have a 1970 gs stage 1 bought car november ran ok thought it was altitude came from east coast to denver mile high tuned it up car still ran rough and got worse pulled valve cover and couple rods bent camshaft is supposedly stock or notch better trying to figure out what to install herd roller rockers way to go then it depends on cam maybe someone has idea what i can go back with ta performance has lots of options thanks john
If the car ran ok in Nov. it was in time in Nov. Bent push rods are an indication of something binding in the valve train. if two were bent, were they on the same cyl.?????? or separated. Check the basic timing, then look for bind in the valve train. determine the cause of the bending before you start spending money. Stock cams or a stage cam should not be a problem in its self. look for sticking valves on the cyls that had the bent pushrods. another possibility is that the engine was over revved at some time.
No need for roller rockers, the stockers are just fine. What you need is a way to adjust your valve train. The simple and economical solution is adjustable pushrods. Carefully inspect all your rocker arms. It sounds like you had too much lifter preload, and this can bend and/or break parts. Look at the rocker arm in the area where the pushrod cup is. The rocker arms will crack in this area under stress. If everything looks good, reuse your rocker arms and adjust your preload with the adjustable pushrods, 1/2 turn past zero lash. Use this procedure. http://www.v8buick.com/attachment.php?attachmentid=35120&d=1098828451 P.S. I'm not trying to be a wiseguy, but if you use periods and commas in your sentences, it's a lot easier to read the post, and understand it.:TU:
2 of the rocker arms are blown out #3 and #5 , but the other side looks fine . it does have adjustible push rods . a friend of a friend is doing the work on it he said the cam and lifters are fine , he and i are both trying to find out what parts to go back with . i would like to keep it as close to stock as i can , so sounds like stock rockers and new set of adjustable push rods way to go.
I would measure the push rods and order the correct lengths from TA performace since the adjustable ones can loosen up sometimes. http://www.taperformance.com/
thanks for info . i am not very good with computers , emails , this is the first time i have posted anything , so i am learning. thanks again john
I have heard of some guys having problems with adjustable push rods. I have never had a problem with them loosening up.
It would be a good idea to check the valve stem height. Remove the rockers and place a straight edge on all 8 valve stems. If the valves with the bad rockers/bent pushrods are higher than the others, that is likely your problem. Sometimes, when seating valves, the machinist will "sink" the valves when cutting seats and surfacing the valve. This results in stem being higher. All Buick valves are to be the same height as per the chassis manual and machining the stems may be necessary. Also, if it is exhaust valves that are having the problem, it could be valve recession from unleaded fuel being used (ask me how I know!). The exhaust valve will sink into the head and raise the stem, causing rocker or pushrod problems. Before you go buying new rockers, pushrods or cam it would be worth checking. Good Luck!
Not saying it couldn't happen but I have never witnessed a valve seat being ground so deep that the valve hit the piston.o No: But if this was the case it should have occured right away so it wouldn't have been running good on the east coast either. I would look at the adjustment or maybe it was over revved and floated a couple valves. Valves will also contact the pistons in the event of a timing gear/chain failure. Good Luck. Bob H.
Bob, I think he was saying there could be push rod geometry problems with sunken valves. Nothing about the valves hitting the pistons because of this. If the valves were recessed into the head, they would be further away from the piston to begin with.
thanks everyone for advice . think i need to measure push rods find right size , order 16 new ones , get 2 new stock rocker assembleys , put back together see what happens . let you know what happens , once again thanks john
I have a 69 400 motor that all 8 exhaust valves had sunk into the heads at least 1/8". :shock: The amount the exhaust stems are above the intakes is frightening. The cam was a Crane .495" lift and they never touched the stock uncut pistons. How this motor ever ran (yes I drove it!) was startling. All I can figure is that a combination of the cam and performer intake with the stock, unjetted carb make it run lean and the lack of lead caused valve seat recession. First time I have ever seen a Buick head with this. The exhaust valve rockers were running on their tips and the metal seat inserts were breaking off the rockers. Some were just laying in the heads with only the aluminum part of the rocker opening the valves. The rocker geometry was so extreme it broke the rockers and did not bend the pushrods. What I suggested to be checked was not just guessing, but experience from what I have seen and have actually had the misfortune to deal with. Just wanted to help him avoid a potentially costly situation.
got the car back runs pretty good . put all new rocker arms and shafts, new adjustable push rods and lifters, new studs and hold downs for rocker shaft. bought a 1970 engine from a wildcat stamped sf , from carb to oil pan used carb on engine in the car . old carb needs rebuilt seems ok . plans are take block and build motor , new heads , cam ,ect. try to make nice street car occasional , run the strip car . i should have some parts left , maybe heads , points distributor , let me see what i have left , hopefully can help someone out
