[64speed]

Gimmick or helpful with high lift cams and heavy springs?

[steve25]

There not a gimmick, but there are only needed with high rate of lift roller Cams where more than 380 psi of open spring pressure is used.

[Steve C.]

'Roller Pressure Angle'

The direction of the applied force lifting a roller lifter is at an angle and not directly along the axis of the lifter. The more aggressive the profile, the greater the pressure angle. Beyond the limit at about 33 degrees, reliability drops dramatically. This side thrust distorts the lifter body and leads to hydraulic collapse. These side loads are not seen with a flat-tappet-style lifter hence the problem is not an issue. The bigger the roller and cam base circle, the less the roller side loading

On a Pontiac application you will often see it touted that a lifter bore brace is typically not necessary until the duration at 0.200" valve lift approaches or is over 200 degrees duration. But even if their roller cams don't follow that guideline many go ahead and install them anyway as insurance

Of interest.... years ago Jim Butler included a list of solid roller cams offered in his catalog (they were Comp Hi-Tech .420 rollers), and with that listing of cams he mentioned specific lobes that he stated "should not be aggressive enough to break lifter bores". Those lobes were from 252 at .050 (169 at .200) thru the top lobe with 282 at .050 (195 at .200).


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[6t7goat]

I run one in my 461. Maybe overkill but it wasn't that much$$$ and i feel better knowing its there.

[Formula8]

With the investment in finding a suitable core block, machining etc. a failed lifter bore would be catastrophic. I added a lifter bore brace as cheap insurance.

[tom s]

The numbers thrown around is when a solid roller cam gets to 200 duration at 200 lift is when they should be used.Tom

[ponjohn]

YOu have to install the lifter bore brace then have the machine shop verify the bores are still round.

[hurryinhoosier62]

After having seen your cam spec, a liter bore brace would be an insurance policy that would probably never be needed UNLESS you later decided to install a roller like Tom has described.

[tom s]

JMO,there is no flat tappet or Hyd roller bad ass enough to need a brace.I ran 200 on the seats and 600 open on many engines with solid rollers at 660 lift and up to 260@50 with no issues.Tom

[Formula8]

Originally Posted by hurryinhoosier62

After having seen your cam spec, a liter bore brace would be an insurance policy that would probably never be needed UNLESS you later decided to install a roller like Tom has described.

Not sure if that was directed at me but (1) most gear heads have a tendency to up their game over time. I am no different and my new motor is built with serious overkill with this in mind. My block was on the stand and I was deburring the valley so the timing was right to add a brace. I threaded my lifter bores for restrictors too although I have no current need for them. Either of these modifications would be a pain in the ass on an engine while it was assembled and sitting in your car. (2) There is a member on this board with exactly the same cam and lifters I am running who cracked a lifter bore. I don't know if he wants to chime in but again, the cost of the fix (new block with all of the attendant machine work, cam, lifters at a minimum) is several magnitude the cost of preventing failure. And the irony is that if you did have a failure and had to do it all over again. I am 100% sure you would buy a lifter brace for your new motor anyway.

[Steve C.]

I suspect the OP is asking for interest or general information. Based on a previous post he has a hydraulic flat tappet cam in mind for his current build, not a roller cam. At first a Summit 2802 cam was proposed but now It appears he will be using a Voodoo hydraulic flat tappet cam with 233 @.050".


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[hurryinhoosier62]

Originally Posted by Formula8

Not sure if that was directed at me but (1) most gear heads have a tendency to up their game over time. I am no different and my new motor is built with serious overkill with this in mind. My block was on the stand and I was deburring the valley so the timing was right to add a brace. I threaded my lifter bores for restrictors too although I have no current need for them. Either of these modifications would be a pain in the ass on an engine while it was assembled and sitting in your car. (2) There is a member on this board with exactly the same cam and lifters I am running who cracked a lifter bore. I don't know if he wants to chime in but again, the cost of the fix (new block with all of the attendant machine work, cam, lifters at a minimum) is several magnitude the cost of preventing failure. And the irony is that if you did have a failure and had to do it all over again. I am 100% sure you would buy a lifter brace for your new motor anyway.

Is your handle "64 Speed"? In most cases, a lifter bore brace is really isn't needed for a NORMAL street engine(under 450hp), Will I install one in the 3" main 421 I'm planning to build? Absolutely, but we're talking a mechanical roller cam.

[Formula8]

Originally Posted by hurryinhoosier62

Is your handle "64 Speed"?

No but I didn't see where he listed what cam he is running. You stated "After having seen your cam spec". So I assume you mean from another of his postings. Not a big deal, I think we are all on the same page. Probably not necessary for this application or mine but nice to have for future growth if it should come.

[Steve C.]

As noted in Jim Butler's comments in my post #3 one would have to run a very big solid roller cam to come near to 200 degrees duration at 0.200" valve lift. The top cam in his list being 282 at .050 with 195 at 0.200". Even a Comp Race hydraulic roller cam with a whopping 276 @.050" isn't close with 185 degrees at 0.200".

But that's observing the ' 200 degrees duration at .200 lift ' adage often mentioned. There is more to consider like spring pressure, and maybe the rocker arm ratio as well. But either way as Tom suggested it's a lot of cam for most street cars here.

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[Lee]

If I were to build a motor radical enough to where I was worrying about the need for a lifter brace, then I'd just go ahead and buy an aftermarket block.

[steve25]

If your not making over 800 hp then 2 blocks of Epoxy and some Aluminum plates tip the scales a lot less then the added 40+ pounds of a aftermarket block .

[Lee]

40 pounds of iron will make the block a LOT stronger, sturdier, and reliable than two blocks of epoxy and some aluminum. Sturdier block could yield enough performance gain to offset the weight.

I've seen epoxy pop off to many times to have confidence that it can be relied upon as a structural element.

[steve25]

Yes, if your at the bore size and power level where things are flexing around.

[Steve C.]

I built a '70 400 block using five Pro-Gram Engineering billet main caps & stud kit, filled the block and installed bolt-in lifter bore bracing with a 279/287 at .050, 0.704/0.680 lift solid roller cam. It was 450cid with a billet 4.125 crank, 4.165 bore and billet 6.8 rods. Assembled it was a 700 hp / 7000 rpm combination. Playing with nitrous it was probably pushing 900+ horsepower. It bothered the heck out of me at that power level enough so that after about a year we retired the block and upgraded to a IA2 block. Others have stated they have run more power with a factory block, personally I thought it was a wise move.


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[64speed]

Desktop Dyno says 525/550 for my combo so I think I am gonna install the brace just because its not that expensive and better to have it and not need it than need it and not have it. I had a hell of a time finding these two blocks and I really want to save the other one for a really rainy day and I dont want that rainy day to be because of something I could have prevented for 250 bucks.