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engine won't rev above 3k?
#143016
10/29/08 08:07 AM
10/29/08 08:07 AM
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Anonymous
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Anonymous
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Thought I would post a message here to see if anyone had any ideas... I just put in a 408 stroker in my dart... runs well up to 3,000 rpm but after that it kind of hesitates, and rpms fall. I have a 727 and it's shifting at 2000-2500? I'm not sure what's going on!
the carb is a edelbrock avs 800, when should the seondaries be opening? I'm not sure that they are... but supposedly adjustable.
I'm using a standard mopar distributer.. set about 15 degress initial.. not sure how much mechanical advance is built in, is it hard to change the springs to adjust this?
anyway... any ideas you guys might have would be appreciated greatly!!
-j
some details
Mopar electronic ign.
carter mech. fuel pump
cam: 474 Int / .474 Exh & 233 Int / 240 Exh duration @ .050 - 110 degree lobe sep
magnum heads.. 9.8:1 compression
edl. mag. air-gap intake
edl. avs 800cfm carb (have not changed jets/rods)..
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Re: engine won't rev above 3k?
#143017
10/29/08 08:16 AM
10/29/08 08:16 AM
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Joined: Apr 2007
Posts: 2,826
NY usa
540challenger
master
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master
Joined: Apr 2007
Posts: 2,826
NY usa
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Quote:
Thought I would post a message here to see if anyone had any ideas... I just put in a 408 stroker in my dart... runs well up to 3,000 rpm but after that it kind of hesitates, and rpms fall. I have a 727 and it's shifting at 2000-2500? I'm not sure what's going on!
the carb is a edelbrock avs 800, when should the seondaries be opening? I'm not sure that they are... but supposedly adjustable.
I'm using a standard mopar distributer.. set about 15 degress initial.. not sure how much mechanical advance is built in, is it hard to change the springs to adjust this?
anyway... any ideas you guys might have would be appreciated greatly!!
-j
some details
Mopar electronic ign.
carter mech. fuel pump
cam: 474 Int / .474 Exh & 233 Int / 240 Exh duration @ .050 - 110 degree lobe sep
magnum heads.. 9.8:1 compression
edl. mag. air-gap intake
edl. avs 800cfm carb (have not changed jets/rods)..
Ok one check your total timing stock distrubtor has alot of mech timing built in. i think mine was around 25 mech  i little much i liked my timing set around 34*total.
Also when does it bog full throttle or just crusing. with part throttle???
Also is this the blue printed 408 crate engine. if so check out this thread.
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Re: engine won't rev above 3k?
[Re: 540challenger]
#143018
10/29/08 08:38 AM
10/29/08 08:38 AM
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Anonymous
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Yes it's a blueprint 408.. It hesitates when I am just crusing... maybe 50% throttle... I'll check the timing later this afternoon... if anyone else has any suggestions of what to try, I would love it! I want to get this figured out before the snow comes  I should add that I have highway gears on the car... 2.something.. and I'm getting pretty awful milage.. less than 10 mpg -j
Last edited by jeh; 10/29/08 08:43 AM.
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Re: engine won't rev above 3k?
#143019
10/29/08 08:43 AM
10/29/08 08:43 AM
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Joined: Apr 2007
Posts: 2,826
NY usa
540challenger
master
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master
Joined: Apr 2007
Posts: 2,826
NY usa
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Quote:
Yes it's a blueprint 408.. It hesitates when I am just crusing... maybe 50% throttle...
I'll check the timing later this afternoon...
if anyone else has any suggestions of what to try, I would love it! I want to get this figured out before the snow comes
did you take the carb apart to check where the floats were every eddy i had the floats where never set right out of the box.
Also i purchased that same motor check out my thread i having not too good of a time with it right now.
-j
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Re: engine won't rev above 3k?
[Re: 540challenger]
#143020
10/29/08 10:35 AM
10/29/08 10:35 AM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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some thoughts, check total timing w vac dissconnected, pull plugs & see what they look like & check rotor phasing at the offending rpm. EDIT retard your initial from 15 back to 5 & take it out for a quick spin.
Last edited by RapidRobert; 10/29/08 11:02 AM.
live every 24 hour block of time like it's your last day on earth
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Re: engine won't rev above 3k?
[Re: RapidRobert]
#143021
10/29/08 11:16 AM
10/29/08 11:16 AM
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Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
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master
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Posts: 4,013
South Park, Pa.
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My  . A few places to start looking. 1. Make sure that you have the coil wires properly hooked up. + gets battery voltage - goes to distributor. 2. Make sure that the secondaries are opening all the way. Don't look at the air valve just the secondary butterflies. 3. Make sure you are getting fuel. Check pressure. 4. Check total timing. Without the vacuum advance connected you should be at least at 35*. Good luck.
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
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Re: engine won't rev above 3k?
[Re: 68LAR]
#143022
10/29/08 12:00 PM
10/29/08 12:00 PM
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Anonymous
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i doubt total timing would stop it from reving over 3 k. my total on my 416 was pretty darn high before I fixed it and I reved up to 6500 quite often.
Id say you need to look at carb first, check the plugs and see if your lean (maye major vacuum leak), valve float. valves not closing. cam timing WAY off
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Re: engine won't rev above 3k?
[Re: kenworth_goose]
#143029
10/29/08 03:32 PM
10/29/08 03:32 PM
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Quote:
My 68 dart did the same thing. It was a ground strap that I forgot to put on it. Make sure you have a good engine to body ground. A good battery to body ground.
I would look for a bad ground. A buddy had same thing. box wasn't well grounded.
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Re: engine won't rev above 3k?
[Re: 68LAR]
#143030
10/29/08 04:26 PM
10/29/08 04:26 PM
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Joined: Feb 2003
Posts: 2,852
Dallas, TX
70challrtse
super gas
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super gas
Joined: Feb 2003
Posts: 2,852
Dallas, TX
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Quote:
Quote:
Is there a rev limiter on your tach?
 Wouldn't it be ironick if it was the tach?????   
Don't ask me how I came up with that suggestion.
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Re: engine won't rev above 3k?
[Re: 70challrtse]
#143031
10/29/08 04:37 PM
10/29/08 04:37 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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I bet ya had a smile on your face when you caught it.
live every 24 hour block of time like it's your last day on earth
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Re: engine won't rev above 3k?
[Re: RapidRobert]
#143032
10/29/08 05:24 PM
10/29/08 05:24 PM
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Joined: Feb 2003
Posts: 2,852
Dallas, TX
70challrtse
super gas
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super gas
Joined: Feb 2003
Posts: 2,852
Dallas, TX
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Quote:
I bet ya had a smile on your face when you caught it.
Actually another member here suggested that I check my tach, when I made a similar post. I had numerous serious gearheads work on the problem, but to no avail, then a member here asked if it had an aftermarket tach and asked if the rev limiter had been turned down. Sure enough it was turned down to about 2500. 
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Re: engine won't rev above 3k?
#143033
10/30/08 02:35 AM
10/30/08 02:35 AM
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Anonymous
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Thanks for all of your help guys... old harness, wire colors were too similiar... had the coil hooked up backwards! suprised it ran at all...
-j
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Re: engine won't rev above 3k?
[Re: 68LAR]
#143035
10/30/08 08:55 AM
10/30/08 08:55 AM
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Thanks bud! You win the diagnostician award of greatness!  -j
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If it was advanced too much, but what if the mechanical advance was retarded too far and the only advance was from the vacuum advance side? There would be no advance when the gas pedal was pushed thus retarding total timing. 
