Alright, so we got the new engine in and all hooked up, but its misfiring and not running on all cylinders. So I could use some help in figuring out what is happening. At 1500+ it sounds fine, but once you start to get down near an idle it starts to shake. I have a vacuum gauge on manifold vacuum and it bounces all around.

To confirm that it wasnt firing on all cylinders I took my infrared thermometer and measured the headers about one inch away from the heads:

cyl deg deg cyl
4 268 120 8
3 119 156 7
2 194 265 6
1 302 272 5

The cool cylinders (3, 7, 8 notably) dont seem to line up to any system. The intake (Edelbrock Performer), has runners sharing (1, 4, 6, 7) & (2, 3, 5, 8), so no pattern there. I purchased a new set of plug wires to confirm that and there was no change.

Looking at the firing order (13726548) doesnt help either, as the problem cylinders arent grouped together.

Heres the engine setup:

400 bored .030 over
Aussie heads from TMI
Pistons from TMI
Edelbrock Performer Intake
Edelbrock 1406 carb (stock jets & rods installed)
Crane XE256 camshaft
FRPP roller rockers
Duraspark stock distributor (new cap, rotor, wires)
MSD 6A ignition
MSD coil
Autolite 25 spark plugs

We havent been able to do a cylinder pressure check as our tool broke, but that is about the only idea we have left. Any advice on how to proceed with diagnosing this? Thank you!

 

try take a cranking compression test. Maybe you have push rods to long and hanging a valve open?

# 3 & #8 are not even hitting, and #7 barely.

 

If you compression number are all over the place, I think you need to have another look at the lifter preload.
This is from the cranecams website if you need it:

Adjusting Hydraulic Lifters for Proper Preload
In order to adjust the preload the lifter must be properly located on the base circle or ?Heel? of the lobe. At this position the valve is closed and there is no lift taking place. You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.

1. Remove the valve covers, and pick a cylinder you are going to set the preload on.

2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder?s intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)

3. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)

4. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at ?Zero Lash?. Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.

5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.

 

Alright, thanks guys, I've had time to do 2 tests.

1) Removed valve covers and bumped over starter: All rockers moved normally

2) Compression check:

cyl psi
4 160
3 180*
2 180
1 180

8 0
7 192
6 193
5 192

So 8 is definatly a dead cylinder. 3 acted a bit odd, where I had to crank twice to really get a stable reading. But I double checked 7, and it read fine. Is it possible that a lifter would pump up and keep a valve open, but during an engine off test it would bleed down and allow compression?

So obviously I need to look at cyl 8 and its lifter preloads and what not. The other interesting thing is how the drivers side wants to be ~192 psi, but the passenger side is ~180 psi. So maybe some combination of milling amounts stacked up to have different compression?

 

Well good news, the engine is running well now.

We went rocker to rocker, and checked the preload by counting the turns on the bolt until tight. Some were as low as 1/4 turn, and others were higher than 3/4. So I was able to move the shims around to make them all between 1/2 - 3/4 turn.

We did another compression check, and this time they were all between 165 and 175.

Still trying to figure out exactly what tune and timing it wants, so far it seems to want about 20% larger rods/jets than the 351 did in the Edelbrock carb, and I'm sure I'll be tweaking that for a while. Probably get significantly worse mpg than the old motor.

So any advice on the timing of this engine? So far I have it at about 6 deg initial, and the distributor advance is still the same as ford shipped it on the 351m. Obviously this needs improvement since its now a 400 and doesn't have EGR. I'm still contemplating making it EFI, so I hate to spend a lot of money on a expensive new distributor if I'll have to swap it for a TFI unit anyway.

 

Is the timing chain still set at 4 degrees retard?

 

No, it is an aftermarket double roller set straight up.

 

Oh, one other oddity that we discovered. The pedestal shims I bought were from Comp I believe, and were supposed to be .030 & .060. Well we measured them with our calipers and they came up as ~.016 & ~.034.

I wish I had a set of micrometers to verify down to a more accurate level, but I think that was why we had to go back and check each cylinder, because from our testing we found that the ".030" shim would add about 1/2 turn. So we thought that the variation cylinder to cylinder would be less than we could shim for. Turns out that our window was more like .016" and the cylinder variation was significant.

 

Set the dist to 10 degrees BTDC, and get stronger springs to keep the mechanical advance from advancing too soon.

 

Alright, so I took a look at the distributor today to see if I can figure out what it is currently set up for.

I took off the cap, and manually advanced the motor, marking each end of travel. It turned out to be 18 degrees. This seems insanely low, considering the recommended initial timing to go with the original 351m setup was 4 degrees.

So I cant help but wonder if a shop previously flipped around the advance to use the small advance side, maybe if it originally had a pinging problem. I hope I havent been running at a max of 30 degrees for years, that would be sad to have lost that much power.

I'm going to get a timing tape since I dont have an adjustable timing light. But I assume the goal would be total timing of around 36-38, with full advance by about 3000 rpm. I upped the initial timing to 12 degrees, and it made a nice difference over even 10 degrees.

 

Alright, well the engine just passed 500 miles. Once we got it setup where it wanted to be I've had no real incidents except for my MSD 6A dieing.

Only concern point left is that I have a ticking on the passenger bank, sound like either #2 or #3. It will only tick once the engine is fully warmed up and idling low enough to not be drowned out. I've had the valve cover off numerous times and visually havent seen anything amiss.

I have some concern about whether some of the lifters are bleeding down quickly enough. I put my dial indicator on the valves, and watched when I set the preload (all of this at TDC for the cylinder). I've done this on cylinders 1 & 2 so far:

2E: Opened ~.080, and took ~6 mins to bleed down to a closed valve
2I: Opened ~.050, and took ~2 secs " "
1E: Opened ~.080, and took ~20 mins " "
1I : Opened ~.040, and took ~2 secs " "

So my intake lifters are fairly quickly absorbing the preload, but the exhaust side is taking forever. I swapped the #1 Exh valve spring for a Comp spring from an extra set thinking that it might be a spring pressure issue but it didnt change anything.

Does this seem abnormal to anyone else?