Need a Carb recommendation

[73' mach 1]

If the engine has the OEM timing set, low and mid ranges will be improved my installing a timing set that does not have the retarded crank sprocket.

Chuck

Ok...I'm confused on this now? You can't just advance the required timing with a screw driver and timing gun? I need to change the sprocket first to get the timing advance I want back over the factory 4 degree retarded? I'm still trying to pick this up.

 

[Mister 4x4]

I think he meant that the crank sprocket is 'retarded' because it's made of nylon (which would actually be the camshaft sprocket, I believe) - or maybe not. Chuck's forgotten more of this stuff than I'll ever know. :chin:

To answer your second questions: Yes, you can change the timing by using a 1/2" wrench to loosen the dizzy clamp and rotate the distributor itself while using a timing light.

 

[TommyK]

If the engine has the OEM timing set, low and mid ranges will be improved my installing a timing set that does not have the retarded crank sprocket.

Chuck

Ok...I'm confused on this now? You can't just advance the required timing with a screw driver and timing gun? I need to change the sprocket first to get the timing advance I want back over the factory 4 degree retarded? I'm still trying to pick this up.

What Chuck is referencing is the cam timing, not the ignition timing. The timing set consists of the cam sprocket, crank sprocket and timing chain and connects the camshaft to the crankshaft. The camshaft controls when the vales open, how long they stay open and when they close. Those events must be "timed" to the position of the piston(s) in the cylinder(s) for all the combustion events to occur with the split second precision needed for an engine to run properly. In order to meet emissions requirements Ford "retarded" the camshaft timing which unfortunately negatively impacts engine performance in the low and mid rpm operating ranges. This was done by using an offset keyway on the crank sprocket. Installing a "straight up" timing set will advance the factory camshaft timing events and provide a modest increase in low and mid rpm performance.

Ignition timing controls the point at which the spark plug fires relative to piston position in the cylinder and is another matter entirely. However it is also an important part of improving the performance of your engine and should not be overlooked.

 

[Mister 4x4]

I like my explanation better. :whistling:

rofl

 

[c9zx]

In an attempt to meet emissions standards Ford retarded the cam in relationship to the crank by moving the position of the keyway slot in the crank gear of the timing set. It did lower emissions but it also made the engine more lazy in the lower rpm ranges. A lot of things they did lowered emission but greatly reduced power and gas mileage. Go figure.

Chuck

EDIT: I didn't see TommyK's post before I responded. I didn't mean to be redundant.

 

[73' mach 1]

Wow! Thanks guys for schooling me proper. With regards to emissions...I remember on my caprice I was able to remove my EGR valve and block that off with a plate. I was also able to remove the air pump and all the hoses with it and then just disable them in the PCM. Can the same be done here? Could I just plug up those vacuum lines or do they truly need to be active to keep some kind of vacuum balance? Here is a pic of my carb. I noticed that there is no vacuum line connected to my EGR and I noticed nothing connected to the fitting on the back of the carb. What is the fitting at the top of the carb go to and is it necessary? I found a hose that has a screw in it blocking it off on one end and I think the other end is going to whats called the temp sensor located on the front of the block. Any info you guys can provide that would allow me to "uncork" all the power ford pulled out due to emissions would be awesome. I understand a lot of the power held back is in the heads and compression but anything else I could get rid of would be great. I'll definitely get the correct timing sprocket. Not trying to be lazy but I just want to make sure I get the correct stuff here...can someone please provide me a part number for the right sprocket and stuff? Like I said, this is my first classic and I'm starting to get excited to get my hands dirty again. I greatly appreciate all the info here guys.

View attachment 31082

 

[73' mach 1]

How does this carb and intake look.

Thunder Series AVS® 650 cfm, Square-Flange, Electric Choke Carburetor #1806 by Edelbrock

http://www.edelbrock.com/automotive/mc/manifolds/ford/rpm-air-gap-351c.shtml

 

[c9zx]

How does this carb and intake look.

Thunder Series AVS® 650 cfm, Square-Flange, Electric Choke Carburetor #1806 by Edelbrock

http://www.edelbrock.com/automotive/mc/manifolds/ford/rpm-air-gap-351c.shtml

It won't fit the OEM intake without an adapter. I'm not a fan of Edelbrock carbs.

Wow! Thanks guys for schooling me proper. With regards to emissions...I remember on my caprice I was able to remove my EGR valve and block that off with a plate. I was also able to remove the air pump and all the hoses with it and then just disable them in the PCM. Can the same be done here? Could I just plug up those vacuum lines or do they truly need to be active to keep some kind of vacuum balance? Here is a pic of my carb. I noticed that there is no vacuum line connected to my EGR and I noticed nothing connected to the fitting on the back of the carb. What is the fitting at the top of the carb go to and is it necessary? I found a hose that has a screw in it blocking it off on one end and I think the other end is going to whats called the temp sensor located on the front of the block. Any info you guys can provide that would allow me to "uncork" all the power ford pulled out due to emissions would be awesome. I understand a lot of the power held back is in the heads and compression but anything else I could get rid of would be great. I'll definitely get the correct timing sprocket. Not trying to be lazy but I just want to make sure I get the correct stuff here...can someone please provide me a part number for the right sprocket and stuff? Like I said, this is my first classic and I'm starting to get excited to get my hands dirty again. I greatly appreciate all the info here guys.

I'd look for a true double roller timing chain set with 9 keyways cut into the crank gear. Please don't do all that work to install a $20.00 timing chain set that you won't want to use if and when you get around to installing a different cam.

If everything is blocked off and the carb has be adjusted to run without the EGR, and the initial timing and timing curve have been optimized, then that is about it with the existing OEM parts.

