wtf???

[Braden]

so ive put about 300 miles on my new engine and 2 days ago it was running great and everything was fine now all of the sudden it runs like shit, something has changed but i cant figure out what it is, i have so far inspected the plugs plug wires dizzy cap rotor, etc also visuallly inspected carbs and matchbox and verified all wires and grounds were tight. now heres the scoop it will start up normal and idle normal but when you go to take off it spits and sputters but it does go as long as you keep it at about 15 percent throttle or less, if you mash on it it will act like the engine is revving up and will make some noise as normal but its real rough like its only hitting on 3 or maybe 3.5 cylinders, its wierd, its b/s, it has the same symptoms of a clogged jet or something but damn i ran all new fuel lines and 2 brand new metal fuel filters and it was running great. my thoughts on the problem make me think its something i cant see such as a clogged jet, or a plug thats fouled but i cant tell it (i did burn them off twice just to make sure), bad plug wire, bad module. thats about all i can think of that would just instantly make it run like shit. i was on my way home and i passed somebody and then it started running like hell, you can give it 100% throttle and it doesnt go anywhere!!! the exhaust also sounds kind of crackly, not like its backfiring but cracklier than normal. anybody have any ideas? im obviously going to probably change the plugs and wires again even though they are brand new. maybe try a different module and try removing the jet blocks and inspecting them (thank god its mikunis), also something that crossed my mind is that damn electric fuel pump i am using, i guess if it was lacking in fuel pressure it could cause a problem like this as well. but hell its all brand new!!! maybe the fuel pump blew out the needle and seat? i just want my power back!!!!!

[bonvo]

sounds like what my car was doing when the ignition module when out have fun with that just that stupid little matchbox sized thing is close to 300 bones

[datzenmike]

Check all plugs. If there's blockage it will run lean and the plug insulator inside will be a very light often white color.

 

Water will pass through a filter and because it's heavier than gas will sink to the bottom of the float chamber and block a jet. Will usually idle fine on another circuit. Go to wallmart paint dept. and buy a liter of methyl hydrate... it's the same shit they they sell for gas line anti-freeze at $2.00 for 3 oz.. Dump half in and drive it. The alcohol will mix with the gas AND the water effective dissolving it and allowing it to be run through the motor and .... gone.

 

There may have been a small amount of water in the bottom of a fuel line. Normal driving was fine but heavy throttle demands more flow from the tank and it maybe got sucked up to the carb(s).

[banzai510(hainz)]

ck valve lash

Fuel pump should be less than 4pounds

 

Im sure the plug wires are fine.

 

Ck the jet blocks and inner venturi air gorn in case they are wiggly inside.

 

swap out another dizzy or reground it.

 

fell coil if Hot but assume you have a MSD Blaster 2 which should be good.

[Braden]

well after inpescting the plugs and noticing that number 4 was quite a bit more sooty than the rest i inspected the jet blocks and found number 4 to be about 3 turns loose, i changed the jets from 150 to 145's threw it back together and it ran fine, i am contemplating running a step hotter on the plugs since the mixture was a bit rich on all 4 cylinders. i hope that downsizing on the jets and bumping up the heat range i can get a more complete burn out of all this 93 octane im going through. fun fun fun, thanks for the ideas guys!!

[banzai510(hainz)]

My jet block turn out loose all the time. I carry a screw driver just for this.

Really should carry a tool box.

 

Last really hot day up here in the Seattle area I went to the store. stopped to get soemthing then took off car felt like it was going to run out of gas. Pull in to a Autozone. Im cking the jet blocks. All look good ,I Autozone kid is bothering me asking if my car is fast and seen me at Pacific Raceways. I said its fast for 1960 tech 4cylinder and I wasnt at Pacific raceways. He said there was a car with a hood like mine(Rising Sun).

 

So Now I take off car cuts out. After driving enough to cool off ther motor figure it was vapor lock from the manifold heating up the carbs. Probably be better if a ran 91 octane.

[Braden]

hainz what size mains are you running? mine had 150's and i switched to 145's and i think it act a bit better with the 145's i guess it all depends on your head/cam/displacement combo

[banzai510(hainz)]

Im running 135 but these are 40Mikunis

I think the 44s come with 160s

 

I would have to open up my yellow car jets to ck them.

[datzenmike]

i am contemplating running a step hotter on the plugs since the mixture was a bit rich on all 4 cylinders. i hope that downsizing on the jets and bumping up the heat range i can get a more complete burn out of all this 93 octane im going through. fun fun fun, thanks for the ideas guys!!

 

You run as cool a plug as possible. The heat range must only be hot enough to keep the tip clean of carbon. Proper jet size will help too. If you run too hot, the tip will sometimes glow. You do not want hot glowing things inside the combustion chamber.

