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[Oct. 2016 UPDATE] Mexican Engine Heads

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Rambler Mexicano View Drop Down
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    Posted: Sep/30/2016 at 7:01pm
I hope everyone finds this interesting.

Here are some of VAM's engine head designs based on AMC's original 232 head design. The following heads are units exclusively used on the 4.6 Liters / 282 cubic inches inline six.

VAM inaugurated its own engine plant in 1964 at the municipality of Lerma, Estado de México. Due to the limited resources available for the investment, the company could only produce one of the two series of American Motors engines. Opting for high volume sales and market size, VAM opted to produce the six cylinder line of AMC, priorizing economy over power.

When it first started operations it mainly focused on assembling engines from complete kits imported from AMC (199 and 232 series only). From the start the company sought to have all importation replaced by local production. So progressively Mexican engines started to grow in percentage of locally-made parts, and thus lowering the percentage of components imported from the US. It was until 1969 that VAM started producing engines fully made in Mexico with all components made inhouse, even though that only covered part of the full engine production. It was until 1970 that the importation of internal engine components was discontinued.

In 1965 VAM launched its company engineering department. One of its first achievements was the full compatibilization of engines in the whole product line, this meant the successful adaption of the AMC inline sixes (199 and 232) in the Mexican Jeep line in 1966, a full five years before AMC. In 1967 and 1968 the engineering department mainly worked on adapting the car line to Mexico's varying altitude, such as testeing the best jet size for the Carter RBS and WCD carburetors, as well as the best rear differential gear ratios. Other results were the upgrade of the three speed manual transmission into the 150-T full synchomesh model since the 1967 models.

From these small achievements we move on to VAM's first self-designed engine in late 1968. The engine in question being the 4.1 Liter / 252 cubic inches six cylinder, focused on making the VAM Javelin more competitive against it's V8 rivals of the Mexican market while also improving the performance of the heavy Jeep line. The new engine as was based on the 232. It's main features were a larger bore of 3.91 inches, an inhouse 266 duration degree camshaft in place of the original 244 degree unit, a new flat piston design raising compression ratio to 9.5:1, a 280 CFM Carter WCD carburetor.

The second self-enginering engine came in 1971 in the form of the 4.6 Liter / 282 cubic inches cylinder. AMC planned to have a six cylinder above the 232 while VAM needed a more powerful engine than the 252. Both companies' main limitation was the crankshaft design and VAM did not have the means to create one. Both companies worked together and... voila! In 1971, AMC introduced the 258 six (alongside the 401 V8) while VAM introduced the 282. The new VAM engine was more than just different piston/cylinder specifications. Like the 252, the engine had a bore of 3.91 inches, but it got a new stroke of 3.895 inches. The other improvements were a larger all-new steel intake manifold coupled to a 360 CFM Carter ABD two-barrel carburetor. Compression ratio and camshaft remained the same as in the 252 six at 9.5:1 and 266 degrees.

The next improvement goes to the 282 six in 1973.

As far as my knowledge goes, this would be the FIRST ENGINE HEAD designed by VAM.


This engine head is characterized by larger valve diameter, 2.02 inches for the intake one and 1.68 for the exhaust one, as well as the lack of the flute-type shaft (independent rockers). As far as I know this engine head was designed in 1967 and used for the VAM Go Pack, which was optional equipment. The VAM Go Pack was the company's offer that would make the VAM Javelin with its six cylinder engines give the other V8 muscle cars made in Mexico a run for their money. It consisted of a four-barrel intake manifold, a four-barrel 650/800 CFM Carter AVS/AFB carburetor, a 302 duration degree camshaft, 5000 RPM range headers and dual exhausts, reinforced rebalanced crankshaft, heavy duty cooling system, and the aforementioned ported head with larger valves. These accessories represented a 35%-40% overall power increase of the engine.

The large-vale head appeared for the first time in regular production models in 1973 as factory issue. On difference in regards to the Go Pack unit was that the 1973 unit did not have the performance-oriented intake porting. As far as my knowledge goes, this engine head was used from 1973 through 1976.

A new head design would appear in 1977.

Exhibit Number One:

Red Series




Quench-type combustion chambers, new for the year. This allowed a compression ratio increase of 8.0:1 against the 7.7:1 one of the 1975-1976 282s, which had an estimated 120 net horse power. This new head design the Holley 2300 (350 CFM) carburetor meant a output of 132 net horsepower or 129 net horses with the Motorcraft 2150 (325 CFM) carburetor.



Stock intake/exhaust porting design.



Rockers



Champion N-12-Y, factory spark plug specification.



VAM 1977-1986 two-barrel aluminum intake manifold. AMC would introduce a low weight aluminum intake manifold in 1980. This unit incorporated Holley 2300 and Motorcraft 2150 carburetors. It had improved flow and was lighter than the previous 1971-1976 steel intake manifold. It also had built-in portions to bolt in the power steering pump. This intake manifold, as also was the previous steel unit, was exclusive to the 282 six, not used in 258 and 232 engines.

Moving On

Exhibit Number Two:

Jeep Head - 1982-1986












VAM Jeep engines had different specifications than the VAM car line engines. The main differences of the Jeep engines were a lower compression ratio and a smaller valve diameter. There a few exceptions like the 1980-1981 Jeep Wagoneer with automatic transmission, which had car line specs in its 282.

