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Author
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Topic: What to do for crankcase evac?
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V8 Thumper
Gearhead Posts: 3467
From: Orange, Ca. United States of America
Registered: Dec 2001
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posted 06-17-2003 07:15 PM
   
First off, I just recently leaked my motor down: 2% average across all 8  , so I'm confident there aren't any 'problems'.When I buzz it to the moon, it blows a little oil out the dipstick tube and a little out the back valvecover breather, but only when I spin it 6800 or more. I've got it chipped at 7k, so the limiter is starting to come in about that time... I am running a pcv. Any suggestions are welcome  ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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bluestreek
Gearhead Posts: 1289
From: Athens,GA
Registered: Jul 2001
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posted 06-17-2003 09:27 PM
quote:
Originally posted by V8 Thumper:
When I buzz it to the moon, it blows a little oil out the dipstick tube and a little out the back valvecover breather, but only when I spin it 6800 or more. I am running a pcv. Any suggestions are welcome
Yeah, don't spin it past 6600!!  ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank and girdle, 5.4 H-beams, Forged slugs, TFS alum. heads, ported Stealth 8020 intake, Xtreme 274 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)full street trim!
DanH
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 06-17-2003 11:03 PM
Do you have a windage tray under that stroker crank? You could run a quart less oil in that big pan too and see if that cures it. Bending the dipstick will keep it in place too. SteveW
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Butch Jennings
Gearhead Posts: 582
From: No. California
Registered: Apr 2000
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posted 06-18-2003 12:00 AM
I'd put a vacuum pump on it.------------------
Butch
460 powered 1967 Comet Cyclone (Broken)
10.271 @ 130.231
Butcher's Home Page
"Friends don't let friends drive Chevys"
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Fastymz
Moderator Posts: 11429
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 06-18-2003 02:15 AM
quote:
Originally posted by bluestreek:
Yeah, don't spin it past 6600!!
Sorry but that was funny,you big show off. 
How about those collector evac systems,I see a few street cars running those. ------------------
SCOOP
oddly obsessed with big scoops on little Mustangs 2.26 60'S
14.9 @ 90.86MPH 65 coupe,351w,C4,Big Boss 429 hood scoop,8"3.40 TracLoc,Cragar SS,Black Suede. https://mustangsandmore.com/ubb/Fastymz.html
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kid vishus
Gearhead Posts: 4538
From: middle of NC
Registered: Oct 2000
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posted 06-18-2003 08:02 AM
quote:
Originally posted by Fastymz:
How about those collector evac systems,I see a few street cars running those.
ANY amount of backpressure makes them useless and not work at all. The guys you see running them on the street must be running them for looks.
I took the dipstick out of the racecar and put a vacum cap on the end of the tube and held it in place with a hose clamp. That solved the problem of it lifting out all the time and spraying oil all over.
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rockafellz
Gearhead Posts: 1291
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 06-18-2003 09:56 AM
quote:
Originally posted by steve'66:
Bending the dipstick will keep it in place too. SteveW
If you bend it, make sure you bend it the right way. My cousin's '68 vert has a dipstick that sort of curves, after I checked the oil one time, he went around the block and it came back clacking pretty bad. I couldn't pull the dipstick out. We had to turn the motor counter-clockwise to unravel the dipstick from the crank  . It looked like it was grinded through the garbage disposal. Erik ------------------
1966 Ford Mustang 2+2
Mine - Restomod in Progress 1966 Ford Mustang Coupe
Dad's - Original Unrestored
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Ryan Wilke
Gearhead Posts: 1501
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 06-18-2003 02:10 PM
quote:
Originally posted by rockafellz:
If you bend it, make sure you bend it the right way.
True Story:
Before I rebuilt the 390 in my '65 F100, it was on it's 3rd dipstick. It would "eat" one every year or so. Turned out that the dipstick tube had gotten bent somewhere along the way and was pointing it toward the crank. Then every now and then it would 'hook up' with the crank and simply get snapped off at the top 'hash mark'.... When I rebuilt the engine, I found the two dipstick lower halfs laying in the bottom of the oil pan. I bent the tube to be more vertical and haven't lost a dipstick since....... Ryan
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V8 Thumper
Gearhead Posts: 3467
From: Orange, Ca. United States of America
Registered: Dec 2001
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posted 06-18-2003 07:14 PM
quote:
Originally posted by kid vishus:
ANY amount of backpressure makes them useless and not work at all.
