DOHC 4.6L V8 build

Those drivers side heads are known for valve guide issues in the earlier heads due to insufficient cooling and are prone to wear when ran hard frequently. To be honest I think all 4v heads have a "ticking" issue. They make upgraded bronze valve guides for them.

If you go the route of having the valve guides replaced, have the machine shop install the 9 thread sparkplug inserts. They are the time certs that are locked in place, will never come back out. I was going to have that done on my brothers 5.4L in his work van.

Intake tube problems

I did some test fitting today and was a little disappointed. The Lightning intake tube ports side are too close to the throttle body and interfere with the valve cover.

I checked for clearance with the tube inverted (facing aft) and it just fits when the throttle body is bolted to the plenum.

I haven't found a suitable alternative (Mach 1 or Cobra) so I'll have to cut off the existing port extensions, plug the holes and install new ports farther from the throttle body - maybe in a coupler. Since that will all be on the bottom of the tube it shouldn't detract from my desired OEM look.

Fuel rails don't fit

Another disappointment today was finding out that my Aviator fuel rails will not fit my Mach 1 intake manifold. The mounting brackets are entirely different from what the intake manifold is designed for.

Also, the passenger side pressure damper interferes with the plenum.

One reason I selected the Aviator rails instead of the Mach 1 is the Mach 1 fuel supply is on the wrong side (passenger side) while the Explorer fuel feed is on the driver side.

I'll probably have to purchase end fed billet rails for the Mach 1 and select my own fittings for my application.

I've read that the stock Mach 1 rails have insufficient flow for supercharged engines so I don't feel too bad. One thing nice about using a popular performance engine compared to my SOHC V6 is that there are a lot of aftermarket products available.

Edit: The fuel rail pressure sensor is the same for the Aviator and the Mach 1 and costs about $75 new. I only paid $50 for the fuel rail with the sensor. I'll keep the sensor and use it on a set of billet rails and try to sell the Aviator rails without the sensor.

What is your reasoning for using the Mach 1 intake instead of the Aviator?

Benjam

Why Mach 1 intake

The Aviator intake manifold has intake manifold runner control (IMRC) which is not supported by the Explorer PCM, takes up more space and is less reliable because of moving parts. Also, the max air flow of the Mach 1 with twin throttle bodies should be greater than the Aviator single throttle body.

Removing exhaust valve cam followers

The valve spring compressor tool arrived today so I tried it out after raking leaves.

There are three different "shoes" for different applications. One shoe fits all of the 4.0L SOHC V6 valve springs. Another fits all of the valve springs on the 4.6L SOHC V8 and the exhaust valve springs on the 4.6L DOHC V8. The third shoe fits the intake valve springs on the 4.6L DOHC V8. I set the tool up for the exhaust valve springs first since they were the most accessible and the crankshaft was in a position with them not depressed on cylinder 2.

I used a cheater pipe to give me more control with my left hand while extracting the cam follower with my right hand.

I was careful to make sure the attachment pin/clip were pushed to one side to clear the camshaft bearing cap.

It's important not to depress the valve spring too far and damage the valve stem seal.

The tool worked fine. The hardest part was wiggling free the slippery cam follower. I labeled a zip lock plastic bag with the cylinder number, exhaust, and forward or rear. Then I placed the bag in a cardboard box with four rows of bags. After the extraction of each cam follower I compressed the valve spring a little to make sure the valve stem could be depressed with my finger.

Removing intake valve cam followers

When the tool is configured to compress intake valve springs the shoe is positioned perpendicular to the camshaft and pointing left or right depending on the particular valve.

Using the tool is a little more awkward with the shown offset to one side or the other.

But it still works fine.

It will be a little time consuming to switch the shoe 180 degrees for the second intake valve at each cylinder.

billet fuel rails

New billet fuel rails are expensive ($300) and that doesn't include the FRPS adapter, hoses and fittings (~$200). Also, they have no provisions for mounting a fuel pressure damper. I want to purchase rails that are compatible with the Kenne Bell supercharger manifold so I don't have to buy rails again if I ever add a blower. I'm used to my Sport's under the hood fuel pressure gauge.

I'd like the same capability on the DOHC V8.

8 cam followers to go

As of today I have all of the bank 1 valve cam followers and all of the bank 2 exhaust valve cam followers removed and the crankshaft still won't rotate more than 330 degrees. So far none of the valve stems are stuck. After I finish removing the bank 2 intake valve cam followers I'll remove the timing chain components and try crankshaft rotation again. Then I'll remove the oil pump since there is a remote possibility it could be broken. I stuck my wand magnet into the spark plug holes and the intake and exhaust ports fishing for anything magnetic that might have dropped into the heads but didn't find anything. I don't have access to an inspection viewer to look into the combustion chambers. If there's a bent connecting rod then the associated head will have to be removed to replace the rod. However, I'll probably remove both heads for inspection. At that point I should be able to decide how to proceed - bore, stroke, forged pistons and rods, cast crank, etc.

Still won't rotate

The crankshaft still won't rotate after removing all of the camshaft followers. When some of the valves closed I heard the sound of grit being pressed. I've started removing the timing chain components in preparation for removing the heads.

My Aviator oil pan and pickup tube arrived today.

I'm pleased that even though the items came from the Northeast there was very little rust on the pan.

