My 302 in my 55 broke a rocker arm today. It has a pretty radical solid lift cam. I am wanting to put a set of stock small block chevy rocker arms on it. I put one on and see no issue, however I have not started it. I have read that this both can and cant be done. One of the reasons I've read it cant be done is because the stock Ford rockers are 1.6 to 1 and the chevy are 1.56 to one. These are early ford heads with adjustable rockers just clarify. I'm ok with the 1.56 to 1 especially if it will reduce the profile of the cam and tone it down some. It's a pain to drive as is. Any thoughts? I really dont want to spend much if I dont have to since I just started my model A build.
Big block Chevys are 1.7:1, you'd have to match up the stud to valve distance, if that is good, bolt one on and rotate the engine by hand to see if it hits anywhere.
Chevrolets(SBC) are available in 1.6:1. https://www.summitracing.com/parts/...MImc6h-bTH5wIVBZSzCh2ZJgNgEAQYAiABEgKb3vD_BwE Standard are 1.5:1, never heard of the 1.56:1. The bigger question is why did it break?
Good article: https://www.hotrod.com/articles/hrdp-1211-will-chevy-rockers-fit-a-ford-windsor/ A little more about rocker arms: http://www.mre-books.com/interchange/interchange5.html Changing the rockers to a lower ratio won't really "de-tune" your cam by much in effect you will change the cams lift but not the duration. You can change the power band of the cam by advancing or retarding it at the timing chain. In order to fully understand how that works this goes into detail: https://www.hotrod.com/articles/mopp-1211-degreeing-a-camshaft/ But by the end of the day you might think swapping the cam to a more streetable grind is really the way to go. This timing set would give you more options to advance the timing: https://treperformance.com/i-937742...el-9-way-adjustable-timing-chain-set-sbf.html
O figured out that worh these heads I cant use the chevy rockers the push rods will walk because the heads do not have push rod guides. That is why this head uses the rockers with the stops on either side of the rocker tip to stay aligned on the valve stem. Some of the ford heads had a machined push rod guide that allowed the different rockers similar to Chevy like the HiPo 289. I just had these and hoped they would work. It broke because of coil bind. This motor was in a 66 unibody drag truck in a previous life and was famous for breaking rockers. I've just never had it do it since I put it in my car. Honestly I hate the solid cam and get tired of adjusting valves.if I had the money I would change the cam. Its the biggest solid cam offer by P.A.W for a 302. I didnt build it jsu freshened it up and put it in the car. It's also 10.5 to compression. I will probably just build the 302 with GT40P heads I have and retire this beast.
Those pictures of your rockers look like the lock nuts are all turned down until they are almost bottomed out. I know you said this is a radical solid cam however if the drive train is constantly breaking vale components then that tells me that the valve ***embly was not machined to give proper clearance between the valve guide and valve spring retainers That or the tolerances are set to close and when the engine gets up to temperature and the parts expand from the heat they start hitting each other and causing your interference issues. You have a nice looking engine there.
The studs do show a lot of thread, but they seem to be uniform and quite possible the threaded portion is longer to fit more applications. I would consider re-adjusting the valves from scratch. Get the 1st one done, turn the engine by hand, look carefully for interference and or bind. Is there any evidence of metal shavings? You should see some if ther is any. Take a couple of rockers off and look at them carefully.
No metal shavings and they were all set with a feeler gauge at TDC with both valves closed. I think the cam is big enough that at high rpm the valve springs are binding. When the motor was raced if it did it they just threw on another rocker. I'm just trying to fix it so it wont do it any more. Honestly I've grown to kinda hate this motor. It's such a temperamental beast. The heads and block were checked a couple different times because it would periodically blow head gaskets. Everything's flat, no cracks. Finally put head gaskets in it meant for a blower motor and that stopped that. I've been told a dual spring with more space in between the coils would solve the problem.
Yes, the intake on #6 cylinder looks like its close to coil bind just sitting there. The original owner may have not changed springs when they added the cam. As I recall, Ford went to the rail rocker arms on non-HiPo small blocks around late 67. Ford did not recommend the rail style arms for racing as they could theoretically jump sideways off the valve stem at high rpm since the push rod hole was fairly large. I never had that happen, but we typically just tapped for screw in studs and used guide plates and used the earlier rockers without the rails. I would either change springs to minimize coil bind with the solid cam, or switch to a milder hydraulic cam and springs. James
I think the milder cam is the solution and maybe the GT40P heads and some decent rocker arms. I've really had my fill of this motor. It was fun for a while but I'm 40 now and I just want to drive it. The big stall converter will go too. I really appreciate all the help. Maybe it just needs a y-block. Heck I might just put the original 6cyl back in it. I'll just have to put the model A on hold for a bit and figure it out. Ive even thought about selling it, but I am really attached to the old girl. I've had it for almost 20 years.
Yeah, cam and heads swap could be done over a weekend. Or just locate a roller 5.0 and swap your intake and distributor on it (be sure to change the distributor gear).
The roller 5.0 uses a different gear? Or is just a br*** gear or something. My distributor is an aftermarket HEI, not a Ford unit.
These after market HEI's can be used with Ford roller cam motors or flat tappet you do not have to change gears that would only apply to some after market steel billet camshafts.
The stock Ford roller cam uses a steel distributor gear and the stock flat tappet cam uses a cast iron distributor gear. Most of the aftermarket HEI stuff comes with a melonized gear that will work with either cam. But with aftermarket cams you should go by the cam manufacturer recommendation because the base materials can vary. We have to run a composite gear on one car that has a billet cam, but I run a regular steel gear with the solid roller cam in my G***er.
The cast "Rail" as ford calls them are still available new from Rock Auto for less than 10 bucks if you wanted a quick fix. https://www.rockauto.com/en/moreinfo.php?pk=7084388&cc=1494273&jsn=492
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