74 J series 440 looking to improve MPG, heads off.

[johnw]

Exactly, depending on what else he drives the torque of a correctly tuned engine with a gearbox in good condition will probably impress him. Even something as simple as a worn convertor can make a car feel sluggish.

Steve

He has had a few air cooled 911s, and some Mercedes, has a racing license and has done some competitive motorsport in Europe. He is not into automatic boxes, and just sees the Jensen as a completely different type of vehicle. He isn't going to be flooring the throttle in it Steve, you are correct.

However Philip, the heads were not looking brilliant at first sight, core plugs gone, and valve work here, anything more than a tin of Chemico, will cost more than a pair of stealth heads. It does sound as though the Stealth heads will give a compression increase and hopefully be more economical than the stock heads as well, so I am not sure it would pay to spend more on the stock heads.

[bkbridges]

The Stealth heads will definitely perk up the car with the planned skim. The larger valves will bump up the area under the curve as will the compression increase. It should be impressive and very noticeable on the butt dyno.
Bruce

[johnw]

Thanks Bruce. Took a while, but I just figured out what a "Butt Dyno" is! lol.

[Grant]

Thanks Bruce. Took a while, but I just figured out what a "Butt Dyno" is! lol.

I haven't

[Phil Hayes]

Some really good input there, covering the whole car, thanks everyone.

Just focussing on optimising the heads and cam for now, assuming highway cruising:

For the SP to hit 16 mpg standard, and given that a wide band lambda sensor lets you manually set your Thermoquad to deliver the perfect mixture, as good as injection when cruising, the compression ratio and cam must be the factors that give the SP better fuel economy.
Am I missing something else? Different air intake from SP air filter is one difference, but I don't see that as really significant when cruising.

Was it the compression ratio, simply the sweet spot and Jensen hit it right on the nail economy wise as well?
Is the cam more or less not a big factor for highway cruising?

What I have gathered now is that we can fit the Source 440 heads, and this will likely up the compression ratio from 8.2 to 8.7 compared to stock 902 heads. That seems to be a nice simple unobtrusive move in the right direction.

For the wideband Lamda sensor, where abouts do people normally fit those on the downpipe? Half way along on the more or less vertical section where the downpipe joins the manifold? Is pointing forwards best?

To note:
The diff ratios are different on the SP, so less cruising revs. This would be the biggest efficiency improvement.

[Joe Schiavone]

I run a stock 74 440 with a 6 Pack. I am working with a 6 pack specialist. When I brought up mpg the first words out of his mouth we in reference to the electrical system related to spark etc. not what I wanted to hear but it opened my mind to the importance of having the optkimal spark power at the right time. Something to keep in your mind or have in your engine compartment race engine heat

[Steve Payne]

Yes you can't beat a fully mapped ignition curve, 4 degrees before it pinks at all RPM and throttle positions. It has the added benefit of making the engine more responsive and probably lower the emissions.

Plenty of kits available these days to give you the ability to do this, all they need is a few hours of tuning.

Steve

[johnw]

Yes you can't beat a fully mapped ignition curve, 4 degrees before it pinks at all RPM and throttle positions. It has the added benefit of making the engine more responsive and probably lower the emissions.

Plenty of kits available these days to give you the ability to do this, all they need is a few hours of tuning.

Steve

OK, so presumably would need 3 sensors for this?
Crank position,
Throttle position,
Anti Knock.

What about vacuum sensor? Was that just an old fashioned/convenient way of approximating throttle position?

One idea then, if you want to keep the car basically stock, but don't mind a few more sensors, would be to splice into the vacuum line, and have a device that stores a vacuum reserve, and independently controls vacuum closed loop, using the old conventional distributor, in order to implement the fully mapped curve.

[RayR]

What kits do you recommend Steve? I assume you mean a passive mapped system with no knock feedback? Is it much better than,say, an advanced initial timing with reduced mechanical advance which, from what I read, improves responsiveness as well. I have been looking and there seems to be a whole variety of options out there.

