[oville]

Looking at various cams around the 230/240 int/exh dur @ like 0.50" like 288XR from comp. Spending time on the Comp website seems like hyd flat tappet, hyd solid & hyd roller all run the same spring pressure. Then there is a 50lb jump in seat & open valve spring pressure for the same profile solid roller.

My block is at Butler's and its a 73 2-bolt 455.. Have rounded a lobe in the past with hyd flat tappet, despite using Rotella, breakin lube & zinc. Would like to go roller (to kick it up a notch), not the cost that scares me or X2 a year valve adj with solid roller, just busting parts of the block & having to start over with machining$$.

Roller hyd or solid seems to get the side loading comments, just wondering where is the "line in the sand" when you need to start worrying about lift/dur and breaking off a lifter bore when it comes to using a roller cam (asked the block, just got silence)?

Hoping to be in the high 11s with a street/strip car so I keep posting in the Race forum; I know its a bit slow, just doing what I can here at limited wallet racing.

Thanks,

[tom s]

the rule of thumb is when the duration at.200 get to .200 lift is when a brace becomes a must.Anything real close to that might be good insurance.Tom

[ponjohn]

Don't purchase an over the counter cam.

Have one of the vendors here spec a cam for your combo.

Same price.

[Elarson]

Ask Rodney Butler. The Butlers were familiar with that issue at least 15 years ago. We ran roller cams in unbraced stock blocks, using Butler's advice and never broke a lifter bore.

Eric

[WARPed]

If Butler is building your motor and are retaining the 2 bolt mains in a 3.25" journal block then it sounds like your goal power wise won't be needing/using a cam that you would need to worry about breaking a lifter bore.

[lust4speed]

Originally Posted by tom s

the rule of thumb is when the duration at.200 get to .200 lift is when a brace becomes a must.Anything real close to that might be good insurance.Tom

I'm with Tom. You have to really have an aggressive lobe profile before you have to start worrying about pushing the side of the lifter bore out. That XR288 cam is a long ways away from the danger point. I've run the XR288 cam along with larger solid roller cams without a lifter brace. The latest cam in the drag car exceeded the 200/.200 rule and I did install one.

[Steve C.]

16 years ago for race applications Jim Butler was MIG-welding braces into the vunerable lifter galley area. Cut and fit.

In those days Jim 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").

As already stated you will often see it touted that a lifter bore brace is typically not necessary untill 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 if there of any significant size.


.

[Tom Vaught]

Jim Brady had a Comp Camshaft, built to a Roy McKinney's specs, (Mike Mckinney's dad) many years ago. Roller profile in the 270s range on the intake/280s on the exhaust and .600+ lift. It had a smooth acceleration profile on the lobe. Jim ran that cam for several years in a basic 455 block with no issues. So some of his Kansas buddies talk him into taking out the McKinney camshaft and putting in a "Better Camshaft". Broke the lifter bores right out of the block. Different block (and possibly a lifter brace) I do not remember if he had other issues. So about 5 years ago, Jim calls me up and wants a Roy McKinney camshaft for his 61 Catalina street/strip car. We found the profile at Comp Cams again and Jim installed that camshaft again without a lifter brace. NO ISSUES.

So it definitely depends on the ramp acceleration rate vs just duration and lift specs.

Tom Vaught