Stroker valve seats out of round?

[zalewskit]

Hello,
I am running a 4.7 Stroker motor in a 85 CJ. Ran fine until I developed a rough idle and found valve seats out of round on 3 cylinders.... both intake and exhaust. the seats not the valve. I did very little research and attributed it to the machine shop not grinding the seats or seating the valves properly for the original build.

Well a year later and 1k miles I have rough idle and low 95 psi on # 1 cyl, down from 215psi after the last valve job. i think I saw this movie last year and assume that something is causing the valve and or seat to distort. Heat comes to mind but i am actually somewhat clueless.

I have a hesco mpi kit, ford 24lb injectors and a hesco rv cam, hesco hiflow water pump and neck. After the last valve job all cylinders were uniformly over 200 psi.
The PCM is a OBD 1 and doesn.t throw any lean or rich codes.
2. I have a HESCO electric external mount pump with a non adjustable Fuel pressure regulator, provides 32 psi at idle if I pull the vacuum hose it jumps to 40 psi. (System has new supply and return lines and a vent line)
I thought first I would check A/F. What tools/setup do you guys use to check A?F?

I don't have any indication of over heat from the cooling system and am stumped as to what could be oveheatin the valve seats to cause warping.

I am unsure how to proceed... obviously pull the head and a valve job. But, what could the problem be? What steps to troubleshoot?

Thanks,

T

[I6FAN]

What valves, stock or oversize? What rockers? For valve seats to be out of round, you have to have worn guides as well.

[SilverXJ]

215 psi was your original compression number? Is that right? What about the other cylinders?

After only 1000 miles and worn seats, you may have something going on with the rocker arm geometry. Are the valves longer than stock?

Before you pull the head I would check your valve train geometry. Just because the wear pattern is centered doesn't mean your geometry is correct. Actually, centering it doesn't matter that much as long as your are about .020" from the edge of the valve tip. What you want is the smallest sweep pattern.

[zalewskit]

(new at orig build) Stock valves and rockers. Hesco valve springs for their RV cam... They look to be small black chevy springs so you have to machine the head to accept. The machineist addressed valve guides on orig build and didn't find an issue on last years valve job.

After last VJ Now
Cyl 1. 210psi 105
Cyl 2. 215 195
Cyl 3. 210 140
Cyl 4. 185 192
Cyl 5. 200 190
Cyl 6. 205 165
Last time cyl 1, 4, and 6 were the worst all at 90psi. Seats out of round on most cyl... both intake and exhuast.
Hesco has you check preload on lifters. Orig build required no shims. after the valve job (Valves sunk lower in the head) I had to shim them as advised by Hesco with hardened washers.

(Funny cyl 4 seals better with1k miles on it)

T

[I6FAN]

Hesco has you check preload on lifters. Orig build required no shims. after the valve job (Valves sunk lower in the head) I had to shim them as advised by Hesco with hardened washers.

How much were the valves sunk? You could possibly be beyond the induction hardening of the valve seat(?)

Before you pull the head I would check your valve train geometry.

x2, bad geometery side loads the guides wearing them so that the valve head is no longer concentric on the seat. That's why I was concerned about the guides.

[zalewskit]

Before you pull the head I would check your valve train geometry. Just because the wear pattern is centered doesn't mean your geometry is correct. Actually, centering it doesn't matter that much as long as your are about .020" from the edge of the valve tip. What you want is the smallest sweep pattern.

Thanks, To undrstand when I put a plan together and pull the valve cover... I will be looking at the contact point of the rocker arm to the valve to see how far off the edge of the valve it is?

About the seat... I was concerned about this going to be the 3rd valve job. I have no way to tell personally if the hardened seat is comprimised but I was going to buy a new core head...Don't really trust replacing the seats. Maybe even de-tuning it back to a factory cam profile factory type springs etc. Hate to give up on the speed parts but that Hesco RV cam sure cranks up some dynamic compression.

T

[zalewskit]

x2, bad geometery side loads the guides wearing them so that the valve head is no longer concentric on the seat. That's why I was concerned about the guides.

Thanks.... The valves needed almost no touch up on the last Valve job it was just the seats that had distorted. We assumed heat. I know to wiggle the valve side to side, have the machineist check for out of round of the guide and fit.. anything else to look for?

[SilverXJ]

Thanks, To undrstand when I put a plan together and pull the valve cover... I will be looking at the contact point of the rocker arm to the valve to see how far off the edge of the valve it is?

If it is less than .020" on the edge of the stem there is definitely a problem. However, I doubt that is the case. Start with seeing how wide the current contact patch is and its location. Then color the valve tip with a sharpie, put a washer under the rocker arm, and run the pattern to see if it gets smaller. This may be difficult to do without an adjustable pushrod. There are better explanations if you google it. With pictures.

