C Straub made a comment in PaulDanas 427 build thread about heavy valve train, flexing pushrods, etc....

Id like to hear more on that. As Im building a 383 that I want to spin to 6200+ What type of valve train will be needed? I want to avoid shaft mount rockers if possible, to keep my stock valve covers (Its a sleeper)

Obviously thin pushrods are no good...what rocker arms,springs, valves and lifters are a "must"? My engine builder recommended Morel Lifters....

Im still a long way off, but never to early to get Edumacated...

THX

 

All I will write is this. And I apologize it is not answering your question...on what parts to buy.

On engines that I deal with that have SERIOUS spring pressure. When the engine/cam is being broke in...a spring is removed so lighten the spring pressure a bit...so when the cam is breaking in...it will do fine...because the spring pressure is still quite adequate...and after the cam has been broken in and the builder is "happy"...the spring is re-installed back to the high pressure that is was built with.

DUB

 

Good to see u posting again Don. Havent heard much of your killer AFR/roller cam upgrade L82 and was hoping to read how it hauled azz - talk of a sleeper.

Well as for high rpm vlv train u have several choices that u can make. But it all leads to controlling the vlv at hi-rpm preventing vlv float. Dont let some hacks tell u lofting the vlv is anything the same as vlv float and just cause NASCAR can do it at 8,000rpm doesnt mean anyone can do it on a street motor from idle to redline - that aint how it works.
Back to topic, controlling the vlv requires spring pressure and the heavier the vlv the bigger/stronger the spring needs to be. So if your running big heavy vlvs then get ready to use big springs and spring life will be shorter with the higher pressures - heck the whole vlv train life will be shorter.
FYI the effects of heavy parts is mostly on the vlv side of the rocker arm as the lifter side can be heavier with less of effect to vlv float and max rpm.
So ever use/hear of "hollow stem vlvs". They are generally 20% lighter. Which in turn allows a lesser spring pressure and lighter spring. Read a lot of the new "beehive springs" these days dont ya. LS6 beehives are on the Fast Burn heads, several GM crate engines and have replaced the LT4 hot cam spring in the GMPP catalog - but they all use hollow stem vlvs. Dont use that spring with solid vlvs - u will lose.
Well a lighter vlv allows a lighter spring and now vlv train life not only gets better but the rpms get higher too. How much u wanna spend? Hollow stem vlvs are 2x the price of solid stem vlvs. Titanium vlvs and retainers are available but u dont wanna know the price.
Add a stud griddle and u should be good for some real spin. But make sure your springs match your cam/lift requirements along with the type (weight) of vlv u choose. Thats the hardest part finding the correct "beehive" for your combo.
Ok u can use lighter lifters, p-rods, rockers and they will help some but not nearly as much as the other side of the rocker arm.

Ok Don i spilled my guts and hope this helps ya,
cardo0

 

Yeah...so much blood sweat and $$$ into the Pace Car, then had to sell it before moving t Smog **** Cali.......Never rally got to see what it would do...(Lost my *** too...)

Anyway, the next one will be even better.......Ordered rotating assembly today...

 

6200rpm isnt much
a good 7/16 stud and quality rocker arm should be enough
I like to run a little more spring pressure on a hr if the ramps are quick wont hurt anything. If you listen to everyone on the internet though your car probably will never run everyone does it different

 

Haa Sooo true.

Ive settled on a pair of AFR 210cc heads with 1.55 OD solid roller dual springs, 225lb seat .710 max lift. My CR is going to round out at 10.8 and ill be looking for cam somewhere near .6" lift...

At what RPM would a stud girdle be necessary? Say I want to try to rev i to 7k.....

 

order the heads with the bigger rocker arm studs ,they will work with a stud girdle .

 

Its not whether they will work, its will they fit under Corvette script valve covers.....No PCV holes on this motor....

 

At what RPM would a stud girdle be necessary? Say I want to try to rev i to 7k.....

