tune help

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jeppe

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okey specs for car first.
dart 71 318
scat i-beams
kb flat top pistons
comp cams nostalgia plus pn#20-670-20
int.dur.adv 280
exh.dur.adv 287
exh. valve lift 0.474
int. valve lift 0.474
speedermaster intake
edelbrock 1405 carb
mopar elec ign
vac advence is disconnect and base timing is about 20 if i remember correctly

so i got the car couple weeks ago. the pcv from carp was disconnected
so i put in back to carp. it idlesh okayeish but like every 30secs it shakes like crazy. it dosent stay running without gas on cold engine and manual choke dosent have like any effect.
i hooked vac meter to carp it only gets 7-10 vacuum, so i tried to adjust the idle mixture screws and it had very minimal change. if i let it idle like 15mins temps rise to 212f where i shut the car off, it dosent puke coolant. but im not sure if the temps is because mechanical fan is 2inch from rad and theres no fan shroud, i alredy checked to thermostat in boiling water and drilled 2mm hole in it. what i should check next :eek: thanks in advance :=)
 
7 inches of vac at 20 before TDC? If you're mixture screws aren't doing anything the primaries are open too far and you have bypassed the idle circuit. But first check your float level. I'd suggest carb removal, reset primary throttle blades for correct transfer slot exposure as a starting point. When you put it back on note where the cold idle screw is to put it back of you have to! Seat your mixture screws and then back them both off about 1.25 turns to start.Im not going to give a lesson on setting up the carb cause that info is readily available but I'd suggest you start with that. Make sure you adjust everything with the car at operating temperature. If you need more idle air you can start by opening the secondary blades a crack before you start drilling holes anywhere! Check that stuff first and it'll only cost you a base plate gasket!
 
66Valiant528 said:
7 inches of vac at 20 before TDC? If you're mixture screws aren't doing anything the primaries are open too far and you have bypassed the idle circuit. But first check your float level. I'd suggest carb removal, reset primary throttle blades for correct transfer slot exposure as a starting point. When you put it back on note where the cold idle screw is to put it back of you have to! Seat your mixture screws and then back them both off about 1.25 turns to start.Im not going to give a lesson on setting up the carb cause that info is readily available but I'd suggest you start with that. Make sure you adjust everything with the car at operating temperature. If you need more idle air you can start by opening the secondary blades a crack before you start drilling holes anywhere! Check that stuff first and it'll only cost you a base plate gasket!
Click to expand...
Shiz just saw its an Edelbrock.....never mind
 
Your fan needs to be close enough to the radiator that you skin your knuckles on the radiator fins putting it in. And then you need a shroud. Your cam timing of 233/240 @ .050 on a 110 LSA. Just curious what cylinder heads are you running?
As far as tuning, you need one of these and some quality time with your carburetor. Directions and several tuning baselines are in the kit.
Performer Carburetor Calibration Kit #1479 for #1405 Carburetors
You’re probably going to have to go over ignition curve and make the vacuum advance operable, too. I’ll post a link to the ignition tech page here when I find it. And, Your engine would probably do better with a larger carburetor, but what you have may provide a good tuning lesson. I would be looking into at least 700 cfm in a 4150 (double Pumper) or maybe a Holley 3310 750 vacuum secondary.
 
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Garrett Ellison said:
Your fan needs to be close enough to the radiator that you skin your knuckles on the radiator fins putting it in. And then you need a shroud. Your cam timing of 233/240 @ .050 on a 110 LSA. Just curious what cylinder heads are you running?
As far as tuning, you need one of these and some quality time with your carburetor. Directions and several tuning baselines are in the kit.
Performer Carburetor Calibration Kit #1479 for #1405 Carburetors
You’re probably going to have to go over ignition curve and make the vacuum advance operable, too. I’ll post a link to the ignition tech page here when I find it. And, Your engine would probably do better with a larger carburetor, but what you have may provide a good tuning lesson. I would be looking into at least 700 cfm in a 4150 (double Pumper) or maybe a Holley 3310 750 vacuum secondary.
Click to expand...

oh yeah forgot to mention heads.i think they from 360 with some heavier springs.
 
