Recommendations and Input

Hi there,

I'm new here but I thought you guys might be able to offer some valuable input. I am embarking to finish a partial conversion I purchased. It is a 66 midget into which I am installing a 151 Iron Duke(2.5L) from what I think was a 1990 S10 blazer, 2wd (based on the support rods on the engine and tranny) The engine is mounted to a Stock S10 T5 tranny. All the tunnel mods are done and I have just completed the front mount modifications(the PO had the block set too high). The fit is snug but not awfully so. I have begun looking at radiators, Drive shafts and the like. I was wondering if you guys had any suggestions Ideas or comments I should keep in mind while i continue forward. At 105 HP and 135ftlbs torque this engine in a midget is very similar to the 2.8 in a B, almost double the stock output.

I know this is a little off topic but the ranks of Midget conversions are considerably smaller than those of the B.

There were a couple of things I did wonder in specific,

1) what did you do for a Driveshaft? A couple of shops I called said that they could not make a shaft for me as they required some special fixture for the MG flange that they did not have. I know I need a custom shaft, any ideas on where to find someone who can do this?

2) how much of the engines vacuum system were you able to trim away? I figured I could drop the booster line and the cruise control lines as well, Do I still need to run a reservoir or can I do without?

3) what sorts of options are there for fuel tanks, obviously I need a high pressure pump, can I just use the existing tank with a modified pickup sump and return fittings or am i limited to a racing type fuel cell?

3a) also has anyone tried installing the safety foam in their stock tank?

4)what have people used for Speedos? Obviously VDO, Sport Comp and phantom sell electronic speedos that will work with the stock output, are there any other options I might consider?

Anything else I should consider or be aware of?

Thanks for any and all input you may have.

I can't answer anything else, But I can answer 3A

Take the tank to a shop that deals with aircraft fuel cells.
airplanes don't actually use tanks, it's right in the wing. So over time they
can leak. When this happens they line the wing with plastic. You can have
it plastic coated, in an accident you won't have fuel spilling everywhere.

Hi Jason,

If you have never looked at the 2.8L, you could have installed that instead and it probably weighs about the same as the iron duke with more power. Also, would have to consider width more than height with the motor you have. I would never recommend the iron duke, but everyone likes something different. The 2.8L was designed to fit within the space that the iron duke originally took.

Some answers:
1) what did you do for a Driveshaft?
Our company supplies these parts if your interested. Normally an entirely new driveshaft is needed, but depending on the length you need, we might be able to use something else. Check out our website for the price on a completely new unit, otherwise I have an idea for a hybrid that might cost less only for the Midget.



2) how much of the engines vacuum system were you able to trim away?
You should be able to trim all of those and anything NOT computer controlled including EGR if allowed in your areas laws and regulations.



3) what sorts of options are there for fuel tanks, ...
You can install an internal pump, which costs more plus has a need to cut into the tank and install.
The other choice is to use an external fuel pump. Much easier, but they tend to be louder a year or two later.
BTW: Its been a LONG time since I looked, but didnt the last year MG Midget have a slightly larger fuel tank? I know the real early cars had a slightly smaller tank. Gee, I should know. I have owned a dozen spridgets of all years!



3a) also has anyone tried installing the safety foam in their stock tank?
Not me. There are baffles in there which would require cutting the tank to shreds.



4)what have people used for Speedos?
Go ahead and convert your T5 to electronic speedo and run one of those. That way, if you change the rear axle, tire sizing or ANYTHING, you'll be able to flip a few toggles. This will cost you less than correcting yor speedometer with a correction box and cable in the end.




Anything else I should consider or be aware of?
Oil pressure connection, Throttle body fitment under sheetmetal, (BTW- there is a weber carb conversion for that manifold I am pretty sure), clutch hydraulics, and other issues will always crop up eventually.

Ask away!

-BMC.

sshack Wrote:

BMC Wrote:

Tanks are not that expensive new but you do have to watch them. Some have leaked. It would be easy to do a leak check before you ever put it in. My new tank had a problem in that the pickup was a few inches off the floor of the tank and I actually ran out of gas ABOVE 1/3 tank. I had to drill a hole and put in a new pickup. The sending unit is VDO. It was no trouble shortening it (quite a lot actually). The holes do not match which is no big deal. I welded up the holed, ground them down, sanded them then drilled new holes to match the tank.

