The Eco-Brick! aka my 80 Dodge van

[aerohead]

Originally Posted by don-vee

A lot of the work I do requires city driving, lots of tight parallel parking, so the boattail may be a lot of work for something I use very rarely.

Gottcha,I leave the tail off the T-100 unless I'm doing long hauls.Some inflatables are circulating out there.But in the city,they're of no value either.

[skyl4rk]

Long, long ago in a galaxy far, far away, I replaced the timing chain on my tired old slant 6 and it gave it new life. It was tired and slow, and with the new timing chain at about 100k miles, it ran with plenty of power again.

[don-vee]

Ah, yes, good call! I forgot to mention, I was gonna try a double roller timing chain and roller rockers. Anyone know if head porting would be worth it mileage-wise? I know what it does for performance, don't know if it will help with the MPG as well, or hinder it.

[99LeCouch]

Probably will boost FE a little bit if you keep your right foot out of it.

For the roller rockers, are those more for high or low RPM power?

[Bullockracing]

You should look at replacing all of the fluids with the good synthetic stuff for starters - you have a lot of fluids that contribute to drag.

I took my driving test as a teenager in an '83 GMC 3/4 ton van, LOL! It had a 305 4V, and I got around 18-19 mpg regularly. In my opinion, 20 in your van should be simple. Look at the list of the 65+ mods, and you should see a lot that apply. Mirrors, wheel covers, lowering, etc. Tires would make a huge improvement as well.

Another item you can look at (I always wanted to and never did) is removing the factory drip rail. If you shave it off, make sure you weld the seam before you fill it, since I think it's a crimp fit in the rail that holds the roof on.

[elhigh]

I don't know how hard this would be to do, but is it possible to retrofit a lockup torque converter into your tranny? That'd be good for when you're steady-speed cruising.

If not, then how hard to, say, replace the entire tranny with a new one, maybe with more ratioes plus the lockup?

This is pretty far beyond me. I can take a tranny out and put it back in - doing stuff inside the case is black magic, beyond my reach (so far).

[fud2468]

Maybe some of the mods used in the Feather Duster could be applied to your van. The 225 used in it had an aluminum intake and free-flowing exhaust manifold. With the overdrive manual trans it was claimed to get up to 36mpg. The Feather Duster used a 1-bbl carb but another version of the 225 (the Super Six) used a 2-bbl carb & the intake manifold from that might be what you are looking for.
There were some later 727 trannys that had lockup but I'm not sure if they were used in the 225's.
Ray Mac

[ceej]

I'm a bit of a mopar slant six guy as well. (I mod on slantsix dot org.)

What percentage would you say is in town driving?

In the 80 you should have a Carter BBD, though some still came with Holley 1 bbl carbs.

Does it have a lean burn system? They were, sadly, terrible.

The rod ratio of the 225 is, for lack of a better term, dismal. A 6.7" long rod for a 4.125" stroke.
Improving the rod ratio is easily done by going to 198 rods, (7.005",) or an aftermarket 7.0" rod then over-boring for a piston with a lower pin height. There are many options. It's easy enough to do, but requires a pretty heavy financial outlay. Installing 198 rods with Neon pistons nets zero deck height. The stock engine configuration leaves the piston at -0.140" or more in the deck. Stock comression ratios run the gammut from 7.5:1 to 8.0:1. No rhyme, not reason, though the trucks tended to get the short end of the stick. We've seen stockers approaching -0.180" down the hole.
My Primary engine runs a 4.440" Stroke, 198 rods, and 3.445" Bore Toyota pistons. (I run the 4 banger pistons, but with a bit less stroke, the '88-94 3.0L V6 pistons from the pickup could be used. The small end of the rod needs to be bushed to fit.) My pistons are 0.070" Down the hole, with 0.125" off the deck. Couple that to 0.040" off the head, and we get 10.3:1 compression.

With an RDP RV cam, engine speed is limited, similar to the stock Marine cam at somewhere in the 4100-4500 rpm range. RDP cams are designed to work with six or four cylinder engines to reduce pumping losses. The intake duration is longer than the exhaust event. Most cam manufacturers utilize v8 profiles that generally have equal duration for both intake and exhaust.
A V8 has 90° of crank rotation between power impulses. A 6 cylinder has 120° between. That means there is a lot longer rotational distance traveled before a power pulse picks up the rotational mass again.

