DEAD 4.7 stroker! HELP!

[crustodd2]

Hey All,
Haven't been on in a while. Lost my business about 16 months ago and have been tryin' to get things back together since. just when a possibility look like it was comin' up ( I own a semi tractor), both my Jeeps took a dump on THE SAME DAY! AAAAAAGH! My '99 Grand just had a bad tranny output shaft sensor. Easy fix. My '94 Cherokee with a 4.7 stroker, BAD NEWS. It had always been "noisy" in the valve train and the last two weeks before it crapped out, it had developed a different and louder tick-tick-tick. I was pretty sure I was losing a cam at 15K like so many of us seem to have. One day last week, it suddenly started running like it was a five cylinder! I talked to my mechanic and he suggested cap, rotor, and plug wires. Did the C&R, made no difference. Tried a different plug wire on #3 cylinder, which seem to be the one misfiring, made no difference. Changed the plugs, too. #3 looked "wet", but it has turned out to be oil and all the plugs looked REALLY carboned up. So a compression check was done and #3 was about 50LBS lower than #2. Decided somethin' was SERIOUS internally, so the head was pulled off. The machinist/builder said that on just a quick visual, the head looks fine, but has pretty heavy carbon build up for such low miles. The #3 combustion chamber looks cleaner than the others and could be indicative of an injector issue. Now the serious stuff. I have the KB 944's, I think. They have been VERY noisy from the start, but usually are totally quite after it's warmed up. I know forged pistons are inclined to that, but it seems like they've gotten progressively louder. I have had oil consumption problems for a long while too. One of the other machinists commented that since the tuning at UniChip resulted in needing to reduce the fuel all across the RPM range, that could have caused the rings to wear prematurely. I had the 'Chip tuning done at about three thousand miles. The cylinder walls show an odd wear pattern down one side, too . #3 piston was pulled and the rings are ALL intact! We expected a broken oil ring at least, but they are all there. BEFORE ANYONE ASKS, the pistons were installed correctly. The quench pad has to be aligned to the one that's in the head, so they were in the way they're supposed to be. I have the Ford #24 lb injectors, Lunati 63501 cam, and I have run water/Meth. part of the time. Also the block was zero decked and the combustion chambers are 54cc. I have been runnin' a 180 degree T-Stat., but it has been runnin' cold so that might account for some of the carbon buildup.

So, here's a few questions

#1-If the #24 lb injectors were WAY over fueling, would it be wise to go back to the stock #19'ers and have them "adjusted" up a little by UniChip to get the fuel output level correct? It always smelled rich to my nose with the #24's.

#2-Can I go to a little thicker head gasket and take some material out of the piston dish to lower the compression? I always run 91 octane and it's still had ping issues.

#3-Since I'm already at .60 over on the pistons, how much can you bore these to fix a problem such as this? I thought about goin' to the 4.2 rods and different pistons to quite things down and perhaps lower the compression, if that's necessary and possible.

ANY SUGGESTIONS WOULD BE GREATLY APPRECIATED! I know there's a MASSIVE amount of knowledge amongst you guys and many of you have been down this road before. This will be my THIRD build of this engine in four years and about 35K miles. The honeymoon is over. The timing is terrible on this for me and I just want to get it back together and reliable, even if it's in a detuned state.

Thanks all,
Todd

[crustodd2]

No suggestions? I could use a little help here folks.

[crustodd2]

Hmmm... I just discovered that the KB 944 pistons are 9.5:1 compression. I thought they were 9.0:1. There doesn't seem to be any way to account for the compression rating of the various pistons on the calculator. Am I missing it? That would have put my static comp. at 10.27:1 That would account for the pinging issues I had. I realized that my combustion chambers are 58cc too, not the 54cc I stated in my first post

[Cheromaniac]

Sorry to hear about your stroker troubles Todd. Hopefully we can help you fix it.

1. I don't think that 24lb injectors are too big. I'm running the same ones. It does seem that the Unichip tune is off but I'm wondering why you even need a Unichip at all on a '94 OBD I. I'm running the stock computer and a MAP adjuster set at 5.2v.

2. Assuming you have a '94 head that hasn't been milled and a '94 block that's been zero decked, the static CR should be 9.6-9.7:1 (57cc heads, 21cc pistons). Not high enough to cause pinging problems on 91 octane.

3. It's a gamble to bore the block beyond +0.060" so see if the cylinders can be rehoned.

[crustodd2]

Hey Dino, Thanks for replying. After I first had the engine together, it ran great. Smooth, torquey, quite. As I accumulated some break in miles, I noticed that it wouldn't rev all the way through the power band. It was stuttery and felt like it was hittin' the rev limiter, but I don't think that was it. this would occur at around 4500-4800 rpms. The valve springs are the dual stage 5.2 springs and the Lunati cam only has a .448/.507 lift, so the springs shouldn't be floatin'. Also, I was noticing some pinging, so I added the water/meth. That seemed to eliminate the ping problem, but it was still stuttering at high rpms, WOT. So I took it to UniChip to try and get the timimg and the fuel tuned in accurately. As I mentioned the tech said it was running rich all across the power band. I had a thought that maybe I accidentally ended up with larger than #24 injectors. Not sure yet. Why would the engine be over fueling?

