Aluminum might unpredictably fail down the road, depending on the alloy and heat treat. The extra weight would help at the shift recovery rpm, much like a heavier flywheel. Pretty simple piece to make.
Will, it would not be that hard to make. Any good machinist with a lathe and indexing head overhead boring machine would be able to turn it up. But as you say it going to add cost to an already expensive bit of gear.
That aluminum hub has been in the truck now for about 3 yrs. since I did the job. Don't know how many miles??? Was also on before I worked on it but very little miles were put on it then to my recollection. As for the wobble. I think you have an adapter from a DynaFlow to a TH400. You grind the flange off the rear of the crank & install the adapter. The flexplate fits over the adapter & the flexplate bolts directly to the crank. Unless Bob's adapter is designed differently??? Maybe with Bob's design you can still use the original longer nose starter??? I can get a different nose for the starter to make it shorter for the TH400 application. I feel that if the flexplate was bolted directly to the crank it would have "More"??? contact area to help make it straighter??? Bolt it directly to the crank & see what happens??? In any case I don't think that the small amount of wobble is going to affect anything. Of course we would all feel better if it wasn't there to begin with, but I don't think it really matters. Maybe at 4000+ rpm's??? Tom T.
It might be a good idea to put an indicator on things, and check as suggested above. The service life for an aluminum piece might exceed the life of the engine ten-fold, esp. if not abused. My comment on failure was just a general statement. I don't see much disadvantage to either type. Nobody's racing seriously with this.
UPDATE 10-28-16 As the time approaches for me to put my 'Nail back together, I just want to make sure all bases are covered which leads me to THIS http://butlerperformance.com/i-24696791-sdp-deluxe-mega-brace-lifter-bore-reinforcement-system-sdp-lbb1-mbdug.html?ref=category:1234854 Does it look like this would work with little to no mods necessary to reinforce my Lifter Bores? I see TA Performance offers a Lifter Bore Girdle kit for the 455, but requires welding to I BELIEVE the block itself.. Im not to fond of that idea, and haven't had a chance to call Mike at TA to confirm tho.. Whats your opinion? The spacing on that Butler Pontiac Lifter Bore Reinforcement Kit looks pretty close. Id be sick if the cam I have with a pretty fast ramp-rate tore one of my Lifter Bores out of the block, and don't wanna think about what it'd take to rectify that, if even possible... As Always, thanks for reading and giving a little feedback! (Attached is the Eye Candy fresh out of the shop!)
Is your lift/degree rate that much faster than the factory cams? What's the spring pressure? I've not yet seen the need for this on a nailhead. I don't think that any off the shelf kits are intended to be welded to the block. The various ones on the market (incl non-Buick) have just enough bolt preload to barely push on the bosses. Some people just epoxy up the valley. There's some 455 girdle and valley mod info in this forum you could search.
Great to see your plan coming together! Are you using a fast ramp cam AND the high ratio roller rockers? Just the rockers will increase the ramp speed of the valves. Add a fast ramp cam and it may be hard to control the rapid valve action..... correct springs are going to be critical. Can the Nailhead even utilize an ultra-fast opening valve? I'm thinking the short stroke/big bore would better utilize the fast rate compared to a long stroke/small bore engine.... In theory. Don't know what works in real life tho.
This is the cam described at the beginning of the build: *Custom Comp Cam (212-218 @ .050) -Similar to stock but with higher lift than other available cams. with a 1.6 Ratio, I should have .489-intake and .505-exhaust lift. Plasma-Nitrided as well *100lb closed and 275 open Valve Springs. I don't see how a flat tappet hydraulic cam specified with those springs and minimal lift could have extremely fast ramps. Do you have the advertised duration as well? That will provide a good idea of the ramp speed in comparison to the @ .050" durations. TA's lifter girdle is only made for the 455 and is bolted to the block. It only becomes necessary with high lift cams with very aggressive ramps. These are solid lifter grinds or roller cams that require much greater spring pressure to control the valve on these ramps. An example would be a roller cam with .650" lift and 255* @.050" duration requiring a seat pressure of 225lbs and 600lbs open. The Nailhead cam described would not have the quick action or high spring pressure characteristics. It would put far less pressure on the lifter gallery then many of the larger and faster solid lifter Nailhead cams available. I have never seen a Nailhead lifter gallery fail using any of those cams. I think you will be just fine cleaning up the flashing and leaving it at that. Below is a picture of the girdle installed FYI: Cheryl
UPDATE 11-3-16 Attached is my Cam Card. The springs I have now are slightly heavier than originally posted. They are HYDRAULIC 2 Springs I got from Russ Martin. HYD 2 Springs- 105lbs Seat / 275lbs @ .500 Lift These Spring numbers are only but "SO" Important, as I am still in the process of gathering enough info to call up either Mike Lewis / Greg Gessler to send my NEW HEADS (without seats) out for some porting, and mainly to be set up with BEEHIVE SPRINGS with my Telesco Rollers. Thats the info I'm still gathering as time permits, as there seems to be a few gaps here or there as far as that goes- new valve heights to help correct geometry/pockets opening up for springs & rocker arm clearance etc... Thats another topic though. As you know, I acquired Toms Roller Rockers, and am excited to use them with the 1.9 +/- Ratio. However, with the rather fast ramp of the cam, combined with the higher ratio Roller Rockers, AKA EVEN FASTER cam opening, and potentially stiffer BEEHIVES, Im worried about the Lifer Bores. (.316 Exhaust Lift X 1.9 Ratio = .600 Lift) It appears as though the TA Performance girdle DOES require welding to the supplied tabs. My thought is that I could drill/tap provisions on the block and bolt the tabs in/weld to the tabs as described in the directions, provided it all fits... As far as I get, theres always more! Assembling short block in the next month or so and re-checking clearances etc.. Ill keep you guys posted as the short block comes together! Keep the input about the Beehives/Roller Rockers/Geometry & Lifter Girdle coming!
