L20B valves not adjusting

[420n620]

I've got 74 620 w/a L20 engine w/ A87 head. I decide to check the adjustment and adjust het ones that need it. I ran into one ( actually 4 total)that wood not let me adjust. After close inspection, I noticed that the ajuster woodnt go down any further, het lock nut is loose.

Before I tear into it, I thought MAYBE someone could tell me WTF is wrong. In the pic u will notice the right one is OK but the left one is being het bitch (screw driver pointing @ no gap). What will I have to do to correct this problem. I've adjusted L20's before but have never ran into something like this. HELP

[sjeff64]

I have never had to back them down that far why are you going that far down? what is your gap between the rocker and the lobe?

[datzenmike]

Hard to tell in the picture but is the cam lobe pointing up out of the way???

 

Has the lash pad turned sideways between the rocker and the valve retainer?

[Pacific coast Datsun]

I had a similar problem on my 1st L 18. Turns out the lash pad had to be ground down just a tad to allow that valve to be adjusted.

[datzenmike]

How the hell does that happen??? Does the valve grow longer? :D

[datsunfish]

Sunken valves will do this.A worn valve seat or a flared worn valve will allow the valve to go up higher and the stem sticks up higher and the rocker points further upward to compensate.I had a head that would not adjust at all and I flipped it over and the intake valves were way too deep.Most a87s are older than most L20bs so I would check into this.

[420n620]

UPDATE: I removed the intake rocker (one causing improper adjust) and noticed that the intake retainer is a little higher then the exhaust retainer, the exhaust lope is @ the 12:00 position - gap @ .012. Before I removed the intake rocker all I could get in there was .006 thats why its ajusted down that low( 1st post pic ). The rocker pad was in het right postion. The only thing that makes sence, like mention above is the valve is setting to low in the seat.

The L20 was running before I decided to check the adjustment and sounded OK so I don't want to tear the head off but what I was thinkn was to find the the most gap measurement on the intake valves and adjust the rest to that gap then put the exhaust @ .012 or file the rocker pad down - HUMMM.

The other intake adjusters look to not give me much for adjustmnt, I'd say someone has done some head work @ one time. Wish I knew for sure.

Heres a pic with the rocker off.

I'll wait and see what u guys think bfore I move forward on the adjustmnt.

[banzai510(hainz)]

I run mine at .006 and .008 I call it good

 

your situation I would be worried that it would run to end end of the rocker to wear it almost off and ruin the cam.

 

look for a spare head and I guess dont travel to far from home.

 

I have a round port head for 50$(local pick up only). I dont know if you eed a round or square port

 

shit, Ted might have a head in Yelm ,something?

[datzenmike]

Maybe the seats were replaced and were set to low in the port. Or the seats were crap and wore down. Either way crappy worksmanship, should not happen.

[420n620]

I've got a couple of heads around here so I'm covered there plus I was at the scrap yard yesterday and noticed they have a smashed KC complete. I'm going to have to talk sweet talk (aka> kiss butt) and see if they will let me pull some parts.

I was wondering if there was a way I could ground down on the rocker where the cam rides or where it touches down on the valve tip to make up the differants so that I can get the .010 gap I need, or ground the rocker pad.

All I need is about .003 to .004 grd off to be able to gap @ the stock measurement. This is just a thought. :blink:

[phatdave]

Just adjust them to .008 paint a japanese flag on it and call it good. :D

 

 

 

 

 

dd:fu:

[datsunfish]

Do not grind anything!The rockers are tempered and polished for a reason.The a87 heads used bronze valve seats in the intake and they do smoosh over time with alot of miles.I have only done 6 & 8 on my regrind cam since that is what the grinders said to do on my friends cam he had re done.All valves should sit at the same height.If not then it is exactly what I have said.

This would be a good time to put in those larger 280 intake valves.

I personally like the round port heads just fine.Larger intake ports and you CAN use them with a square port exhaust mani/header without ANY noticeable issues.

[e_racer1999]

same thing happened on one of my heads. just grind down the adjusting nut a bit. as long as there's at least 1/2 of it there to catch threads and enough for you to grab with a wrench you'l be fine