Ray

[bkbridges]

Just a bit about the six pack intake concept...
The six pack intake in its 2plane configuration as found on the mopar design is actually a variable length intake runner system. Variable runner length can allow the optimization of the "ram effect" with respect to throttle position/ vacuum levels. When cruising on the center carb, the intake runner length is effectively 8 in longer than when motoring at full tilt with all barrels WOT. This pushes the peak torque of the motor down in the RPM range, (about 100rpm/in of manifold runner increase) as compared to opening all barrels at once. More torque down low = more driveability with less throttle... Virtually all IC motors have variable intake runners these days for this very reason... Nowadays its done with internal butterflies and vacuum actuators... The six pack does it externally!
Bruce

[Steve Payne]

This is the one that comes with a lot of good reviews, http://www.aldonamethyst.co.uk/" onclick="window.open(this.href);return false;

I have never actually fitted one but the principle is easy enough.

You lock the distributor advance and retard and set the distributor to the maximum advance it will ever do. All the unit does is it delays the signal to the coil.

It has a built in map sensor so it knows how much throttle you are using and of course it knows the rpm because it is getting a signal from the dizzy.

You can adjust the map usually while driving ( or the passenger can). You keep adding advance to a point and if it pinks retard by 4 degrees. You will end up with an ignition map that looks similar to the alps probably.

For example I am running 24 degrees of advance at idle and by the time my engine is at 1500rpm it had just over 30 degrees in and 38 at 2200rpm. At full throttle at 2500rpm the advance is in the low 20's.

Before you spend the time making a personalised map you need to decide on the fuel you are going to use, a higher compression engine will benefit from high octane fuel but once tuned with this you will need to always run with it. Some units have a switch with alternative maps depending on fuel but these cheaper systems don't.

Steve

[johnw]

This is the one that comes with a lot of good reviews, http://www.aldonamethyst.co.uk/" onclick="window.open(this.href);return false;
Steve

"You can switch between two of your stored maps remotely", the standard one now on offer seems to have that feature. Presumably that allows you load maps for unleaded and premium unleaded from inside the cabin. There are two versions of the product, one using vacuum advance, the other using a TPS, which is a slightly more expensive version.

I am wondering if tha vacuum input version has significant drawbacks over a TPS version?

[Steve Payne]

The advantage of TPS it is more precise as Vacuum can vary depending on heat and altitude.

Saying that if you do a good job of the map over a few weeks in varying driving conditions I am sure the vacuum unit will perform well especially on an engine as primitive as these.

Connecting vacuum is a lot easier than making up brackets and linkages for a TPS.

If I was buying one I would go for the vacuum unit.

As far as the two maps, I would set one up on Super Unleaded and the other just do all the figures less 5 degrees once you are off idle.

Steve

[Joe Schiavone]

No one has mentioned the elec system Plugs wires Gap Timing Distributor advancing the spark. I run a 6 Pack and talked to a specialist who only deals with 6 packs since the late 70’s. This area was the first thing out of his mouth whin I asked him about getting top gas mileage. I have just done a ProForm Dizzy change with a recurve to the mechanical advance and when it occurs certain things need to occur in order to obtain best mpg. With the 6 pack I have one of the outboard carbs that has a bad air fuel screw. Since the middle carb is the main running carb I have read that 37 degrees at speed is the sweet spot. If I interpreted that correct then this weekend should tell me how well the electrical upgrades affected my 15 mpg on the highway. I have opened the plug gap up to 45. I am running Champion plugs and 8.5 mm plug wires and an Orange ECU box also all of the elec wireing for the system is new. Fingers crossed. Racer hoe

[JACB]

My first thought was to switch to Source 440 heads.

440Source.com sells a range of heads that include:

TrickFlow https://www.trickflow.com/search/depart ... 4294961758

Edelbrock https://www.edelbrock.com/catalogsearch ... inder+head

The Stealth Aluminum Cylinder Head http://store.440source.com/Stealth-Alum ... 00%2D1055/

But of course there are many others to be considered such as:

AeroFlow Performance https://www.aeroflowperformance.com/eng ... /af95-2440

Promax https://promaxxperformance.com/product/ ... -bb-mopar/

Sidewinder http://www.mopartsracing.com/parts/Sidewinder.html

..... in the end did you swap the heads or stay with the originals?