My 365 That Isn't

[Michael H.]

Re: My 365 That Isn't

I used Joe and Dukes recommended clearances on both a hydraulic lifter 327-300 and aSHP 427-435 and have only one, sort of, negative comment. The 427-435 valve train is very quiet, many people would say it has hydraulic lifters.
For the 30-30 cam, GM made thousands of Corvettes with these, presumably set at 0.030", so although 0.023" might be ideal, how bad can 0.030" really be?

I've owned a lot of Corvettes, and a few 67-69 Camaros with the 30-30 cam and always set the valves at the correct specs, .030-.030". Several of those cars had over 100,000 miles on them and still ran very well with no valve train issues.

A few were street raced, hard, a lot, with no issues.

In the late 60's, I was involved in serious testing, some with the 30-30 cam and no valve lash less than .030" showed any improvement in HP or torque, at any RPM.

The latest thinking is that the 30-30 cam had a duration that was too long for street operation at .030" so why anyone would consider or recommend setting the lash at anything less than that has it wrong.

Same for the 425 and 435 HP 427. These engines run best on the street at .024-.028" lash. They may sound more powerful at that .022-.026" setting but they're not.

[Clem Z.]

Re: My 365 That Isn't

the original specs for the #346 cam from GM was .025/.025 but i believe they changed it to .030/.030 get a better vacuum signal for the FI engines. JMHO

[Duke W.]

Re: My 365 That Isn't

The 427-435 valve train is very quiet, many people would say it has hydraulic lifters.

That's the way it should be. Think of all the classic era cars that have mechanical lifters. You can usually only tell if the engine is actually idling by looking to see of the fan is moving.

The 30-30 cam's constant velocity clearance ramps are .000360 in/cam deg., and this is the velocity that the rocker will contact the valve tip if running clearance is no more than about .023".

At .030" running clearance the rocker will contact the valve stem at about .0009 in/cam degree or about 2.5 times faster, which increases the shock load.

At 6000 crankshaft revs these velocities in ft/sec are about 0.54 ft/sec and 1.35 ft/sec, respectively.

Valve train "clatter" is the sound of the shock load as the clearance is taken up at much higher velocity than the clearance ramp.

The Duntov cam can be a little noisy even if clearances are set at .010/.016". That's because jerk, acceleration, and velocity rapidly increase right above the top of the clearance ramp. Later lobe design dynamics are more gradual in the first few thousands above the top of the clearance ramp, so even if the lash is a little loose, they aren't as noisy as a Duntov that's a little loose.

Duke

[George C.]

Re: My 365 That Isn't

I keep hearing two thoughts about the change from .025 to .030, one as Clem states is to increase the vacuum for the FI units, the other was to smooth out the idle. I have tried both and agree that both the above are true.
I have purchased the FM CS118R 30-30 replacement cam, but I am also researching the new hydraulic roller cams from Competition Cams. Since I don't have a car that will be judged, maybe it's time to upgrade the internal components to the newer technology. I have two machine shops doing quotes for lower end rebuild, balancing etc. Will be making a decision on which cam to use this week.
George

[Larry B.]

Re: My 365 That Isn't

If you are mushrooming valves they are way out of adjustment, then the rocker slaps the valve, this can also pull the studs' The studs can also pull with to much lift and the retainer kits the guide and becomes solid.Stud are available in .002 oversise. 3 angle vale job helps the valve seal at all RPM.When power happens is controled by camshaft opening,closeing and overlap.You can cause a 10 to 1 to ping with to small a cam.Today you can get any grind you want in 1 degree changes.[not comp cam tech line or summit] Your broach marks shoud lenght wise most aftermarket surfaces are circular.Hone marks doesn't mean anything i,ve seen hone marks left at 80,000 miles what is the clearance top and bottom. I build alot of motors and use CNC equipment any questions call me at 541-218-7754

[Joe C.]

Re: My 365 That Isn't

I keep hearing two thoughts about the change from .025 to .030, one as Clem states is to increase the vacuum for the FI units, the other was to smooth out the idle. I have tried both and agree that both the above are true.
I have purchased the FM CS118R 30-30 replacement cam, but I am also researching the new hydraulic roller cams from Competition Cams. Since I don't have a car that will be judged, maybe it's time to upgrade the internal components to the newer technology. I have two machine shops doing quotes for lower end rebuild, balancing etc. Will be making a decision on which cam to use this week.
George

If you decide to use a modern roller cam, then you will save money on pistons because you'll re-use your existing parts. That's the smarter choice, AFAIAC, and I can design one for you based on your head configuration and other parameters TBD. Have capability to model using EA Pro. You can fine tune your deck height (since pad numbers are no longer a problem in your case), and gasket thickness to provide tailor made SCR for your new roller cam. If you want a solid roller, you can have one custom ground using low duration lobes ground on specified lobe centers. At minimum, this upgrade means that you'll have to use threaded rocker studs, and fitted with guide plates. New rockers, lifters and pushrods will also be needed, as well as a button for the timing sprocket. The spring pockets will have to be expanded to 1.320" which will accommodate a light beehive valve spring appropriate for the new cam. You will have to reinforce the stamped steel timing cover (undetectable from the outside) to handle the thrust forces from the cam, and, if you want to take full advantage of the engine's new-found potential, then a three angle valve job and pocket port to the heads will pay big dividends. The money diverted from new pistons to an upgraded valve train will mean an increase in torque bandwidth in both upper and lower rev ranges, and an increase in peak power and torque.

[George C.]

Re: My 365 That Isn't

Joe,
Hi, the motor is at the machine shop. The plan is for them to recalculate what I came up with for current CR, then consider new flat top pistons, but ones that won't be sunk in the bore .030, potentially Keith Black Hypereutectic. The Cam I want to use is a Comp Cam hydraulic roller grind number is XR270HR, with lift of 495-502 and duration of 270-276.
The three angle valve job, pocket porting and screw in studs were all done last month so heads should just need cleaned and re-installed. I asked specifically and was told the valve springs he installed last month will accommodate the roller cam. New rockers, lifters and pushrods are all in the quote. He hasn't mentioned modifications to the timing chain cover so I will ask.
I will know more in a couple days after everything is measured and final decision on parts is made.
Thank you,
George

[Larry B.]

Re: My 365 That Isn't

Most of this reply sounds like bull. Deck the block and then control compression with gasket is crap .010 thicker gastet is only about 1cc more and if you deck .o1o off the block you are rigth back where you were.Hydrulic roller are expensive more than pistons.With the FI we need to keep the vaccum up don't use a Comp Cam help line out of the book cam .Get a custom ground piece just for your combination.Three angle valve job is standard.Screw in studs and guide plates could be required depending on spring pressure. Give me a call if you would like to talk about this some more 541-218-7754

[Joe C.]

Re: My 365 That Isn't

Joe,
Hi, the motor is at the machine shop. The plan is for them to recalculate what I came up with for current CR, then consider new flat top pistons, but ones that won't be sunk in the bore .030, potentially Keith Black Hypereutectic. The Cam I want to use is a Comp Cam hydraulic roller grind number is XR270HR, with lift of 495-502 and duration of 270-276.
The three angle valve job, pocket porting and screw in studs were all done last month so heads should just need cleaned and re-installed. I asked specifically and was told the valve springs he installed last month will accommodate the roller cam. New rockers, lifters and pushrods are all in the quote. He hasn't mentioned modifications to the timing chain cover so I will ask.
I will know more in a couple days after everything is measured and final decision on parts is made.
Thank you,
George

That cam will develop quite a bit more idle vacuum than the 30-30, and probably more than the 097. The Rochester unit will be very happy with it.