pulleys

[patriotblueram]

ok i dont know alot about pulleys but im looking into buying a set. ive heard good things about Summit pulleys. what do you guess suggest me getting? looking at performance here, i dont have a system so im not worried bout voltage drop. any suggestions

[dr.ruff84]

The 20% summit pulley is the best deal, 188.00 and your good to go.

If u decided you needed the altenator pulley theres a guy that makes and sells them at dt.com for $30.00 Mafaso is is screen name i think.

[patriotblueram]

The 20% summit pulley is the best deal, 188.00 and your good to go.

If u decided you needed the altenator pulley theres a guy that makes and sells them at dt.com for $30.00 Mafaso is is screen name i think.

awsome thanks man, and ill contact mafaso on the alt pulley. are these the only upgraded pulley's i need to get

[dr.ruff84]

All you really need is the summit pulley and a belt. Chefred has a few posts over at dt.com on what belt to use. Also Onebadbee24_7 has some over here, just check there previous posts.

The altenator pulley isn't really needed. Some people said there voltage dropped a little low for there likings so they got the altenator pulley. But for $30.00 why not?

[patriotblueram]

thanks for the help, this is the one im about to purchase right
http://www.summitracing.com/parts/SUM-C2516/

[white lightning]

thanks for the help, this is the one im about to purchase right
http://www.summitracing.com/parts/SUM-C2516/

clicked the link, and yes it's for trucks so that's the one you want.

You need a belt about 99 inches long to have about the same position/tension on the belt tensioner. I'm using a CarQuest #K060988 belt with a 20% u/d crank pulley.

u/d pulley info thread if you're interested:
http://nadodge.com/showthread.php?t=1362

[jmgak47]

ok i dont know alot about pulleys but im looking into buying a set. ive heard good things about Summit pulleys. what do you guess suggest me getting? looking at performance here, i dont have a system so im not worried bout voltage drop. any suggestions

Don't know about you but my truck lopes so hard at idle the interior lights get brighter and dimmer. You have that happen?

[white lightning]

my 2 cents, turn up the idle. a smaller alternator pulley partially defeats the purpose of the u/d crank pulley.

while my cam sounded good with a 500 rpm idle, the alternator needs about a 650 rpm idle to charge right with a 20% u/d crank pulley, so my truck's idle is now 650 rpm.

[Blk05Hemi]

Don't know about you but my truck lopes so hard at idle the interior lights get brighter and dimmer. You have that happen?

All the time.lolol But i have a 550rpm idle in park.It's like a light show i just need to put some colored bulb's in.lolol

[Blk05Hemi]

my 2 cents, turn up the idle. a smaller alternator pulley partially defeats the purpose of the u/d crank pulley.

while my cam sounded good with a 500 rpm idle, the alternator needs about a 650 rpm idle to charge right with a 20% u/d crank pulley, so my truck's idle is now 650 rpm.


I think Larry said it was a 10% o/d so your losing 1/2 of the u/d effect on that pulley.But you are right in what your saying.My light's pulsed before and after the pulley's.With the 550rpm idle the gauge show's it's charging.The light's pulsing say's that's it's not.So i agree with you about the idle.But i love listing to it lope and don't want to change that.lolol That 's the one of the beauties of the DSP 550 idle in park and 700 idle in drive.

[white lightning]

i agree with you about the idle.But i love listing to it lope and don't want to change that.lolol That 's the one of the beauties of the DSP 550 idle in park and 700 idle in drive.

good way to compensate. mean lope in "P", decent charge in "D".

I have DSP too, lotta neat features and end-user adjustments.

[hemi1569]

It's sfi approved right? Wonder if stock bottom end would like repeated 6500rpm shifts with it?

[patriotblueram]

It's sfi approved right? Wonder if stock bottom end would like repeated 6500rpm shifts with it?

yes sfi approved, recieved it but io havnt gotten around to installing it yet

[Blk05Hemi]

It's sfi approved right? Wonder if stock bottom end would like repeated 6500rpm shifts with it?

It's spin tested to 12,000rpm.I don't think it would be a problem to 6500.I will say my motor seem's smoother since i put it on.

[white lightning]

It's sfi approved right? Wonder if stock bottom end would like repeated 6500rpm shifts with it?

both the Summit u/d & new Motoblue u/d are SFI approved.

spinning a stock 5.7 rotating assembly to 6,500 depends on year in my opinion.