jeppe said:
okey specs for car first.
dart 71 318
scat i-beams
kb flat top pistons
comp cams nostalgia plus pn#20-670-20
int.dur.adv 280
exh.dur.adv 287
exh. valve lift 0.474
int. valve lift 0.474
speedermaster intake
edelbrock 1405 carb
mopar elec ign
vac advence is disconnect and base timing is about 20 if i remember correctly

so i got the car couple weeks ago. the pcv from carp was disconnected
so i put in back to carp. it idlesh okayeish but like every 30secs it shakes like crazy. it dosent stay running without gas on cold engine and manual choke dosent have like any effect.
i hooked vac meter to carp it only gets 7-10 vacuum, so i tried to adjust the idle mixture screws and it had very minimal change. if i let it idle like 15mins temps rise to 212f where i shut the car off, it dosent puke coolant. but im not sure if the temps is because mechanical fan is 2inch from rad and theres no fan shroud, i alredy checked to thermostat in boiling water and drilled 2mm hole in it. what i should check next :eek: thanks in advance :=)
Click to expand...
Check your total timing/full advance.
20 initial would more than likely make it run cooler at idle and not hotter.
The fan ,it needs to be about 3/4 -1" from the radiator, not 2, or it will run hot till it gets moving through air 'at speed '.
Pcv hooked up making it cough here n there could be a blow by issue or maybe you are not readjusting the idle mix screws afterwards?
 
MOPAROFFICIAL said:
Check your total timing/full advance.
20 initial would more than likely make it run cooler at idle and not hotter.
The fan ,it needs to be about 3/4 -1" from the radiator, not 2, or it will run hot till it gets moving through air 'at speed '.
Pcv hooked up making it cough here n there could be a blow by issue or maybe you are not readjusting the idle mix screws afterwards?
Click to expand...
the shaking was there before and after the pcv. and i tried to adjust the idlemix after putting the pcv back.
but okey tomorrow i trie to move the fan or radiator closer together. alredy have one diy fan spacer installed but its only like 1inches thick
 
And i dont realy wanna buy new carb because im thinking of upgrading to sniper maybe next summer
 
Do you care to share the rest of the details of the car? I can’t find the articles on re setting stock ignition curve at the moment. Here’s something that may be helpful for not much $ though. You want the ignition manual and limiter plate with spring kit. Any tuning experience you can get now will be helpful when you make the change to the sniper setup. It doesn’t hurt to know and understand what your engine needs to operate properly before you start setting up an advanced engine management system.
 
Garrett Ellison said:
Do you care to share the rest of the details of the car? I can’t find the articles on re setting stock ignition curve at the moment. Here’s something that may be helpful for not much $ though. You want the ignition manual and limiter plate with spring kit. Any tuning experience you can get now will be helpful when you make the change to the sniper setup. It doesn’t hurt to know and understand what your engine needs to operate properly before you start setting up an advanced engine management system.
Click to expand...
thanks so much for help so far. im sorry what more details you like to know?
 
Just what car, automatic converter or if it’s manual, what gear, and compression ratio. Just curious to see if you’ve checked how cranking compression you got with that one?
 
Check if fuel is dripping in from the boosters. Had many of those carbs be sensitive to fuel pressures above 5.5#

I'm sure someone will be along shortly to say something like that should never happen... :)

Low idle vacuum will also likely need a rod spring change.
 
Garrett Ellison said:
Just what car, automatic converter or if it’s manual, what gear, and compression ratio. Just curious to see if you’ve checked how cranking compression you got with that one?
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dodge dart swinger 71. automatic 904. sorry dont know what gear is in it nor the comp ratio. no havent checked compression.
 
Nice Car! But I’ve not met a Mopar I haven’t liked …
:lol:
It’s going to be quite a learning curve. As well as fuel pressure (get a fuel line for the carb with a gauge on it), check your float levels according to E-Brock’s instructions. But work on your cooling first. Then warm it up, pull the plugs, oil the cylinders, and do a compression test on all cylinders and record your numbers for future reference. You’ll be glad you did if you ever have any issues come up. And most of all, have fun, and good luck! You’re going to be a little busy with the tuning on this one.
 