For a 4 banger, it's 180° My Metro's three cylinder runs 240° between power impules.

See where I'm going with this? The engine isn't producing power for the time between those power events but for a short time. The rotation that actually uses the pulse is in the 90° or less neighborhood. Once the crank has rotated 90° past TDC, the force being applied to the crank is drastically diminished, and the engines rotating mass has to carry us to the next brief moment of power. That's why eight or more cylinders can make so much more HP.

The cam choice for maximum economy needs to take this fundamental difference in design into account. The exhaust profile on my engine is basically stock 1974, while the intake has a longer duration event, with no increase in net valve lift.

The ignition curve that is in your truck is not optimized for fuel economy. If you are running the lean burn, there is little you can do with it. Most folks pitch them and install earlier distributors, and various bits and pieces. The GM HEI being the best bang for the buck.

With the earlier electronic ignition from say a 1974, you can change the governer to modify mechanical advance, and you can change springs to modify when the advance comes in. You can also change out vacuum advance cans, some of which are adjustable. My maximum economy was with a 9r governer all in by 3400 rpm, and total timing in the 50° range. I wasn't getting all the mechanical due to laws governing speed. Even with short gears, I'd be going 75 to turn that many rpm.

For primarily in town motoring, going to larger diameter tires will have the opposite effect on your mileage than flat freeway hauling would. Going to a lower final ratio will actually improve economy in urban use.

Out on the freeway, I can pull upward of 23 MPG with the old Valiant on my tall gears only if I don't have to pull hills and passes. Since I tow a trailer and have all my camping gear in the car, I leave the short gears in the rear end. (I run a Ford 8", so can change the rear gears in about 40 minutes.)
Since the whole idea is to keep one's foot out of the go pedal, a shorter ratio for short hauling and towing will net better economy. Unless you are flat landing it for distance on the freeway. If you have to deal with hills, keep your ratio in check. The 225 is an awesome little engine. But it is little.

What carburetor do you have on there? The 2 bbl Carter BBD will do better than the Holley 1945 out on the road. There are a couple of Holley 1920 models out there. The small venturi was on the early 170CI A-Body cars. It will not work well with something like the van. I know your not in a rush, but you will burn your transmission to fine powder running under the converter stall.
The kings of slant six economy were the Feather Duster and Dodge Dart Light. The percentages sold were very low, so your looking at a one year run. 1976. EPA HWY was 37mpg with the package and an A833 manual. Don't hold your breath though, 'cause nobody got that. I have heard plausible reports of 34mpg with the full aluminum sheet metal though. When you think of these cars, think about very poor acceleration. The early A-bodies were actually lighter than these offerings.
With a van, to beat mileage on a well tuned 318 with the slant is possible, but your going to have to build more power in for the bottom end. 2-1/2 inch exhaust is over-kill. If you can, find a Feather Duster head pipe, it is 2-1/4" stainless. They live forever. If it will fit in the van is another question. This is the best bet for a single stock exhaust manifold. Dutra Duals with a 2" Y pipe to a 2-1/4" single back to the muffler, and 1-7/8" tail pipe would be my recommendation. The modified rear keeps carb heat, which is extremely important for economy. The new casting front really breaths. Many folks make thier own.
The fuel delivery of the slant six intake manifold isn't the greatest technology. The center two cylinders run rich, the next two out run perfect, and #1 and #6 run lean. Poor distribution. There are ways to solve this, but none of them are cheap, and many not particularly easy.

I'd be happy to toss ideas around if you like. Getting mileage into the mid-20's is possible, but will require some extensive modification. A van is a brick, weigh's a lot, and the engine is pretty small.

