*z50k2* wrote,
*TR It was suggested to me to get the GM style adjustable rocker arm bolts for my 390 heads.This bolt would allow a smoother rocker function. Is this consistent with your thinking? Thanks for your help...seeya...*
I did that on a 360 for my nephew. 1.6:1 Magnum roller tipped rockers, 7/16"X 3/8" chevy style studs, guide plates, custom push rods, ect,... to try and improve the upper rocker geometry some...
BIG PAIN IN THE A$$ !!
The rocker fulcrum towers machined down OK, and the studs were just like a small block chevy to install...
The center two exhaust towers come pretty close to water jackets and the exhaust passage for intake heating.... so be careful
(If I had to do it over again, I'd use shoulder less 3/8"X3/8" studs instead of the big studs with the 'nut' type shoulder in the middle, and I'd use a cam where I could skip the guide plates)
The rockers mounted all right, but the geometry was not really improved that much.
The push rods had to be custom made. ($$$)
The guide plates were so hacked up and bent up by the time we finished, we should have started from scratch on those also.
USE EXTREME CAUTION WHEN MILLING MATERIAL AWAY FROM THE CENTER CROSS OVER FOR THE CENTER TWO EXHAUST VALVES!
There is a mystery water jacket there...
The factory sand castings were pretty crappy, and the water jacket could be as much as 0.200" closer than you think...
(That makes for some interesting language when someone hits one where it's not supposed to be...)
That means some of the heads had less than 0.025" material between oil and water!
That's not much when you talk about soft and temperamental cast iron...
(If the made the mistake the other way, around the combustion chamber, the head already cracked and was thrown out by now... so we only found them thin on top...)
The 304-360 engines have cast iron crankshafts and connecting rods, so your rev limit should be around 3,500 or 4,000 anyway, so use a good stock type rocker arm.
Just remember to shim it up where it's supposed to be.
With the stock type rockers, you can use stock push rods, and don't need guide plates...
Makes life much simpler!
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I have a friend that just bought a 304 CJ-5, and he thinks the engine is on it's last legs.
(I think it's just the so called 'Tune' it has... The distributor is 90 degrees from where it should be...)
If we have to do an engine, I'm doing a 360 or 390. It's going to be pretty much stock...
Performer cam/ lifters/ valve springs/ timing chain/ intake, Holley 600 vac secondary, Dura Spark ignition, (has points now...) Just little upgrades.... Nothing crazy....
That CJ-5 weighs nothing, so even the 304 just THROWS it down the road...
Wonder how it will do when it gets reasonable fuel mixtures and timing with in 40 degrees of where it should be...
See ya, Aaron.
If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
