Loose valve seats (4V 4.6)

[m-barans]

So on my way to work driving like grandpa I stopped at a red light. A couple seconds idling later the car ran rough.

I see cylinder 8 misfiring in “power balance”

I see cylinder 8 1% low on a relative basis with a “crank speed” compression test.

I have the later run DB/DC heads or whatever and the head cooling system crossover mod but I never upgraded seats, valves, guides or springs!

I figure this was bound to happen because I cut a corner so to speak…

First I will validate my suspicion of the seat becoming loose. Then,

I am asking for advice…

My question: where can get heads rebuilt where they know how to install better guides, cut to install all new seats, upgrade all the valves and install better springs for additional boost?

I haven’t found success in finding knowledgeable ford modular engine machinist services. Does anyone have recommendations that might be more economical than what I’m finding like Modular Head Shop?

Just trying to decide if going with CNC porting and combustion chamber services is worth all that additional cost

Thanks

[Apex]

Maybe I'm misunderstanding, the compression is only 1% low, or it's only showing 1% compression relative to other cylinders (effectively zero compression)?

[m-barans]

On a relative basis, cylinder 8 is within 1% of all others when cranking. It was probably a touch low because of the spark plug ground strap hitting something and closing it shut causing cylinder washing out. I opened the gap up and it runs fine but I’m afraid the piston head and chamber look injured with the camera. I need to remove the heads to do a better failure analysis. I can’t think of debris finding it’s way in somehow after 10k miles. Maybe detonation related to spark timing. Will update

[m-barans]

It wasn’t my tune or my parts selection that was my issue which is great! Stock stroke 4valve with low compression pistons (heavy) and (heavy h beam rods). It was nice to see all the pistons looked great as well as their respective bores. Minor scuffs that couldn’t be felt from the 2618 slugs was all I could find. The blower and the rest of the cylinders had 0% related damage!

Foreign debris (wiper cowel spring clip) was the cause. It dropped into cylinder 8 intake port during a timing cover reseal. (I heard something drop and looked at the intake ports but apparently I failed to detect the intrusion. What a nightmare!) The engine runs fine and has good compression just found related damage to piston crown and chamber on 8.

I disassembled looking for a failure during my analysis and Cylinder 8 wasn’t hurt in the block but I plan to replace the slug and do some chamber refinishing and polishing globally…

I have a few questions for you folks wanting to help…

1. I decided to run heavy h-beams and heavy pistons to take abuse with a stock stroke crank at low compression because I want to tune for up 20 psi boost with a PD blower and keep the rpm’s under 6k. Would I be better off over boring the block and using a stroker crank (machined 3rd gen coyote), with 5.2 predator rods and a custom piston?

2.Would it be better to bump static compression to 9.5?

3.I have been informed that improved exhaust valves, seats and a spring package is a need for FI engine. Should I replace all the guides, use stainless exhaust valves, install new exhaust seats and find a better spring package? If so, I would like to hear pointers…

I may try a coyote crank (machined for 4.6 snout), GT 500 rods and a custom piston for the shortblock…

I do want to improve my cylinder heads regardless of short block repair/rebuild.

Lay those thoughts//answers on me if you have them please

Thanks Everyone!

-Mike

[mbsvt1]

I would reach out to modular head shop for your cylinder head Questions.
I spoke with them when I was going to have them do my cylinder head work done for my current build but decided to use the new heads I have from my previous build.
www.modularheadshop.com

I have heard of valve seats coming loose on these heads that have some miles on them. Sorry to hear about your mishap. Keep us posted on your build...
MB

[m-barans]

Update: Engine isn’t hurt. I put in a new set of pistons to bump the compression a touch and polished the chambers. Engine runs great!