Helix cams

[Fishin Guide]

There is a keyway on the camshaft and gear.



There is no way to dial the cam without doing lots of work. The bolt on gear would be easiest to modify, but it's not very practical. For a press on gear, there would need to be multiple keyways cut into the gear or the cam. For most people, it be inpractical. You would need to pull the cam, press off the gear and reassemble. To take a many hours to get a few degrees would be tough. Not to mention if it needed to be set back!



With a new blank, the valve timing can be set at any point desired. It's just a matter of grinding the cam to whatever specs are needed.



Dave

 

[nickleinonen]

there would need to be multiple keyways cut into the gear or the cam

offset keys maybe? they have been used on other diesels to time camshafts...

 

[Matt400]

I may have been satisfied with simply advancing the cam timing on the stock camshaft but I couldn't find any means for doing that and if a press is needed the R&R the gear then a complete cam makes better sense anyway.

 

[Fishin Guide]

I may have been satisfied with simply advancing the cam timing on the stock camshaft but I couldn't find any means for doing that and if a press is needed the R&R the gear then a complete cam makes better sense anyway.

When you say advancing timing, I start to envision fly cut pistons. Remember, we are just passing air. And it's under pressure. The dynamic is a little different than a "vacuum" motor. IE gasser

 

[Vaughn MacKenzie]

The VP takes far less horsepower to turn than the older stlye 12Valve pumps. So, the chance of the gear "walking" off the cam is extremely remote. So, the press on gear was the choice for me.



If you were running a P pumped truck that was all cranked up, I wouldn't even consider a press on gear. And if you had seen teh two side by side, you would see that the collar engages further on the press on gear. You aren't gonna shear off the end of the cam.

This doesn't completely make sense to me because the cam gear only drives one thing, the cam. The cam gear might transmit power to the injection pump (don't recall the route power is transmitted through the gear train to the pump) but the only drag on the cam gear comes from the cam itself.



Maybe the issue is the torque loading on the cam gear from driving the P-pump hard puts a force off-axis with the camshaft that could potentially loosen it from the cam?



Vaughn

 

[Fishin Guide]

Ah yes, grasshopper Vaughn.



I asked the verry same thing to Don. The gears ar helical (sp?) cut. So, there is a "thrust" load on the gear. So, if you have to have 25 HP to turn the pump, as opposed to under 15 there would be more force on the gear trying to force it off.



The bolt on gear is a must with the truned up pumps!!



Take a look in the manual. You'll see how the power is transmitted through the crank then the cam gear on to the pump. And you are right about the last part.



I guess the newer trucks have straight cut gears to minimize noise. So this is a non-issue. Again, that's just one of the many tidbits Don shared with me, I think. Oh heck, I don't remember! :-laf Where's Doug??



Dave.

 

[Vaughn MacKenzie]

That makes sense Dave, and straight cut gears effectively eliminate this side loading. I wonder if they went straight cut with the 3rd Gens because of the CP3 pump? Maybe it takes as much or more force to turn due to pumping the fuel pressure so high? Straight cut gears are noisier though, angle cut is preferable for quiet operation. With straight cut they have to mesh them carefully to minimize the whine.



Vaughn

 

[Fishin Guide]

Honestly Vaughn, I really don't know. I am just working from memory of one conversation with Don. I could very well be incorrect.



Dave

 

[Matt400]

When you say advancing timing, I start to envision fly cut pistons.

When I say advance, I mean from the emission retarded config. back to a more straight up condition.



I was speaking with the folks at PDR and they had told me the 3rd gen timing is retarded and they address that issue.

That gave me a flash back when in the 80's we would install timing gear sets from a 70 Ford 429 onto various 80's Ford 460's for a nice performance increase along with better mileage. The change brought retarded timing back to 0 for a better cylinder "fill" if thats the word I should use.

Remember, we are just passing air. And it's under pressure. The dynamic is a little different than a "vacuum" motor. IE gasser

True but I would think opening the intake sooner on a diesel would allow for a better oxygen fill which would raise cylinder pressures and thus increase mpg and power same as a gasser.

 

[Fishin Guide]

When I say advance, I mean from the emission retarded config. back to a more straight up condition.



I was speaking with the folks at PDR and they had told me the 3rd gen timing is retarded and they address that issue.