I used the VDO Vision series:





I thought it was a nice not over flashy look. Good balance.

Actually it was pics of your dash that i saw that convinced me that VDOs were what i wanted.

Actually it was the pics of your car that convinced me that VDO was the way to go.

If you have the sender unit in that's half the battle. Even when everything is 100% it seems I always fight something there. My last problem is I did not have the sender quite short enough and the float would come up to 1/2 tank. I had to pull it apart and bend a little more. Those small things drive me nuts.

The sending unit on the trans required just a little more space for me (early narrow tunnel). I cut a small hole and put a rubber seal over it. Gave just enough room should the trans shift during operation.

I like it because it industrial common after market equipment. It's solid and quite available.

I am not familiar with the Midget driveshaft but if it is the same as the B at least the bolt ring and you are using the Midget rear then you can make an adapter like I did or I think Killer B makes one that they sell, and then shorten the stock driveshaft to fit

Here is a picture

We Fiero people call the 4 cylinder engine the "Iron Puke' for the simple reason that it tends to do exactly that - spew it's innards across the road.

It has zero sporting character - it is a low revving torque monster that suits a truck much better than a sports car. The standing fit oil filter and the ECM that kicked it to fast idle immediately after firing, before the oiling system was filled, ensured that the bearings would eventually be trashed and the instances of a rod coming through the side of the block and sometimes causing a fire resulted in the abysmal reputation of the engine. It weighs a lot and grenades with great frequency as it has a weak bottom end on top of everything else.

In other words, it sure wouldn't be anyone's first choice when the 2.8 V6 (or one of the larger variants) are common out there.

If you leave it dead stock and solve the oilingproblem, I'm sure it would work alright in a Midget, but I'm not so sure it would ever be that much fun....

Having owned no less than 6 fieros I am familiar with the enigine. The Version used in the early fieros had 2 issues not shared with the later versions, 1) it had a smaller than normal oil pan capacity due to clearance issues on the fiero. and 2nd it was a PITA to service so many people chose to drive it without keeping up with the oil changes, which as you state led to the destruction of the bearings and ultimately a thrown rod. The thrown rod in conjunction with the close placement of the Cat and exhaust system led to fires and doom for many early fireos.

That said, in a somewhat bulky fiero a 2.5 liter iron duke with a 5 speed is not entirely unpleasant to drive. It was not a streetfighter or anything, but neither is a midget in stock form. It seemed that the lower HP and torque would allow for a very enjoyable conversion without need for extensive brake, axle and cooling improvements.

As to the nature of the engine itself it is the basis for the superduty engine which is one of the most radical 4cyl engines ever produced. The aftermarket is somewhat healthy for it as well, between s10 applications and Fiero applications including Headers and Cams among other things. They are dirt cheap and easy to maintain.

As stated before, i did not Choose to install this engine, the previous owner did. Rather then starting from scratch I felt it would be easier to finish the install and then when finances permit I will upgrade to a 6 or something else.

Perhaps the best reason to start with this engine is that I paid $100 for the entire car(66 midget), engine and Drivetrain with ECM etc. the price as they say was right. If I had 5 k to spend on this project I would be shoehorning a BMW S52 engine in there and planning to wave to all you guys over my shoulder, but I dont so I guess iron duke it is.

Besides how could it make driving the midget any Less fun? with twice the HP and torque I will have a little pocket rocket that will put a little smile on your face for less than 1000 bucks.

There's another process you can do where they blow hot plastic in, it coats
the inside of the tank. Repeat a few times and it is very solid.
jim1971 had this done to his plane and mgb tank. I'm planning on doing the same.


gow589 Wrote:

That's a "Kit Plane process". My brother has done similar on his kit plane but you are not going to find it at airport maintenance shops and it is not a replacement for a good tank. Tanks just are not that expensive.

105HPmidget Wrote:

If you want to keep it cheap, get axles from 1970 or later MG Midgets. They are about 75% les likely to break. I have an overabundance of them for my cars. The 1958-1969 axles are all supposed to be weaker and can be seen as a difference by looking at the end of the splines. There is a small groove about 1/4" inboard showing that the later axles were slightly different and the hardened ones.

