engine break in procedures

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jdeleon
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engine break in procedures

Post by jdeleon »

I'm curious what methods of break in is used by other engine builders on the dyno. Most common ring is moly top, like Speed Pro, Total seal, etc, and normal gm, ford and aftermarket cast iron blocks. Same basic honing procedures most of you guys use on cv-616.
javier
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engine break in

Post by jdeleon »

Okay, I'll try to be a little more specific with what I'm getting at with the above posted question.
After running a (new or fresh) engine on the dyno, I note the exhaust port deposits are usually black..sticky.. greasy like. No signs otherwise of oil consumption or contamination in cylinders or pistons. Minimal if any coloring in intake ports, bsfc depending on engine .31-.49, normally good to excellent power- torque curves. Not a valve guide issue either.
Oil ring tension is generally standard or in some cases low tension but never below 12#radial tension. Top and second ring wear looks right, and engines don't smoke on dyno or down track. Also no vacuum pumps on these in question.
javier
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Post by bill jones »

-I can't tell you why that black goo happens but I had a methanol injected SBC sprint car engine on my run in stand in the early 1980's that bothered me with that problem.
-I didn't want to ship the engine out with gooey ports so and I was doing a leakdown test so I decided to wipe the ports with a rag and carburetor spreay cleaner, got most of the goo out of there, then I sprayed the cleaner right into the exhaust valve and used another air hose to get the last of the port clean.
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-When I sprayed the cleaner into the bowl areas I found there was air leaking full circle past the exhaust valve from the air I had in the cylinders for the leak down test and yet the leakdown numbers were well less than 4%.
-I knew I had done the valve job, the seats & valves pretty darn right yet I had this leakage so I removed the heads, looked at the seats and I couldn't find anything that looked even the least little bit wrong.
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-So I bolted a pressure plate to seal off the PORTS and tried to see if the intake andthe exhaust valve leaked on the chamber side and they were all perfectly sealed up.
-No changes, bolted it back on the engine again and retested and the valves were slightly leaking again as I had previously seen.
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-I went ahead and let the engine go, it ran hard like it should and had no problems.
-I checked that same engine after the first race and there was no evidence of that leakage I had seen on the run in stand, and the leakdown numbers were still about the same.
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-But I then built a 2" thick head torque plate to clamp to the heads when I did the valve seats on other heads, and found that the torquing of the bolts was causing the small leakages I was seeing, and that plate eliminated any further leakages on assembled engines that I did when using the headplate.
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-I found the same thing on 4 valve per cylinder so I have plates made up for a variety of cylinder heads.
-BUT---using the plates really is a lot of work and I don't use'm very often because most people don't want to pay double for the valve job.
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-In all honesty I believe the black goo is caused by the idle and part throttle mixtures being too rich, and because the ports, chambers and piston tops are too smooth.
-Carburetors are a b-tch to get really right at idle and low speed and mechanical injectors have the problem of getting the barrel valves vs the idle idle check right and the injector nozzles are real drippy at idle with virtually no atomization.
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-One other thing that people miss is not understanding the evaporation ranges of the various racing fuels and how that affects the various stages of engine operation.
-You can't get fuel to work until it is evaporated and race engines need a LOT of help at idle and part throttle because there is virtually no vacuum and NO air speed and NO heat to help the fuel get evaporated.
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Post by k-star »

I do not have a dyno but i do run my engines in a test stand. I also notice the same problem you are seeing. One thing i did notice the amount of black goo is different depending on what typ of lube i put on my valve guides.... I am not saying this is the cause but i do notice more of it with the thicker (red) assembly lube then if i used the white based grease... I always wanted to try just some wd-40 on the guides and see if the problem decreased but i never had the guts to try it...

I think you are seeing two problems the rich idle like Bill was describing plus the lube from the guides causing the goo stuff......

Keith
“If I hit you with this you’re going to be numb, that’s why they call them numb-chucks “Si Robertson
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Post by jdeleon »

Bill and Kevin
First thanks for the insite... And Most Importantly...you both are spot on I think!
The last and worst case was last week on a dirt mod alky flat top cast iron head 406 sbc( I don't do a lot of alky on the dyno). As you state powerand torque was good(728hp/635#) No signs of excessive blowby or leakdown. But you gotta make heat and that takes time.
Kevin, I do use a heavy lithium grease on the guides and valves and red assy lube on most components.
I feel better now.. I was concerned I might have a honing or break in issue.
THANKS AGAIN FOR YOU HELP,
javier
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Post by bill jones »