Maybe even de-tuning it back to a factory cam profile factory type springs etc.

I don't think that is the problem.

I had to shim them as advised by Hesco with hardened washers.

How much did you shim them?

You could possibly be beyond the induction hardening of the valve seat(?)

BTW, which valve are having the problem, the intake or exhaust?

x2, bad geometery side loads the guides wearing them so that the valve head is no longer concentric on the seat. That's why I was concerned about the guides.

The geometry is in question, but if the geometry is that bad it would definitely be wearing the guides.

Another possibility is that the springs may not be up to par, causing the valve to bounce and wobble on the seat.

You may want to use another machine shop for a second opinion.

[zalewskit]

Latest on the air fuel ratio... Anything look unusual? Warm idle is very lean 24 to 25 possibly because of valve overlap and 1 bad cylinder? Recorded on the freeway going from 20 or so to 70mph.

time LM_2_O2 LM_2_RPM
(sec) (AFR) (RPM)
0 15.04 1930
0.08192 15.04 1930
0.16384 15.32 1930
0.24576 15.26 1950
0.32768 15.51 1960
0.4096 15.58 1960
0.49152 15.35 1960
0.57344 15.33 1980
0.65536 15.14 2000
0.73728 14.94 2000
0.8192 14.85 2000
0.90112 14.77 2020
0.98304 14.66 2040
1.06496 14.52 2040
1.14688 14.45 2040
1.2288 16.66 2070
1.31072 15.6 2090
1.39264 14.52 2130
1.47456 14.96 2170
1.55648 15.24 2170
1.6384 15.17 2170
1.72032 15.1 2200
1.80224 15.02 2230
1.88416 14.86 2230
1.96608 14.71 2230
2.048 14.61 2260
2.12992 14.55 2290
2.21184 14.45 2320
2.29376 14.27 2340
2.37568 14.11 2340
2.4576 14.27 2340
2.53952 14.48 2360
2.62144 14.39 2370
2.70336 14.2 2390
2.78528 14.05 2400
2.8672 14.26 2400
2.94912 14.3 2400
3.03104 14.39 2410
3.11296 14.36 2420
3.19488 14.17 2440
3.2768 14.24 2450
3.35872 14.39 2450
3.44064 14.35 2450
3.52256 14.17 2460
3.60448 14.29 2470
3.6864 14.44 2480
3.76832 14.33 2490
3.85024 14.3 2490
3.93216 14.48 2490
4.01408 14.83 2510
4.096 14.23 2520
4.17792 14.24 2530
4.25984 15.36 2540
4.34176 14.6 2540
4.42368 14.23 2540
4.5056 14.19 2560
4.58752 14.2 2570
4.66944 14.35 2580
4.75136 14.45 2590
4.83328 14.23 2590
4.9152 14.17 2590
4.99712 14.3 2600
5.07904 14.38 2610
5.16096 14.36 2620
5.24288 14.23 2630
5.3248 14.35 2630
5.40672 14.45 2630
5.48864 14.33 2640
5.57056 14.44 2650
5.65248 14.19 2670
5.7344 14.36 2680
5.81632 14.39 2680
5.89824 14.24 2680
5.98016 14.3 2690
6.06208 14.41 2700
6.144 14.39 2710
6.22592 14.32 2720
6.30784 14.26 2720
6.38976 14.41 2720
6.47168 14.51 2730
6.5536 14.36 2740
6.63552 14.16 2760
6.71744 14.39 2770
6.79936 14.44 2770
6.88128 14.33 2770
6.9632 14.33 2780
7.04512 14.39 2790
7.12704 14.3 2800
7.20896 14.32 2810
7.29088 14.41 2810
7.3728 14.3 2810
7.45472 14.24 2830
7.53664 14.36 2840
7.61856 14.46 2850
7.70048 14.42 2860
7.7824 14.26 2860
7.86432 14.23 2860
7.94624 14.32 2880
8.02816 14.63 2890
8.11008 14.35 2900
8.192 14.23 2910
8.27392 14.38 2910
8.35584 14.57 2910
8.43776 14.6 2920
8.51968 14.82 2930
8.6016 14.23 2950
8.68352 14.29 2960
8.76544 14.05 2970
8.84736 13.55 2980
8.92928 13.2 2980
9.0112 13.02 2980
9.09312 12.99 2990
9.17504 12.94 3000
9.25696 12.92 3020
9.33888 12.94 3030
9.4208 12.92 3040
9.50272 12.97 3050
9.58464 12.83 3050
9.66656 12.88 3050
9.74848 12.89 3060
9.8304 12.82 3070
9.91232 12.85 3080
9.99424 12.85 3090
10.07616 12.86 3090
10.15808 12.88 3090
10.24 12.91 3100
10.32192 13.38 3110
10.40384 13.24 3120
10.48576 12.94 3130
10.56768 12.86 3130
10.6496 12.88 3130
10.73152 12.92 3140
10.81344 12.88 3150
10.89536 12.85 3160
10.97728 12.91 3170
11.0592 12.98 3180
11.14112 12.91 3190
11.22304 12.89 3200
11.30496 12.86 3210
11.38688 12.86 3210
11.4688 12.92 3210
11.55072 12.92 3220
11.63264 12.7 3230
11.71456 12.7 3230
11.79648 12.77 3230
11.8784 13.49 3230
11.96032 14.17 3220
12.04224 14.69 3220
12.12416 14.66 3220
12.20608 14.61 3220
12.288 14.49 3220
12.36992 14.49 3220
12.45184 14.36 3220
12.53376 14.45 3220
12.61568 14.36 3220
12.6976 14.23 3220
12.77952 14.23 3220
12.86144 14.55 3220
12.94336 14.46 3220
13.02528 14.44 3220
13.1072 14.02 3220
13.18912 13.27 3220
13.27104 13.27 3210
13.35296 13.05 3120
13.43488 12.86 3020
13.5168 13.1 3020
13.59872 13.17 3020
13.68064 13.22 3050
13.76256 13.42 3070
13.84448 13.63 3090
13.9264 13.91 3100
14.00832 14.13 3100

