Proper way to adjust valve train?

[WATTSUP!]

What is the proper way to adjust valve train on a 400? First I'll tell ya what I have done to the engine and then what happened. I built a 434 stroker and I am using AFD aluminum cylinder heads with Scorpion 1.72 roller rockers. A comp cams extreme energy cam 268h, with .512 intake and .519 exhaust. The push rods are 5/16's and are 10.610 long with guide plates. Well when I did the intial set up of the rockers I turned the push rods as I tightened the cap screw on the rockers till I felt a little drag and then turned cap screw one half turn to reload lifter. Did this in sequence per haynes manual to all 16 valves. Well when I started engine for break in and it ran for a whopping 10 seconds or so and stopped. Opened valve cover to my amazement I now have several bent pushrods and bent guide plates! Where did I go wrong? Any and all help will be greatly appreciated even if sarcastic!

[hollenjoe]

this happened to me the firts time ive set 0 lash on valves, theres a thing to it, your cam and mine have an overlap, so you could be setting your lash on a ramp, so what do i do? I wait for the intake valve to be fully open on that cylinder to set it, also on the exhaust side... Note, you need hardnend push rods for that type of valve train....

[WATTSUP!]

Got the hardened pushrods. I'm going to pull the motor this evening and do a complete check of everything in it. Need to make sure I didn't harm anything else Then its time to start all over again! What was the length of you pushrods hollenjoe? 10.6 seems to be alot to me especially for a 5/16 pushrod.

[hollenjoe]

Well kinda, Im using also 10.something on my 400, i had to shim my adjustables so the rockers could still have some slack to adjust... If you have slack before adjusting them, then they are good to go, if not simply add some shims under like i did, you just have to check for valve cover clearance....

[WATTSUP!]

Ten-four! I will check back in tomorrow and let you know what I found.

[mark a.]

How did you determine your push rod length in the first place ? Are you sure something isn't hitting somewhere ?

[WATTSUP!]

Well I used a adjustable pushrod checker. I determined the length by inserting pushrod checker and adjusting rocker cap screw until there was drag in the rod and adjusted the length of the rod until the lifter strated to preload. This took several times to get the proper length. But as of last night not sure this was even done properly!

[79F150400M]

This may not be the way to properly adjust valves....but it worked. I noticed that your using the same cam I have, but you have different heads and different rockers. Im using BBC roller rockers, which I am aware that the ratio is a little smaller, anyhoo.....I turned the engine by hand as I adjust each rocker arm until the pushrod would still rotate, but not any tighter to where it won't rotate. The rocker arm still had a little wiggle in it but it doesn't seem to matter as I don't have any lifter clatter. Only in the AM when I start it for the first time, but as soon as the oil press. comes up, things quiet down. Im using stock pushrods for the 400, and the screw in stud kit from Crane. I've been running this setup for the past 10yrs, haven't had any trouble, but I do wonder how much more HP I'd gain if I used the right ratio rockers, as my torque curve seems rather flat till right at 2000RPM.

[WATTSUP!]

That sounds about the same way I adjusted my rockers. The thoughts that I have now after further research are: 1. AFD did not machine enough relief for the 5/16 push rods. there for I had to cut guide plates to enable rocker to valve stem alignment (this has been confirmed though AFD). 2. Not even sure I measured push rods correctly! 3. Did not adjust valves properly. All three of these will contribute to the engine failure I had. Not I guess it's time to start over and this time get it right! Keep the comments coming! By the way I'm pulling the heads today and taking them to my machine shop to have the push rod reliefs machined to the proper angle which is 3 degrees and also open them up to allow me to go with a 3/8's push rod so hopefully this will cure my problems. Hopefully!

[hollenjoe]

WattsUP, to be sure why dont you fire up your engine without the valve covers, see were pushrods are hitting....

79f150400"m" no m in the 400, are you sure bbchevys have the same geometry as a cleveland? also you should try and set some preload on your lifter for even quieter operation and better lift, maybe half turn more, since i asume they are on 0 lash...

[WATTSUP!]

Not able to fire up the engine. When I went to start it up for break in thats when i bent push rods and lifters popped out of there bores. So I have to pull engine and while its out i'm going to have a little machine work done on the push rod reliefs to enable me to use 3/8's push rods instead of 5/16.

[mark a.]

There wouldn't be any reason to go with 3/8 push rods with the springs that would be matched to that cam. Did it look like the push rods might hit when it was put together ? binding ? As far as determining length you don't ever want any preload. Put a light checking spring on the valve then adjust the push rod till the rocker tip sweeps the stem as evenly as possible while turning it over. Once again make sure you don't compress the lifter. You can eyeball it if the engine is out, if not put some type of a marking compound on the stem so you can tune it in. After that measure the rod and add . IMO .030 to it and thats the length. I would also check all the stem heights. It's important for a machinest to control valve stem heights as well as combustion chamber volume.

[WATTSUP!]

The reason for me wanting to go with 3/8 push rods are due to the length on them being 10.610. That is a little long for a 5/16 push rod. One other thing is when I originally measured for the push rods I wasn't able to measure with the guide plates in place. This all ocurred before I had to cut the plates in half for the rockers to line up to valve stem properly. So to answer your question about hitting or binding the answer is yes. The push rod were hitting the push rod relief due to a machining error from the manufacturer.

[79F150400M]

Hollenjoe: (tryin not to hijack)
IIRC, the BBC rockers are a 1:70 ratio and ours are 1:73. Doesn't sound like much, but its .03 diff. I have thought about giving them another half turn to preload the lifter but I'm afraid I'll burn a valve. Im already thinking I have a couple rockers too tight. (have a vibration at 1500 RPM)
I wish I could adjust while its idling, then I can hear and feel when the rockers are too tight or too loose. I have a pretty smooth idle right now. What I really should do is put a vacuum gauge on it and see how the needle acts. Hmmmm......

[mark a.]

You can use a dial gage with a magnetic stand to set preload.