[Braden]

mike with thne 150's i was running the plugs were sooty black. i am running the stock heat range in the ngk v power, do you thiunk i could benefeit from a higher priced ngk plug such as platinum? i have had great success with just the plain old ngk plugs. btu with the rich mixture i was thinking that one step hotter plug and one jet downsize should lean it out and get a better burn? tell me what you guys think. ill probably run a new set of plugs since ive had to burn these off twice.

[zerow]

 

swap out another dizzy or reground it.

 

 

Regrounding is so simple. I suggest a two fold approach... (May need to do a writeup on this one...)

 

1. Completely remove the blackbox from the distributor. The wires are red and green on the inside. You can't go wrong by taking a digital pic of it first BEFORE disassembly. Clean the contacts by scraping them with a small flathead screwdriver.

 

2. The back side of the matchbox is metal. Use some 220 grit sandpaper and rough up the surface. It doesn't have to be pretty, just clean.

 

3. The spot where the matchbox mounts to the distributor body also carries current (Negative Ground current from Battery). Rough up the surface on those areas as well.

 

4. Use any type of wire you want, and run a ground wire from the body earth (where it attaches to the block) around the front of the cylinder head, to the distributor body. I used 12GA solid copper wire (The Romex ground wire works real good) and crimped on eye connectors for the last repair I did. The screw for the vacuum advance is a good spot. Or anywhere on the distributor body iteslf. Remember: The ground you think you have from the physical connection of bolting the distributor to the pedestal, and then to the block, is disturbed by one very important item: The distributor mounting gasket. No ground connection through paper gasket material!!

 

5. Reconnect the matchbox and mount it to the side of the distributor. Fire it up, and enjoy the fact you are getting full spark through the ignition module :thumbup:

[banzai510(hainz)]

my yell car with 44 they are black and I run Pertronix with high resistance sys

My Banzai car is 40 and the plug s are really clean.

 

I just run whatever plugs I find lying around. Mostly NGK 5 or 6s or Nippondenso

[ggzilla]

Instead of the NGK 5's i use Champion 12s 'cause I had eight new ones from my old Impala. They look great whenever I check them, although two heat ranges hotter than the stock.

 

The problem described by OP is most commonly caused by crud in the carburetor. Even happens on very clean Datsuns.

[datzenmike]

Rather than trying to cure the carbon problem by adjusting the heat range, start by going directly to the cause... the rich or over rich carbs. After all the rest of the combustion chamber and piston tops won't be cleaned by a hotter plug. Carbon build up can plug the rings, dirty the oil and will retain heat often glowing hot and that is a source of pre-ignition. Lean them out until plugs run light brown. Start with stock heat range.

[Braden]

Regrounding is so simple. I suggest a two fold approach... (May need to do a writeup on this one...)

 

1. Completely remove the blackbox from the distributor. The wires are red and green on the inside. You can't go wrong by taking a digital pic of it first BEFORE disassembly. Clean the contacts by scraping them with a small flathead screwdriver.

 

2. The back side of the matchbox is metal. Use some 220 grit sandpaper and rough up the surface. It doesn't have to be pretty, just clean.

 

3. The spot where the matchbox mounts to the distributor body also carries current (Negative Ground current from Battery). Rough up the surface on those areas as well.

 

4. Use any type of wire you want, and run a ground wire from the body earth (where it attaches to the block) around the front of the cylinder head, to the distributor body. I used 12GA solid copper wire (The Romex ground wire works real good) and crimped on eye connectors for the last repair I did. The screw for the vacuum advance is a good spot. Or anywhere on the distributor body iteslf. Remember: The ground you think you have from the physical connection of bolting the distributor to the pedestal, and then to the block, is disturbed by one very important item: The distributor mounting gasket. No ground connection through paper gasket material!!

 

5. Reconnect the matchbox and mount it to the side of the distributor. Fire it up, and enjoy the fact you are getting full spark through the ignition module :thumbup:

i have already done this with premium fine strand 8 gauge 99 percent pure copper wire, cleaned all contacts and yes i did sand the back of the module. i have an 8 gauge ground from the engine block straight to the battery bro.

[Braden]

Rather than trying to cure the carbon problem by adjusting the heat range, start by going directly to the cause... the rich or over rich carbs. After all the rest of the combustion chamber and piston tops won't be cleaned by a hotter plug. Carbon build up can plug the rings, dirty the oil and will retain heat often glowing hot and that is a source of pre-ignition. Lean them out until plugs run light brown. Start with stock heat range.

good idea mike i will run these plugs a while longer now that i have down jetted, pull them out and inspect them and then go from there. i have read somewhere when checking plugs after engine is warm run it at mid rpms for 30 seconds then turn engine off to simulate normal driving so you can get an accurate reading instead of the engine just idling and possibly causing soot build up.