rojo
Mar 20th, 10, 12:41 PM
Working on a friends BBC 427 solid cam (new build). We adjusted the rockers with a feeler gauge at .24/.28. Why do these rockers run off to the side? Will they get straight once the engine starts? Pic 1 & 2 are of the same rocker the valve is open. pic 3 is different valve closed and pic 4 is another that is open and it looks nice and straight. I don't have experience with solids.
14892
14893
14894
14895
Z15CAM
Mar 20th, 10, 01:09 PM
Do the Push Rods fit the Guide Plates. It is not uncommon to Bang on the Guide Plates and rotate them around the Rocker Stud (slightly loosen and re-torque) to Center the Rocker Tip on the Valve Stem or to cut the Guide Plate in half to accomplish it. You can pinch the Forks of the Guide Plate to tighten the Guide Clearance or file them larger; whatever it takes to Center the Rocker Tips. Just torquing a Rocker Stud can vary the position of the Guide Position.
It's time consuming but well worth the effort to prevent Broken Rockers and Valve Guide Wear.
Once I have a Set of Guide Plates fitted, I # there position.
Do not run the engine with Rockers Aligned the way you have Pictured.
rojo
Mar 20th, 10, 01:23 PM
The push rod to guide clearence seems okay (may revisit this). The rocker (valve closed) actually will rock side to side. I could push the rocker in pic 3 to the other side with no effort.
fatblock
Mar 20th, 10, 03:42 PM
Like Ron said^.You need the correct guide plate for a given pushrod dia.
Dart makes adjustable guide plates for bbc,s.A set of 8 will run you $50 from Summit racing.
Z15CAM
Mar 20th, 10, 04:58 PM
Another suggestion I would make with that SFT Cam is to invest in 2" ARP Rocker Studs/ Poly Locks and 7/16" Push Rods and Guide Plates. You might get away with LONG Slot Pressed Rockers for awhile but recommend Roller Rockers - Harland Sharp or Pro Mags.
fatblock
Mar 20th, 10, 05:26 PM
Curious as to what cam and spring combo this 427 has in her and what the max shift rpm that you are targeting.
rojo
Mar 20th, 10, 06:25 PM
Stock '69 435hp 3x2 'vette.
rojo
Mar 20th, 10, 06:31 PM
I think I need some "Feeler gauge 101" When I take out all the lash the rockers track great.
Steptoe
Mar 20th, 10, 06:58 PM
Had an issue on a stock sb like that..dont know much about BBs
the valve giudes where machined off center...ended up bending the push rods
So check for bent push rods also.
It was a street engine, we used later model tappets that have a nob that sits either side of the valve top...cant rem the name given to these rockers.
It didnt have giudes but the stock slots in the heads...if theses are worn it can also cause a similar issue.
looking down the line valve top, rocker stud push rod it looks like way out of alignment
So either the push rods are located incorrect or the valves are...or something is bent.
ace's68
Mar 21st, 10, 06:17 PM
Adjustable guide plates fixed this on a sbc.
I agree with the valves being machined incorrectly, or if they are aftermarket heads and the runners are huge they may require offset rockers.
zdld17
Mar 22nd, 10, 05:38 AM
Just looking at the stud and rocker arm , make me think the arm itself is off or the ball is causing this as it pivots off the ball just like the push rods ends do. Wonder if the stud is bent or if a set of roller trunion rockers would help correct this? May do some rocke rare geometry checking here too. Looks bad, stems won't last long like this. Is it only one center head stud on each head that is this way?
rojo
Mar 22nd, 10, 12:13 PM
I pulled all the plugs where I could spin the engine good with the starter and the rockers do tend to center themselves. Even the one that looked so bad in pic 1. I think the lash was a little loose so I've since re-adjusted using the EOIC method, spun it again with the starter and they look pretty good. We had previously used the Corvette manual that says rotate 180 do this one, rotate 180 do that one, etc. etc. I think a couple might could use some fine tuning with the guides, we will double check.
Thanks to all for the advise.