So far, I have not broke any, but my Dad has broke at least two early axle shafts in his lifetime.

I think Moss, APT and Mini Mania sell much better axles, but if you go that direction, you might as well build a purpose built rear axle!

-BMC.

I just replaced the axles, new splines and new rims and a Qualfie diff:

http://www.quaife.co.uk/MGB-Salisbury-axle-ATB-differential

I just couldn't get rid of the knock offs and spokes!

Gary,

Keep in mind you could replace your rear axle with something else and use the knock off conversion kit on anything to give yourself the same wheels. My guess is, the same amount of costs, far more choices in ratios and a stronger rear axle.

I love the idea of the rear axle, but I am more married to the idea of getting power out of the stock MGB motor than trying to put it through the stock rear axle. In some ways, I would like to see more axle conversions in the modded 1.8L I4 B's! :)

-BMC.

Hi BMC,

sounds great but I don't think there is a strength issue with good components with the 3.4l. I am also quite pleased with the ratio, if I had another axle I would be looking for the same ratio. I just wouldn't spend the time adapting what already works well (for me). I certainly don't see it as a weakness here with good components. Now if I were suncloud doing donuts and burn outs in the high school parking lot, well that might be different.

Assuming I'm running factory size tires is realistic to be concerned about breaking axles. I drove my 74 pretty hard and ultimately broke the clutch fork(lubrication problem) never had an axle problem.

sshack Wrote:

Jason, my recommendations are to replace the rear axle with a narrowed unit from a Chevy Monza or other GM 70's small car. Same lug pattern as the Midget and plenty of strength for a 4 or V6, even a small V8 (common Chevy 10 bolt) and there are a lot of ratios available for it. That will solve the driveshaft problem as well, now it would be a common Chevy yolk on both ends.
The later Midgets did have a slightly larger fuel tank and it will fit the early body. If you are running the TBI then you'll need a high pressure fuel pump. You can modify a GM pump and pickup to fit the MG tank or add a return line to the tank and use a remote high pressure pump from some Audis and VW's as well as BMW I think. It's a Bosch unit and pretty much the same for all three. You need something that will put out at least 40psi. If you're running a carb then the stock Midget SU pump will do.
The stock tank has internal baffles, makes adding foam impossible. Unless you're racing then I wouldn't bother, but if you have to have the foam get an aftermarket fuel cell.
Have you had the hood on the car yet? I'd be surprised that it would clear the valve cover in the front, that engine is pretty tall. I used the 2.8 V6 in my Midget with matching T5 from a Camaro and even with a carb the hood would have to have some type of scoop or bulge added to clear that. I used the MPFI and had to make a large bulge to clear the injection. Photos and information on it at http://www.britishv8.org/MG/BillYoung.htm

I have had the engine in with the hood. After removing the heater and battery tray the engine actually sits relatively far back in the engine bay, the crank pully is behind the 6" wide front crossmember and actually sits back a tiny bit further than a 1275 sits(ever adjust the timing on a 1275 and you can just see the marks from below right behind the cross member). I will try to shoot some photos.

The nose of the engine is clear by 1" or more though the normal air cleaner will most assuredly be too tall. I was planning to fabricate an intake cap with a remote K & N filter in the fender area. The only other area I need to look at is the Radiator as the stock one is far to small for the application(besides being a down flow setup). Summit makes a sweet aluminum model thats 23 by 17 for 152 bucks that should fit the bill nicely. If I later upgrade to the 2.8/3.1 I think I will try to use the intake out of a cavalier or other FWD late model car, which would dump the TB out the back towards the firewall while maintaining the low profile under the hood.

I really want to keep the stock body line as much as possible.

I think i will eventually plan to cut down an axle and switch to steel wheels, i will put the wires on my 74 which is still stock. I have a set of Advan ultra High Performance tires on Midget Rostyles that would work well with the increased HP.

I've known about your car for a couple of years now and it was certianly one of the inspirations to get my own midget i could hack into.(the 74 is still original so it would hurt too much to hack it up, the experience of a bone stock midget is something to be savored)

test

I understand why you decided to use this engine. Bear in mind that it has about the torque of a TR4 engine, and a rev range even lower - they produce 90 BHP (similar to the MGB) but at even lower RPM than a TR and are out of breath by 5000 RPM, so you won't find it as revable, and may find the stock axle too short.