[zalewskit]

[quote="SilverXJ"][quote="zalewskit"]


Another possibility is that the springs may not be up to par, causing the valve to bounce and wobble on the seat.

110lbs @ 1.700 spring height... 290lbs @ .470 valve lift.

T

[SilverXJ]

Warm idle is very lean 24 to 25 possibly because of valve overlap and 1 bad cylinder?

That is very very lean. I'm suprised that the O2 sensor even reads that lean. Mine stops at 19:1. I would investigate that further. A misfire could show up as a lean condition. But, I wonder what the PCM is trying to do to correct it? Making the rest of the cylinder rich?
Also, after 3230 your AFR goes lean again, too lean for WOT. You want 12.5-13:1

[zalewskit]

Attached are a couple of screen prints from my new tool... Innovates LM2 and logworks3. 1 is a few seconds at idle.. Way lean but I don't know what the other controls are doing to compensate(HESCO OBD1 ECU) and how much of that is valve overlap from the Hesco RV cam.

The second screen print is accelerating on the road from a roll to 75 mph and a short coast.

Not sure if it is even valid with the bad valve...mostly just learning how to use the wideband.

Regards,

Tom

idle and 70mphrun1.doc

[zalewskit]

[quote="SilverXJ"][quote="zalewskit"]

Start with seeing how wide the current contact patch is and its location. Then color the valve tip with a sharpie, put a washer under the rocker adifficult to do without an adjustable pushrod.

Thanks "XJ", I finally got around to checking the geometry. I am using stock valves and rockers. Tested as I have been running it I have a full contact across all valve stems. All of the blueing was removed after 30 seconsd or so of cranking.
What would be the purpose of using a washer? I assume you are not speaking of the .20 shim I was using for preload.

[zalewskit]

My new machinist evaluated the cylinder head and valves and believes that the combustion process is incomplete causing it to burn past the exhaust valve. The exhaust valves heat up and transfer heat to the seats softening them and distorting them.

So the first thought is timing. Timing is not really adjustable by me right?(Using the HESCO MPI kit) What should it be at idle?? And 2k rpm and above? I do recall not being happy with how the car idled with the distributor clocked as recommended by HESCO. I rotated the distributor clock wise and then counterclockwise until a stumble and marked the point. I then centered the distributor between the two marks. I understood this to be adjusting the fuel injector timing (ford 24lb 39psi max). In hindsight maybe not a good idea…

But how to test upon reassembley? I am thinking of clocking the distributor as directed and shooting the header with an infrared to determine exhaust gas temp. but what is a god temp vs a bad temp.

RV Cam is installed as ground to 4 degrees advanced on a 106.5 centerline (from memory)

Happy Holidays! Tom

[SilverXJ]

If the valve and exhaust gas is hot enough to damage the valve seats I would expect to see damage to the valve as well. BTW, transfer of heat from the valve to the seat is normal, just a question of how much.

You are correct on rotating the distributor that it controls the injector timing. Your procedure was outline by Hesco as well.

I don't think the RV cam is ground with 4* advance in it. I believe Hesco recommend you install the cam 4* advanced for an auto transmission and straight up for a stick.

How is the rest of your exhaust?