Spudders when it's hot..

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kc0r8y

kc0r8y

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Took my Dart out yesterday the temp outside was about 68 in CT. The car is a 408 stroker with a 727. Once the car got up into the 200-210 area is started to spudder as if it was mis-firing. Once it cooled back down to the 190 area it seems to still be there just not as bad. The cooler it got the more it went away. Now I have always felt like a very small spudder when I first start it and hold my foot on the gas to get it warmed up, but it's usually fine after that. I also noticed in my drivers side valve cover breather a little smoke coming out after I shut it off.

I recently purchased this car from someone that use it just for the track so I'm converting it to be more street friendly. I drove it a few times prior to the making some changes and it always ran a little on the hot side but I thought that was because it didn't have a T-Stat in it and the cooling setup was not up to par for street use.

What I've done recently to make it street friendly as well as clean things up a little is:

1. New V-Covers - I put the fabricated ones on. I have both breathers baffled with a hose running down to the header collector. It was like that when I got it and few people suggested I keep it like that for crank case pressure.

2. I added a 180 Miloden T-Stat and changed the coolant from the green stuff over to the Zerex G-05 stuff. The car has a larger then stock aluminum radiator in it and a non shrouded aluminum fan which I'm sure does very little. It also has a pusher electric fan in the front of the radiator on a switch which I'm sure was used to cool the car off after making a pass. Now it's probably just blocking the air flow to cool the radiator. I plan to get a bigger radiator and put in dual Spal fans to cool it. So I know my current setup isn't helping me much.

3. Other small things I recently did are belts, hoses, new pulleys, alternator, swapped the 430 gears to 373s, swapped out a edelbrock carb for a holley 650. New cap and rotor and MSD 8.5MM wires. After these changes the car starts up much faster and stay running quicker.

I just don't know what to look for with this spudder problem when it's hot.

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Any advise is appreciated.
 
Do I understand this correctly, you have the studder when it's cold as well, just not as noticeable?
 
lots of possibilities..... perhaps a gap where there shouldn't be, and when it get warm, it opens up wider.... like an intake or head gasket leak? Does it do it worse as the rpm's build, or is it just an idle thing?
 
it does it all the time. I'll have to double check to make sure all the intake bolts are down tight...
 
kc0r8y said:
it does it all the time. I'll have to double check to make sure all the intake bolts are down tight...
Click to expand...
could even be something electrical, and acts up worse when it gets warm. Does it sound like an electrical snap? or a fuel delivery issue?
 
It looks like your carb does not have a choke plate on it, so that is the most likely reason that it sputters when cold and you first start it up. That is probably a completely separate cause for the cold start sputter versus the hot sputter.

What have you done to tune the carb in terms of the basics: setting float heights and adjusting idle mixture?
 
I just checked the intake bolts and I got a small turn out of most of them.

The carb and gear swap was done by a reputal speed shop. I didn't have any problems with the carb at all. I drove it home from there and it ran fine. I'm wondering if these intake bolts are the issue..

The car still have a 4200 stall in it and with the 373s it's a pig. I need to swap the stall out for like a 2800-3000.
 
Do you know what cam is in there? The TC stall is gonna depend on that plus the engine internals (pistons, deck height and such), and if the cam is pretty radical, then IMHO a cam change may be in order to get the TC stall down to something more normal for street use. If the engine is a pig getting started and it got worse with a lower gearset , it is likely the cam is very big. It's just gonna get worse with a lower stall TC with the same cam.

Then there is the pistons and such......lots of questions.

I'd be figuring all that out and planning/making all those changes first. It is gonna make some big changes in tuning. Not trying to make it harder.....but starting out with a cam that needs 4+ gears and a 4200 stall TC for pure race, and moving that to a street engine, is a big change.
 
ok so I double checked the timing and it's good. I drove it and still missing firing and skipping when under acceleration. I recently swapped the cap and rotor to MSD 8.5 wires and a Firecore HEI cap from Mancini Brothers. (link: Firecore - HEI Vacuum Advance Distributor Cap) I went with that cap because the wires I bought needed a male cap and mine was female. That cap is also described for vacuum advance dizzys which I don't have.

When I put my old cap and wires on the car runs fine, so it's something to do with the new cap and/or wires. Could it be the cap need a vacuum advance dizzy and will not work with mine?

The cap looks identical to my old cap except for the male instead of female wire top.

Anyone else running that cap?
 
The things that pop into mind are:
1. Too much gap between cap and rotor and the spark is either failing or jumping to the wrong posts from time to time
2. The cap being made for a vacuum advance distributor has the posts in a different alignment and the spark is jumping to the wrong posts
3. Poor connections at the top of the posts from the wires
4. Long shot: Ozone build up under the cap due to not enough ventilation causing the spark to jump around
 
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nm9stheham said:
The things that pop into mind are:
1. Too much gap between cap and rotor and the spark is either failing or jumping to the wrong posts from time to time
2. The cap being made for a vacuum advance distributor has the posts in a different alignment and the spark is jumping to the wrong posts
3. Poor connections at the top of the posts from the wires
4. Long shot: Ozone build up under the cap due to not ventilation causing the sparkthe jump around
Click to expand...