No kidding? Wow, I thought that was the whole purpose of the collector evac systems. I'm not disputing your info at all Rob, but can you elaborate? Curious minds want to know In addressing the root cause: since my leakdown netted such great results, am I experiencing ring flutter high up in the rpm range? Capping off the dipstick tube is a great tip, thanks
------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9"
All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html [This message has been edited by V8 Thumper (edited 06-18-2003).]
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V8 Thumper
Gearhead Posts: 3467
From: Orange, Ca. United States of America
Registered: Dec 2001
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posted 06-18-2003 07:18 PM
quote:
Originally posted by steve'66:
Do you have a windage tray under that stroker crank? You could run a quart less oil in that big pan too and see if that cures it.
Yes on the windage tray. I typically run 6 1/2 quarts total; 5 1/2 in the pan, one in the filter. I can run safely run less... I'll give that a try ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 06-18-2003 08:24 PM
quote:
Originally posted by V8 Thumper:
No kidding? Wow, I thought that was the whole purpose of the collector evac systems. I'm not disputing your info at all Rob, but can you elaborate? Curious minds want to know
Kid's right. Back pressure in your exhaust will push exhaust gass into your crankcase.
You can run a evac pump as Butch suggested. But, for the little time you'll be spending at 7000 rpms I think I'd plug the offending orifices. SteveW
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Ryan Wilke
Gearhead Posts: 1501
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 06-18-2003 09:09 PM
quote:
Originally posted by V8 Thumper:
...I thought that was the whole purpose of the collector evac systems. I'm not disputing your info at all Rob, but can you elaborate?
I don't mean to steal any thunder from KV, but to say what Rob said another way is:
IF you are running on the street, you are VERY likely running mufflers....and with mufflers, you would likely be producing backpressure. This backpressure would back up into the crankcase evac system. Now IF you have check valves installed in the evac system lines, in theory, they should keep the backpressure from going up the line back into your engine. However, It's not uncommon for those check valves to fail.... Ryan
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 06-18-2003 09:11 PM
Ryan,I agree, and will add that when the check valves are closed the thing isn't evacuating anything. SteveW
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V8 Thumper
Gearhead Posts: 3467
From: Orange, Ca. United States of America
Registered: Dec 2001
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posted 06-18-2003 10:35 PM
Thanks guys for all the great input I guess it comes down to this. I am 'a little' concerned about it developing enough crancase pressure to blow oil (a sensible concern?). Doing a leak-down showed me very good cylinder seal for a street motor, and that was positive. Of the many motors I've done, this one is by far the highest powered, most high-strung piece of precision machinery I've built. I'm begining to be concerned about high rpm ring seal, or am I getting all worked up over nothing? ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 06-18-2003 11:10 PM
Todd,I love ya buddy, but you need to find something more important to worry about. SteveW
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rockafellz
Gearhead Posts: 1291
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 06-19-2003 02:27 AM
quote:
Originally posted by steve'66:
Todd,I love ya buddy, but you need to find something more important to worry about. SteveW
Yeah, I agree . Now how about "bench" building that 302 block ya just picked up? Erik ------------------
1966 Ford Mustang 2+2
Mine - Restomod in Progress 1966 Ford Mustang Coupe
Dad's - Original Unrestored
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bigblocked85
Journeyman Posts: 41
From: Waterford,MI
Registered: May 2003
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posted 06-19-2003 02:37 AM
It seems to me that if you have a PCV, that you could also run a collector evac system. At lower rpm's the pcv would work as normal and at high rpm's the collector evac would work as it pulls vacuum from the crankcase (with use of the valves of course). BTW, I have used collector evac systems on the street with quite a few cars and never experienced any problems due to low rpm or backpressure. As a matter of fact I've never had a valve malfunction on any of these cars. Now I have to admit that these are not REAL street cars, and dont have 2" exhaust, but if you have a car that sees high rpm repetitavely you probably dont have a small exhaust system and would probably benefit from a collector evac system. Just as a note, I found that I would loose vacuum with the breather cap that was offered in the evac kit and instead went to AN fuel cell fittings. I make a oil deflector with bent up sides and install a piece of scotchbrite inside. It works great. Just my .02
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kid vishus
Gearhead Posts: 4538
From: middle of NC
Registered: Oct 2000
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posted 06-19-2003 08:03 AM
Thanks Ryan. You explained it better than I could have anyways.
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V8 Thumper
Gearhead Posts: 3467
From: Orange, Ca. United States of America
Registered: Dec 2001
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posted 06-19-2003 08:21 AM
Ok Steve, I'll relax Thanks again guys, for all the awesome knowledge! This place kicks a** ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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Ryan Wilke
Gearhead Posts: 1501
From: Stanton, Michigan 49707
Registered: Oct 2000
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posted 06-19-2003 12:13 PM
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