So just "rebuilt" my l98, and started it for the first time about a month ago, and it ran great for the most part. However, after sitting for a bit, I've been trying to start it up, but it seems like after it attempts to ignite the fuel, it'll seize up, which is most likely timing being too advanced at startup, but also at the same time, after a wait a bit and unplug the distributor to prevent it from firing, it will still start to rotate then seize up, when I'm assuming it starts to get compression.

I have flat hydraulic lifters, and the way I adjusted them is I watched the pushrod on the exhaust side start to go up, then adjusted the intake to zero lash. Repeated that for the other 7. Then for exhaust, when the intake valve starts to close, I adjust the exhaust to zero lash. Then I do the first preload, like 0.25-0.5 (can't remember have tried this multiple times). The starter will be able to spin it, and it's either when I add fuel (I think), or maybe it's just random, it seizes up, and then I add more preload, it spins again, and then the whole cycle repeats.

Anyone have any clue what I'm doing wrong, if I need to explain something better let me know.

Thanks!

 

You set the exhaust valves WHENTHE INTAKES CLOSES,
not "starts" to close..
Feel/find the O lash point by moving the pushrod UP AND DOWN. , to detect hhe O lash point.. Do not spin the push rod.... Up and Down.

 

Should I set the exhaust valves when it is almost done closing or when it is completely closed? And yea I've been using up and down instead of spinning it.

 

Flat tappets in an L98? The L98 was always hyd. roller, starting in 1987. Did you use a flat tappet block? If you installed flat tappets in the factory roller block, how's your pushrod length? Flat and roller are different. Why not save a little time and set preload once you get to zero lash on each one, rather than going through the whole thing twice. BTW, unless you plan on running 6K plus, just go with 1/2 turn in. 1 turn is even fine for a factory valvetrain. Either way, a little change in valve adjustment isn't causing the engine to kick back or lock on start up. Not unless you're running way to tight valve to piston clearance.

Try retarding the timing a few degrees. If you go to far, you'll get backfire, but somewhere between there and the motor trying to kick back on startup, is the point where it should crank and start, though it may idle rough if it's too retarded. First thing once it's running, set timing to 8 degrees. If you're still having trouble with start up, check your batt connections and cables. Load test the battery. Do a voltage and current test on the starter. Volt drop test the cables.

 

I think someone before I got it put in a racing cam (serached the numbers of it online) but it failed somehow so I'm just using a bunch of spare parts I have. I'm going to be replacing the cam and rollers with new stuff soon, but out of the 16ish months I've owned this car, I've only driven it like 3 and just want it back on the road if you know what I mean.

 

Set the exhaust valves when the intake has closed.
If you think you went too far, missed it.. Go around again.

IC EO.
Once you have set all 16 valves @O lash you can then add the 1/4 to 1/2 turn preload adjustment to all at once.. Further crank rotation is not requured..

 

Is it possible that the kickback from it being to advanced could temporary seize up the motor for a bit? That seems to be happing to me, even after adjusting the valves the way you guys recommended.

 

Before you do anything else look at your starter motor.

Is the factory starter motir support bracket/brace installed on the end of your starter motor..
If it is missing, STOP and get one. Put it on.
This OEM starter support bracket is a must have critical part.. You risk starter binding, Start nose cone distruction.. Ripping the starter mount bolts right out of the engine block if that $5 starter motor brace is missing...

 

What the heck is that?

By the way this is a new starter and battery. But I don't think any of my previous starters had any brackets? But I've been wondering if somehow the position of the starter and the flex plate could be screwing it up somehow.

 

No.

If it worked before you improperly adjusted the valves, then it will work again, AS IS, after you properly adjust them.

Adjust a cylinder's intake as the exh JUST BEGINS TO OPEN (starts to come off the seat). Adjust the exhaust as the intake JUST FINISHES CLOSING (i.e. has opened, reached full lift, and returned to the seat). Set each to zero lash, then add your desired preload.

Another good way to locate zero lash, better actually but more fiddly, is to watch the same valve on the cyl that's 4 cyls away in the firing order; and when that other one is at exactly full lift, adjust the one in question. For example, you would adjust #1 intake when #6 intake is at full lift. Once you set one to that point, you can rotate the engine in exactly 90 degree increments, and adjust them through the firing order. For example, set #1 intake as above; rotate the motor exactly 90 degrees, adjust #8 intake; 90 more degrees, adjust #4 intake, and so on. Same for the exhausts. Then of course once you have them set to zero lash, which is the point at which all VERTICAL play in the push rod and rocker is taken up - NOT the point at which you can no longer "twist the push rod" - add your desired preload. half a turn should be perfectly fine.

 

Alright I'll try doing it once again, is it possible I somehow bent valves? The weird thing too is I had spark plugs out, and the motor would still seize up sometimes like it had high compression. And then sometimes it would turn over just fine with no fuel/spark, but the weird this is I could hear like a pitch change, like it was rotating faster and then would slow down a bit and repeat.

 

Get the starter brace and put it on.