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Snapped rocker bar
Hi folks.
Hopefully Someone can offer some advice. I have a 1967 428 and I have just managed to snap a rocker bar and bend two push rods. I now need to replace these but I'm not too sure where to start looking. I guess the first thing is, are more than one type of rocker bars. I'm sure the cam is a solid lifter becouse there is no hole for the oil in the push rods. how many types of push rods are there though, and how do I work out what ones I want. I didn't build this car but bought it fully built from a dealer in Cobras and I don't know what the cam shaft is other than it being a crane. Thanks Paul |
:3DSMILE:
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Hi Paul,
It is a relatively common problem. I had a 427 S/O with all Crane valve gear and over a period of 2-3 years, I broke 4 rocker shafts. I assume it has broken across the end post. The problem is that the end rocker is unsupported and with a high-performance valve train, the loads are very high. There are a number of products that include modified end posts that fix the problem. Some of the higher end products also include full roller setups and look very "sexy". Contrary to what trularin has said, I don't think you have a problem elsewhere and you don't need to dismantle your engine. Sleep easy :-) Regards Paul |
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Yep thats exactly where it broke! :CRY: I assume by you saying about Crane valve gear that you get different shafts depending on whose valve gear you use :confused: Unfortunately I'm not much of a mechanic and at the moment a frendly mechanic I know is just looking for anything else that may be faulty. We did check compression with both valves closed and no air seems to be escaping. :) Any suggestions on how to identify the shaft to get a replacement (and the push rods for that matter) I would sooner avoid changing the whole valve setup and cam at the moment. (my wife already thinks I spend too much on it :p ) Thanks Paul |
Hi Paul,
I tried a variety of different shafts but they all broke eventually. I don't think it is specifically down to Crane components unless their valve springs are especially tight. You don't need to change the cam or pushrods (except for the bent ones). I would suggest you get the best steel shafts you can and get a set of end post supports (I'll try to find a link to a supplier, but I'm sure someone else will step in). I used a roller setup which so far has proved completely reliable but that was about $1K. As I said previously, I don't think you need to worry about the rest of your engine. The only slight difficulty is that the cam follower from the broken rocker is likely to have popped itself out so you may need to take the inlet manifold off to get at it to put it back where it belongs. REgards Paul |
post a photo of the shaft and rockers. (dissasembled and the oiling holes in the rocker shaft showing.) The nerds here will be able to sort it out for you.
Steve |
I found this image of a setup from a previous thread:
You can see the supports at the end of the shafts. http://www.clubcobra.com/forums/atta...&postid=109406 These are from a company called Precision Oil Pumps but I can't find a web site for them. Paul |
Paul,
I had that happen to me twice and I was using the stock Ford shafts that came on the engine. I went to Ford and they ordered me some kind of special shaft and I never had another problem. The setup that Paul (Fatboy) posted looks very similiar to the Erson Roller Rocker setup I now have on the engine. Ron |
Thanks for the help everyone.
I'll try and get a pic as soon as I can. Am I to understand that Rocker shafts are basically standard in basic structure IE there are not different ones for solid or hydrolic lifters etc and I only need to look for a good strong one as a replacement? Is this also the case with push rods in that there are ether hydrolic or solid lifter ones? Please bare with me as although I have a basic understanding of the difference between hydrolic and solid lifters I'm not that clued up on such things and I don't want to end up ordering two new shafts and some new push rods to find out they are incompatible with my cam rockers and valves. Thanks again Paul |
Just because your pushrods don't have oil passages in them doesn't mean you have a solid lifter cam. FE's don't oil through the pushrods like other motors. I would be very concerned if your pushrods DID have oil passages. You need to remove one of your lifters and see what kind it is. If it's a shell type lifter, you should be able to see without removing the lifter. Considering you already have broken rocker arms and bent pushrods, it may be a good idea to remove and inspect the lifters anyhow. I have a set of rocker shaft end supports from Precision Oil Pumps that I'm going to use in my 428. Unfortunately I'm still buying parts and the motor's not complete yet. When I bought my heads from Keith Craft, he said he recommended using rocker shaft end supports on ALL applications, no matter how mild.
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Precision Oil Pumps (559)645-1951 or pumpbldr@comcast.net
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Harland Sharp makes heavy duty rocker shafts.
You can buy them from summit and unless you have a really high lift / high spring rate cam, they should fix your problem.
Chuck Link To Harland Sharp Rocker Shafts at Summit |
Re: Harland Sharp makes heavy duty rocker shafts.
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If I can, I think getting end supports sounds a good idea. Are they a bolt on replacement for the current end support IE the one that is just before the last rocker and basically do both sides? If not how difficult are they to fit usually? Anyone have any suggestions about where to get new push rods? Cheers Paul |
I may eat these words... But
Ford won lemans without rocker end stands... I think if your lift is less than .6 or so and your spring pressures are not outrageous you don't really need them. They do look cool however, that's worth something.
Chuck |
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for on the lifter that will tell me if it is hydrolic or solid? I think I'm happy about sorting out the rocker shaft and I think I will go for end supports so I just need to get the push rods sorted now. Unfortunatly, I don't think i'll get it all done before the last major UK kit car show of the year! :mad: as its only a week away! :CRY: It was only just up the road from me as well :( Paul |
Paul,
If you can get all the parts, which shouldn't be a problem, there should be no reason why you can't get to the car show. geting all the new parts fitted will take a couple of hours at most. Regarding whether you have solid lifters or hydraulic, if you have adjusters on your rocker arms, this would "generally" suggest that you have solid lifters, if there are no adjusters, then they are definately hydraulic. Now go get it done and get to that car show ;-) Cheers Paul |
Hi Paul,
I must have hydrolic then becouse I don't see any adjusters. Getting the parts is the fun bit! I'm in the UK and i dont expect to get the bits that quick! BTW how do you normally set pre-load on hydrolics then? I guess on solid ones the adjuster set the lash but I'm not too sure about pre-load setting or how much it should be is there a way of reading that off the other rockers that are still OK? Anyways, I've STILL got to take my wife on holidy in the mean time (before the show) and I don't suppose she will accept 'I've got to rebuild the car honey' as a reason not to. :p Paul |
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Are you going to Donington then? :D Paul |
No joke, I'm serious
...you can straighten the push rods yourself using a hammer and rolling them on a flat surface. Get them "pretty close" and I gaurentee they will work until you can secure the proper parts.
Keep the rpms below 4 to 5000 is good and you'll be fine. This ASSUMES your push rods have a gentle arching bend in them, not mangled or twisted like a pretzel! Might sound crazy, but it aint. |
Hi Slick,
Err.. 'Twisted pretzel' definately describes one of them! (along with 'cork screw' or 'work of art' depending on your veiw point) The other I'm not even that sure it is bent but I think there is a slight bend in it so I thought I'd replace it anyway. Still not too sure how to make sure I order the right type of push rod (assuming there is more than one type) Paul |
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