I think you might be right with one of those. I plan to call Mancini today and ask them about this cap and send it back.

I think I'm just going to have to go with a MSD setup. Dizzy, 6AL, and coil...
 
Look at the indexing on each cap to see if the relationship of the tang that locates the cap has the same relationship to the towers.
 
Next thing I have to do is get rid of these TERRIBLE Hooker Headers. I hate the way they block 5 & 7.
 
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I added one of the add-on shrouds for my fan since I didn't have the stock one (see pic). In the pic. its hard to see how close your wires are to the wiper motor, but mine are really close and while adjusting time had accidentally gouged one of the boots. This would cause an arc to the motor from time to time (not always); and of course a miss.

shroud.JPG
 
I had a cam like that for awhile in my 367. It really liked 4.88s with a 2.66 low gear manual trans. That would be a 12.98 starter gear.
"Timing is Good" means zero to us. OK means zero to me.
That cam wants a ton of timing at idle, and it wants it fast. And it wants the Vcan to bring in a bunch more.
So what's a "ton of timing"? you might ask? Well that would depend on your tuning skills. For me, it liked 20* or more initial, but I figured out a way to idle it on 16*.The engine liked 34/36 at WOT and all-in at 3000. That cam wanted 89 gas on that with 11.3 SCR. I wanted to run 87E10, so I figured out a way to do that Too.
And that cam wanted more than 54* of cruise timing.
In my 367, that cam wanted a 4-corner idle system, so I figured out how to do that too. The secondaries had to be opened for Idle-Air Bypass, but the AirGap did not go for the dry-air back there. So I modded the secondary side to kick in some fuel back there, then took some out of the front by closing the throttles. That put the transfers back into sync, and torque production went back to normal.
That cam pulled crazy hard from 5000 up. But it was a little soft on the bottom. In the end I pulled it and sold it to a racer.

Without the Vcan helping torque production in the Part-Throttle lower rpms, it is a good thing you have a stroker.

So tell a bit more about spudder; what exactly is that?
 
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AJ/FormS said:
I had a cam like that for awhile in my 367. It really liked 4.88s with a 2.66 low gear manual trans. That would be a 12.98 starter gear.
"Timing is Good" means zero to us. OK means zero to me.
That cam wants a ton of timing at idle, and it wants it fast. And it wants the Vcan to bring in a bunch more.
So what's a "ton of timing"? you might ask? Well that would depend on your tuning skills. For me, it liked 20* or more initial, but I figured out a way to idle it on 16*.The engine liked 34/36 at WOT and all-in at 3000. That cam wanted 89 gas on that with 11.3 SCR. I wanted to run 87E10, so I figured out a way to do that Too.
And that cam wanted more than 54* of cruise timing.
In my 367, that cam wanted a 4-corner idle system, so I figured out how to do that too. The secondaries had to be opened for Idle-Air Bypass, but the AirGap did not go for the dry-air back there. So I modded the secondary side to kick in some fuel back there, then took some out of the front by closing the throttles. That put the transfers back into sync, and torque production went back to normal.
That cam pulled crazy hard from 5000 up. But it was a little soft on the bottom. In the end I pulled it and sold it to a racer.

Without the Vcan helping torque production in the Part-Throttle lower rpms, it is a good thing you have a stroker.

So tell a bit more about spudder; what exactly is that?
Click to expand...

Thank you for the reply. I will admit I am a n00b at tuning these things, but in my defense I just got the car in October and it sat all winter so I have only been tinkering with it for a couple months. I will learn!

The timing is set at 35. I've narrowed the issue down to something with the new firecore cap and rotor or the 8.5 MSD wires. When I put the old cap and wires on it runs fine.

I plan to first swap these Hookers for TTIs so my wires are not cooking, then I'll figure out the cap and rotor issue. The car has a MP Dizzy in it. Probably swap that to MSD as well.

The car came with 430s, and a 4200 stall. (It was a track car that I am putting on the street) I've changed the gears to 3.73s. I wanted 3.91s but only options I had for a Dana were 4.10s then 3.73s. No 3.91 option that I could find. Going from 4.30s to 4.10 would barely make a difference. I already have a new stall spec'd out to go better with the gears and keep the cam happy. It all just come down to $$$ from here.
 
"Timing is set to 35"
What's that mean?
35 at idle, 35 at all-in, 35 with vcan still connected, 35 at 2000, 35 at 3000, 35 at 4000.
35;when, and how?

If it's 35 all-in-no-VA at say 3200, then what's the idle timing?

If it's 35 at idle, then that's your problem.

"Timing is good", per post #13 is totally ambiguous. It assumes you know exactly what your doing, and includes no parameters, so is meaningless.
"Timing is set at 35", per post #20, is just as ambiguous, and only slightly less meaningless.
 
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