Liftin' heads

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Re: Liftin' heads

Postby RCCUMMINS89 » Wed Feb 03, 2016 9:06 pm

They have higher pressure. Duration aside, the higher you inject the pressure, the quicker the cloud point, the less timing needed (even pure duration). This is one reason why cr trucks are in the negatives for timing in some aspects.
89 RC on shortened 92 diesel frame - NV4500 w/dual disc/4.10s on 37s. - Self built pump, "hot screw", lots of timing, True high volume low pressure lift pump, 62fmw/68/.7gated, 77lpm SAC Inj., Studs/O-rings,- 423/1220 Mustang - 11/16/2013 http://www.TheHungryDiesel.com full line dealer, if you don't see it please ask.
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Re: Liftin' heads

Postby DMan1198 » Thu Feb 04, 2016 7:02 pm

That's because they have pilot injection. If you reduce pilot without adjusting main timing power is noticeably affected (a 40% reduction in pilot is noticeable) cutting pilot without adjusting makes it run like garbage (undrivable really) I ran my 6.7 at 5* minimum when I first went back to a single event tune with my s480. I'm up to 7* minimum now, but I have a near 30* sweep in timing from idle to 4300rpm. Pressure does make a huge difference though. 2000psi more pressure allows for timing to be pulled 2-4 degrees in the top end generally speaking.
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Re: Liftin' heads

Postby spencerdiesel » Fri Feb 05, 2016 5:59 am

Thanks guys. At what revs does a VE reach full advance?
1992 W250, 5 speed, 4.10, Ext. cab Ext. bed, 12.5k winch, 75 gal. fuel tank

H1C/18

Fuel: THD 12 psi piston pump, THD fuel pin, 366 spring, fuel screw bottomed @ 3 turns, timing bumped 3/16"
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Re: Liftin' heads

Postby RCCUMMINS89 » Sat Feb 06, 2016 8:52 pm

Stock form..... about 2200rpm.
89 RC on shortened 92 diesel frame - NV4500 w/dual disc/4.10s on 37s. - Self built pump, "hot screw", lots of timing, True high volume low pressure lift pump, 62fmw/68/.7gated, 77lpm SAC Inj., Studs/O-rings,- 423/1220 Mustang - 11/16/2013 http://www.TheHungryDiesel.com full line dealer, if you don't see it please ask.
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Re: Liftin' heads

Postby spencerdiesel » Fri Feb 12, 2016 8:00 pm

Thanks. If advance/mechanism/stuff is stock, would the extra 4 deg from the spacer mean that the previous full advance will be around 2200, and the added time from the spacer will come a few hundred revs after 2200?
1992 W250, 5 speed, 4.10, Ext. cab Ext. bed, 12.5k winch, 75 gal. fuel tank

H1C/18

Fuel: THD 12 psi piston pump, THD fuel pin, 366 spring, fuel screw bottomed @ 3 turns, timing bumped 3/16"
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Re: Liftin' heads

Postby spencerdiesel » Fri Feb 12, 2016 8:01 pm

Or is it purely case pressure that decides full advance revs, and it would still be 2200 with the spacer?
1992 W250, 5 speed, 4.10, Ext. cab Ext. bed, 12.5k winch, 75 gal. fuel tank

H1C/18

Fuel: THD 12 psi piston pump, THD fuel pin, 366 spring, fuel screw bottomed @ 3 turns, timing bumped 3/16"
Muffler delete
spencerdiesel
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Re: Liftin' heads

Postby spencerdiesel » Wed Dec 05, 2018 6:52 pm

With whats in my sig, is a skipped tooth a death sentence for my untouched HG?

At 3/16" advanced, running WMO still wants more timing I think.
1992 W250, 5 speed, 4.10, Ext. cab Ext. bed, 12.5k winch, 75 gal. fuel tank

H1C/18

Fuel: THD 12 psi piston pump, THD fuel pin, 366 spring, fuel screw bottomed @ 3 turns, timing bumped 3/16"
Muffler delete
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Re: Liftin' heads

Postby PToombs » Thu Dec 06, 2018 5:26 pm

Maybe not, because the WMO burns slower. It doesn't pop like fuel so there isn't as much pressure. Just MO though.
pete

Just enough power to break everything behind the crankshaft.
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Re: Liftin' heads

Postby spencerdiesel » Thu Dec 06, 2018 6:08 pm

That would be nice Pete, another thing I was going by loosely is how loud the engine is at idle.

3/16" bumped running 60/20/20 oil/gas/diesel is still quieter than stock timing on pure diesel.

Then again, with more BTU in the oil, the truck also pulls a wee bit harder. So many variables.

Does (*should*) the head always come off the block to properly stud a 12v?
1992 W250, 5 speed, 4.10, Ext. cab Ext. bed, 12.5k winch, 75 gal. fuel tank

H1C/18

Fuel: THD 12 psi piston pump, THD fuel pin, 366 spring, fuel screw bottomed @ 3 turns, timing bumped 3/16"
Muffler delete
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Re: Liftin' heads

Postby PToombs » Fri Dec 07, 2018 5:28 pm

IMO that's the best way. Deck the head, new gasket, bottom tap the holes and clean them out good. I knew I was going to end up with compounds so when I had the timing way up and it quit weeping and started leaking at the front corner I did it all, studs, o-rings, decked, the whole nine.
pete

Just enough power to break everything behind the crankshaft.
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Re: Liftin' heads

Postby spencerdiesel » Fri Dec 07, 2018 10:45 pm

Makes sense. I can't invision myself making time to pull the head willingly....guess Ill split the timing difference: jump a tooth and put the pump 1/16" retarded from stock.
1992 W250, 5 speed, 4.10, Ext. cab Ext. bed, 12.5k winch, 75 gal. fuel tank

H1C/18

Fuel: THD 12 psi piston pump, THD fuel pin, 366 spring, fuel screw bottomed @ 3 turns, timing bumped 3/16"
Muffler delete
spencerdiesel
14mm rotor
 
Posts: 1037
Joined: Tue Oct 27, 2015 4:02 pm
Location: Brevard, NC
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