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Old 03-29-2004, 01:55 PM
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Roller Cams

I'm a little confused by roller cams. I was looking on EBay and there was an SBC hydraulic roller cam. The seller said it was for a roller conversion from a flat tappet.

Is there a difference between a later model roller cam and one made for conversion? I thought the conversion was just adding the conversion roller lifters, spider, and keepers.

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Old 03-29-2004, 02:37 PM
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The earlier blocks (pre 1987) had no provision for the spider or retainer bolts and the lifter bore are shorter. The newer blocks' roller cams have a different front end where the timing gear bolts on and the newer cams are compatible with a stock distributor gear. You can't use a newer cam to update an older block. You have to use a set of compatible parts (cam, lifters, distributor gear, etc.) to use an older block with a roller cam. If one has an older block and wants more performance than what a hydraulic cam offers, he could use a solid cam for a fraction of the cost of putting a roller in the earlier blocks (if one isn't allergic to occaisonally checking and adjusting the tappets).
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Old 03-29-2004, 04:05 PM
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I think Tom was right on the money. If you have an early model block, you will need the conversion kit for the roller setup. There is no cam retainer for the early block with a roller conversion, so you have to get a timing chain set with the cam sprocket having either a thrust washer or torrington bearing on the back side and a cam "button" in the center of the cam sprocket the rides against the timing cover. The washer or bearing is needed because the button is pushing against the cam sprocket and you cannot let the sprocket ride on the block. You will also need a set of lifters that are designed with the link bars because you will not have the "spider" to hold them in place (The spider has eight legs that hold the lifters in the bores so they cannot turn... same idea with the link bars for the conversion kit... they hold each pair of lifters against each other so they cannot rotate). Hope this helps, Rick
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Old 03-29-2004, 04:46 PM
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Quote:
Originally posted by Delirious2000
There is no cam retainer for the early block with a roller conversion, so you have to get a timing chain set with the cam sprocket having either a thrust washer or torrington bearing on the back side and a cam "button" in the center of the cam sprocket the rides against the timing cover. The washer or bearing is needed because the button is pushing against the cam sprocket and you cannot let the sprocket ride on the block. Hope this helps, Rick
Hmmm, did my son make a boo boo?

On his older 400 block, he installed a Comp 286 roller cam and lifters. There is/was no bearing on the back side of the cam gear. We installed a bearing on the front of the cam and were told to achieve a distance of .010 on cam movement. We did that by "adjusting" the stamped timing cover, using a dial indicator comming in through one of the big oil return holes behind the cam sprocket.

Mark
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Old 03-29-2004, 07:13 PM
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Hi Mark...
I am not sure if it is a bad boo boo or not. I always though that you needed either the bearing or washer, but I don't know if it will screw up the block face or sprocket if you lack it. I also went with a Comp cam, but I wanted a billet Manley double roller w/bearing. I also got the three piece timing cover and it included the roller thrust button. I left only about .003-.004 end play on my kit, but I also checked it from the front of the cover because it has a hole for the dial indicator. I know if you check from the backside, you will have a different angle on the indicator shafts and it might through it off. I just checked my Manley specs and they recommend only .001-.005" end play. The clearance might be so tight because the cover is 1/4" solid aluminum and has NO flex at all. They might really want a tight clearance so you don't screw up the lobes and lifters. I had also heard of the .010", but I trusted the recommended specs and liked the idea of it being extra tight. We'll have to see how it holds up.
If someone knows if the bearing or washer are a MUST... please let us all know so no motors are ruined because of a simple mistake...

Rick
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Old 03-29-2004, 07:57 PM
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While it's nice to have a thrust washer or torrington bearing behind the cam gear, it's not really mandatory. As long as the thrust faces on the block and cam gear are not damaged, you should be okay. I have seen a lot of blocks damaged at the cam gear/thrust face junction, but that was caused from using a hi-vokume oil pump.
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Old 03-29-2004, 10:54 PM
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how does the high volume pump hurt the block? I too am looking into getting a comp roller cam this is some good info on the subject. im looking into the comp 288 roller. thanks
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Old 03-30-2004, 12:42 AM
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It's harder to turn, and the turning of the oil pump/distributor causes the cam to be drawn rearward by the angle of the gears. The harder it is to turn the pump, the harder the cam is drawn rearward, causing more pressure on the back of the cam gear & the front of the block.
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Old 03-30-2004, 01:28 AM
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h v pump

PLEASE-as i noticed this....and have been told a few times...

are high volume oil pumps a bad thing....

and running one on a 383 stroker with a roller cam----is that a bad thing as well...

While-quite a few folks said to go with them at the time i knew less then nothing...i put one in my dart block....

and now that i almost know 1 thing---everyone tells me it's a bad thing and the cause of a few of my problems----leaks--etc....

is a high volume oil pump---in a rough and tough daily driver---doing over 50k miles each and every year.....a bad thing.....

so you know i only have 9-1 compresion and at 4,500---ii am all done with anytype of hp.....

please let me know---i am the kind of guy who can't sleep at nite--if i think even 1 thing is wrong with my engine...

thanks
alaskan
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Old 03-30-2004, 05:02 AM
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Thanks for the info on the HV/HP pumps. I didn't have a pump with my block, nor would I have trusted the old pump, so I got a new HV/HP pump. I hope that I do not cause havoc on my block surface. Hopefully the extra oil will keep that bearing well lubed!
What types of problems have you seen with the gears causing extra force on the inward walk of the cam? Is this really anything to worry about? Are there block protection plates that should be run to save the block surface?
Hey Alaskan... No more poems! They are too hard to read. JK
Make sure you get your sleep at night... I would die if I saw your posts with you falling asleep at the keyboard. I would never find my way through it. JK
Keep us posted... Rick
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Old 03-30-2004, 09:16 AM
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A lot of good info. Stuff I didn't know, but should.

Anyway, my original question was: Is there a difference between roller cams used in earlier blocks and those used in later, true roller blocks?
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Old 03-30-2004, 09:21 AM
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As far as oldsmobile goes, the blocks are different, the roller blocks have two holes in the lifter galley for the spider to be placed. On non-roller blocks these "bumps" are not there. Also the lifter bore is bigger on the roller blocks.

The cams are not different except the lobe design. Both olds cams interchange with one another except you couldnt use a hyd. camshaft with roller lifters, the lobes hit the side of the rollers, trust me I almost got that desperate because the prices are insane.

For oldsmobile, no, all the camshaft designs from about 64-90 are all the same one design(for V-8s that is).
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Old 03-30-2004, 10:30 AM
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Not the blocks, the cams.
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Old 03-30-2004, 11:28 AM
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Yes, the cams are different. The area where the cam gear bolts on is different. While you are on line, you can go to www.compcams.com or www.cranecams.com and see for yourself.
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Old 03-30-2004, 12:22 PM
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From what I have found they basically seem to be the same, but the retrofit cams have a smaller base circle. I don't know why they are ground with a smaller base, but it may have something to do with a clearance issue. With a smaller base circle, the lifters will be further down in the bore when on the backside of the lobe. If you throw a standard roller cam in the old block, the lifters will constantly ride higher, and with tall roller lifters, it might cause the lifter to pushrod connection to flex.

I have heard that it will work, but I have never tried it for myself. The late model blocks use a thrust plate to hold the cam in place, so you will need a modified late-model thrust plate without the factory ears, or basically a thrust washer or bearing.
The button will help hold the cam in place, taking the place of the factory thrust plate that has the fasteners to keep the cam in place.

The best thing to do is to call the cam companies and ask. Let us know if you what they have to say...
Rick
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