Intake Camshaft HPFP Lobe Specs

[liquidennis]

The saga continues with my misfiring and I have now opened up the timing chain cover to check out the timing chain, just in case that might be the issue. It's nice and tight as can be (of course). I did previously experience the problematic cam follower issue where the HPFP piston blew right through and started hitting the intake cam lobe. I do see some scratching on the lobes, but no real gouges or anything to really write home about. I'm not sure though if the lobes have been worn down from multiple hits to the piston, the end of the HPFP piston was pretty banged up so I replaced the whole pump. I have a caliper tool, but I'm not sure what the measurement is supposed to be. Looks to measure about 1.675".

By the way, if you're thinking about removing the timing chain, that cover is an absolute nightmare. All rear-facing bolts on the firewall. My hands are about to jump ship and boycott.

Thank you for any assistance on this never-ending story.

[Jayz691]

What year is your b7? In the US, the early models(BPG) came with a soft 1 piece HPFP lobe. Later BPG had a revised cam(2-piece hardened).
A pic of the lobe would help here.
Here's an old diagram of the stock hpfp lobe. It's more about lift than overall size.
If you have the early version, they wear bad, that's why a pic will really help.

Sent from my CPH2611 using Audizine Forum mobile app

[liquidennis]

Please see the photos below. Thank you for the diagram, it's perfect.

[liquidennis]

Doing the conversion for inches to millimeters, the lobes seem right on spec. So it does not appear that wear is the problem. Should I just replace the timing chain and components while I'm here as preventative maintenance?

[Jayz691]

Yeah, that's the newer revision cam. They don't really wear, but can get scratched from cam follower failure. Even if you don't feel it, it can be there. Best thing to do is check your cam follower every oil change until you figure out the change interval. Depending on how fast it's wearing through the coating, that'll decide if you want to change the cam, or just keep changing the follower. My car had a failure before I got it, and that same cam as in there 130k miles later. I just changed to cam follower every other oil change. Ideally you wanna change it before the coating fully wears through.
Far as the cam chain/tensioner, if it's over 100k miles, and no record of being done, I'd do it. Use OE/OEM parts.

Sent from my CPH2611 using Audizine Forum mobile app

[Nizmo]

There is a very nice conversion kit for a roller follower.
https://www.ecstuning.com/b-iabed-in...-103-107blkkt/

DO the timing chain, replace the chain, tensioner, 3 square cut seals on timing cover and get a gasket. You will need the cam locking tool to do this correctly, as well as special socket for the timing gear bolt. Have a good torque wrench.

If was me while back there I put in the metal coolant elbows, saves the headache later.
https://www.ecstuning.com/b-assemble...06d121132ckt5/

If you can't find the tool for rental, I'll loan it to you. Your 1 state away.