So, UniChip set the 5 position switch with, #1-minus fuel and 3 degree - timing, #2- 2 degrees + timing and minus fuel, #3- 4 degrees + timing and minus fuel, #4-5 degrees - timing and minus fuel, #5 Same as #1, but 50% fuel added back

I usually ran it on the #1 position, but in the last 5000 miles it had gotten to the point of pinging even on the #4 switch setting. I thought it could be bad fuel, and the water/meth had been leaking and not spraying correctly. The heavy carbon buildup could account for some of this too, I suspect. If the KB 944's are 9.5:1 pistons, that should put those compression specs .5:1 higher though, shouldn't it? That's be over 10:1 static and I can see how it would ping on these iron headed engines, even on premium. I'm only about 150' above sea level where I live.

At any rate the engine has been consuming oil, so there is a problem in the bottom end. The machinist will have it apart today and I should have a clearer idea of what went wrong/is wrong

[Cheromaniac]

Oil consumption will cause the engine to ping since the oil lowers the effective octane rating of the fuel.
How much did you have milled from the block & head?

[crustodd2]

Hey Dino,
I think about .050 have come off of the head and .045 were removed from the block to get zero deck height.

[SilverXJ]

I'm not very familiar with OBD I, but I would assume it has an open and closed loop like OBD II. In closed loop the engine would be reading off the O2 sensor for fuel trims. If it was indeed rich in closed loop than the injectors are either too large for the PCM to pull enough fuel out (which I doubt), or possibly a faulty O2 sensor or other sensor. Too much fuel would cause excess carbon build up, which could increase pinging. The stuttering/seeming rev limiter issue could be caused by a bad fuel pump (did you check your fuel pressure while driving?) or again, a faulty sensor. The excess carbon build and rich could perhaps be caused by a weak fuel pump as well. I.e. not enough pressure to atomize the fuel coming out of the injector. Instead of a spray you end up with a thick stream.


IIRC the Lunati cams are very similar to the Comp cams in their lobe profile, which will make some noise in the valve train.

The KB pistons are forged, but shouldn't be very noisy. KB's initial batch was of the 2618 alloy, and their later ones are of the 4032 alloy. the 2618 will expand more and requires more piston to wall clearance. They are stronger though, but for a NA stroker the 4032 will be fine. The 4032 will require more clearance than hypers, but less than the 2618. I've had both versions of the pistons. IIRC the 2618 had .004" clearance and the 4032 had .003" clearance. Neither were very noisy. During the summer it wasn't even noticeable. I only really noticed it in the winter and the engine just seemed louder than usual, not really excessive. You saying that it was very noisy is a cause for concern. If you want to know what alloy yours are out of call KB. There are numbers on the piston they can use to find the alloy that was used. Perhaps they are the 4032 alloy and the machinist set them up at 2618 clearances, or just based his clearances on larger bore engine he had built with forger pistons. Either way they shouldn't be very loud.

[crustodd2]

Hey Silver,
Thanks for the input. O2 sensor was new at time of rebuild. I have the Hesco FP regulator too, but not sure if it was adjusted. I remeber Bernie saying they are set to 44lbs, it seems like. Yes, it was rich in closed loop. I'll look at the fuel pump possibility, but the Jeep only has about 95K original miles on it to begin with, and I didn't have fuel pressure problem when it was a 4.0.

Now the bad news. The cam is toast. One lobe is almost completely gone. Yet another one dies. Two of the KB pistons are scored bad enough that they're gone too. I think that if I'm correct and those are 9.5:1 pistons, which I would have issue with KB over, then that put my static comp at about 10.27:1. TOO much for an iron head, iron block engine. The cam death? I used Brad Penn oil and cam additive the whole time and it lasted 15K so I just don't know. That's TWO "performance" cams in this engine in about 25K miles for me and I'm not likin' it. Because I've taken a fair bit off the head and block, that could be some badness in the mix too.

So here's my thoughts. I am considering, strongly, a different block, to get the compression down (less decking), 4.2 rods and hyperutectic pistons, for a better and quieter fit, and either a stock cam, ala Dino's approach, or maybe the 505 roller. If I went back to a stock cam, which year do you guys recommend? I have a big valve conversion on this if you all recall. Would I keep the added 5.2 springs or new stockers? Which brand of pistons are you folks likin' at this time?