The shape of the pan makes it difficult to add another port for an external electric oil pump and I don't want to install one on the bottom due to ground clearance issues. I'll try to find a T fitting that will fit the existing drain plug threads.

Wow, that doesn't leave too many more things to keep it from turning. It will be interesting to see what you find when you take off the heads. Hope you don't find any rust in there. The grit thing is ominous. Suppose it could be sugar? Dirt from a flood? It's surprising you didn't see any issues from the bottom if it's that locked up. Fingers crossed.

sitting on a pallet

The engine was sitting on a pallet pushed against a wall inside the tune-up shop and uncovered for six months. I found needle bearings in the valley between the heads and near some of the cam followers which I removed with a wand magnet. Since there was no intake manifold anything could have fallen into the intake ports.

Fuel rail progress

This evening I won a used pair of DivisionX fuel rails for a Mach 1 for $128 (with free shipping) that is compatible with most of the available blower configurations (Eaton, Whipple, and Kenne Bell).

The driver side has the fuel rail pressure sensor (FRPS) block off plate (A in photo) and two 1/8 inch NPT ports (B in photo). Fuel feed is at the end and the used rails come with fittings at all four ends since it was on a return fuel system.

I'll have to purchase a Ford feed to AN adapter, a splitter or T, some hoses and some caps, fuel pressure gauge, and a FRPS adapter. There are no provisions for a damper on the rail. I'm anxious to receive the rails to see how they fit and determine where everything can fit.

another needle bearing

Removing the lower timing chain components and the oil pump did not allow for crankshaft rotation more than 330 degrees. I did not remove the upper camshaft sprockets and chains because a special tool is needed to time the camshafts and prevent them from rotating to loosen the sprocket retaining bolts.

I removed the driver side head because I was encountering interference when piston 8 was near TDC and found the source of the interference.

One of the needle bearings had worked its way into the combustion chamber and was wedging between the piston and the head. There were no bearings in the other three cylinders.

The valves look pretty good. You can see the mark on chamber 8 where the needle bearing was wedging. Fortunately, it was away from the valves. Now the crankshaft rotates 720 degrees with no interference.

Cool! Simple fix there.

right head removed - no surprises

The only thing I found after removing the passenger side head was a lot of grit.



There is no significant ridge on the cylinder tops so removal of the pistons should be easy. I plan to continue disassembly until I find something that could be the source of a lower end knock. A set of manganese bronze guides for these heads cost around $200 plus the machine shop cost to press out the old guides, press in the new guides and then ream them. They last longer than stock guides and cool the valves better. However, I don't race and only drive about 3K miles per year so I don't know if they're worth the additional cost even if my stock guides need replacement.

Head bolts, rod bolts, and main bolts are all TTY and can't be reused and ARP bolts are expensive. I've read that the stock block and reciprocating parts can survive 500 bhp with the pistons and rods being the weakest. If I have to get the block bored for any reason I may opt for a 5.0L stroker kit with forged pistons and rods and a cast crank which can survive 500 bhp. That way I wouldn't have to pull the block later. I've learned from 4pointslow that head studs require more room to remove/install heads than head bolts. Also, I prefer six point cap head bolts over 12 point nuts.

Excellent project Dale, it sounds like a lot of fun.

front 3 pistons & rods

I was able to remove the front 3 pistons and rods today and briefly inspect them. None of the rings are broken. The rod bearings are worn a little but still good. The piston skirts are in pretty good shape and there isn't a lot of piston pin play. I found nothing obvious that would cause a low end knock but I didn't make any tolerance measurements because I don't have any tools (other than plastigage) to do so. I'm hoping that changes when I receive my Christmas presents. After I finish removing the other 5 pistons and rods I'll measure crankshaft end clearance before removing the main bearings. Because of the cost of replacing gaskets and TTY bolts I don't want to reassemble this engine without making a significant improvement. Increasing the displacement to 5L is desirable if I can find a street kit with adequate oil control. That requires shorter than stock rod lengths and minimal decrease in compression height.

Rod bearing failures

Today I found multiple sources for the low end knock. Rod bearing 6 had been spinning for quite a while and wore grooves in the crank and rod.


The rod is definitely unusable. I haven't measured the depth of the crank groove yet but I suspect it's deep enough that the crank is also unusable.

Rod bearing 7 was also spinning but for less time.


The puzzling thing about bearing insert 7 is what happened to the short section that's missing. It wasn't stuck to the journal and I don't think it fell out. Tomorrow I'll check the block thoroughly for it.

Rod bearing 4 had failed but was not spinning.


Rod bearing 8 was also in pretty bad shape.


When I found the excessive clearance for bearings 6 and 7 I became concerned about loss of oil pressure which could affect the camshaft journals and caps. I realized, however, that three rod journals and bearings were in good condition indicating no significant loss of oil pressure. It bugs me that there are no camshaft bearing inserts and if a cap breaks or a bearing surface fails the head is trash. Just because the camshaft spins half as fast as the crankshaft in my opinion does not justify eliminating bearing inserts.

I was going to remove the main bearing caps but my 3/8 inch drive, 6 point 13 mm socket busted in half on the third side bolt. Anyway, I had enough surprises for one day.

Needing a replacement crankshaft and at least one rod has tempted me to purchase a complete stroker rotating assembly if I can find something suitable in my price range. I have lots of research to do and may wait until after I purchase a 2002 or 2003 Explorer to decide how to rebuild the engine.