kamshaft
Well-Known Member
what is the best carb to run my truck i have a holley 4150 650 dp right now and i cant get anything set right
just floods out the motor
just floods out the motor
-
Welcome Visitor! Please take a few seconds and Register
for our forum. Even if you don't want to post, you can still 'Like' and react to posts.
carb for a 302??
- Thread starter kamshaft
- Start date
kamshaft
Well-Known Member
motor is a 302 out 0f an 86 t-bird boared 30 over with nickoff victor high rise and e303
I'd rebuild the Holley.
lairdt
Active Member
Carb needs to be tuned for your engine combo. You'd have significantly fewer issues with a vacuum secondary carb, and better mileage, but since you have the DP I'd say get a Holley tuning book and tune it. You should be able to research your engine combo and get a starting place to dial it in. Note that this will take carb parts you will have to buy, and a lot of time and patience.
If this isn't for you, get a 600cfm vac sec carb.... Holley or otherwise there's a lot less tuning to do.
If this isn't for you, get a 600cfm vac sec carb.... Holley or otherwise there's a lot less tuning to do.
baddad457
Well-Known Member
He needs to start by replacing the Vic Jr intake with a good dual plane intake, then top it with a vacuum sec Holley carb, like a 570 Street Avenger or an 1850 600. The carb is too big, the intake's only making it worse.
Last edited:
Another discussion, but I ran a 650 DP for a couple years on my '67 Cougar...
The carb is 'dumping fuel' because of an internal malfunction and not the combo.
That's a tough combination of parts. Your engine was originally rated at 150hp @ 3,200rpm. It was designed to lug a station wagon around with a 2.50 ring gear. The heads were not designed to flow the 5,500rpm your camshaft selection is capable of--and your choice of intake manifold is rated to flow up to 8,500rpm. The carb could actually work on that manifold, but not on that engine.
Ford was focusing the torque right off idle, and the torque converter was designed to work with it. When you kill the torque, the converter won't flash anymore because you aren't hitting it hard enough. That means the car won't start moving, the engine won't gain rpm, air won't get flowing. to make it worse, you have a) a giant single plane intake which exposes the slow moving pistons to a giant volume of air that has too much inertia to actually move into the chamber. On top of that, you have mechanical secondaries with no air valve above them and that's way, way too big a hole for that 3,200rpm cylinder head to deal with.
You have 3 design philosophies at work here, and they don't work together any better than a grenade would replace a scalpel or a pipe wrench would replace tweezers. Pick one a) station wagon engine, b) street engine, c) race engine, and focus your parts on that goal.
I think your goal is b) so i would do what Baddad suggests and get rid of the Victor/double-pump. That cam is too much for your heads, but it could be made to work. Or at least it will run well enough until you can get decent ones. That cam focuses power above 2,500rpm so if you are using the stock converter, it won't be great. I would get a higher stall converter. Trucks tend to have a little deeper gears so you might be alright there.
If you insist on trying to make the double-pump work, think of it this way--big = slow airspeed at low rpms. Low airspeed = poor cylinder filling at low rpms. Low airspeed means poor carb signal--it needs air speeding through the venturies to pull fuel out of the bowls. To crutch it, you need a long, small squirt from the carb shooters. That's trial and error. There's nothing magic about a carb. You don't even need a carb to run an engine--a small, metered trickle of fuel right down the manifold will do the job. That's the theory of tuning a DP for the street.
A well-tuned, good running engine of 150hp is better than a theoretical 300hp that runs like dogcrap.
Ford was focusing the torque right off idle, and the torque converter was designed to work with it. When you kill the torque, the converter won't flash anymore because you aren't hitting it hard enough. That means the car won't start moving, the engine won't gain rpm, air won't get flowing. to make it worse, you have a) a giant single plane intake which exposes the slow moving pistons to a giant volume of air that has too much inertia to actually move into the chamber. On top of that, you have mechanical secondaries with no air valve above them and that's way, way too big a hole for that 3,200rpm cylinder head to deal with.
