Commonrail tappets in a 12v??..

dont see how changing the dia of a flat lifter is gonna change your dur

sorry

bigger tappets allow for more lift but that is ground into a camshaft

going to radiused tappets from flat will decrease dur

lift and dur are both ground into the cam, if you dont change the cam or the clearance neither should change (lift or dur) no matter how big a lifter you run

least thats been my experience

don
 
I have talked to several cam people and they all said there will be interference, that being the case why risk it? And if you don't need the lobe on a cam just grind it off. There should be no reason (atleast in my thinking) why you could not just grind the lift pump lobe down small enough with a bench grinder.

Now if the CR lifter will actually make a small gain I would be interested in using them.
 
much misinformation

The CR tappets do not rub on the fuel pump lobe on any engine using the Helix 2. There are thousands of CR's running a Helix 2. Nothing rubs and there is plenty of clearance.

Also, we have run the Helix 2 on many engines with a mechanical pump for fuel delivery. We actually used the H2 in 24 valves for this reason years ago. We even had custom mechanical pumps manufactured to do the conversion to a mech pump for the 24V engines before the CR's came into use. We decided to drop the mech pump idea when friends developed other mech ideas ( mitusa ) and some of the electrical pump companies were taking shape ( FASS, Airdog, etc. )

Finally, the pushrod length does not change with the use of CR tappets in any engine. CR tappets have a shorter stem, but the location height of the push tube seat remains constant between all the tappets in use to date. Yes, the 12V tappet is longer than the CR, but location of the seat is constant. The shorter stem was designed into the CR tappets to allow them to be changed "in-frame" with the larger diameter of the foot being used. The wide foot CR tappet would not turn the corner and slide up into the block from the tray without making the stem shorter.
 
Soup Nazi said:
The CR tappets do not rub on the fuel pump lobe on any engine using the Helix 2. There are thousands of CR's running a Helix 2. Nothing rubs and there is plenty of clearance.

Also, we have run the Helix 2 on many engines with a mechanical pump for fuel delivery. We actually used the H2 in 24 valves for this reason years ago. We even had custom mechanical pumps manufactured to do the conversion to a mech pump for the 24V engines before the CR's came into use. We decided to drop the mech pump idea when friends developed other mech ideas ( mitusa ) and some of the electrical pump companies were taking shape ( FASS, Airdog, etc. )

Finally, the pushrod length does not change with the use of CR tappets in any engine. CR tappets have a shorter stem, but the location height of the push tube seat remains constant between all the tappets in use to date. Yes, the 12V tappet is longer than the CR, but location of the seat is constant. The shorter stem was designed into the CR tappets to allow them to be changed "in-frame" with the larger diameter of the foot being used. The wide foot CR tappet would not turn the corner and slide up into the block from the tray without making the stem shorter.
Click to expand...

i bought ur helix 2 from mike @ hrd. from what i interpret in ur post this is a beneficial mod - correct me if im wrong.
 
Soup Nazi said:
The CR tappets do not rub on the fuel pump lobe on any engine using the Helix 2. There are thousands of CR's running a Helix 2. Nothing rubs and there is plenty of clearance.

Also, we have run the Helix 2 on many engines with a mechanical pump for fuel delivery. We actually used the H2 in 24 valves for this reason years ago. We even had custom mechanical pumps manufactured to do the conversion to a mech pump for the 24V engines before the CR's came into use. We decided to drop the mech pump idea when friends developed other mech ideas ( mitusa ) and some of the electrical pump companies were taking shape ( FASS, Airdog, etc. )

Finally, the pushrod length does not change with the use of CR tappets in any engine. CR tappets have a shorter stem, but the location height of the push tube seat remains constant between all the tappets in use to date. Yes, the 12V tappet is longer than the CR, but location of the seat is constant. The shorter stem was designed into the CR tappets to allow them to be changed "in-frame" with the larger diameter of the foot being used. The wide foot CR tappet would not turn the corner and slide up into the block from the tray without making the stem shorter.
Click to expand...

that clearly explains where the magic 12° of duration came from

thanks

don
 
DTanklage said:
that clearly explains where the magic 12° of duration came from

thanks

don
Click to expand...

