6.7 roller cam

Smoking S

Smoking S

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Nov 23, 2006
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Are they putting roller cams in these motors? Seems like it might be a little more diffcult to do since there is no side cover.
 
I am pretty sure they do, if you cant do it with the block you can always use a 5.9 block with 6.7 goodies in it, pretty much same thing, i still run a 5.9, but when i need to swith i will run 6.7 weather it be in a 6.7 block or 5.9.
 
why , if the engine had a roller , I would convert it to a flat tappet.
the flat tappet allows a lot better cam profiles, not possable with a roller tappet.
the 5.9 CR and 6.7 CR are the same engine with the exceptition of the bore and stroke

the advantages of the 6.7 is the bore, it allows a lot bigger intake valve. with this big valve you can get flow on this cylinder head to .600 plus lift.
 
COMP461 said:
why , if the engine had a roller , I would convert it to a flat tappet.
the flat tappet allows a lot better cam profiles, not possable with a roller tappet.
the 5.9 CR and 6.7 CR are the same engine with the exceptition of the bore and stroke

the advantages of the 6.7 is the bore, it allows a lot bigger intake valve. with this big valve you can get flow on this cylinder head to .600 plus lift.
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Correct me if I am wrong, but don't most, if not all the Mod trucks run roller motors?? Also Comp what RPM are you running the flat at? Are you running OEM lifters.
 
the problem i am having with flat tappet is breaking lifters and cams. Thats why a roller cam is in question.
 
what valve springs are you running? are the lobes going flat or are you breaking the tappets?

we run our 8620 cams and steel coated lifters to over 5800 rpm with no issue. the key is a proper valve train setup.

nascar runs flat tappets at over 8500 rpm for 500 miles at a time and dreams of having an 1.5 dia tappet

to the people saying mods run roller, most do however just because someone does something doesnt mean its right.

anyone that wants to run roller be my guest, but your leaving horsepower on the table. if you take a look at some cam profiles you will see this as plain as day.
 
you are correct the advantage to roller is the ability to run higher spring pressure. nhra prostocks run over 1200lbs on the nose, this would not be possible with a flat tappet however we dont need that kind of spring pressure as we dont run those kind of rpms.

lifters failures are also possible with roller lifters often the needles go flat in the wheel and the lifter fails and sends them through the engine. If I was running roller I would use isky ez roll red zones they have no needles in them.

I would also make a 60mm cam core to get some of the intensity back that you lost going roller.

jmho
 
gotta12v said:
what valve springs are you running? are the lobes going flat or are you breaking the tappets?

we run our 8620 cams and steel coated lifters to over 5800 rpm with no issue. the key is a proper valve train setup.

nascar runs flat tappets at over 8500 rpm for 500 miles at a time and dreams of having an 1.5 dia tappet

to the people saying mods run roller, most do however just because someone does something doesnt mean its right.

anyone that wants to run roller be my guest, but your leaving horsepower on the table. if you take a look at some cam profiles you will see this as plain as day.
Click to expand...

Dead on , and 8500 on a NASCAR is the low side.

I have 20 60 mm com cores going to heat-treat now along with rocker systems that are dead on with geometry, on the 12 valve ,24 valve and Dmax , these are not the simple rocker replacement , but complete systems that replace all of the rocker parts including stands . The ratios are from 1.65 to 2.10 .
This was the direction I went in my competition eliminator engine programs, and we left the line stalling the convertor at 9200+ rpms and going thru the traps at 11,000 rpms.
The world of diesel is moving to electronics and high rpms . We have the ability to bush the block for Jessel roller lifters, that easy. But why would you trade a 1.500 mushroom tappet for a .890 wheel, Unless you have to. You are giving up a huge advantage
Now with a 60 mm core you can get close with a big ratio rocker .
The 24 valve heads that I am seeing on the flow bench are wanting 600+ valve lift, increase the valve size to 1.450 to 1.5 like in a 6.7 and the valve lift needs to be around .650
12 valve heads on the flow bench want lift of .900+ this is the real need for big core cams and big ratio rockers
 
COMP461 said:
Dead on , and 8500 on a NASCAR is the low side.

I have 20 60 mm com cores going to heat-treat now along with rocker systems that are dead on with geometry, on the 12 valve ,24 valve and Dmax , these are not the simple rocker replacement , but complete systems that replace all of the rocker parts including stands . The ratios are from 1.65 to 2.10 .
Click to expand...

i take it that you left material for finish grinding because they will not be dead on after heat treat.
 
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