My engine sure seems to want more jetting

[Lil Demon]

The spark plugs need to be replaced before any additional tuning takes place. That or clean them off with a 150 shot of n20

Haha, I don’t have any laughing gas setups so, new plugs it is.

 

[Jeremiah (jd)]

What plug is in it currently? -6 or -7 ngk ?

 

[MobileCustoms]

I agree those plugs still look like crap but I don’t think they would clean up from the level of fuel they had on after a quick 10 minute drive. It was just a test to see if they would “clean” up. New plugs will be going in tomorrow and oil.

As far as my 15 inches of vacuum. That was forced just cause I was at a higher RPM than usual. With the 3.91’s 28 inch tires and the 6 speed my RPM range is closer to 1200 to 3000 and cruises at 1800 to 2200 depending on gear and speed obviously. I almost never use 6th. So with that being said my cruise vacuum is usually well below 10. I may even try the 8.5 I have there. Max I have is the 9.5 after I put the new plugs in tomorrow and see how it does. I prefer running the smallest jets possible I was just obviously needing direction cause this one has kicked my butt for a while.

You may have a vacuum leak somewhere in the system... bad pcv valve, intake corner or at the brake booster, if you have power brakes. Never hurts to double check everything. Is your carb gasket good, and snugged up for sure?

 

[Lil Demon]

You may have a vacuum leak somewhere in the system... bad pcv valve, intake corner or at the brake booster, if you have power brakes. Never hurts to double check everything. Is your carb gasket good, and snugged up for sure?

No power brakes. During my vacuum testing I’m canceling the pcv valve. Why do you think it may have a vacuum leak?. The driveability improved with the tune suggested by the members. It seems it’s going in the right direction, or am I missing something? Do you feel my manifold vacuum is too low?. I can make the engine idle down to 500rpm without it stalling either. It just runs rougher than I would like.

 

[Lil Demon]

What plug is in it currently? -6 or -7 ngk ?

It’s actually an Autolite 3922

 

[MobileCustoms]

No power brakes. During my vacuum testing I’m canceling the pcv valve. Why do you think it may have a vacuum leak?. The driveability improved with the tune suggested by the members. It seems it’s going in the right direction, or am I missing something? Do you feel my manifold vacuum is too low?. I can make the engine idle down to 500rpm without it stalling either. It just runs rougher than I would like.

I don't THINK you have a vacuum leak, just suggesting you verify and eliminate all the possibilities you can. Even a small leak will affect how it's pulling fuel in. It does seem like your vacuum could be low though, if it's pulling less than 10 at 1800 rpm? I don't really know more than enough to be dangerous. Just trying to help you cover all the simple basics first.

 

[Lil Demon]

I don't THINK you have a vacuum leak, just suggesting you verify and eliminate all the possibilities you can. Even a small leak will affect how it's pulling fuel in. It does seem like your vacuum could be low though, if it's pulling less than 10 at 1800 rpm? I don't really know more than enough to be dangerous. Just trying to help you cover all the simple basics first.

Got ya, hmm.

 

[RustyRatRod]

I think I go along with the "It needs more carburetor" crowd.

 

[Lil Demon]

I think I go along with the "It needs more carburetor" crowd.

I have gone down that path before with the car. I’ve run 750VS, 750MS, and an Edelbrock 800. All had the same issue. I have never been able to tune it out. I decided to go to the 650 for improved throttle response and more appropriate for street use. With this latest tune suggested by the members, it’s the best it’s ever run. Now just gonna start perfecting the tune.

 

[RustyRatRod]

I have gone down that path before with the car. I’ve run 750VS, 750MS, and an Edelbrock 800. All had the same issue. I have never been able to tune it out. I decided to go to the 650 for improved throttle response and more appropriate for street use. With this latest tune suggested by the members, it’s the best it’s ever run. Now just gonna start perfecting the tune.

That would make me suspect it's not carburetor related. What'd ya do with the Edelbrock 800? lol

 

[Lil Demon]

That would make me suspect it's not carburetor related. What'd ya do with the Edelbrock 800? lol

I still have it. I got lots of carbs at hand. Different builds etc.. of all the cars I’ve messed with this one has always beat me. I think it’s the whole gearing setup that threw me off and has been beyond my capabilities

 

[Bewy]

I would be increasing the IFR in 0.002" increments. The IFR supplies fuel for transition & it sounds like your lugging problem is just off idle, the transition cct.