'03 & '04 have a weak toner ring and it could be risky revving to 6,500 rpm.
'05 and up have a better toner ring and an SFI crank pulley cancels/absorbs vibration better than a stock pulley, so '05 & up with an SFI pulley can probably handle 6,500 rpm safely.

my truck is an '05 with stock rotating assembly & SFI crank pulley and has been to 6,600 rpm a few times with no problem so far.

I think proudhemi has been spinning his '05 to 6,600 rpm with the stock internals and stock pulley.

[patriotblueram]

i doubt it will have a problem spinning at 6500, i have shifted that high several times with the stock one

[proudhemi]

It's spin tested to 12,000rpm.I don't think it would be a problem to 6500.I will say my motor seem's smoother since i put it on.

If your tach's reading 6500 your cranks spinning 13,000rpm. Just FYI.

[Blk05Hemi]

If your tach's reading 6500 your cranks spinning 13,000rpm. Just FYI.

Say what!!! Please explain.

[proudhemi]

The crankshaft turns at twice the rpm as the camshaft does. And from my understanding, the tach reads camshaft rpm, and not crankshaft rpm. Each time a plug fires for the power stroke the crank would have made 2 revolutions to get to that position on the camshaft for both valves to be closed. Plus on a older motor with a distributor, the distrbutor is ran off of the camshaft. So it makes sense to me that engine rpm is camshaft rpm and not crankshaft rpm. Not 100% sure though.

[Blk05Hemi]

The crankshaft turns at twice the rpm as the camshaft does. And from my understanding, the tach reads camshaft rpm, and not crankshaft rpm. Each time a plug fires for the power stroke the crank would have made 2 revolutions to get to that position on the camshaft for both valves to be closed. Plus on a older motor with a distributor, the distrbutor is ran off of the camshaft. So it makes sense to me that engine rpm is camshaft rpm and not crankshaft rpm. Not 100% sure though.

That's intresting info..Guess i should've paid a little more attention when i was spining the crank to check to make sure the push rod's were seated when i put my cam in.I'm sure it's was tested the same as any sfi approved pulley.So i assume it was tested to 12,000 rpm on the tach.

[hemi1569]

When a tach is reading 6k, the crank has turned 6k times

[proudhemi]

So does a tach only count half of the times that a plug fires??

[proudhemi]

When a tach is reading 6k, the crank has turned 6k times

It's spinning at a rate of 6k time a minute. The question to me is crank or cam?

[hemi1569]

It turns twice but it counts it once if that makes sense, i believe?

[RandTx]

If your tach's reading 6500 your cranks spinning 13,000rpm. Just FYI.

The tach rpm and engine rpm are based on the crankshaft rpm.
If the engine is running at sat 6500 rpm, the crank is going 6500 rpm and the cam 3250 rpm.

[white lightning]

So does a tach only count half of the times that a plug fires??

I think for those of us with "wasted spark", the PCM counts sparks per minute on #1 cylinder and divides by 2:
13,000 sparks dv. 2 = 6,500 rpm on the tach, 6,500 rpm on the crank.

not sure, but I think that's how it works.

[proudhemi]

I think for those of us with "wasted spark", the PCM counts sparks per minute on #1 cylinder and divides by 2:
13,000 sparks dv. 2 = 6,500 rpm on the tach, 6,500 rpm on the crank.

not sure, but I think that's how it works.

It's not so much just our trucks, but all of them. It just has me curious on how a tach measures rpm. On older vehicles you hook the tach wire to the neg side of the coil, and it gets the pulses from there. So it has to either be based on 16 pulses equals one revolution, or it's based on twice the amount of time and still uses the 8 pulses. Either way it wouldn't be hard to "program".

Sorry for the false info, I just figured engine rpm was camshaft rpm.

Me
:moron:

[white lightning]

I've hooked up a couple of "old school" tachs. nice and simple! and decent ones have a switch on the back to calibrate between 4, 6 & 8 cylinders.

like you say, easy to program on newer computerized stuff, pick a formula and input, done.

[RandTx]

Generally on any type of motor the rpm is measured on the output shaft. (including gear motors)
for instance if you are calculating mph on a in 3rd gear you'd use engine rpm ( crankshaft) x trans gear (1:!) x axle ratio..... factor in the tire circumference or revs per mile etc.

[proudhemi]

Generally on any type of motor the rpm is measured on the output shaft. (including gear motors)
for instance if you are calculating mph on a in 3rd gear you'd use engine rpm ( crankshaft) x trans gear (1:!) x axle ratio..... factor in the tire circumference or revs per mile etc.

Yeah, you know I was going on how the tach would get it's reading from the spark for my logic, and if I would've looked at it like that it makes perfect sense.