Engine Health - Spark Plug & Valve Pics

[blay127]

I bought a previously built stroker motor (Clegg kit) and dropped it into my TJ buggy. Previous owner claims to have put 2000 miles on it before I received it. I've been having some trouble getting it to run just right, been adjusting distributor, injectors, fuel pressures, etc based on the great wealth of info i've read here. I've gotten it to behave decent but I think its still not as great as it could be.

'93 block, 0630 head, stock valve train, stock '97 ecm, bosch 703 injectors (had ford blue injectors previously but ran rough with them)
I dont have a wideband, but have monitored long term fuel trims several times and its always been +/- 5%

I pulled both manifolds off last night as i'm installing a new header and making a 2.5" exhaust. Good time to look at the back side of the valves.

I noticed cylinders 1, 2, and 6 exhaust valves were brown/rusty/slightly damp and sooty ports as seen here




While cylinders 3, 4, and 5 exhaust valves were white and fairly clean ports as seen here


My old 150,000 mile motor that i pulled out has all 6 white exhaust valves. I figure thats what they should look like?

When I got the motor, I pulled the spark plugs that were in it (stock heat Autolites) and put in NGK ZFR6F11 as recommended here. I have maybe only 10-12 hours on these spark plugs. What would you say is going on with the wide variation in colors?













Any help is greatly appreciated! Thank you!

[Cheromaniac]

I can only guess but I suggest you replace the distributor cap, rotor arm, and plug wires unless they're fairly new. A mild misfire could cause some cylinders to run richer.
Another thing that might help is to replace the older log style intake manifold with the newer curved runner unit. It provides a more homogeneous airflow to each of the runners so unlike with the log type manifold, you won't see the outer cylinders running richer and the center cylinders running leaner. Since you already have everything apart, it's the perfect opportunity to do the intake manifold swap as well.

[jsawduste]

I bought a previously built stroker motor (Clegg kit) and dropped it into my TJ buggy. Previous owner claims to have put 2000 miles on it before I received it. I've been having some trouble getting it to run just right, been adjusting distributor, injectors, fuel pressures, etc based on the great wealth of info i've read here. I've gotten it to behave decent but I think its still not as great as it could be.


From this post plus our conversation over at irate, you have a lot going on.

1st off its hard to determine how the engine was built without knowing the quench, cam, cam timing etc. You mentioned 944 pistons and the Clegg kit, that helps some.

I`m sure someone will mention about the full dish 944`s.

Also understand Chris is trying to provide you a tune. Tunes only sharpen the image. They don't make poor running engines run better.

What exactly does the engine do that makes you think its not running well ?

lets do a compression test and see what your numbers are. That will be a baseline. If you have the manifolds off taking the head off to see what the deck height is would be another step in the right direction. Overly large quench`s simply don't work well. No amount of tuning will solve that.

I know you're heading to SMORR in a couple weeks but we do have a little time to work with.

A little work setting a baseline. Knock the ears off the dist. Let the engine go into closed loop. with it idling turn the dist CW/CCW till you find the sweet spot. The engine will tell you where it wants to be. Lock it down and don't move it unless you change the cam or cam timing.

I don't know what the heat range of the NGK`s are that you put in compared to stock. Guessing since you got it from here they should be a step colder. Which is what you want.

For injectors I`ve only used Accel`s in a 24 or 26 lb flavor. They work well and are a common standard. My stroker uses 24`s (should be 26`s Chris increased the duty cycle a tad to accommodate them) FP is around ~42 with the hose connected.

What temp does the engine run ? It needs to go into CL for any of the ECM programming to be effective.

The color differences between the plugs could be so many things that giving a hard answer is impossible. At the very least the new manifolds will have new gaskets so that should eliminate and vacuum leaks.

Speaking of programming. Sure, a good tuner can modify the trims/trim delays and timing/timing rates but the biggest advantage is adding reliability. Enough fuel, not overly advanced timing etc. The extra performance is just an added bonus.

[blay127]

Thank yall, I really appreciate the feedback and i'll try to fill in a few blanks.

What I'm seeing is there is a slightly rough idle, a hesitation right off idle, and sometimes surging under load at idle or just above (rock crawling). With the blue ford injectors it would stumble real hard right after startup in open loop and then clean up in closed. I have an adjustable fuel pressure regulator and it didnt matter if it was 35 psi or 55 psi, it always did it. Switched to the bosch 703 injectors at 49 psi and the cold start stumble went away. The hesitation and surging went away too but after a weekend of rock crawling it seems to have come back. Like its learning itself stupid.

