[dutch injun]

I was wondering how the tiny pits ocurred. Is this from detonation? No signs of that furthermore, everything looks good.
Combo is a 476, Procharger F1R 10 to 15 lbs boost.

[62fatcat]

yes you did. glad you fond it before you killed it.
i would take about 2 degrees of timing out of it at the higher boost numbers.
do you have any picts of the pistons?

[firechicken]

I'd like to see the pistons as well. That looks alot like corrosion and a hit from a carbide burr in a die grinder.

[guccieng]

was that the only chamber that looked like that?

[wrench]

Originally Posted by firechicken

I'd like to see the pistons as well. That looks alot like corrosion and a hit from a carbide burr in a die grinder.

And show us pics of the plugs if you can.

[dutch injun]

Fatcat: I did not photograph the pistons as they looked normal, no aluminum specks or anything. I did have them coated though.
All of the chambers have it, although this one is the worst by far.
No sign of pinging on the plugs they looked a little rich to me.

My compression is 8.8 and I am running C16 on the track. My timing is 34 locked with half a degree retard per pound. So at 15 lbs I was at about 27 total. I have a LM1 graph of a typical run. I feel like I have a pretty safe tune?

[PONTIAC DUDE]

From my take of the pic. And aluminum Edelbrock head.
Any water contamination in that cylinder can cause the same look. Especially with only one cylinder showing that.

I had the same basic look with an aluminum head, nitrous and slight water contamination. As long as it checks level and you might want to pressure check it as a power adder with high cylinder pressures would be in order.

If Ok run it and have fun.

[Brian Baker]

Originally Posted by PONTIAC DUDE

From my take of the pic. And aluminum Edelbrock head.
Any water contamination in that cylinder can cause the same look. Especially with only one cylinder showing that.

I had the same basic look with an aluminum head, nitrous and slight water contamination. As long as it checks level and you might want to pressure check it as a power adder with high cylinder pressures would be in order.

If Ok run it and have fun.

You would know more on this than me...I just wanted to add you're probably on to something, given the impression left in the head from the gasket looks like a standard Fel-Pro gasket is being used.

[mysticmissle]

he built shortblock he should know

[PONTIAC DUDE]

Originally Posted by Brian Baker

You would know more on this than me...I just wanted to add you're probably on to something, given the impression left in the head from the gasket looks like a standard Fel-Pro gasket is being used.

He had Cometics. But with 4 bolts per cylinder and boost. Mileage, etc. Never say never.

But with the E-head water holes so close to the gasket and cylinder edge with a 4.350 bore, seapage can occurr. I drill the block different (IA II block) then most and move (drill) the holes in the deck towards the outside of the head holes but the head & gasket are still a bigger hole.

[bad69bird]

Originally Posted by dutch injun

My compression is 8.8 and I am running C16 on the track. My timing is 34 locked with half a degree retard per pound. So at 15 lbs I was at about 27 total. I have a LM1 graph of a typical run. I feel like I have a pretty safe tune?

DI,

27* at 15lbs is WAAAAAYYY safe; however, if I am looking at your graph right, you had two really good spikes during that run (12-4-12.7ish range). I would look to get that graph more flat that it is, via carb tuning. What carb are you running again? If your pistons don't look "peppered" then I would think that you are ok. But, do you have any idea what your intake temp is? That F1R is a bad Mo Fo and creates alot of heat. Your AFR's appear to be ok, but if your cylinder temp is too high because of the intake temp you will detonate (Trust me I know...LOL). Did you leak-down the motor before you pulled it apart? If so, was the motor hot or cold and what was your results? I'm ASSuming that you are running a BTM box by your statement, are you sure that it is pulling the timing out? If your not running a BTM and you are using a MAP sensor...throw that F'ing thing in the trash! The one nice thing about the Digitial 7 box is that if you have the timing retard wired into your transbrake button it is easy to check to make sure it is working properly.

I agree with the others that you might be having seepage issues. Like Dude said, 10 head bolts, boost, 4.350 bore, and 200 miles round trip to the track is a receipe for head gasket issues, IMO.

The questions that I pose to you are just leads for you to investigate...16lbs of boost is in the medium range of boost, IMO, but you are starting to get to another level of maintainance. Again, IMO, FWIW.

Good luck and let us know what you find out!