 

[SixPaksRule]

coolant temp?

 

[Sterling]

I had a 318 in my dad's 74 Dart Sport, with a Edelbrock Proformer intake and a Thermoquad carb. I was tuning, and ended up with the largest jets and the smallest metering rods in the carb. The car continued to improve but I thought that a 318 shouldn't need that much fuel. I think that the intake was leaking vacuum in the cam valley. I changed the intake and installed a Holley carb and made a drastic difference. So you might have a vacuum leak you can't find.

 

[Kendog 170]

Thanks for all the great feedback. Given the latest results, would you say I should expose them to square?

IMO yes. I'm no expert though but it should help at the red light starts. Barely visible transition holes to me spells stumble. Good luck and I hope you get things sorted out.

 

[Dave999]

can't add much to this no idea about holleys but i found it impossible to tune with plugs all fowled up..

and getting the right heat range of plug is very necessary.

AF/Lambda tune to 14.1 not 14.7 for modern ethanol 5% 10% fuel
and until your car can successfully fire off the mixture all the time ignore what it says for any flat spot situation... it will lead you the wrong way
useful from good tuning to best
no use whats so ever from bad turning to good... it will mess with your head....

its tech for FI cars, it was never designed to cater for how WRONG you can get it with a carb and distributor, However can be very useful for getting from 1970s style "Fat mixture" kinda good everywhere, to really right, with a carb

Dave

 

[Lil Demon]

Operating temperature is 180 degrees.

I have been considering messing with the IFR but wasn’t sure. I will check if I have the jets to make a change in that circuit.

Intake manifold leak IS something to consider, sorry I just realized I texted isn't. Yes something to look at.

Again, it’s practically cured since I applied the setup by fishmens67,
so I will replace plugs, change oil and continue to drive it to see how it works

 

[Super-Cuda]

Dyno time is very expensive. My Modi operandi is to get the baseline tune done long before it goes on a dyno. Do the final trimming and wot power stuff on a dyno. Doing drivability tuning on the rollers is definitely easier but my money is spent elsewhere. And that’s coming from someone who has friends that own and operate a dyno.

View attachment 1716482392

BTW....

Love the truck!

 

[a-bodyguy]

Plugs look worse as you went
I had almost same cam specs on a 108/106 a lil more comp 650 dp 3.23s stick car as i recall i was 18 19 base timming

28 squirter maybe instead of 31
square transition
8.5 pv
stock jets
stock float height
thats alot of base timming
go from there to many cooks in the kitchen

 

[TT5.9mag]

POST THE MODEL AND LIST NUMBER OF THE CARBURETOR SO WE CAN LOOK IT UP AND TELL WHAT THE TUNE UP IS. I hate yelling but 3-4 of us have asked. You still have a lot of tuning to do but I’m glad you’re willing to do it. Cudos for that. And now that we know you can cruise it and get 15” of vacuum you need an 8.5pv at minimum. Maybe even a 10.5.

 

[Lil Demon]

I'm sorry to make you yell, LOL I hadn't noticed anyone asking for the list number. I don't have the carburetor in front of me but its a Proform 67212 carburetor and here are the specs I looked up on their website. Hey and thanks for taking the time to educate me. I am all for learning and have total respect for those of you who are proficient in carb tuning. That's where I want to be

Air Bleed Material	Brass
Air Bleed Size (Inner High Speed)	28
Air Bleed Size (Outer Idle)	70 / 70
Air Bleeds Included	Yes
Base Plate Material	Billet Aluminum
Booster Style	Down-Leg Boosters
Carb Setup	Drag Racing
CFM	650 CFM
Choke	Electric Choke
Discharge Nozzle Size (Primary / Secondary)	.031 in. / .031 in.
Emissions	49 State Legal
Finish	Vibratory Tumble Polished
Flange Style	Square Bore
Ford Kickdown Bracket Included	Yes
Fuel Bowl Inlet Thread	7/8-in. x20
Fuel Fittings	5/8"-18 Inverted Flare
Fuel Inlet	Dual
Fuel Line Inlet Distance	9.313"
Fuel Type	Gasoline
Height (IN)	3.25"
Main Body Material	Lightweight Aluminum
Material	Aluminum
Metering Block Material	Billet Aluminum
Net Height From Carb Flange	3.25-in.
Number of Barrels	4
Primary Main Jet Size	86 / 93
Primary Power Valve (Hg)	6.5
Secondaries	Mechanical Secondaries
Throttle Linkage	Universal

 

[Lil Demon]

I wrote a note on the box regarding original jetting: Primary 70 Secondary 76

 

[Illahe]

Operating temperature is 180 degrees.

