch being placed right around the cylinder I was checking to make sure I wasn't giving extra clearance. I then went on to use the Clay method. after cutting out a sample, on the exhaust side I measured about .085" or so of clearance. (The valve reliefs on these lq4 pistons only add clearance for the exhaust side.) On the intake side, I measured roughly 0.94", likely a tad more, but it was tricky to use the caliper on the clay without squishing it at all. I Wasn't too concerned about it not being exactly .0100" since the intake valve chases the piston down, correct? (Will attach pics below of everything). So based off these numbers it seems like I should be ok to go with a 0.45" head gasket?. I will also be running the BTR platinum dual spring .660 kit, which from what I've heard is pretty solid, and should keep everything under control. Let me know what you guys think of this? as many of you have been doing this much longer than me.
I use .030 valvespring shims simply because they are all exactly dead nuts .030, and It removes any guesswork in the math involved. You can get them in many different thicknesses, but I like the .030’s. Washers are always going to be a .0xx…ish measurement. Anyhoo…carry on here. Looking good.
I use .030 valvespring shims simply because they are all exactly dead nuts .030, and It removes any guesswork in the math involved. You can get them in many different thicknesses, but I like the .030’s. Washers are always going to be a .0xx…ish measurement. Anyhoo…carry on here. Looking good.
I agree on being certain the washers/shims are all dead nuts on. Years ago, 30 or more, most all hard washers were +-.001" to +-.0015", which was pretty good for production washers.....When they were made here in the U.S. Not anymore, when they're made in Malaysia, China, Singapore, etc. I've gotta measure every hard washer I use now in a stackup situation. They can vary over .010" now. Sad.......
10-11-2023, 04:15 PM
. I will also be running the BTR platinum dual spring .660 kit, which from what I've heard is pretty solid, and should keep everything under control. Let me know what you guys think of this? as many of you have been doing this much longer than me.
