Converting VV top end to 4-barrel

[P72Ford]

The transmission in my car is fucked, so nevermind my impressions at this point.

I will say this: After I did the 4 bbl intake and carb, my car still had the stock transmission. There was a power improvement, and an enormous change in the sound of the engine. After I did the exhaust (BBK 15110s, custom 2.5" catted header back) I distinctly remember stabbing the gas at 40-50 mph (in the rain), and blowing the tire off. I liked it. Plus, I could really cruise with the 2.73s...

I could roll into the gas at 100 mph (2000 rpm in OD), and the car would pull.

So it wasn't all a wash... but the transmission issues left me with an indifferent feeling on everything.

I mean, the car ran a low 16 in August with the ill-shifting transmission (1-2 at less than 2000 rpm), crappy stock cam, and crappy stock heads. I'd say high 15s with a properly shifting transmission would be very achievable for me.

There is still alot of performance on the table for the red box.

Actually, if I wanted to make an ecnonomy piece, I'd probably try a Rochester 2 Jet. The TV cable would be interesting, but, eh. My friend had one on his 394 Oldsmobile; despite the cubic inch, the carb worked really well. No problems blasting the tires from a stop.

[Outlaw440]

Through a 3 2bbl intake on and 3 VV's on it. Performace issue solved.

Tuning 3 carbs to work perfectly is something not many can do.

It has a "cool" factor though.

[johnunit]

I think I've been convinced. The Variable Venturi rebuild kit and manual go into deep storage, and I'll start looking for a 4bbl pairing.

I'm sure a 2150 or 2-jet would perform well enough on the car, especially with the currently stock engine, but I guess my thought is I either want it all original and funky, or to just go for broke (or.. get money then go for broke) on performance. If I'm going to start seriously deviating from original equipment, I might as well go with the sound and performance potential and bragging rights that come with a 4-barrel.

[gadget73]

If you want to go closer to stock, maybe the intake from a 351 HO pickup truck from the mid 80s is more to your liking. Those trucks ran a 390 cfm Holley if I'm not mistaken. I know its a smaller Holley of some flavor. We had one on the 87 F250 at the marina. They also have an EGR spacer and EGR valve if you need that for emissions. Its probably a crappy intake as far as performance goes though.

[P72Ford]

I think the 3783 is basically the same as the 351 HO intake. It doesn't rise as high as the regular Performer intake (due to the EGR plate), and the ports aren't as large either.

Ed (Mercracer) said he had a regular 351 HO intake that he was willing to part with, but that was some time ago. I have an EGR plate from a Mustang too (its cast iron, as opposed to the Edelbrock 8053 which is aluminum. Might be outrageous to ship to Canada though.

[johnunit]

I hadn't thought about the 351 truck motors. That does sound like it's worth looking into.


P72ford, you're probably right about shipping. It'd be at least 20 bucks just to get the spacer here, let alone an intake, so I'll probably go local for most of the parts.

In the short term, I'm more concerned with low end torque, so I don't really mind if the intake has limitations, within reason. If I have to swap it out down the road I won't be too bothered. The carb, however, should be something I won't need to worry about as long as it's an N/A daily driver. 600 or even 550CFM should be more than enough.

[P72Ford]

I was thinking about this yesterday...

The Edelbrock 3783 has a coolant crossover at the back of the intake, which the regular Performer series, Performer RPM, etc do not have (at least I don't think they do). You could make a crossover if you used one of those intakes, but its nice to have one out of the box.

[gadget73]

I wonder what gains you get from that. Factory intakes don't have a crossover. I guess it promotes somewhat better coolant flow, but I wonder how much it helps.

[johnunit]

Don't some SBF's have some issues with the rear 2 cylinders acting differently than the rest? I forget the details but maybe the coolant crossover would help.


Where does this crossover feed from? Does it come from a coolant port in the head or from something coming lengthwise along the manifold?

[1987cp]

From a coolant port. The heads are identical left and right, so the passage that's used for the crossover up front is the same one that's used in the back.

[gadget73]

usually its just a cross in the back, if it exists. When it doesn't exist, those two rear coolant ports in the head are dead-ended. And yeah, its because the heads are identical left and right.

[King_V]

Hang on - with regard to the need to stick to emissions regulations . . exactly how much in the way of electronics is involved?

I know GM's stuff a *little* - they had an electronically controlled carburetor, and a TPS so that the computer could adjust the Mixture Control Solenoid, as well as activate the lockup torque converter at appropriate times.

Oh, and approximately 15 miles of vacuum line because pretty much everything else was, ah, well, vacuum controlled.


What exactly is involved with the feedback systems and all of carbureted Ford V8s in general (and the VV 351 in particular)?

[1987cp]

The VV is also electronically controlled. Far from the same animal as a feedback Rochester (actually, I'm not sure, but I'd guess a VV is probably a better carb in some ways than a feedback Rochester because the Rochester relied on constantly jabbing its metering rods up and down to get the correct mixture *on average*), but it came from the same line of thinking - trying to apply outdated carburetor technology to the computer-control age. I like carburetors, but if my engine's going to be electronically controlled, I strongly suspect that in 99% or cases I'd prefer the mechanical simplicity and superior tunability of real fuel injection.

In my old '79 LTD wagon, there were no oxygen sensors or anything - the emissions junk was all vacuum and thermostatically controlled, even the EGR valve and continuous adjustments to ignition advance. My '81 LTD came into my possession with a non-feedback carburetor but also with a little computer on the fenderwell (next to the ignition module) to control things like EGR and monitor oxygen sensors and adjust all those little surplus solenoids you don't really need just to have your car run properly.


Did the GM stuff of the '80s really have an electronically-controlled lockup torque converter? I've suspected as much from driving a pair of '90 Oldsmobiles, but it's a neat concept either way.

[johnunit]

So what is actually electronically controlled on the 7200VV? Are there O2 sensors? Do the air pump and EGR take their commands from the same computer as the carb? I'm trying to figure out how it's all interconnected.

[1987cp]

All I know about for sure is the plastic air doors that go over the top of the venturi (hence the "variable venturi" name, I believe). I also know that there's at least one O2 sensor and a throttle position sensor to go with the electronic temp sensor and EGR position sensor (the EGR is still controlled by vacuum, but I think that's modulated by a solenoid on the VV stuff). According to another guy's thread, the idle mixture screws are capped off at the factory .... it also only makes sense that there's some provision for electronic calibration adjustment on the fly, but I have no idea how closely it does or doesn't resemble the Rochester system.

For more specific info, you can probably PM Nathan in MI; I don't think he knows exactly how they work, but he's successfully rebuilt one and got 20mpg afterward, so he knows more than most anyone else these days.