I Have A Stock 90 Lx With A 302 In It. I Been Talking To Difrent Cam Companys And Some Telling Me That I Can Use Them Some Say I Cant Any Help??? The Guy Told Me That With A 1.7 R R Will Ad .30thosand And Will Cause Vavle To Piston Issue
Nope, don't worry what so ever with P/V clearance using stock heads and cam. I've got 1.7's, with .030 cut off of my stock heads and still have tons of room. At the same time though, without other breathing upgrades, don't expect huge power from them either.
If your car is all stock, then I wouldn't expect very much from them. If you have some stuff done, then it would help. It will give you some more lift, so you will get more flow, and it will be roller, so it will be smoother then the stock rocker arms. Maybe 10 hp? Hard to say.
I've seen dyno tests in car magazines that showed a LOSS of 1 HP on a lightly modded engine too -- each combo is different. I wouldn't count on more than 5HP; if you get more, be grateful. Are your stock valve springs up to the task of managing the increased lift? Tired springs are known to float early with the stock cam and stock rockers. THe 1.7's are gonna really put them to work; if your springs are already tired, the 1.7's could lose you power due to valve float. Not always as simple as just bolting stuff on.
The 1.7's will increase your peak valve lift from .444 to about .472. However, they will only reduce your p to v clearance by about 3 THOUSANDTHS. At peak lift the piston is well down the cylinder - there's no clearance issue then. Clearance is tight during overlap when valve is only open about .050" -- swapping the 1.7's makes that about .053" -- not enough to worry about especially with stock components. I don't think I'd give my money to companies that are giving you that unsound advice on the clearances.