You can get o 9.8-10.0 with the open chamber heads and single relief flat top pistons IF you near zero deck the block and mill the heads. Even more if you want to spring for thin Cometic MLS head gaskets (spendy).

I'd make sure the current part are optimally adjusted/calibrated and drive the car some to see if you really want/need more "go faster" before starting to buy parts. Once you start, it will snowball. "We'll since I'm this far I might as well .......".

Good Luck,

Chuck

 

[73' mach 1]

Ok guys here is where I'm at. I'm picking up an edelbrock performer intake and I've decided on a Holley carb. Now my question is 600CFM or 650CFM? The 600 I'm looking at is the Holley 4160 the 650 would probably be the 4175. Both have a vacuum secondary and electric choke. The motor is pretty much stock except for an Mallory electronic dizy. I'll be adding long tube headers along with mufflers and x pipe. I'll also be changing the cam gear to get back those 4 degrees of timing. The trans is the stock 4 speed toploader and the gears are 3:89's but I might be changing those to 3:55's I feel like the 3:89's are a little too much to cruise with (opinions/suggestions here please). Now later down the road if/when something happens to the motor I'll cam the motor and redo the heads. So with my short term plans with this motor should I just go 600CFM or just go 650CFM to possibly support my future mods?

 

[kcmash]

650 is the minimum based on research on this forum. I am looking at the same decision for mine and actually considering going 750 to make sure my Cleveland can breathe!

Maybe not quite 2 cents worth, but that's my opinion anyway.

 

[73' mach 1]

This is why I ask here for some real life answers. I've read so much that would say based on my stock setup that I'd be over carbin' my motor above 650. If you use that calculator that assumes 100% motor efficiency I should be using a 585CFM carb!

 

[Bill73Ragtop]

This is why I ask here for some real life answers. I've read so much that would say based on my stock setup that I'd be over carbin' my motor above 650. If you use that calculator that assumes 100% motor efficiency I should be using a 585CFM carb!

Yup, I ran a 525 cfm carb on my 351c for years with good performance and decent mileage. So unless you think you'll be spending a lot of time above 4500 rpm and you're tracking every micro-second of performance, a 600cfm Holley will work just fine once its dialed in.

 

[c9zx]

Just some food for thought, the stock OEM 4300D was rated at 715 CFM. I've owned several 351 4V powered cars all with 750 cfm Holley 4150 style carbs. Some were vacuum secondaries and the deep geared cars with mechanical secondaries. All worked well after being calibrated. The more adjustability a carb has the easier and cheaper it is to get it calibrated. Given the mods you plan I'd look at 750 cfm vacuum secondary street carb from Quick Fuel. If you can't stand the bright finish then look at a Holley. The vacuum secondaries will only open as much as the load and the secondary diaphragm spring allow. The spring is changeable to get the calibration you want join terms of when it starts to open and how long it takes to be fully opened.

The Edelbrock performer is going to flatten out at about 5400 RPM. We tried that intake in the 70s and the car slowed down significantly comparde to the stock 70-71 iron intake (DOAE-L). If you want more RPM than that in the future, consider another intake.

Chuck

 

[73' mach 1]

Just some food for thought, the stock OEM 4300D was rated at 715 CFM. I've owned several 351 4V powered cars all with 750 cfm Holley 4150 style carbs. Some were vacuum secondaries and the deep geared cars with mechanical secondaries. All worked well after being calibrated. The more adjustability a carb has the easier and cheaper it is to get it calibrated. Given the mods you plan I'd look at 750 cfm vacuum secondary street carb from Quick Fuel. If you can't stand the bright finish then look at a Holley. The vacuum secondaries will only open as much as the load and the secondary diaphragm spring allow. The spring is changeable to get the calibration you want join terms of when it starts to open and how long it takes to be fully opened.

The Edelbrock performer is going to flatten out at about 5400 RPM. We tried that intake in the 70s and the car slowed down significantly comparde to the stock 70-71 iron intake (DOAE-L). If you want more RPM than that in the future, consider another intake.

Chuck

I would definitely like more RPM down the road. What would you suggest for an intake that would work with my 4V heads and one of those carbs? I would get one of the blue thunders but I'd have clearance issues with my ram air hood.

 

[c9zx]

Just some food for thought, the stock OEM 4300D was rated at 715 CFM. I've owned several 351 4V powered cars all with 750 cfm Holley 4150 style carbs. Some were vacuum secondaries and the deep geared cars with mechanical secondaries. All worked well after being calibrated. The more adjustability a carb has the easier and cheaper it is to get it calibrated. Given the mods you plan I'd look at 750 cfm vacuum secondary street carb from Quick Fuel. If you can't stand the bright finish then look at a Holley. The vacuum secondaries will only open as much as the load and the secondary diaphragm spring allow. The spring is changeable to get the calibration you want join terms of when it starts to open and how long it takes to be fully opened.

The Edelbrock performer is going to flatten out at about 5400 RPM. We tried that intake in the 70s and the car slowed down significantly comparde to the stock 70-71 iron intake (DOAE-L). If you want more RPM than that in the future, consider another intake.

Chuck

I would definitely like more RPM down the road. What would you suggest for an intake that would work with my 4V heads and one of those carbs? I would get one of the blue thunders but I'd have clearance issues with my ram air hood.

I'm not sure about the ram air clearances with various intakes. There are several threads here on ram air clearances with different intakes. I have enough reliable feedback to suggest the Edelbrock air gap RPM as a good option. Manifold height information is here. http://www.edelbrock.com/automotive/mc/manifolds/ford/rpm-air-gap-351c.shtml

Chuck

 

[mrmach1]

I've been running a Holley 715 cfm (Shelby GT350) carb. I'm using a M code intake from a 1970 351C. I've been running this combo on my 72 Qcode for many years with no complaints. Just a suggestion.