CJ

[don-vee]

Wow, CJ, you are the CHIEF!!! So much information, I think my head's gonna pop.
I'm mostly on the highway, I'd say it's currently 75% highway, but it will probably be even more than that with all the trips I intend on taking. I think this van may already have the lockup converter, not too sure. I thought Mopar went to lockups in '78. If not, I can check to see if they are out there. The Lean Burn is long gone, the current engine is supposedly rebuilt. It's got the 1bbl on it, and I do intend on finding a 2bbl. Also, did I mention I'm pretty piss-poor? The mods you mentioned, while totally awesome, just won't fit into my budget. I don't intend on cracking this engine open at all, everything's gotta be bolt-on or close. I think the most hardcore I wanna get with this thing is the roller timing and rockers.
Yep, I know 2 1/2 exhaust is overkill, but it's what I have hanging on the wall of my garage, that's the reason I was going to work with it. As for the roller rockers, I'm not sure exactly where on the RPM chart the power gains are, I was thinking of it not only for the power gain, but for the friction loss.

[ceej]

The only folks running roller rockers are the race crew. There is friction to be shed there, but you will find it is at engine speeds that you won't be running.
For the slant, those rockers are pretty expensive. They are only available for mechanical valve train engines.

With an 80, you should have a hydraulic cam. (If there are no adjusters on the rockers, that's what it is.) The hydraulic lifters are fed oil from the rocker shaft, through the rockers, and down through the pushrods. Weird, huh?
I do not know of a roller tip rocker that will work with the hydraulic top end.
The stock cams are pretty good, so there's not much reason to mess with them unless they are worn.

First, identify the carburetor that is on the engine. For purposes of Hypermiling, the 1bbl can be worked to deliver better results than the 2 bbl. If you are dealing with heavy traffic, and find yourself having to stand on it frequently, the 2 bbl will do a bit better. If you can't find the list or tag number on your carburetor, take a photo of it, and I'll see if I can figure it out.

The best bang for the buck is to get the best tune up parts you can install.
Get the Echlein MO 3000 rotor, and Standard CH-410X "Blue Streak" cap with copper contacts.
The Echlein caps have spotty production QC, so you can get a good one, or one that is off center. Stick with the Standard.

To make absolutely certain that somebody didn't bolt up an older head, tell me what your spark plugs look like. Are they small taper type plugs that install directly into the head, or are they large ones that insert into aluminum tubes with seals on the outside lip that fit down inside the head?

The "Peanut Plug" head is the later version, the "Drool Tube" head is the older one. For a taper seat Peanut plug head, use NGK UR4GP plugs. For Drool Tube heads use NGK ZFR5N plugs. Always remove the crush washer from the plugs before installing in a drool tube head. The aluminum makes the seal.

These plug options are extended electrode type plugs. This puts the ignition spark in a more ideal location for proper combustion. A peanut plug and a drool tube plug are not interchangeable between the different heads. Make sure you get the right ones.
Some folks swear by indexing the plugs in these engines. With the extended electrode plugs, the point is moot. You don't have to mess with it.
Platinum, irridium and all the boutique plugs aren't worth messing with in this engine. Don't mess with multiple ground strap hype or any of this. It's a low compression engine. That stuff doesn't help, and in some cases will deliver poor results.

Depending on the mileage of the engine, it is likely that the timing set is worn out. The chains have a life expectancy of 100K Miles. While you have the plugs out, roll the engine in one direction with the distributor cap off. Now roll it the other direction. If there is a lag before the rotor starts to turn, it's time for a new chain.

Now, Tell me about your distributor. Does it have a vacuum advance on it? Is the advance hooked to the ported vacuum on the carb? Have you got a dial back timing light or access to one?

Do you still have EGR? Is it working?

If you have a lockup converter, cool. If you don't, the entire transmission has to be replaced to install one. This is true of the Mechanical lockup and the electronic.
What transmission did you say was in there? The A904 costs you about 25 or 30 HP at peak power, while the A727 takes about 60 HP. If you have the A727, which would be rare, your probably not going to make the 20 mpg point. If everything is stock, it's extremely doubtful you have the 727 in a 1/2 ton of this vintage. They were more common in the late 60's heavy half ton and larger pickups.

If the rest of the crowd wants, we can move this offline to Private Messages, unless of course the crew is interested in the mileage of our dinosaurs!

CJ