Pushrod Length Question
Pushrod Length Question I'm installing an '02 z06 cam into an '03 6.0 LQ4 with Patriot Dual Extreme springs, stock heads and stock lifters. I have a set of comp 7.450" pushrods and was wondering if I would be able to use these or if I will have to go to a smaller pushrod length closer to the stock height of 7.400". I think the z06 cam has a smaller base circle than the ls1 and then the 7.450" would be ok to run but I'm not sure what the base circle is on the LQ4 Camshafts. Any help you could give me would be great.
This is going on a 78mm turbo car, would you still recommend switching springs? Will there be any adverse effects of running the Extremes opposed to the springs you recommended? I've ordered the pushrod checker so I guess I'll figure out what height is needed when it gets here later this week.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
IMO, you need just the right amount of springs. The extremes have too much seat pressure for those cam lobes (even with boost) You are looking at cam with very negative overlap. Basicaly what I am trying to say is that you are straining your valvetrain for no reason.
Being boost though, I would look at a thicker walled pushrod for less deflection.
Look at the extreme specs:
Install Height: 1.800"
Max. Valve Spring Lift: 0.660"
Spring Pressure Closed: 155 lbs. @ 1.800"
Spring Pressure Open: 410 lbs. @ 1.140"
Coil Bind: 1.090"
Retainer Material: Titanium
These are the specs for the PAC 1518 (what I would run)
OD: 1.290"
130 lbs @ 1.800"
337 lbs @ 1.150"
Lift: 0.650
Now that is more than enough for that cam under boost.
Being boost though, I would look at a thicker walled pushrod for less deflection.
Look at the extreme specs:
Install Height: 1.800"
Max. Valve Spring Lift: 0.660"
Spring Pressure Closed: 155 lbs. @ 1.800"
Spring Pressure Open: 410 lbs. @ 1.140"
Coil Bind: 1.090"
Retainer Material: Titanium
These are the specs for the PAC 1518 (what I would run)
OD: 1.290"
130 lbs @ 1.800"
337 lbs @ 1.150"
Lift: 0.650
Now that is more than enough for that cam under boost.
IMO, you need just the right amount of springs. The extremes have too much seat pressure for those cam lobes (even with boost) You are looking at cam with very negative overlap. Basicaly what I am trying to say is that you are straining your valvetrain for no reason.
Being boost though, I would look at a thicker walled pushrod for less deflection.
Look at the extreme specs:
Install Height: 1.800"
Max. Valve Spring Lift: 0.660"
Spring Pressure Closed: 155 lbs. @ 1.800"
Spring Pressure Open: 410 lbs. @ 1.140"
Coil Bind: 1.090"
Retainer Material: Titanium
These are the specs for the PAC 1518 (what I would run)
OD: 1.290"
130 lbs @ 1.800"
337 lbs @ 1.150"
Lift: 0.650
Now that is more than enough for that cam under boost.
Being boost though, I would look at a thicker walled pushrod for less deflection.
Look at the extreme specs:
Install Height: 1.800"
Max. Valve Spring Lift: 0.660"
Spring Pressure Closed: 155 lbs. @ 1.800"
Spring Pressure Open: 410 lbs. @ 1.140"
Coil Bind: 1.090"
Retainer Material: Titanium
These are the specs for the PAC 1518 (what I would run)
OD: 1.290"
130 lbs @ 1.800"
337 lbs @ 1.150"
Lift: 0.650
Now that is more than enough for that cam under boost.
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