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another cam bites the dust......472 BBF jetboat
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disturbthepeace1
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Joined: 14 Jun 2003
Posts: 303
Location: Stanton, CA
10195.60 points


1965 Volkswagen Beetle

PostPosted: Fri Jun 29, 2007 11:45 pm    Post subject: Reply with quote

Quote:
clay wrote:
I think BBF's, Boss 302's with which I have had personal experience on wiping out a cam, and probably Clevelands have another cam break in disadvantage - the high rocker arm ratio - 1.73 I believe which would put even more load on the lifter given the same spring pressure on a SBC for instance. Of course once broken in, then it becomes and advantage . Clay





i would think lift is lift
the spring doent know what kind of rocker is on it
it only knows how far it compresses
and how fast compared to spring rate

in that case if i were a valve spring id want to be in a small block chevy with their limited lifter diameter =they can only ramp up so fast compared to any ford or mopar






the ratio will multiply the pressue that is between the lifter and the cam lobe itself... the larger the ratio the more force its going to take to open the valve...


I.E. 1.1 pushing 200psi is easier then 1.6 pushing the same spring..........

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wagon train
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Joined: 07 Jun 2007
Posts: 258
Location: Orange City, FL
7307.16 points


1983 Mercury Capri

PostPosted: Sat Jun 30, 2007 3:43 pm    Post subject: Reply with quote

If the case of the witness on the piston,it may be a valve float issue.What is the rpm limit of that grind.Even if you had the right springs and clearence the cam lobe can only rev so high.Also did you check every cylinder or just reference one.All pistons are not created equal,pocket depth,CD height.Are the rods all the same lenght.Are the seats taller in that cylinder,more margin on that valve.All those numbers can stack up against you.


In the case of the home hone job.It will work, if you get the right stone grit for the rings you are using.If the grit is to course it will only scratch the moly off the rings(assuming that the ring you are using).Lots of coolant ,lube while doing it and clean it very good warm water high detergant soap.If you want to go pro way and you end up with too much clearence you can send piston to a coating company and they (Swain is what I have used)Coat the skirts and will take up the clearance.I think they can go up to .004.Don't take that number to the bank, though.


Hope all that helps.

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PACE429
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Joined: 01 Oct 2006
Posts: 5
Location: Havre de Grace, Maryland
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1973 Ford Mustang

PostPosted: Tue Aug 12, 2008 8:49 pm    Post subject: Wiped camshaft Reply with quote

I would recommend using a hyd. roller cam and lifters. Use a solid roller if your going to rev over 6,800 on steady basis. Hyd. set -up would reduce your amount of valve adjustment maintenance.

By using the roller set-up, you won't have to remove the inner springs and worry about special break-in procedures.

Take the time to degree the cam. Then install the heads and check to ensure that your valve clearances will be correct.

If you have a oil supply issue, make sure to open and chamfer the feed holes in the block at the oil filter area. Also, make sure the oil galley plugs located at the rear of the block, were installed in the correct positions. Some are standard and the others are tapered to allow oil flow.

There is a good article on the engine masters web site detailing BBF 460 & stroker engine builds and things such as the proper galley plug locations.

Finally, use a oil such as Rotella "T" or Delvac for your break-in period. The EPA has recently removed the some additives from automotive type oils for environmental reasons. The removal of these additives is causing cam & lifter failures, as reported by Comp Cams and other cam manufactures Good luck, Mike
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disturbthepeace1
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Joined: 14 Jun 2003
Posts: 303
Location: Stanton, CA
10195.60 points


1965 Volkswagen Beetle

PostPosted: Wed Aug 13, 2008 11:25 pm    Post subject: Reply with quote

Those are all great suggestions and roller would have been great but it wasn't in the budget. I did make some changes to the motor though i.e.; switch to a lifter with a oil hole drilled in it's face and I grooved the lifter bores for better oiling as well.. Valvoline racing has ZDDP and that is the only oil i use on any flat tappet cam..




Basically,

Did a home hone job

Comp supplied a new solid flat cam and new (better)lifters

oil grooved the lifters bores

No bearings were hurt in failure of this cam..

Used same head gaskets too..

This motor has been running incredible all summer long. 84mph on the GPS with a "B" impeller.. still have yet to use the bottle but it will be sprayed the end of the summer for sure...

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squeeezer
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Joined: 02 Mar 2007
Posts: 2427
Location: new richmond WI
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1991 Chevrolet Camaro

PostPosted: Thu Aug 14, 2008 3:33 pm    Post subject: Reply with quote

good to see everything is back up n runnin thumbsup
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cutlass389
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Joined: 29 Apr 2006
Posts: 268
Location: NC
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1978 Oldsmobile Cutlass

PostPosted: Thu Aug 14, 2008 10:18 pm    Post subject: Reply with quote

I also use Valvoline racing oil for its ZDDP content for flat tappets. I've recently read about break-in rockers with a 1.2-1.3 ratio. Easier to use but obviously more cost.
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