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Author
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Topic: 5000 and its done Help
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-14-2002 08:12 PM
   
Glens 390 67 Mustang GT 4 speed 3.50:1 68 390 block 30 over
The main problem/symptom the engine does not want to go over 5300 rpm
Heads are new Edelbrock had the springs and retainers changed to crane 99886 triple springs 120# closed 410# open and spring cups. Crane 99281 hyd lifters. Erson adjustable roller rockers, adjusted 3/4 turn in, Edelbrock Performer RPM intake, Holly 750 DP 75/86 jets. Crane HI 6 Ignition Timing set at 12 deg initial and 38 deg total at 3000 mechanical advance Mallory Unilite Distributor. Hooker supercomps 2 1/2" Flowmasters dump just befor the axel.
Engine at idle has 6�� Vacuum oil pressure is 20 psi at idle, 70-75 psi at 5000.
I did try the old ignition system a HP 406 Dual Point Mechanical Advance Dist. with just the Mallory 29440 coil. with the same results as the Crane HI 6. I don��t believe that this is an ignition related problem.
6�� of vacuum at idle may be an indicator. I just don��t know what to do now.
The engine runs strong till it hits 5000, then falls on it��s face.
Crane Cam
3600-4000 cruise RPM, 10.0 to 11.5 compression ratio advised.
Basic RPM 3000-6500 PowerMax H-298
Cam Specifications
Degrees Duration @ .050 Int./Exh. 236/236
Degrees Advertised Duration Int./Exh. 298/298 Degree Lobe Separation 108
Open/Close @.050" INT 15 BTDC /41 ABDC EXH 51 BBDC/ 5 ATDC
Cam Lift Int./Exh. .325/.325
Gross Lift Int./Exh. .572/.572
Cam Timing@ .0037 INT 43.5 BTDC 74.5 ABDC EXH 51 BBDC/ 5 ATDC
[This message has been edited by Glens67 (edited 07-14-2002).]
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n2oMike
Gearhead Posts: 1547
From: Spencer, WV
Registered: Jan 2001
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posted 07-14-2002 08:34 PM
And the exhaust system....??????------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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Butch Jennings
Gearhead Posts: 582
From: No. California
Registered: Apr 2000
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posted 07-14-2002 08:47 PM
The last time mine acted like that I had my fuel pump go away, it would fill a 5 gal jug in under a minute free flowing but when I ran it through the regulator it wouldn't hardly fill the bowl. I sent it in for a rebuild and all was good, just something to think about.------------------
Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.231
Butcher's Home Page
"Friends don't let friends drive Chevys"
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-14-2002 08:54 PM
quote:
Originally posted by n2oMike:
And the exhaust system....??????
Hooker supercomps 2 1/2" flowmaster 2 chambers dump just befor the rear axle
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-14-2002 08:55 PM
quote:
Originally posted by Butch Jennings:
The last time mine acted like that I had my fuel pump go away, it would fill a 5 gal jug in under a minute free flowing but when I ran it through the regulator it wouldn't hardly fill the bowl. I sent it in for a rebuild and all was good, just something to think about.
Brand new holly red pump 6 psi at cruse drops to 4 psi at the top of each shift.
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bluestreek
Gearhead Posts: 1289
From: Athens,GA
Registered: Jul 2001
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posted 07-14-2002 10:42 PM
If you have a good fuel supply and you're sure that there is no restriction in the fuel system, then by golly it oughta run to at least 6000 rpms if the firing and timing are right. The only other things that I can think of are:
Carb not wide open or secondaries not opening on carb,
Voltage loss to the ignition or Coil breakdown,
Too much spark advance or cam advance,
Possibly a wiped out cam (valve train would be noisy though).
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-14-2002 11:51 PM
This is a new rebuild less then 200 miles
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Greg Pettit
Journeyman Posts: 75
From: Dallas, TX
Registered: Nov 2001
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posted 07-15-2002 09:15 AM
Things that come to mond, which you have most likely already checked are:Lifter pump up/lash too tight
Timing issues
Fuel pressure/carb
Some kind of exhaust restriction
Some kind of intake restriction
Cam installed too far advanced Just hooking a fuel pressure gage up and running hard up to 5000 will tell you what you need to know about the fuel pump. A vacuum gage used the same way will tell you about the lifter pump up, and may hint at things like exhaust restrictions and timing problems. 3/4 of a turn may be too much on the lifter preload. I like to run as little as possible without lifter noise. (Impossible on my Cleveland!) Good luck, Greg
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Greg Pettit
Journeyman Posts: 75
From: Dallas, TX
Registered: Nov 2001
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posted 07-15-2002 09:19 AM
WHOA! I just re-read your post....6" of vacuum??? Was this at 200 RPM? If the engine is at a normal idle speed in neutral then this seems to be too little vacuum for that cam, even with the 108 LSA. This makes me suspect too tight preload even more. It seems like you should be seeing at least 10". Greg
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-15-2002 07:10 PM
quote:
Originally posted by Greg Pettit:
WHOA! I just re-read your post....6" of vacuum??? Was this at 200 RPM? If the engine is at a normal idle speed in neutral then this seems to be too little vacuum for that cam, even with the 108 LSA.