Good question Don. 7,750rpm

 

I have AFR 210's on my solid roller 383. You don't need or want 225# seat pound springs on a sub 7500 rpm motor. You could ask if they can be installed at a higher installed height to get them down to 200 ish pounds.

larger dia. rocker arm studs is a good thing. All you need for push rods is Comp Cams .080 wall chromemoly. I like steel roller rockers. In s solid roller or H-rollor motor you want to end up with about 236/242 with those heads.

Personally every average Bubba builds a 383. I quit building them years ago because for the same price you just make a 396 ci.

I put on a couple hundred miles on my 383 yesterday and it is still kind of fun with a 5 speed.

 

I considered a 4.0 stroke crank...but really 383 is gonna be too much for the car as it is....

 

You hardly ever hear the word "Too Much" in the way of HP or motor

Anyway a 4.030 bore and 3.750 makes @ 383 ci 4.030 and 3.875 makes @ 396 a 4.030 and 4.00 is more like 408 ci


I've done the 4 inch strokers and i would not recommend it in a stock or even Dart SHP block

 

my sbc; dart pro 1 heads, lunati cam 5.60 lift, shift lite set at 7200rpm. insurance -stud girdle- need tall valve covers. the 69 L48 I installed harlen sharps rockers under the painted covers. T

 

The largest diameter pushrods you can fit in the heads is your best choice.

Stud mount rockers I recommend Crane Only.

On the pushrod side of the fulcrum build for endurance not weight saving. On the valve side of the fulcrum build for durabilty and weight. You are always better off to go with the smallest diameter valve spring that gives you the seat and open pressure desired.

 

I was hoping you would chime in....

How do I determine the largest pushrod my heads (AFR 215cc) will take? Trial and error?

Obviously springs will be dictated by the cam..
What cam specs would you recommend?
At this point : 383CI, 10.8:1 CR AFR 215cc heads. 5 speed 3.73 gears. Light 3100lb 63 convertible
target operating range: 2500-6500+

 

Call AFR. I had the same questions with my AFR195s. Obviously, the larger diameter the better in terms of controlling flex, but what I was told was that the limiting factor on my AFRs was the hole in the head the pushrods went through. Depending on the valve train geometry, the pushrods move through an angle so they need some space. They are designed for a 5/16 diameter rod and would need to be clearanced for a 3/8 pushrod. The issue is that in the clearancing you are getting VERY close to the wall of the intake port and there is a chance you will make it too thin/break through during the clearancing. I'm not saying a pro couldn't do it, but for me it didn't seem quite worth it (not gonna see above 62/6300 rpms).

That's my .02, of course, my motor is sitting in the frame about 5' below the body on my lift at the moment

 

I still like Bee Hive springs.... I ran them in my 383 and they were good to 7K RPM, yes they do not have a damper for spring break backup, but....... they generate a lot less heat to break, a lot less seat pressure, AND LOT LESS HARMONICS. THEY USE THEM ON MODERN ZO6 427 ENGINES... a light valve train handles higher revs, higher revs = more HP. and i still also like the Comp-Cams Ultra pro magnum RR.

 

You just have to think about bending forces and not RPM per say. aggressive solid roller lobe profiles with higher ratio rocker arms and bigger open valve spring pressures are brutal on the rocker arm studs.

Going to bigger ARP rocker studs with guide plates is the first defense. Crane gold stud girdles are the next best thing compared to full shaft rockers.

The heavy wall 5/16th are good for street motor small blocks. I was only used 3/8th heavy wall on all out race motors.

I have a different opinion on valve spring diameter. The larger diameter the dual spring is the cooler they run and the longer they last before they loose spring pressure. also the taller the installed height to stay away from coil bind or max lift rated. I run .800 lift springs on my .700 lift cam

 

Can you explain the difference between lofting and floating the valve? What do you think of rev kits?

This wouldnt have happened if only you'd payed attention!