Answers to these questions I am using a JTS prepared head, the man knows his stuff.

What springs - JTS DOUBLE VALVE SPRINGS
What installed height - 1.610"
What valves - 40MM INLET 33MM EXHAUST (DATSUN 1600) OK THESE ARE HEAVIER THAN STANDARD
Whats the valve length - CUT TO STANDARD 1200 LENGTH MINUS ROOM FOR LASH CAPS
Whats your seat pressures - 110LBS SEAT AND 290LBS @ .470 LIFT

I have pulled the engine down and there are no marks on pistons or block it is not a clearance issue. and the spring i am using are not little, I don

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I am really curious what is going on here.
I would also say to go back to standard and see what happens.If reliability increases, then you know that they are not that good for racing applications.Strange, these things are very expensive.They are suppose to give you good quality for your money.

seems like the man from YT knows something!
they will make it and sell it , but they dont have to prove it's better,
i used TRW lifters once .

Does anyone know how much the other brand of aftermarket rockers weighs? (I can't think of the brand name right now)

When I bought my set I spoke to one of the guys at YT
He said his kid had a 1200 he raced in junior speedway
This is why they designed the rollers for the A series... usually a company like that wouldn't care about an obscure little engine if there wasn't a reason

He told me that he used the 1.55 ones on his kids car and it regularly revved out to 9500.

I went with the 1.65 for some free lift and I knew I wouldn't be turning mine that hard anyway

I'm not saying its not the rockers causing an issue
You guys have used them and had issues so I'll believe you
And truth be known my engine seems to run out of puff around 7700 rpm which if you look at the specs it shouldn't... it should scream to over 9000
But.... I never planned on turning it hard anyway so for me its not yet an issue
Maybe with different rockers and valve springs I could spin some more revs out of it
But looking at my dyno sheet (98.7hp atw... whooo hoo) the beast stops making usable power at 7000 and starts to drop away anyway.... so after that its just noise.... I just change gear.

I wish you luck finding a solution

I wouldn't be trying to lighten the rockers without consulting YT first though. They may be able to tell you where you can and can't have a diet