Top End Miss

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BBBCUDA said:
For some reason, when I saw you mentioned MSD, I was thinking it was a whole system. If you have a stock style distributor, pull the cap, and pull the rotor/center shaft side to side. My brand new MP distributor had a ton of slop, and the reluctor wheel would contact the pickup at about 5,000 rpms. Dead short, bad miss. Sound familiar? Swapped in an MSD distributor, problem solved. If that is the issue, tighter bushings will fix the stock distributor.
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if MSD made a dizzy it might have been a thought... as i remember it was not loose... but i will check it...
 
805moparkid said:
if MSD made a dizzy it might have been a thought... as i remember it was not loose... but i will check it...
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Mine was in the 383 I did recently. Worth checking. I had checked and set the gap, but the slop in it was greater, and allowed contact. Ran fine to 5K, then popcorn.
 
805moparkid said:
ok did the volume test! it was 1 minute and 5 seconds for 1 measured gallon...

and the 750 vac carb didn't change anything
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:cheers::cheers::cheers:
Okay, now's your chance to rant on me! -It's been so many years since I did that test, I don't remember what a good number is! Of course, horsepower produced will affect this number. Your test sounds like you're getting enough, though.

Maybe some others will post their thoughts.

There ain't much left to check/try. Wanna buy a 74 Dart Sport? jk!

Got your pm. Thanks.
 
SpeedThrills said:
:cheers::cheers::cheers:
Okay, now's your chance to rant on me! -It's been so many years since I did that test, I don't remember what a good number is! Of course, horsepower produced will affect this number. Your test sounds like you're getting enough, though.

Maybe some others will post their thoughts.

There ain't much left to check/try. Wanna buy a 74 Dart Sport? jk!

Got your pm. Thanks.
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well at a gallon a minute thats roughly 60 GPH which isn't very good... so im left with to things... One there is a restriction and Two the pump is going out...

now i replaced the Etire fuel system, brand new lines, pick up, sock, filter, rubber lines... and emptied and cleaned the tank... so what gives!

im gonna check all my rubber line to see if its closing up and replace if necessary... then throw on my holley black pump and try again...
 
ok so i opened up the pick up gap from a couple thousandths to about .016 with my finger on the shaft for "tension" (about .001 or .002 movement)...

anyways re checked timing and went for a drive... right off i noticed i had about a .5" more vacuum at cruise (this being over yesterday after installing and tuning the 750)... seems to pull better to... anyways hammered on it and it was hard to tell if it missed at 5800 or 5900, so there could be gain there! so i'll let it cool and open it up some more and try again...

also for the first time it idles in gear without two footing it! only have about 6" of vac at 700 rpm but it still runs, and not trying to die either...
 
ok for giggles opened it up to .025... it wouldn't start... then .020 and it wouldn't... so it looks like .016 is it...
 
I skipped a few pages in the middle but it sounds like it wants a little more valve spring pressure. A .060 shim might be enough to do it. My slant liked 32 degrees total timing also.
 
pmarvetz said:
I skipped a few pages in the middle but it sounds like it wants a little more valve spring pressure. A .060 shim might be enough to do it. My slant liked 32 degrees total timing also.
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i already have it shimmed as tight as it goes (with a .060)... but i'll see what springs i can get that are stronger...

on another note i installed the holley black pump and set pressure... set it at 7psi and set floats...

no difference on the miss... but man it revs a whole lot faster now!!!
 
805moparkid said:
well at a gallon a minute thats roughly 60 GPH which isn't very good... so im left with to things... One there is a restriction and Two the pump is going out...

now i replaced the Etire fuel system, brand new lines, pick up, sock, filter, rubber lines... and emptied and cleaned the tank... so what gives!

im gonna check all my rubber line to see if its closing up and replace if necessary... then throw on my holley black pump and try again...
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Sounds like you don't have enough volume. I found this: http://forums.corvetteforum.com/c1-...5-hi-volume-mechanical-fuel-pump-testing.html
About half way down the first post he mentions how much fuel you should pump for a given car. He's talking faster, more powerful cars, but it seems you're right, the 60 gph you're seeing isn't enough.
New parts don't mean good parts. Go through your delivery system closely.
I don't have anything running to do a test on. You know anyone whose car you could test to compare?
 
You should be able to run the regulator up to 9psi with out it blowing threw the the needle ans seat... If it does just back it up.....

Hope this dose not have points?
 
racerhog said:
You should be able to run the regulator up to 9psi with out it blowing threw the the needle ans seat... If it does just back it up.....

Hope this dose not have points?
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well with the black pump im not worried about fuel delivery lol...

and no it has a mopar electronic dizzy hooked to a MSD box
 
racerhog said:
Did you try swapping the wires for the pick up?
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umm... no?? why would you do that? did it before i had this dizzy and MSD box in it... i had the other dizzy with a petronix points conversion in it and it didn't spark scatter until 9K lol...
 
I have found in the passed that if the wires for the pickup are not hooked up rite... They run funny..... But when you swap the wires for the dizzy to work rite, it's a whole new animal......
It's just a hunch....Thats why I asked....
 
racerhog said:
I have found in the passed that if the wires for the pickup are not hooked up rite... They run funny..... But when you swap the wires for the dizzy to work rite, it's a whole new animal......
It's just a hunch....Thats why I asked....
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hmm... well i can try it! but i think i have them right...
 
Give it a woral....Dont have much to loose.. If I'm wrong...It's just one more thing off the list....
 
racerhog said:
Give it a woral....Dont have much to loose.. If I'm wrong...It's just one more thing off the list....
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exactly... and valve springs are really gonna get expensive now that im looking at almost 400lbs spring rates... 350 open lol
 
If I remember rite.... (Not to say it might still be a springs)
But I think you already upped the spring pressure with no improvment?
The 6's have heavy valve train parts I agree.... But I'd do some more number crunching before buying a set of exhaust valves when where not sure thats whats needed just yet...
 
racerhog said:
If I remember rite.... (Not to say it might still be a springs)
But I think you already upped the spring pressure with no improvment?
The 6's have heavy valve train parts I agree.... But I'd do some more number crunching before buying a set of exhaust valves when where not sure thats whats needed just yet...
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i upped from the springs that came with the cam (about 15K miles old( 250 open/75 seat)) to cranes 307 open/130 seat and gained 200rpm on the top end
 
Still sounds a little soft.... But I'm just shooting from the hip....
Is it a high lift cam? Roller or Hyd or Solid... I'll shoot you a recommendation from here...
Just to toss around...
 
racerhog said:
Still sounds a little soft.... But I'm just shooting from the hip....
Is it a high lift cam? Roller or Hyd or Solid... I'll shoot you a recommendation from here...
Just to toss around...
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solid flat Erson custom grind

.475 lift, 246 @ .050 106 LSA installed at 102

im thinkin it needs right under 350 open /120-130 seat
 
After a quick phone call, just for the heck of it.... Just as a second opinion....
It appears the seat numbers @ 120-130 should be good.... We all 3 agree...lol
I was thinking more like 395lbs open... My partner threw out a 375lbs open ... And you were down at 300lbs....Humm

Well food for thought....????
 
racerhog said:
After a quick phone call, just for the heck of it.... Just as a second opinion....
It appears the seat numbers @ 120-130 should be good.... We all 3 agree...lol
I was thinking more like 395lbs open... My partner threw out a 375lbs open ... And you were down at 300lbs....Humm

Well food for thought....????
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so i was close at my 350 open... those numbers seem high for a flat though arn't they?? i mean i only rev to 6K
 
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