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First...throw the pushrods in the trash and get a real set......and you need to measure for this length before you order.......those fusion welded pushrods will eat themselves alive against those guideplates.....
You will most likely be about .050 longer than stock which is 7.300......but I see over 7.400 on occasion......
You need a light tension spring to measure pushrod length/geometry and an adjustable pushrod checker.......
I can eyeball your photo and tell you the pushrod is too short.....
First...throw the pushrods in the trash and get a real set......and you need to measure for this length before you order.......those fusion welded pushrods will eat themselves alive against those guideplates.....
You will most likely be about .050 longer than stock which is 7.300......but I see over 7.400 on occasion......
You need a light tension spring to measure pushrod length/geometry and an adjustable pushrod checker.......
I can eyeball your photo and tell you the pushrod is too short.....
Jebby
Yow! OK, I'll do that. Thanks, Jebby. Are you aware of a good tutorial for doing this, maybe on YT or another site or book? Have never done this, I know I need to buy some tools and don't even know what to go with.
Yes you need hardened pushrods for use with steel guide plates.
There are pushrod checkers available, and "checking springs" and screw adjustable checking pushrods.
Then you put sharpie on the valve tip and see where the roller tip contacts. Either centered or at least touching some over the center during a stroke.
I checked your valve springs, AFR #8020. 125# on the seat, should be 288# open with your .510" lift cam.
I suppose your magnum rockers will be OK with them since they say up to 350#. But I still like full stainless roller rockers better for a fast opening extreme cam.
I would even prefer Summit or house brand rollers over those magnums. No aluminums, I have seen too many of those crack.
On the magnums, just put moly on both the pushrod ends and the ***** during final assembly.
The main thing is to prime the oil pump with a drill first and make sure you have good even flow out of all the pushrods. All of them. It happens more frequently than people think. Or the ***** will go dry and burn.
Never heard of putting deflectors on the rockers on a running engine. SBC don't tend to squirt that hard.
But IIWY I would make sure your valve covers have drippers. Those "*****" need all the help they can get.
And they still might burn.
If they do burn, you'll hear it and it's not a disaster, you can just change them out later. You might get lucky. But I just see zero advantage to those things except $100 cost.
Last edited by leigh1322; Nov 4, 2023 at 10:05 PM.
The rocker arms will be ok....this isn't a radical combo and not big RPM.....500 lift, no problem.....but only if the geometry is spot on and the side to side of rocker tip to valve tip is set as well....
You will need and adjustable pushrod that goes from 7.0 to 7.5".....and a light check spring, oh, and a sharpie marker.......no need to do I and E as the valve train is inline....both will be the same.....
The other reason the pushrods will be longer is the aftermarket cam has a slightly smaller basecircle.....7.300 is for GM spec cam....
You have to remove a valve spring and install the light spring.....
You have longer than stock HR lifters and a shorter than stock cam circle.
You will probably need a valve spring compressor also. An elbow one is fine for your valve springs.
Measuring the long pushrod could get tricky. You may need to get someone to help you or borrow a tool because those 12" dial or digital calipers are not that common. There are several slight variations on the measuring method. The most important thing is that the rocker slot does not bottom out on the stud, or hit the retainer corner, ever, as the valve goes up/down. Make sure you have some visible/measureable clearance. Beyond that you want the roller as close to the middle of the valve as practical, as it rolls. It must not hit the edge of the valve tip.
The guide plates position the pushrod/rocker sideways. The pushrod should not bind, it should just barely touch the guide-plates, should not touch the holes in the head, and the roller tip should be completely on the valve tip, not part way on. Usually that stuff is all OK, but sometimes not. But it is good to check. If something is off with the guide plates just come back here.
This is what I mean by having drippers inside the valve cover. Little bumps on the inside right over the ball studs. These are aluminum. Steels ones have something similar. All GM ones have them. But aftermarket implementation is very spotty. With full roller rockers it doesn't matter. With ball-n-stud it can matter a lot. I have seen guys have valve train problems just because they changed to fancier prettier valve covers and did not have these! Duh!
Last edited by leigh1322; Nov 5, 2023 at 08:52 AM.
...drippers inside the valve cover. Little bumps on the inside right over the ball studs. These are aluminum. Steels ones have something similar. All GM ones have them. But aftermarket implementation is very spotty. With full roller rockers it doesn't matter. With ball-n-stud it can matter a lot. I have seen guys have valve train problems just because they changed to fancier prettier valve covers and did not have these! Duh!
@leigh1322 Thanks for the guidance. I think I'm going to try to return that kit, as it included the rods. Can you recommend rockers I should use?
Regarding the covers, I got my hands on some Edelbrock but as you say, they're bare necked inside. Thinking I'll probably sell those here, as I bought them from a neighbor, and get some that get it right.
Tell you one thing; the deeper I get into this the more I wonder how any engine I ever built actually ran, let alone lasted without exploding. Guardian angel, I suspect. I'm half inclined to break it all down and re-do everything. There are assumptions I made based on work other people did; for example, my machinist chose my bearings when he did the balancing so I didn't check those clearances. Same with the rings; I checked a couple and gap was .018 easily (.020 fit tight) so I assumed that sampling was good enough. When I turn the engine it's... tight. Doesn't bind, just that I have to put a little muscle to turn it. As I'm going through this, then, I'm seeing that building a 383 requires a lot more math and verification (and that, even beyond the math, it's still dynamic, e.g. having to actually measure to determine the right rod length.). And to your point, even the choice of valve covers seems to be more critical.
Like Jebby said, those rockers will be fine with those springs & cam. Just make sure you a a cover with drippers.
If you want to go to roller rockers, I would go stainless, not aluminum. Then you can run any valve cover you want.
Even these are better than what you have now: Summit
Found another flick on pushrod length. What’s your opinion on this approach (ie starting with geometry to determine rod length) vs the magic marker method?
And I'll just say I think there's way too much worry about valve cover drippers etc. Won't hurt a thing to have them....but there are many SBC running around without drippers even from the factory. It's a ball type rocker and they need oil on them...but there will be plenty up there.
Aluminum roller rockers are fine as long as you stay away from the cheapest Chinese imports. And even they work OK IF you have very mild springs and cams...but in that case stock rockers are fine too..and probably better. The "half" rockers with a ball socket and roller tip really are nothing special and I'd just run a set of stock rockers if cam was mild. Stainless are nice...and any of them with roller trunnions are going to do fine with even limited oil. GM ran aluminum rockers on the LT4 C4's with no issues...and heck....look what LS's do with their litle rockers.
Building a 383 is no different than any other engine. Other than some block grinding in some cases...and even that is usually not necessary if you get the right rods....it's just building a good engine.