That is at 800 RPM. I tried 1/2 turn would not get past 5000 1/4 turn sounded like  3/4 Turn seemed to improve 5300 I'm going to try 1 full turn tonight.
Now I need a fan shroud for a Big Block 67 Mustang.
This makes me suspect too tight preload even more. It seems like you should be seeing at least 10". Greg
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Slow65Stang
Gearhead Posts: 113
From: Reading, PA, USA
Registered: Feb 2002
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posted 07-15-2002 09:39 PM
CRIPES, 6" 200 rpm is an overestimate at idle........
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 07-15-2002 11:59 PM
Glen,Hope you get it sorted out. If you need help, you know my cell number. I don't think we'll be there this week, but have fun and good luck! Alex, Can you help Glen out? This one is puzzling.  SteveW
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Clevo377
Gearhead Posts: 312
From: Blackburn, Victoria, Australia
Registered: Nov 2000
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posted 07-16-2002 07:03 AM
Are the springs installed at the correct height??Paul
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-17-2002 02:13 AM
Yes every thing double checked. Reajusted valves to1 full turn got to 5800 power good. I will run it wed night and see...
those triple valve springs may be too much, for the lifters. Maybe I will pull the juce and install a solid...
Thats 6'"at 800 rpm[This message has been edited by Glens67 (edited 07-17-2002).]
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kid vishus
Gearhead Posts: 4538
From: middle of NC
Registered: Oct 2000
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posted 07-17-2002 09:06 AM
quote:
Originally posted by Glens67:
those triple valve springs may be too much, for the lifters. Maybe I will pull the juce and install a solid...
Triple springs on a juice cam? I dont even use triple springs on my solid roller. Are you sure they only have 410# open and not alot more than that?
Hopefully, you have found your problem. A problem like that is incredibly frustrating.
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n2oMike
Gearhead Posts: 1547
From: Spencer, WV
Registered: Jan 2001
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posted 07-17-2002 11:06 AM
They are probably doubles with a dampr.------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-17-2002 01:37 PM
Yes Double with damper. :?)
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steve'66
Gearhead Posts: 6522
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 07-18-2002 11:04 AM
Glen,How did it run last night.
SteveW
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-18-2002 06:44 PM
It sucked
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Mike Harris
Gearhead Posts: 122
From: Oakfield, Ga USA
Registered: Jul 2002
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posted 07-21-2002 11:47 PM
Here's my thoughts on it. First and foremost, that open spring pressure is HUGE for a hydraulic camshaft. I believe you are effectively collapsing the plunger which in itself creates problems. The other eyesore that I see in the mix is the fuel pump. That is more motor than a Holley Red should be given to deal with. 6psi at cruise and 4psi at the top of each shift DEFINITELY tells ya something. There should not be a 2psi drop. Ya need something more in line with a Holley Blue that will keep up with the demand and I'd suggest atleast a #8 fuel line.I don't want to get into a long winded diatrebe on how it happens, but the change in preload and actually collapsing the lifter, changes the way the engine sees the opening and closing events of your cam. That's why going to 3/4 of a turn and 1 turn made it see more rpm. The cam effectively produced less cylinder pressure and load on the engine, so even though the fuel supply was not as good as it should have been, it was under less of a load and could increase. Once you get the springs and fuel system checked out/fixed, the lifter preload ticket is 1/4 turn past zero for a high winding motor. On a few class specific cars with lots of limitations and the like, we have run .005 lash....yes you read that right, lash, to get a few hundred more rpm out of it on the big end. Not something ya want to do on a regular basis unless you do regular maintenance/repairs like these race cars. The chance of valve loft is increased 100 fold with this trick. (Read, don't try and do that and make it live on the street). But seriously, all you are trying to do with preload is ensure that the pushrod stays in contact with the lifter to avoid plunger damage. The more preload, the more chance of pumping up the lifters. Did I talk too much?
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kid vishus
Gearhead Posts: 4538
From: middle of NC
Registered: Oct 2000
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posted 07-21-2002 11:54 PM
quote:
Originally posted by Mike Harris:
Did I talk too much?
Nope, very informative.
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Glens67
Gearhead Posts: 325
From: Petaluma
Registered: Mar 2002
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posted 07-22-2002 06:37 PM
Mike Harris
Your Right On I installed a mechanical pump. Now have 7-8 psi still stops at 5600. I'm going to install a Holly Blue With a regulator. and am thinking of installing lighter springs.
Glen
:-)
Will have to run Wed. night to set base line with what I have. I'm running for points on Saturday. Still in 3dr place.
Thanks
Glen.
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n2oMike
Gearhead Posts: 1547
From: Spencer, WV
Registered: Jan 2001
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posted 07-22-2002 11:15 PM
I'm glad you're making progress, but a 236/236 @ 0.050" cam with a 108 lobe seperation isn't going to pull much past that rpm in a 390. 6000 rpm max, and it's going to be all done. It might spin up a little higher, but won't really making more power by doing so.The fuel delivery was definitely questionable... as were the valve springs. I'd look into some of those new 'beehive' valve springs from Comp Cams. David Vizard did a nice review on them in the August Muscle Mustangs and Fast Fords issue. They seem like a really neat setup! (I picked up that issue today) It said "display until 7/29, so it should still be available for a few days. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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