#21  
Old 02-13-2024, 05:56 PM
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https://www.summitracing.com/parts/m...kaAtjIEALw_wcB

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  #22  
Old 02-13-2024, 07:01 PM
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I tried that block off plate from the fuel with a -12 fitting to evac the oil pan and it didn't help much. I went with a vacuum pump.

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Old 02-13-2024, 07:29 PM
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could not find the pic of the one I described, it was on a friends RAIV race engine

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Old 02-13-2024, 07:43 PM
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Quote:
Originally Posted by 461-69bird View Post
Steve, yes he did a leakdown test before running it up to 3000 to see for himself if it came out the dipstick, which it did.

Chuck, do you think that brace is the cause? It's the same set up as when I ran the solid roller when it was built originally by Len and Shaker. It always leaked from the pan gasket before, but perhaps the rings sealed better when they built it than now on this rebuild. Yes and that is possible. More blow by from the rings.

If that's part of the problem, short of removing the epoxy or drilling vent holes, would putting a breather where the valley pan pcv grommet is, relieve some pressure? It's currently plugged as I'm not running a pcv.
So your compounding the situation with no pcv system.



I'm a novice at best. There are lots of folks on here with tons of experience. Having said that, common sense to me that your pushing a s**t load of oil out the dipstick from the post you showed with a container tells me the crankcase is being pressured up. How it gets there, well I'm no mechanic. I do not like the fact that the valley area of the engine is sealed up. so how are we gonna remove the pressure in the oil pan? Well I would ask the builder to drill 1/2" holes to see if you can relieve pressure from the crankcase. Also, how is your oil getting back to the oil pan from the heads?

Like mentioned, The front of the oil pan is open into the timing cover area, but from there, that's where it ends. You could try venting from the fuel block off plate if your not running a mechanical pump. I don't think it will solve your issue though.

So alot of folks also run a Mega brace on Pontiac engines and they either run external lines to the oil pan of the heads and probably run a vacuum pump.

When running a vacuum pump air is being pulled from the internal oil parts of the engine. From oil pan right up to heads.
Block pic is for reference. That's alot of open area from the oil pan.
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Old 02-13-2024, 08:03 PM
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With a Mega Brace installed it isnít completely sealed up.

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Old 02-13-2024, 09:12 PM
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Chuck, it's not completely sealed, there are 2 holes in it already. This may not be enough but Len says it's not creating extra pressure into the crankcase and he designed and poured it.

I've not been able to run a pcv as it sucked oil through it. That was in the valley pan, not sure if would be any different if it was in a valve cover. Also the problem only occurs at 3000rpm and above when I have higher vacuum, so would having a pcv make a difference?

I don't think the rings sealed completely and that may not be helping. The builder has agreed to rehone and fit new rings and try again, all at his expense.

I will ask him if it's possible to drill extra holes while it's apart just incase.

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Old 02-13-2024, 09:22 PM
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Quote:
Originally Posted by 461-69bird View Post
Formulas, my current set up and problem is lower hp and tq than before. 542hp 581tq now against 620hp 601tq.

Total timing is the same at 34 so do you think setting it at 30 will help?

Its easy to pull a little timing out, might do nothing, might be an eye opener, costs nearly nothing

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Old 02-13-2024, 10:33 PM
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Quote:
Originally Posted by 461-69bird View Post
Chuck, it's not completely sealed, there are 2 holes in it already. This may not be enough but Len says it's not creating extra pressure into the crankcase and he designed and poured it.

Hmm, It may not be enough area.


I've not been able to run a pcv as it sucked oil through it. That was in the valley pan, not sure if would be any different if it was in a valve cover. Also the problem only occurs at 3000rpm and above when I have higher vacuum, so would having a pcv make a difference?

Makes sense, any area that allows air to escape is bring oil with it.


I don't think the rings sealed completely and that may not be helping. The builder has agreed to rehone and fit new rings and try again, all at his expense.
Ya, this is probably your issue. Rings are allowing blow by.
I will ask him if it's possible to drill extra holes while it's apart just incase.
Probably good to open area up some, plus a rehone. Put the engine on a dyno after and seat the rings. Also good time to set carb and timing. and if you have issue.