I have been considering messing with the IFR but wasn’t sure. I will check if I have the jets to make a change in that circuit.

Intake manifold leak IS something to consider, sorry I just realized I texted isn't. Yes something to look at.

Again, it’s practically cured since I applied the setup by fishmens67,
so I will replace plugs, change oil and continue to drive it to see how it works

Quick explanation on air bleed tuning effect:

 

[Newbomb Turk]

I'm sorry to make you yell, LOL I hadn't noticed anyone asking for the list number. I don't have the carburetor in front of me but its a Proform 67212 carburetor and here are the specs I looked up on their website. Hey and thanks for taking the time to educate me. I am all for learning and have total respect for those of you who are proficient in carb tuning. That's where I want to be

Air Bleed Material	Brass
Air Bleed Size (Inner High Speed)	28
Air Bleed Size (Outer Idle)	70 / 70
Air Bleeds Included	Yes
Base Plate Material	Billet Aluminum
Booster Style	Down-Leg Boosters
Carb Setup	Drag Racing
CFM	650 CFM
Choke	Electric Choke
Discharge Nozzle Size (Primary / Secondary)	.031 in. / .031 in.
Emissions	49 State Legal
Finish	Vibratory Tumble Polished
Flange Style	Square Bore
Ford Kickdown Bracket Included	Yes
Fuel Bowl Inlet Thread	7/8-in. x20
Fuel Fittings	5/8"-18 Inverted Flare
Fuel Inlet	Dual
Fuel Line Inlet Distance	9.313"
Fuel Type	Gasoline
Height (IN)	3.25"
Main Body Material	Lightweight Aluminum
Material	Aluminum
Metering Block Material	Billet Aluminum
Net Height From Carb Flange	3.25-in.
Number of Barrels	4
Primary Main Jet Size	86 / 93
Primary Power Valve (Hg)	6.5
Secondaries	Mechanical Secondaries
Throttle Linkage	Universal

Now we need to know how many and what sized emulsion homes you have open.

That .028 main air bleed is ok.

 

[TT5.9mag]

I'm sorry to make you yell, LOL I hadn't noticed anyone asking for the list number. I don't have the carburetor in front of me but its a Proform 67212 carburetor and here are the specs I looked up on their website. Hey and thanks for taking the time to educate me. I am all for learning and have total respect for those of you who are proficient in carb tuning. That's where I want to be

Air Bleed Material	Brass
Air Bleed Size (Inner High Speed)	28
Air Bleed Size (Outer Idle)	70 / 70
Air Bleeds Included	Yes
Base Plate Material	Billet Aluminum
Booster Style	Down-Leg Boosters
Carb Setup	Drag Racing
CFM	650 CFM
Choke	Electric Choke
Discharge Nozzle Size (Primary / Secondary)	.031 in. / .031 in.
Emissions	49 State Legal
Finish	Vibratory Tumble Polished
Flange Style	Square Bore
Ford Kickdown Bracket Included	Yes
Fuel Bowl Inlet Thread	7/8-in. x20
Fuel Fittings	5/8"-18 Inverted Flare
Fuel Inlet	Dual
Fuel Line Inlet Distance	9.313"
Fuel Type	Gasoline
Height (IN)	3.25"
Main Body Material	Lightweight Aluminum
Material	Aluminum
Metering Block Material	Billet Aluminum
Net Height From Carb Flange	3.25-in.
Number of Barrels	4
Primary Main Jet Size	86 / 93
Primary Power Valve (Hg)	6.5
Secondaries	Mechanical Secondaries
Throttle Linkage	Universal

Thank you. That gives us a little bit of info. But it’s likely they never published the emulsion package anywhere so you’ll need to pull the blocks off of it and pin them.