Eric Dorenbush

I'm looking for some advice on intake manifolds.

Over the last few years, my 2005 Ford F150 STX 4.6L 2v V8 has started pitching plugs (it is getting close to 200k miles). I've been re-sleeving the cylinders with the TimeSert kit (I had Ford do a helicoil on one and that lasted 8 months). I had already done 3 of them that blew, so after the 4th pitched out last week, I decided to spend the time to do some preventative maintenance and do all the rest.

Cylinder reaming action

Things were going fine until I noticed that the intake manifold gasket near the #5 cylinder had a crack and was leaking a bit. So, I did some research on the internet, including this forums and saw that this is something that does happen and doesn't seem like too much more work than I have already committed to. So, I pulled everything off and found that the gasket was not in the best shape.


Most of the time, when I do repairs, I take the opportunity to replace the parts that I have off and upgrade them if possible. So, I am probably going to replace the water pump and alternator since the alternator is off anyways and the water pump is easy to get to now.

The only replacement intake manifold I can find for this year model is the Dorman. I have seen some mixed reviews on it. All of the custom/performance intake manifolds that I can find for this engine seem to cut off at the 2004 4.6l 2v. However the Dorman is for that engine model also. I have also done some research and seen that the difference between the mustang and truck intake manifolds are that the truck intake manifold uses a high profile setup for longer inlets and more low end torque, and the car models use a lower profile and shorter inlet for higher mid/high range torque.

So, here's the question- does anyone know if there are any performance intake manifolds that fit this application?ex: the Edelbrock Victor Jr. EFI Intake Manifolds 28385
Also- if these do fit, would there be any negative performance impacts or other modifications I might need to make?
I am also looking at replacing the throttle body assembly, thermostat, radiator hoses, and upper plenum.

Reference pictures:

DarrinT04

the 04, 05 4.6 is the same in the f150
that is bull****. there is no reason why it wouldn't work on an 05 4.6.
it will likely have more power if you choose that because it is recommended for racing and not for the street.

Eric Dorenbush

Thanks- so far my research is telling me the same thing. But internet research for vehicles can be a bit like trying to medically diagnose yourself on WebMD, so I figured I'd get a bit of a peer-review reality check. I see that it will give you some more Hp, but I have also seen that it tends to shift the torque a bit later in the RPM band. In addition to driving off road a lot for work, I also frequently tow a trailer that is loaded down pretty well. A couple years ago I swapped the front and rear diffs for G2 4.56 gear and re-tuned it with my SCT tuner, which helped towing and Mileage CONSIDERABLY with my larger LT305/70R17 Nitto G2 tires.

Eric Dorenbush

Cleaned things up a bit today, finished the Time Sert fixes on all but one cylinder. Going to finish the last cylinder tomorrow and then clean up the area the new gasket and manifold will mate up to.

Planning on figuring out the intake manifold and the rest after. Seems to be a bit of a rabbit hole with some of these mods with fuel rails, egr valves, tunes etc.

Eric Dorenbush

Another quick question. In most of the videos and articles- people seem very specific about plugging the intake ports to the cylinders with rags or something to ensure no debris makes its way down there.

However, I'm already vacuuming and blowing out the cylinders when I ream and sleeve the TimeSert's in to make sure there are no aluminum shavings and then inspecting the cylinder with a scope camera.

So, couldn't I clean out the gunky intake ports and then vacuum, blow out the intake ports and cylinder, and then inspect with the camera- or is there somewhere else the debris could go that I couldn't access and inspect or is there some other damage that could occur?

DarrinT04

great choice. it is a great way to keep most of dirt from getting in
no matter what you can't prevent dirt from getting in the cylinder 100%. but yes that is good way to get the debris out. alternate doing both
sure, just make sure you don't leave ANY of it in there because it can cause problems.

Eric Dorenbush

That's good. The gunk is driving me nuts. Also, thinking of porting it to gasket match with the manifold so that would alleviate needing to pull the heads off.....

I think I've decided to keep the stock aluminum manifold for now until I do more research into the impact of using a performance manifold with shorter runners. I'll probably still swap the throttle body out and maybe space it.

So, I started prepping my manifold for porting, polishing, and then paint (high temp). Did a first round of oven cleaner on it and scrubbed it out a bit. Got most out, probably will do another clean tomorrow. It is pretty satisfying to see the deposits slide out in a big blob...

DarrinT04

that is very nasty. needs a lot of TLC

Eric Dorenbush

So, I've run into an issue. I decided to run a leak down test before I put things back together and I'm not sure what is wrong. The engine was running alright, without error codes prior to this work (other than the spark plug pitching out). The work done was sleeving 5 of the cylinders so I wouldn't need to deal with it later. The engine has not run since. 3 cylinders were sleeved prior, between 2 years ago and a few months ago. No issues after those sleevings and no noticeable change in engine mileage or performance.

Results of the leak down test were:
1- 100/18. 5- 100/19
2- 100/20. 6- 100/18
3- 100/19. 7- 100/20
4- 100 28. 9- 100/28

Do, I'm seeing leakage between 72% - 82%. I have double checked to ensure that I am at TDC. I have also tried it just prior and just after. Also Tried BDC, same. I also tried rotating the engine with pressure running while visually observing valves to see if they would close. The pressure leakage obviously increased when the valves would open, but would not fully shut and the leakage was present at all points of all cycles.

Leakage is only occurring through the intake valves, but it is the same on all cylinders.

I've made a video of what I'm seeing during the test:
Not quite sure what is going wrong. Going to do some research today, but unless anyone has some suggestions, it looks like head removal for Christmas...

Eric Dorenbush

Talked with a client of mine who is on one of the Ford nascar racing teams. He brought in a couple master techs he knew and seems they all agree that it is probably some deposits on the seat that didn't get cleaned out when I cleaned the ports. They said to put it together and run it. I guess it will run or not and I'll know if new heads will be on the menu then.