Did you check how close the lifter bores are in location between the two engine types? Looks like a pretty easy piece to make with a drill press or mill.
nice cam choice. the only thing you have to do is use a 30 thousand thick shim under your 105-275 springs. 105 seat is to low. that should put you at 120-125 seat pressure. i been running 130-300 spring pressure for years with no problems, girdle is over kill. you only need to shift at 5200 rpms at the most, any higher would be a waste with that size cam.
Will, I'll only add that with my friend's car when we used a cam that was 284*/284*@.050" with a .400" lobe lift we were capable of a .790" lift at the valve using MY ROCKERS. At the advertised lift with a .400" lobe, theoretically, we were supposed to get .640" lift at the valve. Which in reality turned out to be .525" at the valve with the stock aluminum rockers. This was with a 106LSA. We had 155lbs. on the seat & almost 400lbs. over the nose. We ended up with about .660" lift because of the availability of off the self valve springs using a shorter push-rod to lessen the amount of lift. We were bringing it up as high as 6800RPM's (mostly around 6200 ) & had NO PROBLEMS with the lifter bores. Today a Roller is installed with about 550lbs. over the nose & NO problems associated with lifter bores as of late. I think/feel your over thinking/going overboard here with a lifter valley girdle. Just my thoughts. Tom T.
Better check for coil bind with those springs. At the full ratio of 1.92, lift at the valve can be as high as .590" & .610". Of course you could use a shorter push-rod to lessen the ratio if needed. Should be NO PROBLEM with V/P clearance as the pistons are made to accept as much as a .700" lift & using a 1.940" intake.
why .600 lift ? whats wrong with .550 lift. are your heads going flow that much more from .550 lift to .600 lift . if you go all the way to 1.9 rocker ratio, would that put a lot of side pressure on the valve guides?. you would not want all that lift on the exhaust valve anyways.
The benefit of more rocker ratio and lift beyond max flow has little to do with whether or not the port is tapped out flow wise or concerning the intended shift rpm. There's more degrees of crank rotation from mid lift, over the nose and back to mid lift, making it easy to duplicate a roller cam's valve lift profile while still using a very tame flat tappet cam. Sounds like a great idea for a starved induction design. Curious if the OP has plotted out piston demand vs. air flow capability for every degree of crank rotation, esp. at max piston speed, to verify Delta P.
It's been proven more than once about TOTAL valve lift. Just because the head flows best at .550" doesn't mean it has to stop there as long as it doesn't start going backwards. So going from max flow at .550" & going to .610" it will be flowing MORE AIR to fill the cylinder. Going from 550 to 610 & back down from 610 to 550 the cylinder gets a bigger shot which in turn produces more POWER. The "Nail" needs ALL THE HELP it can get as far as air flow & this is one of the ways to accomplish this. I can't tell you how many more degrees of piston movement crankshaft rotation are but the valve is open for a longer period of time & while it's open longer it's continually filling the cylinder. MY ROCKERS have made an improvement on any cam that's been installed. Tom T.
Tom we know your rockers make hp. they say 1.75 ratio on intake is max. the exhaust does not respond well with the extra lift. might even hurt the flow. dont forget the valve guides too.
I haven't used Tom's rockers yet, but as I understand...if you can vary the pushrods to adjust the ratio slightly due to the arc position (?) might be a smart way of taking some ratio from the exhaust side. (As stated above) The increases from more ratio to the intake side would certainly outweigh any slight lack of 'balance' to the exhaust/header/overlap/blowdown event on the exhaust side of things. On such mild cams, a high ratio flat tappet can outpace a roller's lift profile.
with Tom's rockers you can vary the ratio from 1.6 to 1.9. that is why they are nice to have. like Tom says the stock rocker arms dont really stay at the stock 1.6 ratio. at higher lifts the stock rocker arms go down under the 1.6 ratios.
