Pre-J Mooney Mods (Under Construction)


By Richard Zephro

Alrighty then. Let’s talk some about modifications, particularly the earlier models. I am often asked which mods I would recommend for the best speed increase and I rarely have a set answer.

Can you imagine the “Zef” not having a set answer?!

Well, there is a good reason for it. You see, Mooneys are all hand built and they’re all a tad bit different plane to plane and I have seen some planes really benefit speed wise to the so-called speed mods while others show a negligible difference.

I know it sounds weird, but we experimented with that and of course have flown Mooneys with every combination of modifications imaginable, in fact one year, oh back at around the early 90’s I represented Southwest Texas Aviation’s 1965 M20E for marketing. After taking a few flights in that good looking bad-boy I exited the cockpit scratching my head. Why? Because I owned a stock M20E; N79823 and it seemed to fly as fast as the fully modified E model and the only mod I had was a single piece (not 201 style) windshield which would in no way increase performance, just visibility.

So at my request, we put a pilot in the modded plane while I got in my un-modded E model. We zoomed up to 2,000′ side by side and on radio command we went balls to the wall as agreed. For the first moments nothing happened and then the fully modded E model began to ever so slightly pull away but really, not by that much. Later I noticed that I had left my cowl flaps open while the other guy shut his, but the cowl flaps on an E model aren’t that draggy but maybe just a bit and again, that’s about all I could attribute his “pull-away”. I seriously doubt that there would have been more than a few minutes different on say a 200 mile trip.

HOWEVER……..I need to make a couple of points. First off my E model was a fast bird from the get-go. I would usually see about 165 MPH indicated at and below 5,000′ and my bird would normally true out at around 185 MPH. I have flown other E models where I would not see more than 170-175 MPH true so for all I knew, that modified E model may have been one of the slower E models to begin with.

NOW………Rarely was the time I had seen a C model with mods go as fast as a stock E model, but I have seen that on occasion, but for the stretched F model beginning with the 1967 year run, I would rarely see one true out more than 150 kts TAS with mods where I figure the average F model un-modded usually runs at 147 kts until I got one in stock to market a couple of years ago and that baby flew at an unbelievable (to me) 157-158 ktas! That plane was a couple of knots faster than the average J model (201) which rarely flies more than 155 kts true! I flew a couple of Mooney gurus in that plane and even they couldn’t figure out why the bird was that fast. It had no more mods on it than the standard 201 has, so there was no explanation to be made. It was just phhhhast!

SO……….Based on all of my experience with nearly every mod there is on differing Mooney models, I usually give this standard answer to those asking which mods are best: Put any mod you wish or can afford on your plane, but do it for esthetics as opposed to speed and if you happen to get a speed increase, so much the better, which is about as good as I can answer that common question.

THERE ARE……….several Mooney Mod Shops, and Mooneyland has certainly done our share, but if you check with some of the original mod shops, some of them have a scale of speed increases to expect with this or that mod. Well….if you add up the advertised speed increases per given mod, I have figured that the average Mooney with those full set of mods would or should run at over 180 kts for say an E model and that ain’t happenin’! Not even close, so take speed increase claims you read about with a tiny grain of salt.

LET US NOW………talk about some mods shall we?

The MOONEY WING! While it is difficult to find a better looking and better constructed wing in its class of aircraft, it seemed as though Al and his Boys would figure; “well, this wing should end at about here” so they used a saw to cut it off at that point which left the wing with a bit of an unfinished look, so my first and foremost favorite mod for early Mooneys were the 231 style wing tips introduced on production models in 1979 with the 201 wing tips showing up a couple of years later. Those wing tips were not only sexy looking and finished off an otherwise incomplete looking wing, but there was some benefit to adding the wingtips. What I found was a better roll rate with the tips installed, however the roll rate of the original M20 (short body) series was already great and way better than the stretched version beginning with the F model, and the F model benefited from the wing tips. NOTE: The first year of the F model; 1967 had an orphan wing of sorts, the “Twisted Wing” see for more info on that issue. The F model seemed to enjoy the better roll rate of the 201 which even with wing tips was not quite as good as the short body’s even without the wing tip mod.

Mooney without Wing Tips

Mooney with Wing Tips: You can even enclose some antenna’s in these Wing Tips if you’d like. Some difference eh?

It will not be long no doubt before the newest “Winglet” Wing Tips found on the new Acclaim Mooney become available. Kinda looks like someone did turns about a point a bit too close to the ground however, but there are supposed to be some benefit to winglets on this application at least.

The wing root fairing ala 231 also adds some smoother lines to the wing

Another favorite mod of mine is the 201 style sloping windshield which began as a production run in 1977 with the introduction of the M20J or 201.

Pre 1965 M20 Windshield…….

1965-1976 Pre 201 Windshield

1977 and onward Windshield Except the 1977 M20C and M20F models.

As you can see, the pre ’65 Mooney windshield went high up the cabin whereby the ’65-’76ers were squared off at the top and rounded at the bottom edges, but the real improvement began with the 1977 201 models, but like everything in aviation, there is a trade-off. Pre 201 Mooneys had a wonderful instrument compartment inspection panel on either side so radios, instruments, and wiring could be accessed from outside the plane while standing up as opposed to upside-down aerobatics required on the post 201’s unless you took the instrument panel apart in sections. The upside was a quieter ride, less susceptibility to a penetrating bird strike, and a much, much more modern and aerodynamic look, so the windshield mod sits high on my list of esthetic add-ons.

Dorsal fin and tail root enclosure mod cleans up the gappy tails of the early models.

