According to Wikipedia

I did not add the VAM specs to the Wikipedia page, but I DID add them to a VAM club page that was hosted in the now-defunct MSN Groups service. Someone took those specs and added them to the Wikipedia article. As I was able to obtain more information over the years I did add specs that were missing from the MSN site (I was still collecting VAM data back then, and still am) to the Wikipedia article and correct several aspects, such as the 1975-1976 compression ratio spec that appears as 8.5:1 in the owner's manuals but that is in fact 7.7:1 according to VAM employees I know. These compression drops were not announced due to marketing reasons.

What I DID add myself to the article from a scratch were the correct model applications for the VAM engines.

Aside from Frank, I do have contact with one person in charge of keping the AMC wikipedia articles, Christopher Ziemnowicz.

I have personally written 80%-90% of the VAM section of at least thirteen AMC model Wikipedia articles. They have been edited sereval times but I don't have a problem with that as long as the information is accurate.

Here are the links:

Mexican Rambler Six and V8

VAM Rambler American (original)

VAM Rambler Classic (original)

VAM Rambler Classic (Rebel)

VAM Javelin

VAM Rambler American (Hornet)

VAM Classic (Matador)

VAM Gremlin (original)

VAM Pacer

VAM American (Concord)

VAM Gremlin and Rally (Spirit)

VAM Lerma

AMC Straight Six Engine - VAM 252

AMC Straight Six Engine - VAM 282

As for the drop in horsepower over the years, it was mainly due to compression ratio drops (piston type and combustion chamber design) but it wasn't the only reason, the intake manifold design (steel in 71-76 and aluminum in 77-83), carburetor model (360 CFM in 1971-1974, 350 CFM in 1975-1977 and 325 CFM in 1978-1983), intake porting design and ignition type (points in 71-74 and electronic in 75-83) also influenced the finaly results.

It all started with an announcement from the Mexican government  that all gasoline engines produced in the country would have to pass emission certification, which would take effect at the beginning of the 1974 model year.

All regular production VAM 282s have the same camshaft, the VAM-engineered 266 duration degree unit introduced in 1969 for the 252. AMC's original cam was a 244 degree unit. Also, all VAM 282s have the same valve diameter (2.02 inches intake, 1.68 inches exhaust) with the only exception of the 1971-1972 units that had smaller valves. The crankshaft was also the same in all years.

The 1971-1973 282 is the most powerful because it has flat pistons, all 1974-1983 units have concave units.

Unfortunately, we still have very little info on the 1974-1976 282s. What we do know so far is the following. Through 1976 there were two combustion chamber sizes, we still don't know the actual year this practice began, I would speculate 1974 is when it started.

There was a large combustion chamber for lower compression ratio and a small combustion chamber for higher compression ratio. Exactly how much CR each version had we still don't know. I would SPECULATE that the small chamber would be a 8.5:1 compression ratio unit and the large chamber the 7.7:1 units. Like I said, I STILL have no way to prove this.

Also, we don't know what models of this period had the small chamber/higher compression and which had the large chamber/low compression. From 1974 through 1976 pretty much the only car that had the 282 was the VAM Classic (Matador). They were divided in two luxury models and one performance model. The formers being the Classic DPL (Matador sedan) and Classic Brougham (Matador Brougham coupe) while the latter was the Classic AMX (Matador X coupe). The only exceptions were the 1976 Pacer (luxury model), the 1976 American Rally (Hornet X, performance model) and the 1976 American ECD two-door (Hornet DL two-door, luxury model).

I would like to think the small chambers were used in the American Rally and Classic AMX while the large ones found use in the Classic DPL, Classic Brougham and Pacer.

Since VAM enginers told me an approximate NET horse power figure for the 1975-1976 282 would be around 120-125 units, I would like to think 120 horses go to the 7.7:1 compression ratio version and 125 to the 8.5:1 compression ratio ones.

The third generation of 282 engines came in 1977. It's main feature was a brand-new quench-type combustion chamber. It had 8.0:1 compression ratio. The 1982-1983 regular production 282s as well as the high performance 1979-1981 units got a higher compression ratio (8.5:1 instead of the 8.0:1) due to the use of a different head gasket.

Finally a new head design with plastic valve cover, smaller spark plug specification and round intake ports appeared early in 1982, which would take the regular production 282 (with the new 8.5:1 compression ratio) to no less than 135 net horse power with the standard 325 CFM Motorcaft 2150 carburetor (against the 129 net horsepower of the 1978-1981 regular production 282s).

However, we still don't know if this head design was actually tested performance-wise by VAM's engineering department since it came right at the time the economy bombed and the whole Mexican auto industry went downhill and VAM interruptd several operations.


Edited by Rambler Mexicano - Dec/07/2016 at 3:35pm

my 195.6 OHV is 138 hp -- flywheel rating. rating systems changed in the 70's or 80's. it's silly d*ck size comparisons anyways, no one drives stock cars like that. and a lot of car "specs" are taxable emphasis TAX or shipping weights. a 3000 lb actual weight car might be listed as "2800 lbs" as a way for federally regulated freight system providers a discount (since they can't by law charge less than a regulated amount per pound, they agree that the item weighs less).

The rating change explains the big drop from 1971 to 1972 (in the US.... 79/80 in Mexico, apparently). The drops that occurred later were mostly due to changing emissions standards and getting an engine design in the 60s to comply with increasing emissions restrictions without a total redesign of the head and combustion chambers. Takes a lot of R&D (money!) to do that.

AMC finally did redesign the head, when the 2.5L four was introduced. The 258 soldiered on with pretty much the same old head (with minimal changes over the years) through 1989. The 4.0L got a head update. Little known is that while the 2.5L four was essentially a shortened 4.0L, the 4.0L head was essentially a lengthened 2.5L head. Different ports (intakes were smaller than 258 but raised and with a better shape that flowed more than the old big ports with a 90 degree turn over the valve. Of course the ports were raised a bit more (on the 4.0L head, don't know about the 2.5L) for 1991 HO models. Better combustion chamber, and the center two exhaust ports were separated instead of together as on the 258.

On a different note, some schools won't allow using Wikipedia for papers, some will -- but you better have another source as well, and/or cite the Wikipedia article sources (and check them). That's always a good idea. Wikipedia does note when citations are missing/needed from an article. Of course I get to cite one of my own books as a source... but the info from that comes mostly from official AMC source material.


Edited by farna - Dec/08/2016 at 6:27am