The machinist thinks the new oils are the main culprit on the cams dying and he's gonna' start selling the Joe Gibbs Hot Rod oil. He said it should be the fix for our flat tappet engines. He also thought that the high compression combined with the forged piston likely resulted in the oil consumption.

Thoughts anyone??

[crustodd2]

By the way,
Where would I get a NEW factory cam, should it be the dual pattern, will I still get the benefit of the big valve head, and what lifters should I run with it?

[SilverXJ]

Now the bad news. The cam is toast. One lobe is almost completely gone. Yet another one dies. Two of the KB pistons are scored bad enough that they're gone too. I think that if I'm correct and those are 9.5:1 pistons, which I would have issue with KB over, then that put my static comp at about 10.27:1. TOO much for an iron head, iron block engine. The cam death? I used Brad Penn oil and cam additive the whole time and it lasted 15K so I just don't know. That's TWO "performance" cams in this engine in about 25K miles for me and I'm not likin' it. Because I've taken a fair bit off the head and block, that could be some badness in the mix too.

Yeah, given the 54cc on the head that would put your compression a bit high. Hrm... what is your cam break in procedure? Did you check for binding in the valve train? Check for valve bind, retainer to seal (if your seals are fubar'd it could explain the oil), and check the pivot point on the rockers. I know with stock rockers that could be a problem. .507 might be a bit high for some stock parts.

So here's my thoughts. I am considering, strongly, a different block, to get the compression down (less decking), 4.2 rods and hyperutectic pistons, for a better and quieter fit, and either a stock cam, ala Dino's approach, or maybe the 505 roller. If I went back to a stock cam, which year do you guys recommend? I have a big valve conversion on this if you all recall. Would I keep the added 5.2 springs or new stockers? Which brand of pistons are you folks likin' at this time?

I would replace the head with one that wasn't cut so much. 54cc is small. The big valve conversion isn't worth much, if anything in terms of power. If i was going with the 505 cam I would tell them do not touch the lifters and put my own oil passages in them instead of their trenches. From your description the KBs were installed with too much clearance. They shouldn't have been very loud at all.

[Cheromaniac]

Hey Dino,
I think about .050 have come off of the head and .045 were removed from the block to get zero deck height.

Wow, no wonder you had pinging problems! The SCR was a way too high ~10.4:1. Since you have so many damaged parts (cam, lifters, pistons, block cannot be overbored again, head milled too much) I suggest you buy a decent junkyard 4.0 long block (preferably '91-'95 for the stock cam/head) and start with a clean slate. You can rebuild it into a copy of my 4.6 "poor man's" stroker for very little cost. The only extra parts you'll need are 4.2 rods, 677CP pistons, rings, bearings, and gaskets/seals. You can salvage the 258 crank and any other good bits from your damaged engine and keep the ones you don't use as spares.

[crustodd2]

Hey Dino,
Yeah, when I realized that I pealed the block down to get the zero deck for quench and the head to get to 58 cc, I started to see the error. That with the extra .5:1 that the pistons actually are, and it's kinda' surprising the problems weren't worse. I'm gonna call KB on the pistons, maybe they will hook me up with a set of the SilvOLite's. Do I have to use a '94 block to work with that head? External tabs and bolt holes bein' considered. If I start with a "new" block, but I'm still gonna' use the big valve head, what CR pistons should I use and what should the block be machined to so that the quench is correct?

[crustodd2]

Silver,
I seem to recall the KB's were installed with .003 clearance. The machinist was aware of the fit issues. Also, the chambers were 58cc, not 54. My error. The rockers are the Yella Terra 1.6 and the machinist,who has 30+ years building flat tappet engines, spent quite a bit of time checking the valve train geometry to get it right. He said the head looks fine overall and the dual stage 5.2 Mopar springs are supposed to be good up to .525 lift. It was only at 1-3K rpm's most of the time, as I drove mine jeep pretty mellow mostly. In the past couple of months I've done some 2-3 hour freeway/highway trips and that may have just finished it off. The pistons were REALLY noisy on cold start up, but got quite as soon as they were warm. Then again, with the valve train noise in there too, it's hard to say. What do you guys think was causing the oil consumption? It really only started to ping bad under light driving conditions recently and even then the ping wasn't severe. Mainly at about 1/2 throttle and on uphills. It had started to smoke recently too, lightly. So the cam went and it's schrapnel probably scored the pistons, but all the rings were intact. Lotsa' crud in the combustion chambers, so oil was gettin' past the rings.

[SilverXJ]

Where are you getting 10+ cr from? Even with a 0 deck clearance and .043" gasket I still get 9.77:1 static on the calc. When you say cold start, are we talking dead of winter cold, or just summer cold engine?

FYI the dish on the KB944s is 21.7cc

One other thought is that the oil was coming through the CCV system, not the rings.

How did you break the cam in though?