-the first time I ran a methanol injected engine taught me about how much fuel these engine consume, like 5 gallons wouldn't last 20 minutes just setting the timing and with no load.
-All you have to do is touch the headers at idle and you realize you can nearly hold your hand right on'm they are that cold.
-People always seem to brag about how cool their methanol engines run and those type of guys are easy to beat on the race track when you learn how to build heat in the methanol engines.
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-One other detail about methanol.
-the temperature is so cold inside the intake ports and that temperature is directly transmited into the oil, and is a very effective oil cooler of all the oil that splashes up onto the bottom of the manifold runners and that oil that washes about the intake port of the heads.
-There is lots of square inch area of cooling taking place inside the intake ports that turns keeps that methanol from ever evaporating.
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-One more detail: what do you do about exhaust valve stem seals?
-Have you ever noticed the black trail from the valve guide up and out the roof of the exhaust ports?
-How do you test the stem seals to see if they are actually sealing?
-what did you do about the trail from the guide along the roof?
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engine break in

Post by jdeleon »

Bill, good point and food for thought.
Guess I'll 'paint" the inner side of the manifold to see if any thing noticeable shows up.
I use teflon seals on both int and exh valves on all my motors. There is always a press diff between each end of the guides. (In fact, i'll bet the motion of the valve spring-retainer acts like an air pump right down the guide.)I don't think you can eliminate that leakage completely, without adding a vacuum pump(or can you?).
I'm sure you've figured that out too!
I'm all ears!
javier
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Post by bill jones »

-nothings been said here about what type of engine you are concerned about so there are specific things that we could talk about if we knew exactly what we are dealing with.
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-I've had several good running engines that "burn oil" for no apparent reason so this leads to checking a lot of things that we usually take for granted.
-one such street engine I found that low tension oil rings were the problem but the standard tension rings had enough extra drag that the power drops appreciably.
-another was traced to SBC AFR heads that are poorly designed in the valve shim end of the valve spring pockets and the oil level is constantly at or above the bottom of the valve stem seal.
-On these heads I machine an oil drainage trough that cuts the bottom of outside diameter of the spring pockets so the oil can drain away.
-These same heads have the oil holes at the ends of the heads too high so those holes need to be modified.
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-I fabricated a valve stem with an O-ring on one end that would seal the valve guide then cross drilled a hole down thru the valve and the cross drill was just before the O-ring so that I could plumb air pressure into the valve to guide clearance area and I found that with the white teflon seals that they all leak at the bottom of the seals below the expansion joint of the metal band that encircles the the seal.
-If that expansion joint happens to be down in the flooded oil then it sucks oil real easy.
-Another recent engine was using oil so bad it fogged the oval track to the point the car would get black flagged off the track.
-The only change made to fix it was valve stem seals, went from white teflon to the metal encased rubber push on seals and that was the magic it took to fix that engine.
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-All of these oil burning stories may not have anything to do with your wet exhaust ports but maybe something else is the culprit here.
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-On the methanol exhaust ports, if I see a shiney washed clean path out the exhaust port anywhere, I touch up that area with a stone-rough it up a little, and that area then looks right next time the engine comes apart and usually runs better.
-I also do the same stone finish thing in the chamber and on the piston tops and inside the intake port and on the underside of the intake valves if I witness the "clean" washed areas.
-Most guys running titanium valves don't care for me to put a stone finish on their valves but I feel they are too slick and steel valves can be swirlpolished and nodody thinks anything about that.
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-If there's a streak from the guide out along the roof towards the header I work on better oil seals and at keeping the oil from flooding the bottom of the springs and the stem seals.
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-I don't know what the reason is you'd paint the inner side of the manifold.
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engine break in

Post by jdeleon »

Bill, again thanks for the insite.
"I don't know what the reason is you'd paint the inner side of the manifold."
I guess I'm showing my age,.... Todays manifolds, the runners are separated from the valley tray. I was thinking of 'improving' the heatsink ability of the lower runners with the oil. Since, especially with alky motors, I tend to leave a pretty rough floor surface finish and could do the same to the outside of the runner if only it was exposed to the oil splash. The paint was in reference to stuff I had gotten from Techline many years back, that would help absorb heat.
I'm going to look into the metal/rubber valve seals.
The engine in question was a sbc 406 for a limited modified dirt track team. Dart 23 deg iron heads.
Thanks again,
javier
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Post by bill jones »

-Generally when I see an oiling problem the first thing I check is the valve guide clearances and when I see'm around .0016" on a 11/32" stem I feel the guides are just too loose, but I have run knurled or spiraled guides that loose with no obvious problems.
-I had one SBC 406 engine in an early 4wd S10 Blazer where the oil pan was a nightmare to fabricate, too small and too tight and no room for internal volume, and that engine was another oil user until we took it out and changed pans and installed it in another vehicle.
-Didn't burn any oil at all in the second car.
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-I see problems all the time where the oil level is too high and the cranks are whipping up on the oil and this creates an oiling problem and brings on the oil pressure light way too soon on the race track.
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