Need some engine help

[fstik]

Hello all,

I bought a used 302 engine off of one of the members here as a replacement when mine died. I finished swapping the motors and had alot of valve noise as well as backfire through the carb. Not being sure about the origin of the motor, I checked the casting number on the block and found it to be a 302 1970-1974. I pulled the valve covers and found that they are not the stock heads, but what looks to be adjustable valves and "302 4V" cast into the head. Not sure what kind of cam is installed. I will have to determine the firing order by rotating the crank and watching the valves, but I need to find out how to adjust the valves for this motor. I did a search on the site and found the method of tightening the rocker nut until the push rod starts feeling resistance, then going a half to a full turn past that. Is this the correct procedure for these heads, or do I need a feeler guage and specs? Any help would be appreciated. Thanks.

fstik

 

[saxman]

you are right. that is how I did mine. I did my 3/4 of a turn from when I started feeling resistance. If I am not mistaken, you should still be able to twist the push rods once everything is tightened up, not for sure though. anyone else can chime in on that....

 

[NoJoe]

Hi: If the rocker arm nut is a locking nut it may be adjustable, if it seats on the stud the nut will be concave on the bottom to seat on the convex of the stud, if it has a locking friction all the way off it may be adjustable. After you determine locking nut or not I can tell you the easy way to adjust them. Joe

 

[broncnaz]

those heads are fairly rare as few early 302's actually had 4V heads adjustable valves are a plus.
There are many ways to adjust the valves one method is to start with the #1 cylinder at TDC then loosen the rocker nut until the pushrod has play then tighten till no play then 3/4 turn more. adjust the rest in firing order while turning the crank about 1/4 turn to bring the next cylinder to TDC. I've also done it a similar way but a little longer process and thats to adjust the intake valves when the exhaust valve is fully opened that insures that the intake valve is on the base circle of the cam and when the intake valve is fully opened adjust the exhaust valve this works really well for aftermarket cams that may have different lobe centers than stock but either way will work. Theres a few other ways to do it but it takes more explaining

 

[fstik]

Well, I got the valves adjusted and the distributor clocked correctly. It starts without that godawful clatter, and no more backfire through the carb. Of course, things couldn't be perfect, I have a miss on one of the cylinders that I now have to track down. Hope it isn't too serious. I hate pulling the spark plug wires when the motor is running, always get bitten! Thanks to everyone who chimed in with help. It's nice to have a place to come and get answers. Maybe one day I can return the favor.

fstik