[dutch injun]

Thanks everyone, I am learning as I read.
Badbird: Those spikes I have always had even on other engines and carbs. You can see it through all the rpm range. I don't know if it is fuel related or ignition or other, are yours smoother? . I thought it was normal because of the smoothing option you have to get a more flat reading. BTW this graph is with a .24 smoothing.
I don't have a intake temp gauge, that maybe something to look into. I just felt it wanted alot more timing with C16, it makes so much more power with a few degrees, and the motor just seems happier.. peppier...
I did not do a leakdown test, I pulled the motor because of an oil pressure issue (stock pan, no windage tray), but that is solved now hopefully.
I am running a Mallory Hyfire VI with MAP sensor and boost retard, I checked it with a compressor and timing light and it pulls timing. I will recheck it though. I do have an MSD digital 7, but don't trust it for longevity on a street car, which mine is. And the MSD does the same thing, pulling timing via MAP sensor?
I will keep an eye on the water seepage, will check leakdown before and after my runs, which are only a dozen a season or so...

[bad69bird]

Quote: "Those spikes I have always had even on other engines and carbs. You can see it through all the rpm range. I don't know if it is fuel related or ignition or other, are yours smoother?"

Answer: Yes, mine are alot smoother. The version that I have of the LM-1 I can't find the smoothing option. LOL I've used it a while ago, but can never find it when I'm looking for it. I pull up the gauge and so it down to a 1/8 speed and watch the readings there. I'll post up a pic of my graph shortly. I have to go out in the garage and get my laptop out of the car.

Quote: "I don't have a intake temp gauge, that maybe something to look into. I just felt it wanted alot more timing with C16, it makes so much more power with a few degrees, and the motor just seems happier.. peppier..."

Answer: I'm looking to do the same thing this winter. I think I'm going to buy the LMA-3. I hear ya with the motor wanting more timing.

Quote: "I am running a Mallory Hyfire VI with MAP sensor and boost retard, I checked it with a compressor and timing light and it pulls timing. I will recheck it though. I do have an MSD digital 7, but don't trust it for longevity on a street car, which mine is. And the MSD does the same thing, pulling timing via MAP sensor?"

Answer: I am not a fan of the MAP sensors even if you use it with the Digital 7. I have seen too many guys burn their chit up with the MAP sensor deal. I would set the base timing and go from there. Either use the time based or RPM graph options. IMO, FWIW. Ask Brad about his dealings with MAP sensors...

Quote: "I will keep an eye on the water seepage, will check leakdown before and after my runs, which are only a dozen a season or so..."

Answer: The seepage is from the heads lifting. Do yourself a favor and buy a leakdown tester and check it regularly...a leak-down tester is your friend!!!

[62fatcat]

i might have been wrong if it is only 1 cylinder that has the problem.
i would still try less timing and se if hurts performance or not.

Brad.

[bad69bird]

DI,

Here's a photo of two of my logs from Norwalk. The runs are at the beginning of the recording. The "ramp" that you see atg the start of the run is when the timing is getting ramped back in. The first photo my AFR's varied .3 (10.6-10.9). The second run the AFR's varied .4 (10.5-10.9).



PS. I found the smoothing option! LOL The pics above is raw data...no smoothing.

[dutch injun]

That does look ALOT smoother. All of my inputs have that spikyness: RPM, PSI and AFR. Though AFR is the worst. I smooth them all. I use the RPM convertor for the other inputs. My sensor is in the pass side collector. I will have to look into that.

I have to admit that I never retorqued the headstuds, I thought Cometic did not recommend that. And when we disassembled it, a couple were looser. That might have been the cause?


Badbird, thanks!

[bad69bird]

Originally Posted by dutch injun

I have to admit that I never retorqued the headstuds, I thought Cometic did not recommend that. And when we disassembled it, a couple were looser. That might have been the cause?


Badbird, thanks!

YES retorque. Do a heat cycle and let it cool down over night, then retorque the heads. Do one bolt at a time loosen it a 1/4 turn, then in one full sweeping motion retorque the stud. Once you're done, I always go back and recheck'em (make sure the wrench clicks or beeps depending on which torque wrench you have.)

It's possible that might have been the cause...

Who's carb do you have?

[BruceWilkie]

You may want to check out this Nelson 1500hp 406 build I posted

http://forums.maxperformanceinc.com/...d.php?t=618082

take note of how he seals the heads. You may not be able to re O ring the way he has but I would at least coat copper gaskets with 2 stroke case sealer. Yamabond4 brushes on and dries to a plasticy compound(feels like same plastic used for toy soldiers) Your local Yamaha dealer should stock it, if not they can order it. Very tough stuff and doesnt gel when exposed to fuel oil or antifreeze. Works great for pan and timing covers. I've used it successfully without gaskets. Surface needs to be clean and oil free for best results. Enamel reducer helps remove the stuff but a scraper (sharp wood chisel) and a stiff wire brush in a die grinder work best.

[dutch injun]

I think I have the same carb as yours, an 850 CSU.

[bad69bird]

Are you running the boost reference power valve(s)? If so, little movements can make HUGE differences with how steady your AFR's can be. I would call or e-mail Kevin and talk to him about your carb...maybe it's time for some upgrades.