You have 3 design philosophies at work here, and they don't work together any better than a grenade would replace a scalpel or a pipe wrench would replace tweezers. Pick one a) station wagon engine, b) street engine, c) race engine, and focus your parts on that goal.
I think your goal is b) so i would do what Baddad suggests and get rid of the Victor/double-pump. That cam is too much for your heads, but it could be made to work. Or at least it will run well enough until you can get decent ones. That cam focuses power above 2,500rpm so if you are using the stock converter, it won't be great. I would get a higher stall converter. Trucks tend to have a little deeper gears so you might be alright there.
If you insist on trying to make the double-pump work, think of it this way--big = slow airspeed at low rpms. Low airspeed = poor cylinder filling at low rpms. Low airspeed means poor carb signal--it needs air speeding through the venturies to pull fuel out of the bowls. To crutch it, you need a long, small squirt from the carb shooters. That's trial and error. There's nothing magic about a carb. You don't even need a carb to run an engine--a small, metered trickle of fuel right down the manifold will do the job. That's the theory of tuning a DP for the street.
A well-tuned, good running engine of 150hp is better than a theoretical 300hp that runs like dogcrap.
85_Ranger4x4
Wallows in rivers
TRS Event Staff
TRS Forum Moderator
Article Contributor
V8 Engine Swap
OTOTM Winner
TRS 20th Anniversary
VAGABOND
TRS Event Participant
With the stock cam mine gets along fine with a jetted down 500cfm 4bbl (Edelbrock 1403, vacuum secondaries, electric choke...) Mine is an '87 non-HO which I am pretty sure is the same engine as your '86 started out.
If you would stick different heads on it (provided you have the E6 heads) it will really help.
If you would stick different heads on it (provided you have the E6 heads) it will really help.
baddad457
Well-Known Member
Well Will hit the nail on the head (abeit a little long winded) In short, the Vic Jr and the DP combine to a zero vacuum signal when you nail the go pedal from a dead stop, and not much better all the way up to around 3 grand in the rpm band. No vacuum signal = no fuel gets pulled from the bowls. You're basically relying on what fuel gets squirted by the accellerator pump to get the truck moving. The E303 is fine for it, maybe not if it's got E6 heads though. If it's got E7's it'll do fine.
tempforce
Well-Known Member
a 460 cfm carb will give you excellent low and mid range power. you will loose some top end. but a small carb will give better mpg numbers.
also take a look at this for trouble shooting your carb..http://www.edelbrock.com/automotive_new/misc/tech_center/install/carb_faq.shtml
also take a look at this for trouble shooting your carb..http://www.edelbrock.com/automotive_new/misc/tech_center/install/carb_faq.shtml
His motor has no top end so he can't lose it. The most important part of any motor is the head. Everything else is bolt-on. He's got an '86 'bird which has the 150hp motor. It's tuned to really zip from idle to 3,000. It feels really powerful from a stop, but when you run it out, it falls on it's ass and you are lucky to get the car over 85mph. Honestly, I wouldn't have messed with it at all--I love that type of motor. Anything you do to it will take something away from that off-idle explosion of torque.
I made plenty of mistakes when I was building hotrods. I've worked on a lot of carberated engines. I don't mess with them anymore, except my sister's '65 Mustang and equipment, but I'm not passing anything along that I haven't done or witnessed firsthand.
It's like this guy that bought a Summit tunnel ram kit for a stock 302 Mustang. We made it work, but it wasn't fast. Performance means it is in a high state of tune, not that it has cool looking parts. You can't get the wrong parts into a high state of tune.
Yes, I'm wordy. My kids dream of chopping me into bits with axes I'll bet.
kamshaft
Well-Known Member
wooooow learned alot btw im running a t5 and soon replacing the heads with ported 351 heads motor is boared .030 over and hei single wire dis..
Sponsored Ad
Sponsored Ad
TRS Events
Member & Vendor Upgrades
For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.
Recently Featured
Ranger Adventure Video
TRS Merchandise
Follow TRS On Instagram