That gave me a flash back when in the 80's we would install timing gear sets from a 70 Ford 429 onto various 80's Ford 460's for a nice performance increase along with better mileage. The change brought retarded timing back to 0 for a better cylinder "fill" if thats the word I should use. True but I would think opening the intake sooner on a diesel would allow for a better oxygen fill which would raise cylinder pressures and thus increase mpg and power same as a gasser.

O do understand what you are referring to, but most of the gains are made on the exhaust side, not the intake. So, simply advancing the cam does not fix the entire issue. Did I explain that right? So, the intake could be moved say 5 degrees and the exhaust may need 13 degrees.



Now, as far as advancing the intake, true, opening the valve a little sooner may help, but you have to be concerned with pushing combustion chambers pressure off the chart if you aren't careful. By manipulating the exhause side, you can get rid of much of the stored energy of the engine and reduce pumping loss.



Now, in regards to that point, the 3rd gens see the most benefit from the exhaust side. Or so I am told.



Dave

 

[Matt400]

I follow you. . and good reason for going with a new cam vs a regrind that has obvious limitations built in.

 

[Fishin Guide]

Glad you were able to pull that out of that post!



I am not a good communicator. That's why I fish, those little critters and I speak different languages.



And for the parting thought of the day. Why do fish roll and jump in the water?































Because they don't have middle fingers! :--)





Dave

 

[rubberneck]

Ok, this is what i want, an extra noisy set of straight cut cam gears. Like the pete jackson noisy ones they run on the gasser v8s. Would make the truck sound like it had a blower on it. :-laf

 

[Matt400]

Because they don't have middle fingers!

Ok Dave. . I didn't get that so pulled some resources and asked a few fisherman I know what the heck that means and they don't know either so I give! Please tell me what that means? :-laf :-laf

 

[Fishin Guide]

Ok Dave. . I didn't get that so pulled some resources and asked a few fisherman I know what the heck that means and they don't know either so I give! Please tell me what that means? :-laf :-laf

That's hard to explain on a "family" site!



Dave

 

[Matt400]

Thats ok. . you can pm me, I now have others waiting.

 

[rivercat]

Just a quick question why would anyone ? ? ? don's work after owning a set or riding in a truck with F1 injectors. Don put the key where it is cause Don did all the time and work in to figure out where it needed to be to be the BEST! Some people cant leave well enough alone. lol

 

[rubberneck]

We are not questioning dons work. having the ability to index a cam allows the end user to make sure that the cam is perfectly in time with where it should be. Don can machine all the cams to the "ideal" spec, but he can not allow for variations in tolerance on the rest of the motor. Look, don't stress, i am going to buy one of his cams, and like i said before, it probably is a waste of time for the majority of us down here in the real world HP numbers anyway. I only asked the question about being able to dial the cam for info. I guess im just anal that way, i like to know everything. (probably the reason i get so frustrated with the diesel aftermarket in general) I am just used to my high perf gasser motors, where we were looking for every extra fraction of HP we could get and still meet all the rules. Its not always the parts in the motor, but how/who assembles it that can make the difference between winning/losing, or breaking/finishing. I guess i just like to sweat the little things.

 

[rubberneck]

Ok, to get this thread, back on track, this is what i have learned. Helix 3 all out HP cam. Jetpilot just made more hp on a vp44 than anyone using this cam and some of dons experimental injectors. Helix 2 quicker spool, smoother acceleration and increased top end. Good for us "moderately bombed" guys. A couple of members have chimed in who have this one and seem to love it. Valve springs needed (highly recomended) with this one. Haven't heard from anyone with a Helix 1 grind. hopefully someone will chime in. All the cams have lobe for mechanical lift pump Oo. No need to replace tappets, which will definitely make install easier. Besides the special handle tool you made fishing guide, anything else we should know about?? any tips if you were doing it again? Guess it's time to get out the credit card.

 

[Matt400]

I am certainly not questioning Don's work. Just the overall discussion of cams gets me interested in what the aftermarket is doing and their results. I better come clean now and say that I did purchase a cam last week during this discussion but it wasn't a Helix.

I have no doubt the Helix is great, I just decided I wanted a new PDR cam.



It does have more lift & duration with corrected timing and they don't recommend valve springs so my guess is due to design limitations will be similar to a Helix 1.

If I were to wait until both companies posted specs for comparison I would be too old to care so I caved and bought with my gut feeling.