That's a tough question to give a short answer to. Let's start here.. which "stock" rocker setup are you talking about.. the 67-9 400/430 Rockers, the 70-71 cast Alum rockers, or the 72 up stamped steel setup. JW
I have a 1970 455 block, heads. Was looking at the TA shafts and rockers.....assume they are stamped steel. What cam can they handle? My goals ar a 12 second Buick gs. Will purchase the stage 2 TA heads, headers......just not sure I need a rollerized cam and rockers to achieve this. That’s why I asked about largest cam with stock....make that TA stamped steel rockers and shafts. Thanks
I have had GS cars with all the available rockers. I turned my stocker to 6300+, It had the stamped steel factory rockers and stock shafts. Remember at that time that was all that was available. My brother turned over 7000rpm with the same set up. We all had factory un-ported Stage 1 heads. My car, less the driver had to weigh 3800# min. ET was 12.42 @ 108. Also ran 12.23 at a test track. I did put a pushrod thru the stamped steel ones on the NHRA stocker twice. With aluminum heads and intakes now available, it will be easy to run faster than those times with the same weight car. There are many cams available and JW at Tri Shield should be able to help. I am making a moderate priced rocker for all sportsman motors. Hope to have them at Bowling green with my billet heads and the pro rockers we already have. That should take the ouch out of the equation. Stock rockers are for stock motors!
Why don't you tell us what Cam your thinking of running as I left my Crystal ball and my truth serum at home today,
If you are asking me, something in the range of a old Kenne-Bell MK C 113 or equivalent. Why take a chance when much better rockers are available soon at reasonable prices!
Sandy's X, iron intake, stage1 heads, iron manifolds, 3,42 rear, 3000 converter, 118 cam, 9.7 compression, 12.7 et with street stickies, 69 rockers.
My car, with drag radials, runs 11.8x's with iron 430 heads and stage 1 valves, stock rockers, an aluminum intake, 10 to 1 compression and a cam with specs @500 lift and 232/242 duration on a 113 centerline (similar to an old Poston 113A cam).
Thanks everyone. There are some decent combos running with stock rockers. I think I will just save some cash up and go roller rockers.
If the cam is too big with stock rockers, one of two things will happen. You will put a push rod through the rocker arm tip, or the shaft will break. Proper push rod length and lifter preload is important as well.
I have stock 73 rockers n push rods. 1973 engine. Comp 278 extreme energy cam. 464 ci, going 12:30 to 12:40s best ets. Complete stock weight heavy car. Look forward to hearing about the new shaft systems being released.
on my Buick 350 I had a ta's upgraded stock style rockers. had one rocker break right at the bottom where it goes around the shaft and basically folded in half, and others had a ton of stress cracks in them. that was with a 227/231 .525/.525 cam. Definitely worth the extra money for the rollers.
I ran Poston's 105 with stock 67 rockers as well as several healthy cams before that. No problems but something to consider, sooner or later their will be metal fatigue, those stock parts are getting old. The last 455 Buick was built in 1976 42 years ago. Bob H.
Just a shout out on my experience with the '68/'69 solid cast aluminum rockers and high lift/high spring pressures on my 455, more like a lesson on "too much". I put a lot of hours on the big solid lifter cam from TA, 308S, and ran the recommended spring pressures using these original rockers. I used TA's solid adjustable hybrid pushrods, which meant oiling through the rocker shaft like the original 400/430 did. The problem with the 455 is that there's no oil feed on the RH deck, so I plumbed an oil feed directly to the RH rocker shaft. My reasoning for this was even though many folks have successfully oiled these early rockers through the pushrods, they're bushed for a close fit to the shaft and drilled to oil the wear area (underside) under pressure. After a rocker failure, teardown showed some really high shaft wear even with the original oiling strategy, and that's with some really good oil pressure. I switched to another TA solid cam with similar specs, the TA 294-04F, and moved on to TA 1.65:1 roller rockers when I installed the TA aluminum cylinder heads. In the end I think I was lucky to have gotten away with using those stock rockers as long as I did, even with the extra work to retain the original shaft oiling method. Looks like fatigue in the rocker arm itself is what finally caused the breakage. Even the hardened tip inserts held up! Those early rockers are tough, just not THAT tough. High lift and the necessary high spring pressures took their toll. Devon
Stock "stamp steel" rocker can handle approximately .550" lift. I wouldn't run past that if you can help it. Running more will cause the rockers to wear faster, folks have higher liftes. Mark Busher ran 70 aluminum rockers years ago on "Little Joe", I believe with 600+ lift. Another thing you should be considerate to how much spring pressure is present. Try to keep your closed pressure below 135lbs, open below 320. High closed pressure tend to let you find the pushrod arrow-ed through the rocker.
Also, with the high lift cam, make sure your piston to valve clearance is good. You're going to want at least .100. My car has stock style pistons with no valve reliefs and I had my block decked so that my pistons were only .003-.005 in the hole. With a .510 lift cam and 246 duration, I had @.125 clearance still.
It's not max cam lift that affects p/v clearance but duration instead. At max cam lift the piston is some 2" or more down in the cylinder.
