24v rpm & timing question.

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24v rpm & timing question.

Postby ellis93 » Wed Apr 15, 2015 10:25 am

Time frame is kinda tight here on this so if you all have any ideas at all,please throw it out there.

On the line of rpm limits.....I would assume that the 24v would be subject to an rpm limit like the 12v. What throws a question in my mind is the fact you have double valves and springs....intake and exhaust. Wouldn't that fact alone say that maybe you could achieve rpms greater than 3200 before your valves float? Assuming that the lbs of the spring at closed height is the same as the 12v. The same boost numbers are required of the two so I would think the seat pressures would fall in line.

On timing.....I know that I'll need to advance the pump gear one tooth just to be able to have the ve pump mount to the timing cover and have the pump body clear a protruding boss from the head. While I'm there should I jump another tooth (total of two) to maybe allow for a lot of timing available for future mods?
From owning,driving and working on the vp powered 24v they've all seemed to appreciate a lot of timing in the higher rpm range. In order to achieve the same with the ve pump I would figure that the base timing would need to be set pretty high to begin with. That is if we are talking only a 10 to 15* increase of timing advance with the ksb on. That should be a total of 25* at full advance,high rpm and 2teeth jumped with the pump retarded fully on the cover. Iirc when monitoring the data feed on the 24valve I've seen 28 and 32* before.

Y'all's thoughts.
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Re: 24v rpm & timing question.

Postby oldestof11 » Wed Apr 15, 2015 4:28 pm

You have 2x the valves but they have less pressure. You have more valve surface areas than before too. My buddy hit 4k many times with his VP truck and didn't have a problem until he had more boost. Valve float is a 2 fold deal. Boost and rpm. I wish I had my old phone. I hit 4k and 35lbs of boost with my old w250. I had 60lbs springs and I had soot in the intake.
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Re: 24v rpm & timing question.

Postby ellis93 » Wed Apr 15, 2015 7:02 pm

I guess I need to look up the seat pressures on both engines and compare them. I just figured that the valve seat pressures would be the same between the two.

What's your thoughts on the timing Jon?
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: 24v rpm & timing question.

Postby ellis93 » Wed Apr 15, 2015 8:12 pm

Flexed my google foo and and found a spec of 78 to 83lbs of installed seat pressure for the 24valve. X2 that's a bunch of pressure for the lifters to be pushing up and for the lobes to be handling. Seems a few so called performance gurus thing 35psi and 3500rpms is the max......we'll see.
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Re: 24v rpm & timing question.

Postby oldestof11 » Thu Apr 16, 2015 4:14 am

I made a mistake. You have less seat pressure due to LESS surface area per valve. I woke up this morning thinking that. Why, I don't know.

35psi and 3500 rpms is pretty universal.

The thing about more timing is less torque, more HP. So keep that in mind. This also raises cylinder pressure. More cylinder pressure, more stress on head bolts.

I'd keep it to 1 tooth until you see how it does. I'm playing conservative as I cannot remember the timing on my buddys truck. It was high teens, low 20s.
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Re: 24v rpm & timing question.

Postby Tacoclaw » Thu Apr 16, 2015 6:31 am

Just run it, if the valves are slow to close the cylinders will give them a helping bump. Since they all run parallel, it can't hurt anything. :grin:
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Re: 24v rpm & timing question.

Postby DMan1198 » Fri Apr 17, 2015 1:23 pm

Iirc Hamiltons website states 3800rpm and 50psi. I've spun my 6.7 to 3800 a few times, but with stiffer springs in there it definitely felt stronger through the whole rpm range
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Re: 24v rpm & timing question.

Postby DodgeFreak » Thu Apr 23, 2015 12:29 pm

Tacoclaw wrote:Just run it, if the valves are slow to close the cylinders will give them a helping bump. Since they all run parallel, it can't hurt anything. :grin:

I like your way of thinking Levi....lol
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