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Choke disengages fine, Fuel filter is brand new - as is 90% of the drivetrain
I have the throttle linkage set so that the butterflies are fully open when the pedal is all the way down.
Ignition system is "stock" Duraspark distributor and control box.
Runs strong up to 2k, no surging, popping, sputtering, or misfiring ... at 2k-2500 rpm (not a specific rpm, just 2000-2500 or so), it behaves as if it is "loaded" ... just like if it was in drive with my foot on the brake (and no ... it's not in gear) ... it just won't rev any higher ????
With vacuum advance disconnected, she doesn't hardly rev up at all, and the timing doesn't move.
... and again, initial timing is set at 10 BTDC. With vac advance connected to ported vacuum, total timing at 1500 rpm or so (dwell + tach meter only goes to 1200) is (at the crank) 34 degrees BTDC.
... and when I wack the throttle fully open at lower revs, the Vacuum reading drops to zero (as it should ? )
Put on the new coil, verified that the throttle fully opens the primaries, thoroughly re-checked for vacuum leaks with LOTS of carb cleaner - all around the intake and carb (except I can't really get under the main water inlet ... all 1992 5.0 accessories on the front of the motor)
Rag over the primaries shuts her down (somewhere else a suggestion was made that if it keeps running with a rag over the primaries, it is definitely a vacuum leak).
If its any help ... in addition to everything else I've done to the car, I also did an AOD swap (rebuilt AOD).
Could my problem be caused by the TV cable setting being slightly off ?
If the plates are fully open...even if the timing is pretty crappy (especially on the advanced side) it should still rev dangerously high until the valves float, or it scatters or it knocks it self to death.
So you're saying it comes on strong then just flattens out at about 2000 rpm?
Lets say its at idle and you just flat out mash on the throttle does it try to stumble and die or does it rip right up until it hits 2k (in about a 1/4 second) and then it just hangs there even at WOT?....If yes all I can is the control box has a 2k rev limiter installed...that's it!
-Gun
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Masters of Industrial Technology intelligence thats why I own guns made to drop elephants.
Check your firing order with the cam that you installed (llok on the cam specs). I had the same issue when i fired my baby up. Turns out the cam i bought used the 351 firing order not the 289/302 order. she still sounded strong but wouldnt rev. When i finally found out. OMG what diff.
Monster Billy - you may have something. He did say he's got a roller cam in his initial post, although I thought it would be running very rough at idle if his firing order was off.
Whack the throttle open at idle = no stumble at all, goes right up to 2-2.5K and just sits there.
... control box is STOCK duraspark box.
It is a roller cam and firing order is set for 92 5.0.
Installation instructions from Trick Flow explicitly call out the roller firing order.
... someone PLEASE correct me if I have the wrong info ....
.... isn't it true that you can only get a roller cam for a 289/302
which has the "new" (5.0) firing order ?
And .. as Crunchy said, I'd think it would run like doodoo if the firing order was that far off ?
Billy, when your's was set wrong, did it idle smoothly ?
... did it run "perfectly smooth and strong" up to 2500 rpm ?
And Further:
Does no advance without vacuum = Mechanical Advance is not working ?
... at what RPMs is the mech advance supposed to kick in ?
No fuel regulator ... New Edelbrock Mechanical Pump which is limited to about 6 psi ?
Someone had a similar problem and suggested that maybe my timing marks were off ?
Timing marker is stock 92 5.0 ... Damper is new racing damper (can't remember the brand name) for 92 5.0.
If advancing the initial timing doesn't cure it,
.... and if I don't find the mech advance rusted shut in the reman dist,
I'll pick up a junkyard dizzy this weekend (but I'll have to change the dist gear {I already have a spare steel one} unless I find an 86 manual trans carby mustang ! )
almost all aftermarket cams for 289/302 now use the 351 firing order
If the firing order is wrong the car will run on 6 cylinders or less in all ranges. That's not what I call smooth and strong. If you swap the 302 with the 351 firing order it doesn't run at all or very very crappy as you are on 4 cylinders then
as far as blocked exhaust goes, just remove the headers or easier the pipe behind the collector. will be load, but just to be sure that's not the cause.
The car will run normally when you disconnect the vacuum advance at distributor and block it. Only mechanical advance will then kick in.
The mechanical advance does something like 2 degrees every 300 rpm. this is not a set value. but what I'm saying is it starts to kick in between 700 and 1000 and goes up steady to around 20 advance at 4000. so if your initial at 700 is 14 degrees you'll likely find something like 20 degrees at 1500 and 34 degrees at 4000. don't quote me on that. it's just the rough idea.
but you will need to disconnect the vacuum advance for this test as otherwise you can't tell anything about mechanical advance.
I still believe there is some limiting going on. I never heard of a great running engine that just sits at 2500 without one .... i can't get my head around it ... good luck in hunting this one down
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1964 1/2
302ci, Edelbrock RPM heads and cam, 650 speed demon, Long Tube headers and Flowmaster 40s
Quick Performance Racing 9" rear, Moser axles, 3.5:1 trac-loc from FRPP and T5 transmission.
CSRP disc brakes front and FRPP discs back. http://www.gascc.ie
Did you do the engine work or did a shop do the work?
When its at WOT does any smoke come from the exhaust...what color?
Does you distributor have a vac fitting on it? If yes Im pretty sure its a vac advance dizzy. There for it will not advance with the vac line off. I dont think they make a vac and mech advance dizzy...its either one or the other.
-gun
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Masters of Industrial Technology intelligence thats why I own guns made to drop elephants.
my $0.02 worth of ideas if the above suggestions don't help:
- if you have a rev limiter it's hooked up to the wrong input and thinks the engine is spinning 2x what the actual rpm is. fairly easy to do if you're using a wasted spark system. i'm not very familiar with duraspark systems but i don't think they're wasted spark.
- your primaries are clogged or something is blocked in the metering circuit of the carb. once it comes off of idle and transitions into the mains fuel is all but getting cut. OR it's going way too rich but you would see black smoke. try spraying a little carb cleaner or starter fluid down the carb while it's at the rev limit. if it speeds up it's a fuel problem.
- advance in the distributor isn't working at all and you're sitting at the initial advance. try revving the engine up and spinning the distributor while it's at 2500 rpm. if it changes rpm as you advance/retard the distributor you have a timing problem. wear gloves. arcing hurts.
- you say it's a new engine? flat tappet? did you break it in right? use a high-ZDDP oil or ZDDP additive? have you checked the oil for metal flakes? it's possible you dropped a lobe or two and it's running out of air when it revs.
have you driven the car? is it actually running strong to 2500rpm or does it misbehave with a load?
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