OTOH, what the heck - do the swap and look for something more interesting later. May I suggest a modern Ecotec when the block or head, or both, crack as they have a habit of doing on the Duke....

For 1990 in the S10 that engine is rated for 105HP and 135ft/lb torque, keep in mind, the stock midget is only rated for 55 HP as its only a 1.275 Liter engine to the Bs 1.8. Yeah the Rev Range is lower but its about the same as a 2.8 which tops out by 5k as well. The axle is certainly a little on the low side but not horrendously so compared to stock midget which isn't exactly known for its long legs. Eventually I will go for a monza axle or something but if I can track down a 1500 midget rear in the mean time that drops the final drive from 4.22 to 3.9 which cruises at 75 to 80 mph for 3500rpms which is pretty tolerable. With all the extra torque I could just drive it from 2nd gear when the need for squealing the tires is not present.

I would love to track down one of those little monsters out of the solstice with the SC but thats probably fantasy at this point. another possible would be one of those DOHC 6 cylinder Northstars they have in the buicks(saw one in a junkyard once tow but didnt have the cash. Last option was to pickup the 525i I saw the other day for $500 bucks with the 2.8 liter inline 6 engine which is rated for quite a bit more than 105hp(i think my 528i is rated at 190hp in a fairly light package) Would be a tight fit but boy would it run.

BMW makes GREAT engines. A 2.8 525i engine would be very interesting to see!


peace, Kyle

Jason,
I have a Bugeye Sprite with a 3.4L V6 that I have recently converted to a Ford 8" rearend. Previously I was running a narrowed Vega rearend with 3.70 posi. I also have a set of 4.11 gears and other parts. The entire setup drum to drum with springs and tube shocks is for sale. I'm sure it could handle the Iron Duke engine in a Midget, since that was used in Vegas, correct? More details and pix are on Craigslist at http://rochester.craigslist.org/pts/438479786.html
Contact me off list if interested, and good luck with the project.
John

kind of steep for my price range considering whole car was only 100 but I will think about it.

Heres the ratios i have for this Tranny, Any thoughts?

2.5 Liter wS10 T5, 4.22 stock rear end

Tire Diameter 24
Final Gear 4.220 RPM(shiftpoint) MPH RPM Drop
1st Gear Ratio 3.730 4,500 20.41
2nd Gear Ratio 2.180 4,500 34.93 2,630
3rd Gear Ratio 1.420 4,500 53.62 2,931
4th Gear Ratio 1.000 4,500 76.14 3,169
5th Gear Ratio 0.720 3,000 70.50 3,240


2.5 Liter wS10 T5, 3.9 1500 midget rear end

Tire Diameter 24
Final Gear 3.900 RPM(shiftpoint) MPH RPM Drop
1st Gear Ratio 3.730 4,500 22.09
2nd Gear Ratio 2.180 4,500 37.79 2,630
3rd Gear Ratio 1.420 4,500 58.02 2,931
4th Gear Ratio 1.000 4,500 82.38 3,169
5th Gear Ratio 0.720 3,000 76.28 3,240


Stock Midget

Tire Diameter 24
Final Gear 4.220 RPM(shiftpoint) MPH RPM Drop
1st Gear Ratio 3.200 5,000 26.44
2nd Gear Ratio 1.916 5,000 44.15 2,994
3rd Gear Ratio 1.357 5,000 62.34 3,541
4th Gear Ratio 1.000 3,000 50.76 3,685

With twice the tq and bhp, you'll be wishing you had a taller rear end ratio. You'll be running out of gearing in every gear faster then normal. With a 1275cc motor, the power band is narrower and thus a low speed/high numerical rear axle is best. With the little tires of the Spidget, the light weight and the power that you have, a 3.0 or 3.2 would be great. Camaros and S10s of the 1980s have about 6" on the rubber height of your car and most came with 3.23 (F-body) or 3.42 (S-10) ratios though far more ratios were available.