The CR lifters have a bigger "footprint". This means that the cam will contact the lifter both earlier AND later in the up-down cycle, which means the overall time the cam touches the lifter is going to be longer.

Longer time=Longer duration.

Thats the best time I can explain it. Anyone else care to try?
 
Hey man,

That magic 12* of duration was measured with a dial indicator and a degree wheel, no magic in the equation. I was just trying to help... When my cam was degreed in it had 12 more degrees duration on intake and exhaust than what my cam was ground for.

Now, will you get 12* added duration going from a 12v lifter to a cr lifter? Most likely not, because my cam was ground from a lobe master designed for a 1" or bigger diameter lifter. So I had a .5" diameter increase which made 12 more degrees for me. It may be different for you.

but still going from a 12v 1.1" diameter to a 1.5" cr lifter should add some duration. I thought Hasilys was selling a 1.75" lifter?
 
fnschlaud4620- Was the cam duration quoted from your manufacturer at .050", .006, or .001" lift. At what lift did you measure your duration numbers on your new cam in the engine? Did you measure it on the pushrod, or on the valve retainer. Did you do a measurement with your new cam and stock lifters before moving to the cr lifters?

Zach
 
i was gonna ask that but i am sure he went off the card if the card said x dur at 050 lift thats where he checked it

thinkin about it and if the bc is really big and stock lifters are only 1.1 i can see how you could lose dur at around .200 lift i just cant see how the factory would have the lobe hangin off the side of the follower

thats why i asked what the bc is

don
 
The cam was measured from the pushrod at .050. When I degreed the cam in the duration was 12 more degrees on the intake and exhaust that what was on the cam card. Did I make an error? Unfortunately I did not compare 12v lifter to cr lifters. I never measured the base circle of the cam lobe, but it is a 24v regrind ground to get .300+ lobe lift on the exhaust.

If I made an error I am sorry to lead people astray, I just thought I did something right for once...
 
This is kind of a grey area. Cam cards can be done in several fashions. Some people factor in valve lash and rocker ratio, some call it right at the lobe. Our cams specs are listed at the lobe for comparrison to other companies. Really the best way to measure actual duration on these cams is to read directly off of the retainers. For instance with our 181/210 @.050" cam, the 181@.050" lobe timing(with .010" lash) translates into approximately 222 degrees at the valve when read on the retainer. Our 210 @.050" exhaust is only 235 degrees at the valve. This is due to the greater lash .020", and the fact that the rocker ratio is approximately 1.34 to 1 compared to the 1.37 to 1 on the intakes.

At .020 lash and with a 1.34 rocker the first .0149" lift will not be seen at the valve

On the intake with .010" lash and a 1.37 rocker, the first .0073" lift will not show up at the valve.

If it is an aggressive ramp rate .0149" of lift might take 3 degrees of crankshaft rotation to accomplish. If it is a slow ramp it could take 10 degrees of crankshaft rotation to accomlish. This is why having correct lash is so important. Lash can have a major effect on lift and duration numbers.

In short it is hard to say how much duration at X lift you gained unless you mapped out the cam vs. crank angle and compared that against the numbers you got using your factory lifters.

Zach
 
on a stock cam, cr tappets will hit the lift pump lobe. Ask me how I know! I am going through that right now on my 4bt.
 
For 12 valves wanting to run larger tappets we typically suggest going to the 24v tappet. The wider face is about as good as your going to get as far as handling agressive ramp rates and spreading load on the lobe, and you don't ever have to worry about hitting the fuel pump lobe. They are also quite a bit lighter than the CR tappets and just a few grams over the 12v's.
 
so with the added duration of the CR tappets..... at how big of a cam do you start to have to worry about piston to valve issues??

Lance
 
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