Engine New Cams Install Question

Jhussey1280 · Nov 29, 2014

Hey guys I'm getting ready to so the PI swap on my Mustang and I have a new set of comp cams and valve springs to go in with them. My question is, I was planning on changing the valve train with the heads off the car. Assemble the PI heads with the new Comp Cams stuff the put the heads on the block. Is this a good idea or is there something I'm missing that makes doing it this way a bad idea? Thanks!

wmburns · Nov 30, 2014

What is the Model Year of your Mustang? If it's a 96-98, recommend that you contact the maker of your cams and let them know of your plans. They may recommend having the cams degreed to reduce the chance of PTV contact.

Take TONS of pictures when setting up the timing.

Jhussey1280 · Nov 30, 2014

wmburns said:
What is the Model Year of your Mustang? If it's a 96-98, recommend that you contact the maker of your cams and let them know of your plans. They may recommend having the cams degreed to reduce the chance of PTV contact.

Take TONS of pictures when setting up the timing.

It's a '98. I contacted Comp Cams, just waiting for a reply. Yeah I've been taking tons of pictures of everything, thanks for the tip!

IH8BOWTIES · Nov 30, 2014

Jhussey1280 said:
Hey guys I'm getting ready to so the PI swap on my Mustang and I have a new set of comp cams and valve springs to go in with them. My question is, I was planning on changing the valve train with the heads off the car. Assemble the PI heads with the new Comp Cams stuff the put the heads on the block. Is this a good idea or is there something I'm missing that makes doing it this way a bad idea? Thanks!

I have always done mine off the engine. Whole lot easier. With the cams out of the way, a standard valve spring compressor works great which I like best. I'm a little old school. Just remember prior to installing the heads to put your crank timing mark at 6 o'clock and cam timing marks at 12 o'clock. (Once the heads are installed, these marks will be 10 o'clock passenger and 2 o'clock driver due to 45 degree angle.) The valve springs may prohibit you from getting them exact just get close. In this position, all pistons should be below deck and valves closed. If you're reusing the old timing chain, you may not be able to see the brightest links due to wear. Simply lay the chain out and pull the slack out. Mark the link at each end that is 90 degrees and presto, you have timing marks. Ford made the 4.6 very easy to time. Once the chains are installed(minus tensioner), an 18 mm on break over bar on the cams will get you lined up. Don't need any special tools like they say. If your cams are greater than 262 lift, you could have ptv issues with stock pistons. Once it's together, ALWAYS turn the engine without you plugs. It should turn freely. If it doesn't, something was done incorrect. Hope that helps. I've done many 4.6's this way with no issues. Good luck.

Jhussey1280 · Nov 30, 2014

IH8BOWTIES said:

I have always done mine off the engine. Whole lot easier. With the cams out of the way, a standard valve spring compressor works great which I like best. I'm a little old school. Just remember prior to installing the heads to put your crank timing mark at 6 o'clock and cam timing marks at 12 o'clock. (Once the heads are installed, these marks will be 10 o'clock passenger and 2 o'clock driver due to 45 degree angle.) The valve springs may prohibit you from getting them exact just get close. In this position, all pistons should be below deck and valves closed. If you're reusing the old timing chain, you may not be able to see the brightest links due to wear. Simply lay the chain out and pull the slack out. Mark the link at each end that is 90 degrees and presto, you have timing marks. Ford made the 4.6 very easy to time. Once the chains are installed(minus tensioner), an 18 mm on break over bar on the cams will get you lined up. Don't need any special tools like they say. If your cams are greater than 262 lift, you could have ptv issues with stock pistons. Once it's together, ALWAYS turn the engine without you plugs. It should turn freely. If it doesn't, something was done incorrect. Hope that helps. I've done many 4.6's this way with no issues. Good luck.

Click to expand...

Awesome thanks for the info!

Here's the specs on the cams:

Comp Cam Data Sheet
Part Number: 102600 Grind Number: XE270AH
Lifter Type: None - OHC Engine Type: FORD 4.6 and 5.4 SOHC MODULAR 2-V (1992-Present)
RPM Range: 1800 to 5800 Valve Timing : 0.05
Lobe-Center Angle 113 Intake Center Line: 109

Intake Exhaust
Valve Lash: Hyd. Hyd.
Duration: 270 274
Duration @ .050" Lift: 234 238
Valve Lift: 0.55 0.55
Lobe Lift: 0.3 0.3

Valve Timing @ 0.05" Lift: Open Close
Intake: 8 BTDC 46 ABDC
Exhaust: 56 BBDC 2 ATDC

IH8BOWTIES · Dec 1, 2014

Jhussey1280 said:
Hey guys I'm getting ready to so the PI swap on my Mustang and I have a new set of comp cams and valve springs to go in with them. My question is, I was planning on changing the valve train with the heads off the car. Assemble the PI heads with the new Comp Cams stuff the put the heads on the block. Is this a good idea or is there something I'm missing that makes doing it this way a bad idea? Thanks!

IH8BOWTIES · Dec 1, 2014

Ok. Your duration is 270 which means if these cams are installed on a 96-98 4.6, you need to notch your pistons to avoid piston to valve interference. 262 cams are the most you can go without notching. Ford used a deeper piston on 99 and up PI equipped engines to keep compression down. That being said, you'll be running around 10.5:1 compression so premium unleaded fuel is A MUST. First ping and you toasted an engine.

Jhussey1280 · Dec 1, 2014

Thanks IH8BWTIES, guess it's time to investigate some pistons. Might as well work the whole rotating assembly since I'll be there.

sneaky98gt · Dec 12, 2014

It is not required that you notch the pistons. You'll just have to retard the cams a bit to increase the PTV clearance. I'd either ask someone knowledgeable (like Nick at MHS) to see what to degree them in to, or manually check the PTV with clay.

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