The cam is a Clegg stick. Per the specs it doesnt seem that much more aggressive than the stock cam. My idle is "lopey" and fluctuates more than i would think it should for this cam (20-40 RPM). But maybe thats normal?

Duration 263 Intake | 267 Exhaust
Duration @ 0.050 Valve Lift 209 Intake | 213 Exhaust
Valve Lift 0.443 Intake | 0.443 Exhaust
Lobe Seperation Angle 114 Degrees

No i don't know for sure the specifics of any machine work that was done to this motor. I'm aware of the poor quench associated with IC944's and no decking. It was "running well with no complaints" in the previous owners Jeep and I know he talked with Russ P a lot during the build so hopefully he got it right (you know what they say about hoping...) I will pull the head eventually and check to make sure. But with my trip next week I'll have to do it after. I cant fix that now anyway and its running good enough to wheel for a weekend.

Distributor ears are knocked off and I have played with the indexing. I have done it several times per Dino's writeup as well as moved it CW/CCW while the engine is running to find the sweet spot. I believe I'm there, but I'm curious just how big of a spot can it be? Do i need to be within a couple thousandths or is the window more like an 1/8"?

Yes these NGK plugs I put in are a heat range colder than stock, as I have read here.

The engine runs between 190 and 205. I have a big aftermarket aluminum radiator and electric fan that keeps it in check pretty well. I believe it has a 180 degree thermostat in it.

Dist cap, rotor, and plug wires have some use on them, but i wouldnt call them "old". I'll pick up a new set anyway as they're cheap and i'll have some extra spares.

[jsawduste]

Depending on the cam for indexing. Some have a pretty narrow bandwidth while others are wider. Problem is we don't know if the cam has any advance built ground in it. Or if the PO played with cam advance retard with the timing set.

About all you can do is rotate the dist. to where it wants to be and eliminate that variable.

195 is the normal `stat and the engine likes heat. If it is not reaching temp it may not be into closed loop.

From the plugs it almost looks like 1-4 are a bit on the lean side. The stumble, rough idle etc might have been a vacuum leak. A FI engine shouldn't do those things unless there is an big issue. The fact you bumped FP that high suggests a leak. Sincle new gaskets are going in its logical to think if there was a leak it would correct itself.

Check the rest of the vac lines including the 90 to the map to see if any are broken.

Pull any codes by chance to see if the ECM doesn't like something ?

That cam is mild and should run fine with 24`s. Again I`ve only used Accel`s so I do not know what you have are rated for.

Have run into the injector connectors/terminals being worn out and the terminals themselves arced away. HIGHLY suggest Googling FI connector replacements and making sure you have good connections. Found this one thing really helped my stroker to run well.

https://injectorrepair.com/fuel-injector-connectors/ I used the EV1 "BatWing" connectors that lock on real nice. If you call them they will make the wires any length you need.

You're close, its only a couple minor things to check and you should have a smooth running torquey engine.

[blay127]

I will check all that. Thank yall!

[blay127]

Was finally able to get around to running compression numbers this weekend. Ran a test on a cold engine, then got it up to operating temp and ran test again:

Cold
1 - 140
2 - 120
3 - 140
4 - 145
5 - 145
6 - 135

Hot
1 - 135
2 - 115
3 - 140
4 - 140
5 - 140
6 - 145

So obviously hole 2 is a little weak, but is it enough to really be concerned at this point?

Aside from that I'm still having the same issue as before. All the injector plugs are still good. I mounted thermocouples to all the exhaust header tubes at equal distance from the head and all cylinders read within 50 degrees of each other (~800 F at idle). Was hoping I would have some colder cylinders so that i could swap injectors around and see if the temp drop followed, but no luck i guess.

Had a great time at SMORR a few weeks ago and aside from the slightly rough idle the motor did good. However it did seem to starve for oil on inclines a lot worse than my old stock motor did. As in, oil pressure would drop on less steep inclines than before. I dont suppose there is any difference in oil pans from a 93 to a 97? Would it be ok to add an extra qt of oil for a mostly slow going rockcrawler?

I'll keep driving it and keeping an eye on it, and let yall know if i come up with anything. I will probably look to put a newer intake on it next.

[Cheromaniac]

You could add an extra baffle at the rear of the oil pan like I did to keep more oil in the sump when going uphill.