MOPAROFFICIAL said:
Carb should be fine.
Click to expand...
I’m going to second that motion. Keeping it simple will cost less and may leave money in the budget for things that may be a bigger performance advantage. An Edelbrock 1906 650 AVS2 manual choke carburetor would make for very good driving manners.
 
First things first.
- Do not assume initial timing is 'about' 20*, check it because that cam will need AT LEAST 20* if not more for BEST IDLE.
- Remove the carb. Turn up side down & check how much transfer slot is showing at idle. Any more than 0.040" [ 1mm ] is too much. It is likely to be MUCH more than 040 because you are not using the PCV, which would normally add some air; the blades are now opened further to compensate. Leave the PCV disconnected for now because it will NOT work with your low vacuum.
- with carb off, remove airhorn & check that float level is 7/16". Unlike brand H & clones you will not need gaskets if you are careful.
- If f/level is correct, you will need to drill a small hole in each secondary t/blade [ not the primary blades as most recommend ]. Start with a 3/32" hole. Refit carb & test again for idle etc. I suspect the 3/32" hole may need to be much larger, up to 9/64", but try in increments. Aim is for 040 - 020 & less is better of T/slot showing at hot idle. You get that by drilling the blades. Trial & error.
- if the f/level was incorrect, set it correctly & do the above test.
- Report back once this has been done.
 
Bewy said:
First things first.
- Do not assume initial timing is 'about' 20*, check it because that cam will need AT LEAST 20* if not more for BEST IDLE.
- Remove the carb. Turn up side down & check how much transfer slot is showing at idle. Any more than 0.040" [ 1mm ] is too much. It is likely to be MUCH more than 040 because you are not using the PCV, which would normally add some air; the blades are now opened further to compensate. Leave the PCV disconnected for now because it will NOT work with your low vacuum.
- with carb off, remove airhorn & check that float level is 7/16". Unlike brand H & clones you will not need gaskets if you are careful.
- If f/level is correct, you will need to drill a small hole in each secondary t/blade [ not the primary blades as most recommend ]. Start with a 3/32" hole. Refit carb & test again for idle etc. I suspect the 3/32" hole may need to be much larger, up to 9/64", but try in increments. Aim is for 040 - 020 & less is better of T/slot showing at hot idle. You get that by drilling the blades. Trial & error.
- if the f/level was incorrect, set it correctly & do the above test.
- Report back once this has been done.
Click to expand...
hey sorry for taking so long me to reply but been kinda busy. tomorrow i will be taking the carp of and checking the float and prob start drilling. one thing. why to drill secondarys and not primarys? thanks :)
 
Two reasons:
- when the engine needs more air, it doesn't care where the air comes from...as long as it gets the air.
- the 1405 carb is a 600 cfm unit & has small primary bores. That means air passes through at a higher velocity than say the larger 750 cfm carb, that has larger primaries.
Drilling the pri blades means that the air must pass through the carb & there is a possibility that the high velocity air will pull/dribble fuel from the pri boosters. [ nozzle drip ]. Because the sec bores are larger, velocity is slower, so no nozzle drip.
 
okey i drilled the secondaries with 3mm holes. now my mixture screws work! but i have another problem... now when i pump the gas the rpm stays high for like 5seconds before coming back down. tried to find vac leak and even did new carb and spacer gasgets. could too big drilled holes cause rpm to hang? And when i but my hand over air horn the rpm raises EDIT: i riveted the drilled holes back and the car runs like it used to
 
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I suspect the high rpm could be either the pri or sec blades hanging up slightly & not fully seating. Sometimes using thick base gaskets, it will twist the body slightly & bind the throttle shafts.
 
Can anyone recomend pcv valve for low vacuum. I know about the mevagner valve buy thats like 200 euros when shipped to me....
 
PCV. I have done this on MANY low vacuum engines.

The orifice size at idle, pulling vacuum, on the PCV is about 7/64". I weld/braze a disc across the PCV opening. Once in place, I drill a 7/64"hole in it. Job done.
 
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