Engine Cam swap question

Joshua Sizemore

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May 7, 2012

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Feb 9, 2013

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• Feb 9, 2013

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Hey guys, working on my 91 LX. It has stock heads, stock rockers, stock pushrods, and hydraulic roller lifters. I swapped the stock cam for a F303 put in new springs and retainers. After assembling the heads there was some unusual play in the pushrods... probably a couple tenths and least. One of my buds, he is a chevy guy so don't hold that against him, thinks that since everything was drained that the hydraulic lifters need to be pumped back up with oil pressure and that play will get taken up. Not sure and I don't want to have to order new gaskets and take the time to take it apart later and find out that wasn't it. Has anyone else come across this? Any thoughts would be very appreciated. Thank you.

 

ratio411

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Feb 9, 2013

#2

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If you put everything back together as it was, changing only the cam, it should be same preload as before.
There is not really any play to be taken up, as the lifters aren't a zero lash deal. They actually have less than zero lash, called preload.
The only new part you used was the cam, correct? (Springs/retainers don't count)

 

ratio411

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Did you have the heads off?

 

Joshua Sizemore

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Yes, the only new part was the cam and the heads were torqued down. I had the heads decked while off... not sure if that matters since that should make things tighter.

 

ratio411

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Joshua Sizemore said:

Yes, the only new part was the cam and the heads were torqued down. I had the heads decked while off... not sure if that matters since that should make things tighter.

Click to expand...

Yep, it should have made it tighter... unless you used thick head gaskets.

 

f8tlfiveo

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Feb 10, 2013

#6

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Why did you put a cam in a stock headed motor? Just for the sound? Don't be surprised if the car is no faster than before.

 

Joshua Sizemore

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I had a friend port them out really good... for free. Have not had them measured so I have no idea how much they flow but he took quite a bit out. Looks dramatically different so hopefully that coupled with the cam will give me something better. New heads are way further down the road and not in the budget right now.

 

Joshua Sizemore

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So should I assemble everything get fluids back in and see how it sounds? The head gasket was not overly thick or anything. I got it in a gasket kit from summit racing.

 

ratio411

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Joshua Sizemore said:

So should I assemble everything get fluids back in and see how it sounds? The head gasket was not overly thick or anything. I got it in a gasket kit from summit racing.

Click to expand...

Most gaskets are rated as to their thickness.
Sites like Summit, especially, list the thickness of every gasket they sell.
I don't buy them thicker than .040". They sell some that are much thicker.

 

Mustang5L5

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#10

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f8tlfiveo said:

Why did you put a cam in a stock headed motor? Just for the sound? Don't be surprised if the car is no faster than before.

Click to expand...

Not to mention an F camshaft...in an AOD convertible car.

IIRC, that F cam was recommended for 5-spd cars because it made all it's power in the upper RPM band. It won't matter if the heads are professionally ported (and not just hogged out), because the stock lower intake will be a huge restriction. That cam has some high lift, so new springs on the heads are recommended.

Not really sure the parts selection is the most ideal

 

Boydster

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Feb 11, 2013

#11

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How are you tightening down and adjusting the rockers when you see the play? Are you using the torque wrench and counting the turns? Every rocker is being adjusted on the bottom of the cam lobe? Didn't swap the heads left to right?

 

Joshua Sizemore

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Mustang5L5 said:

Not to mention an F camshaft...in an AOD convertible car.

IIRC, that F cam was recommended for 5-spd cars because it made all it's power in the upper RPM band. It won't matter if the heads are professionally ported (and not just hogged out), because the stock lower intake will be a huge restriction. That cam has some high lift, so new springs on the heads are recommended.

Not really sure the parts selection is the most ideal

Click to expand...

I have a March ram air kit, 70MM TB, 73MM mass air, cobra intake (garbage I know), 2.5" summit racing catback exhaust, 1 5/8" equal shorties, MSD 6a ignition, 24lb fuel injectors, dual roller timing chain, AOD trans (going to C4 or manual in the future too), 2400 RPM torque converter, and 3.73 rear gears. Probably should have put this in the first post...