Rambler 195.6 ci overhead valve six

updated april 2019

you can contact me at it is as if at protonmail dot com

section index

cylinder head
lubrication system
cooling system
block and accessories
ignition system
crankcase ventilation (PCV)

this site is documentation of the work i'm doing on the Rambler 195.6 OHV inline six that powers my rambler roadster. in addition to plain old documentation and information my goal is to build modern levels of reliability and power. while this is a very modest design (putting it nicely), with the dubious distinction of having no performance parts available for it other than the factory two-barrel option ("Power Pak") it has proven to be a reliable engine, with forged crankshaft and connecting rods. most of it's shortcomings are easily overcome.

why "195.6"? Nash engine nomenclature included the decimal, i would guess as part of some long-forgotten "Nash Precision" marketing trope, otherwise, it's sort of annoying. AMC continued it, and that is what appears in service manuals and most internet search results, although enough people call this engine "the 196" to confound searches and identification. annoying or not, it's what all documentation uses so i continue it here.

Thanks to Frank Swygert for much information on this engine and for corrections to these pages.

brief history

This section by Frank Swygert:

Nash's economy L-head six was fitted with an overhead valve head for the 1956 model year. (No L-heads were sold for 1956 or 1957, but it reappeared again in 1958 and was available through the 1965 model year.) The 1956 model of the OHV still had the side mount water pump. The front mount pump came in 57.

The original L-head was a 172.6 designed specifically for the first unit-body Nash, the 1941 Ambassador 600. This increased to 184 inches in 1950 for the Statesman, and the new Nash Rambler got the 172.6. 195.6 came in 1952, again for the Statesman. The Rambler got the 184 in 1953, Hydramatic Ramblers got the 195.6 (small wonder -- the Hydramatic was heavy and took a lot of power!). 1952 was the last year for the 172.6, 1954 last year for the 184. All three engines used the same 3.125" bore, strokes were different (3.75", 4.00", 4.25" respectively). This was unusual since the crank and rods were forged -- the usual practice was to keep the expensive forgings the same and alter the cheaper to change block casting. I guess pennies didn't need to be pinched as much then as after the "merger" with Hudson.

AMC factory Technical Service Manual

if you are going to work on these motors you really need to have a legible copy of the factory technical service manual (TSM). a Haynes or Motors manual is no substitute. the TSM has detailed information you simply won't find elsewhere. for reference, here are the relevant 1961 TSM engine pages, along with the few 1965 TSM pages pertaining to the differences from the earlier motor.

this particular engine's history

this particular engine has been rebuilt at least three times. twice by me. when this engine was in the 1963 Rambler American 440 Twin Stick hardtop i got in 2005, it had a commercially rebuilt engine in it, .030" overbored. within a year i rebuilt the cylinder head due to sticking valves (old gasoline, foolish mistake).

in 2010 the engine was pulled and i did what i thought at that time was a careful rebuild. many of the successful modifications i made to this engine were done at this time. on this site i refer to this as the "2010 build". in 2014 i again removed the engine, did a cosmetic freshen then installed it in the current chassis, my rambler roadster. in august 2016 i drove the roadster in the LeMons Hell on Wheels '16 Rally, very hard in very hot weather, steep grades in Death Valley, which did some unpleasant things to the bottom end. when i got home the engine was once again removed, torn down, and this time, after careful diagnosis of it's various shortcomings and problems, completed what i call here the "2017 build", by a professional engine builder, Pete Fleming. that turned out to be a great (if expensive) decision as his machine work is impeccable, finding and fixing problems previous machinists either neglected or couldn't see. you get what you pay for.

as of this writing (november 2018) the 2017 build is broken in and has 27,000 fairly hard miles on it -- at a performance level that the 2010 build was not capable of and certainly would not have survived.