1G Camshaft/Rocker Clearance

[4g64Starion]

OK I'm not sure this is really a bolt-on but it's not hyper technical either. So here's the deal, I have a 1g big port head, and sent it off to a shop back in early 2019, for them to check it out and assemble it. It has GSC 280 cams, 2g hydraulic lifters, GSC beehive springs and retainers, GSC +1 mm valves, basically everything in the head is new.

Anyway The head has sat for about a year, until I finally cranked the car this weekend. I heard a noise, stopped, and tried to turn the engine by hand, and it was stuck.

Pulled the cam cover, saw that 2 of the rockers on the exhaust side had fallen out? Then noticed all of them were loose on that side! I could pull them out by hand. The intake side was firm, and had an invisible amount of lash.

I did not bleed the lifters, but after sitting a year (They were still covered in assembly lube) I didn't think they'd need it. Wouldn't bleeding them make the problem worse anyway?

Pictures always help right?

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[2gjlc]

sounds like bent valves if you can't rotate it by hand. Also, that is probably the case since the valve isn't seating anymore and won't allow the stem to go up enough and maintain contact between the rocker and camshaft. Sounds like the engine wasn't timed right when the head went back on or maybe the combination of large cams and oversized valves caused an issue and contacted the piston.

 

[4g64Starion]

I thought bent valves too, at first, but what was stopping it was the rocker had fallen off and was jammed between the camshaft and the head, thankfully not a lobe area. Now with the exhaust rockers out, it spins easily. I may end up pulling the head this weekend to check though. A compression test would tell too, I think.

 

[Mech Addict]

I’m not experienced in this myself, but from reading various sources there is a pretty important and specific way to prep the lifters (sorry, lash adjusters, but like lifters) So they start with the right amount of lash and no air in them. I believe the FSM recommends filling with diesel fuel so the adjust quickly.
Did you try spinning the engine by hand before cranking?
Bummer to remove the head again, but probably advised, at least for a look. From your other descriptions this sounds like a fairly high hp build (more then 25% over stock?) so you don’t want to start out it’s ew life with something already out of spec.

 

[1990TSIAWDTALON]

I soak then bleed the lifters of all oil. They are lubed but loose until oil pressure hits them and then they pump right up and do their job. Just my way of making sure I don't ruin any valves....AGAIN. L O L
If you can get ahold of a bore scope you can probably look in and take peek at the inside of the cylinder.

 

[streetraceboi]

Sadly it seems you have bent valves. That's usually a tell tell sign. Try bleeding the lifters...but that's a pretty large gap even for collapsed lifters.

 

[4g64Starion]

Got the head off today. The valves had a little meeting with the pistons, all 8 exhausts did at least. New +1mm valves and Cometic headgasket ordered. Pistons have some very minor bumps, nothing to be worried about I think. But on the plus side, I can remove that casting flash in the oil return, and clean up the messy bits in the exhaust ports while waiting on the new parts to arrive.

 

[1990TSIAWDTALON]

Sorry for the loss, glad you found it and fixed it along with opening up the oil returns. I do the same!
Crossing fingers for you!
Make sure you check all of the intake valves. That "ping" didn't come from a piston to valve impact. It's when it just barely touches another valve.
Just be sure while you are already there! It's important.
The piston contact is or should be just fine, make sure there are no sharp spots but that happened AFTER the valves got tweaked in my experience. Please report back that they are all concentric and good so this has a good ending.
Marty

 

[4g64Starion]

Ah hey guys, so thought I'd follow up. Luckily the engine didn't run, and I think I actually bent the valves, by hand of course! When I first assembles the motor I noticed it was hard ot turn over, assuming it was the 80 lb springs, I forced it and that is where it went wrong now that I think about it.

Anyway, things have been kinda busy and crazy owning 3 of these cars. I got the head back on, and made a tensioner adjustment tool from stainless rod, so I can set the t-belt correctly.

So far I found TDC and checked with a dial gauge and piston stop type setup. I put the crank on #1 TDC. Then I put the cams with the lines straight up. But the center lines, don't line up? I think this is due to the different block height of the 6-bolt rwd block mating to the 1g dohc head. I have adjustable AEM cam gears. Now I think I just need to correctly adjust them. I made a tool to bar the motor over-the crank bolt is loose-so that I can carefully turn it to check for piston/valve interaction. I get about 180 degrees of rotation before if feels like I'm meeting resistance! This is with the t-belt in place of course, and the lifters bled down. Should the lifters be pumped up, so that they're following the cam more closely? I'm kinda lost there.

I'm not sure what I'm doing wrong now. Unless there's too much material removed from the head/block that the pistons are hitting the valves? The machinists who did both did a bare minimum to deck the head and block. I have the .5mm head gasket from cometic as well.

Sorry about some of the pics, my phone would NOT focus on anything correctly.

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The little gold dot is the 6-bolt timing mark I highlighted, on a Kiggly 12 tooth wheel. I made it a 12-1 with a gridner.

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The belt is supposed to be for Galants with the 2.4.

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[jed344]

Did you figure out the issue? It looks like if you rotated to where cams lined up you could be off a tooth on crank. I have also seen it where you can install the factory 6 bolt plate that lines up TDC backwards (cough i have done it), as for the HLA. I always bleed them down install everything then before timing motor spin oil pump and let it pump up the lifters then time it. This way i can assure that everything is as should be and also does not tick on first start.

 

[4g64Starion]

Yep got it all sorted out, thanks a ton guys! Rotated engine 6+ times and everything lined up like it's supposed to. Need to double check the t-belt tension, but I think it's close when checking with 3mm drill bit.

Sorry for the long delays, I'm doing body work on a second mostly stock Starion that will be for sale soon, as well as helping my dad with his Supra, so work on the black Mitsu is slow.

Some pics of where the timing ended up. It was a lot easer to do all of this with the right tools! Go figure.

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[1990TSIAWDTALON]

The right tools certainly make things easier most of the time. The timing tools are used the most in my shop tho.
Glad its all ligning up.
Now why does a lil Supra take precedence over a DSM???