Totally agree except for the 750. It will be too much. If you do not have your foot in it and go up above 5,000 RPM a 4V is a waste of money. 9F is right on the money! Looks impressive but without fine tuning you will realize very little. If you have plans in the future to go further such as a cam shaft, heads, and headers, then by all means take this first step.
Rob
I was curious what kind of response I’d get from raining on the 4v parade. I’ve seen it enough times that expectations aren’t quite met with doing one component, but not the rest. I run a 2v with exhaust manufolds and it runs pretty darn good and gets about 21 mpg on the highway. Let me rephrase my suggestion: Rebuild 2v, recurve distributor —and— install an AOD. Now you have a car you can cruise anywhere and do so efficiently.
Great discussion, thanks for all of the thoughts.
I put a modern four-speed, similar to an AOD, in my Interceptor and it was a nice improvement. Imagine that would be the case here too.
Sounds like the two barrel Holley unit would be the most cost-effective/easiest bolt on?
An Autolite or Motorcraft 2100 would work well too. What carb do you have now?
+1 on all of 9F’s thoughts. I would use the Autolite over the Holley every time. They are bombproof and easy to tune in. The AOD and set of 3.25 or maybe 3.50 gears would be a huge performance upgrade. And better mileage!
Back in the day a big carb was always the go to bolt on. And in some cases the car ran worse. Gear ratio’s with AOD or a 5 speed is the best performance upgrade you could do.
Rob
Good morning gentlemen - I have a 2100 now. She is smooth but I have a stumble and feels like she is choked down.
Make sure you have no vacuum leaks, your ignition parts are in good shape, and the timing is working properly (the advance comes in the way it’s supposed to). Most drive ability problems are due to the aforementioned, and incorrectly attributed to the carb (which rarely need tweaking). If the stumble persists: dig into the carb at that point.
You can research your carb online to find out what version you have. Once it all runs the way it should, then you can decide if a few more CFMs are needed/worth it.
PS - if you don’t all ready have them, adding the factory H pipe/dual exhaust is a great way to give more usable torque (& muscle car aesthetics).
Once your have the electrical sorted out we can go further. I would increase the initial timing to at least 12 degrees BTDC. If a stumble off idle is your main complaint, it may be as simple as a new accelerator pump diaphragm. I can rebuild your Autolite and wet test it on a known car to ensure it is correct. You may need to be stepped through some basic tuning.
No need for a 4 barrel.
Rob
There may be a tag on it or if you look at the front driver side mounting nut there may be a number stamped just below the nut on the throttle body. Provide me the number and I will tell you if it correct for your car.
Rob
Hi Rob.
I did recently replace the accelerator pump diaphragm as it was leaking, good first thing to check however.
Let me check timing and get the carb number.
Thanks!
I too upgraded my 351c 2v. First I put 4v heads with a holly 600,headers and a CJ cam. Big mistake! Tons of power in top end nothing in bottom end. Put my 2v heads back on and better performance cruising. But still not what I hoped for. Put it on a Dyno and only has 218hp to the tires. Was hoping 300hp. Think my problem is the stock fmx transmission and 275 gears. Good luck with your makeover
The gears make no difference on a dyno. The FMX transmission might be using 50 - 60 HP if you read 218 at the wheels. Overall the FMX is not too bad for efficiency. 218 at the wheels would likely be a low 15 second car in the 1/4 mile if the gears were 3.25 to one.
The 4V heads only work if you raise compression to 10:1 or better. That means using leaded race gas or 100 octane unleaded. Both of those are expensive. The 2V heads are better when compression is under 10:1.
Same for performance cam shafts - the more compression that you have the more power you get. Installing a big cam with 2.75 gears, big 4V cylinder heads, and low compression would result in a real dog.
So we are back to the “do it right or don’t do it at all” point in the discussion. Grin.
@superbond - sorry it was a disappointing experience.
Including tax and shipping and everything, a new Edelbrock intake and carb is going to run 800+ dollars. I’d be pretty disappointed if there wasn’t a noticeable improvement.
Thanks for the sympathy I needed that.
I know gearing wouldn’t change the Dyno. All I wanted after doing the mods is at least be able to do a burn out once in awhile😊
Sadly it’s a mistake I made several times when I could not afford to. Back when I was young, bullet proof and invisible, I also had no money and I did not bother to read and understand the directions that came with camshafts. I just put them in and was completely disappointed when I discovered that compression was right there and so were warnings about rear end gear ratio.
I think I had great hair back then too.
to experience. Like I tell my teenagers: It’s OK, 17 y/o me would have thought I was an A hole too.
As a sign hanging on the wall at a paint shop I worked in way back when said; “Hire a teenager while they still know everything”. There is not replacement for experience, or displacement.
Love it Neal. What is it they say? “Good judgement comes from experience, and experience comes from bad judgement.”
Are there good bolt on heads that work with a stock bottom end, or do you need to swap cams etc to consider swapping heads?
Anything that gives better airflow would help even with a stock cam so long as you don’t lower compression at the same time. This is why installing stock 4V heads on a 2V engine is generally a bad idea. The 4V heads have bigger combustion chambers so the compression drop negates any power gains from air flow.
So it depends on the CC capacity of the chamber.