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76 Trans am, TKX .81 o/d, 3.73 Moser rearend,
468 with KRE D-ports, Doug headers, 3" Exh.
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Old 02-13-2024, 10:34 PM
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Be nice if you could post a closer pic of valley area.

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Best so far 10.12@133 mph. 1.43 60 ft.
76 Trans am, TKX .81 o/d, 3.73 Moser rearend,
468 with KRE D-ports, Doug headers, 3" Exh.
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Old 02-13-2024, 11:34 PM
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Not trying to hijack this but learn something. What is the purpose/benefit of the pour over the mega-brace?

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Old 02-14-2024, 05:38 AM
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Quote:
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Be nice if you could post a closer pic of valley area.
Looking again it has more holes along side the lifter bores.
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Old 02-14-2024, 07:02 AM
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It's probably worth sending a oil sample out to see if there is excess combustion residue in it.

If so then you know that could only be coming from blowby and the many reasons that could make for that problem, like ring grooves that are not right or even the wrong rings being used in regards to the ring grooves in the Pistons.

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Old 02-14-2024, 08:35 AM
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Quote:
Originally Posted by 461-69bird View Post
Looking again it has more holes along side the lifter bores.

Take this with a grain of salt so to speak. That is not enough holes or open area in my opinion. Those holes will be full of oil draining back from the heads. Make sense why your issue starts happening at 3000 rpm. The oil pump will be putting out it's full pressure or close to it, and lots of oil flow to the engine. I do not like what is done to the valley area. Why does it look so dirty?

Why do you need a brace anyway, for what your doing? We made close to 600hp 600 torque with no brace. Ran like that for years no issues. We had another engine with 550 hp no issues. Sorry to sound so critical. I would almost invest in another block and start fresh.

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Best so far 10.12@133 mph. 1.43 60 ft.
76 Trans am, TKX .81 o/d, 3.73 Moser rearend,
468 with KRE D-ports, Doug headers, 3" Exh.
  #34  
Old 02-14-2024, 09:09 AM
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The brace was done for when I had the solid roller, done for extra insurance I guess.

Another block is not an option, there are no good ones here in England and by the time I shipped one from US, it would cost too much. Plus not knowing if it was good or not.

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Old 02-14-2024, 10:23 AM
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Quote:
Originally Posted by chuckies76ta View Post
Take this with a grain of salt so to speak. That is not enough holes or open area in my opinion. Those holes will be full of oil draining back from the heads. Make sense why your issue starts happening at 3000 rpm. The oil pump will be putting out it's full pressure or close to it, and lots of oil flow to the engine. I do not like what is done to the valley area. Why does it look so dirty?

Why do you need a brace anyway, for what your doing? We made close to 600hp 600 torque with no brace. Ran like that for years no issues. We had another engine with 550 hp no issues. Sorry to sound so critical. I would almost invest in another block and start fresh.
As there are many ways to skin a cat there are more ways to make 600 hp. I believe it's important to disconnect horsepower and torque numbers from the discussion about using lifter valley bracing. It is more important to discuss the need for bracing in terms of camshaft lobe design.

One test you may want to look into is doing a pressure test using a differential pressure guage. Remove the dipstick and put one leg of the guage on the tube and the other end in the valley pan. Run the engine and read the difference in pressure between the pan and valley. You could use two guages for this if you confirm the guages are calibrated and are reading the same across their range.

Once you have some data it is easier to make the correct decision.

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Old 02-14-2024, 10:25 AM
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Drill some holes in there and see if that fixes your problem. At some point you have to try something. Seems like the least expensive option with minimal effort. If the problem is still there you know the next step.

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Old 02-14-2024, 10:52 AM
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IMO, the main issue is excessive crankcase pressure caused by poor sealing from piston rings to the cylinder walls. This can be poor fit of pistons to bores, distorted cylinder walls, surface finish, detonation, or any combination of the above. Adding some additional drain back holes from lifter valley to crankcase will not hurt a thing but won't solve the problem until the root cause is addressed and corrected. Personally, I have never used or installed a lifter brace, street car or race car up to 1100 HP including big roller cams with lift of .900 at the valve. Never broken a lifter bore. I have used cams designed around the inherent weakness of the unsupported lifter bores. Guess I have been incredibly lucky. Get the cylinders to seal, the problem will go away.

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