5.2 Voodoo Heads on Stock Gen 3 Shortblock?

[zackmd1]

I am trying to figure out if PTV clearance with the stock gen 3 pistons will be sufficient with 5.2 heads and predator cams (14mm lift 270 duration). Been looking around and have yet to find anyone document this configuration... Ford performance states that 5.2 heads on a 5.0 will require piston mods but give absolutely no specifics.... Comp cams Gen 3 cams have very similar specs to the predator cams and appear to not require mods or any VCT limitation. Has anyone here seen a 5.2 head/predator cam configuration or have any info?

I currently have a set of Voodoo heads at the machine shop and would like to purchase a stock gen 3 shortblock to bolt them to. The predator cams would be required due to the use of a gen 3 PCM. The FP 5.2 cams are identical to the predator cams but with gen 2 trigger wheels for the cam sensors.

Sponsored

 

[AZlb5.0]

It could be something as simple as deck clearance. The piston could protrude just that much further on the 5.0 block than on the 5.2 block and that could be rod length, piston size or just about anything. In the LS community we always check PTV clearance when installing a cam and I’d suggest you do the same just in case. You don’t want to find out the hard way. Use some clay on the pistons and turn the engine over by hand to see what you get. Then it could be as simple as cutting relieves on the piston. It’s about $500 for LS engines I don’t know how much it would be for ours but shouldn’t be that much more.

 

[zackmd1]

It could be something as simple as deck clearance. The piston could protrude just that much further on the 5.0 block than on the 5.2 block and that could be rod length, piston size or just about anything. In the LS community we always check PTV clearance when installing a cam and I’d suggest you do the same just in case. You don’t want to find out the hard way. Use some clay on the pistons and turn the engine over by hand to see what you get. Then it could be as simple as cutting relieves on the piston. It’s about $500 for LS engines I don’t know how much it would be for ours but shouldn’t be that much more.

Checking PTV on an LS is far easier considering it is a pushrod motor plus you have options if the PTV clearance is not within spec. With this setup, i pretty much only have the predator cams to choose from. I would have to make clearance changes in the pistons if needed. I am hoping someone has firsthand experience with this setup considering the popularity of the gen 3 shortblock to gain some confidence before purchasing.

 

[engineermike]

What about a gen2 voodoo short block, swapped over to a predator crank? No PTV issues plus a stronger block and more displacement. I see used predator cranks on eBay around $700 from time to time or $1100 new.

 

[zackmd1]

What about a gen2 voodoo short block, swapped over to a predator crank? No PTV issues plus a stronger block and more displacement. I see used predator cranks on eBay around $700 from time to time or $1100 new.

I was shooting for the gen 3 simply because you can buy the complete short block from Ford for a decent price.

 

[illtal]

It could be something as simple as deck clearance. The piston could protrude just that much further on the 5.0 block than on the 5.2 block and that could be rod length, piston size or just about anything. In the LS community we always check PTV clearance when installing a cam and I’d suggest you do the same just in case. You don’t want to find out the hard way. Use some clay on the pistons and turn the engine over by hand to see what you get. Then it could be as simple as cutting relieves on the piston. It’s about $500 for LS engines I don’t know how much it would be for ours but shouldn’t be that much more.

It could be as simple thicker head gaskets.
This one of the setups that's going to need modified followers.

 

[illtal]

I am trying to figure out if PTV clearance with the stock gen 3 pistons will be sufficient with 5.2 heads and predator cams (14mm lift 270 duration). Been looking around and have yet to find anyone document this configuration... Ford performance states that 5.2 heads on a 5.0 will require piston mods but give absolutely no specifics.... Comp cams Gen 3 cams have very similar specs to the predator cams and appear to not require mods or any VCT limitation. Has anyone here seen a 5.2 head/predator cam configuration or have any info?

I currently have a set of Voodoo heads at the machine shop and would like to purchase a stock gen 3 shortblock to bolt them to. The predator cams would be required due to the use of a gen 3 PCM. The FP 5.2 cams are identical to the predator cams but with gen 2 trigger wheels for the cam sensors.

You can use gen3 cams as well they are about 100 bux a piece

 

[zackmd1]

You can use gen3 cams as well they are about 100 bux a piece

Gen 3 cams won’t fit in 5.2 heads unfortunately. They changed the diameter of the first set of cam journals.

Thicker gaskets are a last resort due to the possibility of affecting cam timing due to it being a DOHC engine.

 

[illtal]

Gen 3 cams won’t fit in 5.2 heads unfortunately. They changed the diameter of the first set of cam journals.

Thicker gaskets are a last resort due to the possibility of affecting cam timing due to it being a DOHC engine.

ah is this causing an interference?

 

[zackmd1]

ah is this causing an interference?

All that I have found thus far is a small note on the FP product page of the 5.2 heads that states PTV clearance issues with 5.0s. But no generation info and we all know there are some significant differences between generations.

 

[illtal]

All that I have found thus far is a small note on the FP product page of the 5.2 heads that states PTV clearance issues with 5.0s. But no generation info and we all know there are some significant differences between generations.

You wouldn't run 12:1 Compression in this car would you?
The lower compression should lower the dome of the piston.
If you are using a 5.0 Crank it should be in the hole at least .003 maybe more.

 

[engineermike]

I think stock is in the hole like .008. The gen3 controls exhaust cam timing totally different from all the others, which is why the journal is different. The phasers are different as well. It’s more like an ecoboost.

 

[illtal]

I think stock is in the hole like .008. The gen3 controls exhaust cam timing totally different from all the others, which is why the journal is different. The phasers are different as well. It’s more like an ecoboost.

Ah you're right: on my build it is .003 which is why I cannot use a predator Head Gasket.

 

[PC_GUARD]

Hasn't lmr sorted out the recipe? I thought someone like that had figured the ins and outs

This setup intrigues me

 

[illtal]

Hasn't lmr sorted out the recipe? I thought someone like that had figured the ins and outs

This setup intrigues me

This is what I thought. Previously we discussed this in another thread. Something about needing the modified followers when using coyote cams because the lobes are misaligned.

That information is from MMR

I'm assuming the OP will be running E-85 constantly with this setup. I don't have a Ford technical manual with me. That would be where he can find the stock piston to valve clearance.

Sponsored