Some early Mooneys didn’t even have dorsal fins! Full of gaps.

Tail fin enclosure mods

Tail fin enclosure from factory on later models Smooooooooooth!

Pre 201 models had a huge gap on the underside of the wing, so flap gap seals are another good add-on which does help rate of climb. And aileron gaps seals clean things up as well for cheap.

The fiberglass single piece belly is a good mod but expensive and like fiberglass is, it will require maintenance from time to time but saves time at annuals.

And, for the money, brake caliper reversal kits are a good investment and finally another good choice is the cowl enclosure mod before after There are complete 201 style cowlings available, but one of the great things about the original cowling is that the engines run considerably cooler with the standard or standard with cowl enclosure, and of course the engine is easier to get to with the old style having removable side panels with quick cam-lock screws (’65 and newer pre 201).

Certainly not a body mod, but the Sky Tech lightweight high speed starter does wonders for quicker starts particularly on fuel injected pain in the butt hot starting engines.

AND FINALLY…….if you have an early M20 and you fly IFR; it is a good idea to have the oil cooler re-location mod done because if you ride through impact ice, it can cover the air flow to the oil cooler and you could overheat your engine.

THERE ARE…..a whole slew of mods available for almost any Mooney to consider, but I say again not to expect super speed increases unless you’re one of the lucky ones or perhaps one that has one of the slower than average Mooney’s, and then there’s no guarantee, so do your mods for the looks alone and any appreciable performance increase will just be a bonus for you.

List of some mods
available for various Mooney models:

Engine and Cowling Mods


201 Style Engine Cowling Kit-Includes new engine baffle system,oil

relocation, new oversize high-cooling spinner system (M20E & M20F)


201 Engine Cowling Kit-Includes new engine baffle system, oil cooler

new oversize high cooling spinner system & new air induction system.

(M20C & M20G)


Lower Cowl Closure (M20A,B,C,D,E,F,G)


Oil Cooler Relocation
(M20E & M20F 1967 & later)


Second Landing Light
(M20E,F, 1967 & later, & TSE)


Landing Light Lens Kit
(All Models)


Standby Vacuum System
(All Models)


Sky-Tec Light Weight 12v Starter (All Models)


Dukes Fuel Pump-Overhauled (All Models)


Alternator Retrofit Kit 
(Lycoming Wide Deck)


 Alternator Retrofit Kit 
(Lycoming Narrow Deck)



Fuselage Mods


201 Style 1-Piece Windshield Kit (M20A,B,C,D,E,F,G)


One-Piece Windshield Replacement for pre-1967 Models


Smooth Belly-New Style (M20B,C,D,E,F,G,J,K)


Fresh Air Vent (M20C,D,E,F,G)


Replacement Side Glass (All Models)


4 Window Models


6 Window Models


Window Sealant Per Mooney S.B. M20-208B


Single 201-Style Rear Window (M20F & M20G)


Mooney S.B. M20-208B Insulation Kit (All Models)


Landing Gear Mods


Brake Wheel Cylinder Rotation (All Models)


Landing Gear Biscuits (Ea.)


High Carbon Black Steel Brake Discs


Wheel Well Liners (M20C,D,E,F,G,J,K)


Nose Gear Truss Oversized Bushing (M20A,B,C,D,E,F,G,J,K)


Nose Gear Truss – New Style with Steering Limit


Steering Horn Assembly for Nose Wheel-Overhauled (Pre-1969 model


Factory New Nose Gear Steering Horn Assembly
(1969 & Later M20’s)


Steering Horn Assembly Retrofit Kit-New


Stainless Steel Hub Caps & Tie Down Kit (All Models)


Wing Mods


201-Style Flush Mount Wing Tips


Wing Tip Fairings With Nav Antennas


3-Seal Combination Package-Flap Gap, Aileron Gap, Rudder & Elevator
Hinge Covers


Flap Gap Seals (M20B,C,D,E,F,G)


Aileron Gap Seals (All Models)


Flap Hinge Covers (M20B,C,D,E,F,G,J,K)


Inboard Flap Fillet Fairings (M20C,D,E,F,G)


Wing Root Leading Edge Fairings (All Models)


Whelen Strobes-2 or 3 position (All Models)


Precise Flight Speed Brakes/Electric


Fuel Bladder Tank Retrofit Kit (54.7 Gal.) 



Fuel Bladder Tank Retrofit Kit (64.0 Gal.) 



Upgrade Existing 54.7 Gal. Bladder Tanks To 64 Gal Total Capicity


Tail Mods


Dorsal Fin w/Vertical Seal (M20B,C,D,E,F,G,J)


Tail Root Fairing/Horizontal (M20B,C,D,E,F,G,J,)


Rudder & Elevator Hinge Covers (All Models)


Interior Mods


201-Style Full Width Avionics/Instrument Panel (M20C,D,E,F,G) this


Instrument Panel Retrofit (9-hole, pilot side only) Not STC’d


Head Rest-Unupholstered (All Models) priced separately


Arm Rest Attached to Seat-Unupolstered-priced each


Lap Belt w/Shoulder Harness (All Models)


Lap Belts Only (All Models) Color Choice 


1.5" Rudder Pedal Extensions


Cabin Interior Replacement Panels

So as you can see, some of the mods are great fun and add much personality to your older Mooneys but think! The expense of adding too many mods is such that in the end you will ask yourself; “why didn’t I just upgrade to a later model with most mods as factory standard”? Duh, right? Well, not completely so because there are that dyed in the wool few staunch original M20 body type guys out there that want the older models but with modern sass, so like anything else; to each his own!

Knowledge Pack