Hyd Roller vs Hyd Flat tappet on SM heads
- Thread starter Cuda416
- Start date
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PRH
Well-Known Member
I thought the usual situation with the SM heads and SM/PRW SS rockers was this:
cookietruck
Well-Known Member
Just got a set of these heads today. Flat tappet springs.
I have some 1.5 prw rockers so i might check this tonight.
For some reason I just thought about blending the ridge from the top cut into the chamber so I googled it.
found this below.
Seems it will be worth it, might blend the top cut. Smooth the bowls if needed and gasket match. And get a backcut on the intake valves..maybe even get the valve job fancied up a bit haha.
Just need to find some valves with the margin removed..
My 170 promaxx heads got upgraded stem seals and the valve stems needed polished. The guides were a little tight for my machinists liking. Everything else was good. Concentric was spot on.
cookietruck
Well-Known Member
Seems a 1.4” diameter retainer. Maybe 1.45” spring.
Might put beehive springs on…
The rocker stands are still a little sloppy, seems like it would be perfect to throw a thin shim in old school style haha.
Might put beehive springs on…
The rocker stands are still a little sloppy, seems like it would be perfect to throw a thin shim in old school style haha.
cookietruck
Well-Known Member
Not much to gasket match. Actually prob need to trim the bottom of this gasket.
cookietruck
Well-Known Member
Just pulled two valves. The exh bowls could use a little more blending than the intake. The intake short side feels pretty short and laid back.
Here are a few pics.
Here are a few pics.
Same here. Valves a hair right for my liking. But otherwise good. Mine are the CNC Shockers. I widened the pushrod pinch with a brass tube insert and a minor trim for the gasket. Otherwise, they were really very well built.
The valve springs don’t meet the requirements of the cam I’m running. So they were swapped out for the cams matching spec requirements. Not a big deal. Valve spring heights were spot on and rechecked with the stiffer springs.
They are a good head.
The B3 racing geometry correction put me into the pushrod clearance issue. I'm running 1:6 PRW rockers and hardened shafts. I told Mike that I can elongate the shaft hold down bolt holes for the geometry correction and he laughed at me.
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Newbomb Turk
Well-Known Member
You can use a beehive spring but you don’t fix the problem.
That is 100% a geometry issue and nothing else.
PRH
Well-Known Member
Old Crane golds………room to spare.
cookietruck
Well-Known Member
I ordered two valves to use as sacrificial valves so i can smooth the chambers a bit.
Ordered 5.015” chevy valves and will see if that helps the geometry. Thought i read the speedmaster +.100 are longer than that.
Ordered 5.015” chevy valves and will see if that helps the geometry. Thought i read the speedmaster +.100 are longer than that.
I used 5.010" chevy valves in mine, needed a considerable correction to fix the geometry with PRW 1.6 ratio rockers - I would recommend a call to Mike at B3.
Pushrod holes needed some clearancing with the kit but I used 3/8" pushrods.
cookietruck
Well-Known Member
What’s laser etched on your heads?
Did you check contact patch before and after the kit?
They have aeroflow etched on them - but it is the same casting as the speedmaster heads. They just have a different valve job cut on them and the brand name etched on.
Valve sweep before the kit went on was quite wide and off towards the edge of the valve tip and the rocker arm would contact the retainer with a straight spring (1.45" diameter retainer I think it was). Contact patch after the geometry kit went on was centred and about 0.030" or so wide.
Valve sweep before the kit went on was quite wide and off towards the edge of the valve tip and the rocker arm would contact the retainer with a straight spring (1.45" diameter retainer I think it was). Contact patch after the geometry kit went on was centred and about 0.030" or so wide.
mopowers
Well-Known Member
How much did the rocker shaft hold down bolt holes need to be opened up?
Quite a bit - probably amost half the width of the existing hole in the shaft. I did it with a carbide burr but would definitely recommend taking them to a machine shop - those shafts are quite hard so it's pretty easy to get too much heat in the burr and make it dull.
cookietruck
Well-Known Member
About .080” contact pattern going to .600” lift. Who’s scared of it?
Edit: PRW rocker arm.
Edit: PRW rocker arm.
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PRH
Well-Known Member
I’ll say it…….
That wouldn’t bother me even a little bit.
That wouldn’t bother me even a little bit.
Newbomb Turk
Well-Known Member
I’ll say it. That’s too wide and I’d fix it. But that’s me.
That sweep should be half of that.
That sweep should be half of that.
The rocker length has to be taken into account when checking the sweep pattern on the v/tip. The SBM is a very short rocker [ as many have found trying to fit larger valve springs ]. That means for a given travel [ valve lift ], the sweep pattern on the v/tip will be wider because the rocker tip sweeps a shorter arc.
Newbomb Turk
Well-Known Member
mopowers
Well-Known Member
Real question - If the rockers are too short, why do all of the B3 kits I've seen photos of on this site move the rockers up and away from the valve?
cookietruck
Well-Known Member
As the rocker shaft moves up it gets closer to the valve tip
Look at the centerlines of the valve and the shaft stands
Newbomb Turk
Well-Known Member
Because the shaft mounts end up too low and too close to the valves as the valves get longer.
The shaft location was based on a little over .400 lift and whatever the stem height is supposed to be. I forget the stem height number.
When you change the length of the valve, lift or both you need to move the shaft.
Also, switching to a roller tipped rocker changes shaft location.
And certainly the length, ratio, adjuster location and overall length of the rocker changes where the shafts need to be.
If you picture in your minds eye a straight line running through the stem of the valve you’ll notice that that line gats closer to the engine centerline. That means the tip of the valve is now closer to the shaft.
The ONLY fix for that is to move the shaft away from the valve, moving the shaft closer to the engine centerline.
Then you need to raise the shaft to account for the longer stem height.
A much better and correct explanation of this is in the tech section at b3racingengines.com.
I suggest everyone study Mike’s tech pages. If everyone would read his stuff there’d be far less screwed up, out of control, guide eating Chrysler valve trains out there.
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