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#21
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Carburetor building & modification services Servicing the Pontiac community over 25 years |
#22
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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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68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 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. |
#23
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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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Carburetor building & modification services Servicing the Pontiac community over 25 years |
#24
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Quote:
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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68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 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. |
#25
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With a Mega Brace installed it isn’t completely sealed up.
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#26
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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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69 Firebird 472, Bullet SFT, KRE 85cc, Victor, 850xp, TH400, TSP 9.5" 4800, 3.90 10 bolt, Viking DA rears, QA1 single fronts, 3558lbs. best to date 11.14@120 |
#27
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Quote:
Its easy to pull a little timing out, might do nothing, might be an eye opener, costs nearly nothing
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If your not at the table you're on the menu A man who falls for everything stands for nothing. |
#28
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Quote:
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68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 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. |
#29
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Be nice if you could post a closer pic of valley area.
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68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 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. |
#30
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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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Johnny US Army Retired 1978 T/A 463 Pontiac, KRE 74cc 292CFM D-ports, Lunati VooDoo, V-max lifters, TKII, ATM 850 E85 carb, TCI TH-350 race tranny, 3600 converter 3.73 12 bolt 11.63@116.68mph 1981 T/A 4-speed 406 Pontiac, Merrick ported 6X heads, Comp 270S cam, Crosswind intake 750 Street Demon, 3.42 30 spline Eaton posi street car. 1980 Formula 350 Pontiac back burner project 1972 LeMans 350 Pontiac |
#31
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Looking again it has more holes along side the lifter bores.
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69 Firebird 472, Bullet SFT, KRE 85cc, Victor, 850xp, TH400, TSP 9.5" 4800, 3.90 10 bolt, Viking DA rears, QA1 single fronts, 3558lbs. best to date 11.14@120 |
#32
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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.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
The Following User Says Thank You to steve25 For This Useful Post: | ||
#33
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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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68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 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
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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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69 Firebird 472, Bullet SFT, KRE 85cc, Victor, 850xp, TH400, TSP 9.5" 4800, 3.90 10 bolt, Viking DA rears, QA1 single fronts, 3558lbs. best to date 11.14@120 |
The Following User Says Thank You to 461-69bird For This Useful Post: | ||
#35
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Quote:
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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If it breaks. I didn't want it in the first place. _____________________________________________ 69 GTO \ 72 FIREBIRD \ 1/2 OF A 64 GTO \ 70 JAVELIN \ 52 FORD PU \ 51 GMC PU \ 29 FORD PU \ 85 ALFA ROMEO SPYDER \ A HANDFUL OF ODD DUCATI'S \ 88 S10 LT1 BLAZER & MY DAILY DRIVER 67 SUBURBAN. |
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#36
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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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Be carefull of the feet you step on today.They may be attached to the a$$ you kiss tomorrow. |
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#37
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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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