Also, the S10 came with a T5 that was a choice of 3.76 or 4.06 1st gear and 0.82 or 0.72 5th gear, so you may have the two named from a later S10 or you may have the earlier 4.06 and 0.82 unit that came earlier.

Hope this helps,

-BMC.

I have been quite happy with the ratio in my rear end (boy that doesn't sound right). My T-5 I got from Ebay $150. I believe it came from a V6 Camero. I pulled it apart and it looked new. Syncros and gears all looked (to me) perfect. I took it into the transmission shop to have it checked out and to check the seals for a couple bucks and they agreed.

With the Banjo axle, the car likes 1st from a dead stop, second from a rolling stop. The MG hp was so anemic as a car doubling the hp doesn't make it a rocket ship, it only puts it where it should have been. I like the way it moves through the gears.

60mph is 2000rpm.

I personally would not change the ratios on mine.

I think you won't be pleased with the car if you keep the original 3.9 rear axle ratio or anything lower. GM used ratios up around 3.08 up to 2.73 with the Iron Duke in most of the applications, mostly for fuel economy but the engine has enough torque to pull these gears even in a vehicle much heavier than your Spridget. I run a 3.43 ratio in my V6 Midget and find it pretty close to perfect. I might try a 3.23 someday if I can find one though. Remember most of the V6 swaps are into Bs with taller 14" wheels and they can live with the 3.9 because of the larger tire diameter.
One point about changing the rear axle that is seldom mentioned and that is brake cylinder size which can soak up a lot of pedal travel with the stock Midget master cylinder. You may be able to find a smaller bore wheel cylinder that will fit by looking through the parts catalog at your local auto parts store.
One nice thing about the Monza axle in a Midget is that there is enough steel in the axle at the point where it needs to be cut and resplined that no welding is required, so you can use the stock axles resplined instead of having complete custom axles built.
I'm currently working on a method of installing a Chevy 10bolt carrier section in between MGB axle tubes to retain the brakes and wire wheels.
You could probably do the same with the Midget housing and not have to change the brakes or wheels, but you'd still have to have special axles machined.
You can use the bolt on wire wheel hubs with the standard Monza lug pattern, but will need shorter studs to clear the wheel. Good luck and let us see some progress photos from time to time.

Sounds as if I'll have to look into either a better geared T-5 or a new rear axle at some point.

The brakes should not be a problem as I am seriously considering a Wildwood type pedal kit with the three master cylinders(1 for the Clutch, 1 for rear brakes and 1 for front brakes) This will allow me to get more line pressure and have infinite tuning of the front to back bias as well as allowing for disc brake upgrade in the future. See this link for details.

http://the-mite.com/mite39.htm

Does anyone have any recommendations as to what would constitute a "good" set of overall ratios for this size and type of car? Or perhaps a better question would be what do you all consider to be a pleasant or proper set of red line speeds(ie 25 to 30mph in 1st, 45 to 50 in 2nd etc.) or shift points for this type of car(small and British)? That way I can play the numbers and see what is available.

Overall first gear ratio appears to be really critical as well as a 2500-3000rpm cruise speed in the 60 to 70 mph range, anything else to consider?

As long as you have the later T5 with the 3.76 1st and the 0.72 5th, about the stock size tires (not going drastic, but lots of leeway here), use something like a 3.0 to a 3.3 ratio rear axle. This will give you wide spacing (presuming the 2.5L does not have any more limited power band than the 2.8L!!) but always stay within the power range.

-BMC.

These guys have a GREAT gear ratio calculator with a side by side graphing comparison. Check it out!

http://www.fatboyraceworks.com/gears/index.php?MaxRPM=4500&TireDiameter=23.2&GearRatio1=3.76&GearRatio2=2.18&GearRatio3=1.42&GearRatio4=1.0&GearRatio5=.72&GearRatio6=&FinalDrive=3.36&TireWidth=185&TireAspect=70&RimDiameter=13&MaxRPM_2=5500&TireDiameter_2=22.65&GearRatio1_2=3.19&GearRatio2_2=1.916&GearRatio3_2=1.357&GearRatio4_2=1.0&GearRatio5_2=&GearRatio6_2=&FinalDrive_2=4.22&TireWidth_2=175&TireAspect_2=70&RimDiameter_2=13&Calculate=Calculate%2FGraph&Compare=1