The valve diameter for this engine head is 1.77 inches for intake and 1.38 inches for exhaust.

For example, the 1971-1973 VAM Javelin with the 282 had 9.5:1 compression ratio while the 1972-1973 Jeep Wagoneer had 7.75:1 compression ratio. While the Javelin was rated at 200 gross horsepower, the Wagoneer was advertised at 185 gross horsepower.

Using the 252 as another example, the 1970 Javelin had 170 gross HP and 9.5:1 compression ratio while the Wagoneer and Pick Up truck had 160 gross HP and 7.46:1 compression ratio.

MORE TO COME

After VAM released the Red Series head came another new design for the Car Line, a head design with smaller spark plug outlets, larger round intake ports, the spark plug side of of it was also changed to a straight line instead of being undulated. This last aspect was based on AMC's new plastic valve cover design.

This head was introduced in early 1982 and used through the 1983 model year. This is the head I have installed in my car's engine. Unfortunately I don't have pictures of it. The next time I disassemble my engine (I'm planning changing the stock 266 degree came for Crane's 304 degree unit) I will take pictures of the head for everyone to see.


Edited by Rambler Mexicano - Oct/12/2017 at 5:35pm
Mauricio Jordán

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- Vehículos Automotores Mexicanos S. A. de C. V.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote uncljohn Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2016 at 7:30am
Thank you for supplying this information. I am enjoying reading it and making comparisons, many of which I neither had thought of nor knew. I've built a few I-6 engines and it almost makes me want to come across a 282 Cu in engine to build. A really big six would be interesting.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote one bad rambler Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2016 at 10:30am
Pretty interesting for sure...Thanks for the information...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2016 at 12:41pm
Thanks everyone for your comments. Here's more.

1971-1976 Steel Intake Manifold







Applications:

1971-1973 VAM Javelin
1972-1976 VAM Classic (Matador)
1976 Pacer
1976 American Rally (Hornet X)
1972-1976 Jeep Pick Ups and Wagoneer

These were coupled to Carter ABD (1971-1974) and Holley 2300 (1975-1976) carburetors.
Mauricio Jordán

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- Vehículos Automotores Mexicanos S. A. de C. V.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mramc Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2016 at 5:52pm
Interesting information. I've heard the VAM plant was responsible for first putting the AMC six in the Jeep Comanche, as it originally had that weak keened GM V-6 and in Mexico  they only build the the sixes. LRDaum
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2016 at 12:13am
one can imagine a small business exporting Mexican AMC six cylinder heads, manifolds, valves, etc...  that stuff is shippable via UPS or USPS. 

have you done any side-by-side, Mexican heads vs U.S. heads? how good is the porting? runner dimensions? is that early aluminum manifold unique? blocks are blocks, big or not, but the combustion chamber is controlled by the head (and pistons of course). a good flowing head is path to power.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2016 at 11:32am
 According to a Oct.69 issue of Rod &Custom you have to notch the block for both exhaust and intake valve clearance when you install the VAM head on the smaller bore US blocks.
 
They installed the 252 VAM head, which used the same valve sizes as the later 282 VAM engine, on a US made 232 block.
 
  They also say the exhaust valve was moved over to make room for the bigger intake valve on the VAM head.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 232jav3sp Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2016 at 12:06pm
This is some cool stuff.  I'd really like to get a 282.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2016 at 4:20pm
Renault had determined from the start that the AMC 258 would not fit in the then-project Jeep Cherokee XJ models. As we all know it was intended to carry AMC's brand new four cylinder and GM's new line of V6s.

VAM wanted to to introduce the Cherokee to the Mexican market, but for to happen it would have to carry the I6 inevitably, since the company did not produce any other type of engine, and buying any from the other manufacturers of the Mexican market would not be a cost-effective procedure. Also, importation of engines was legally banned at the time.

The only way to go would be by installing the I6. VAM had gotten a semifinished prototype from AMC in 1982 and the company's engineering department got to the task, eventually succeeding in installing the I6 in the Cherokee's engine compartment. AMC was informed about the project and developed considerable interest and recalled the prototype.

That was cornerstone of the 4.0 six.

Unfortunately, while I've found some American-made AMCs around here I've never had the chance of making head to head comparisons. I do have seen VAM's aluminum two-barrel intake manilds on AMC-made sixes, and as far as I know there is no need to modify anything, remove and bolt-on accessory change only. VAM engine blocks and AMC blocks were indeed cast differently. The most you can bore out an AMC 258 block is up to 274 cubic inches. The VAM Go Pack was available at Randall American dealership in Meza, Arizona.

If anyone wants to test a VAM 282, I have a friend who took a 1981 VAM Rally AMX (Spirit GT) to Houston and he plans to install an AMC 360 V8 in the future on it. He'll let me know when that happens.

I'll let anyone here know when this 282 engine is available for sale.
Mauricio Jordán

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- Vehículos Automotores Mexicanos S. A. de C. V.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 73Gremlin401 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/05/2016 at 5:03pm
I had the good fortune of coming across a VAM aluminum 2bbl intake, and ran it on my 258 motor in a Gremlin for several years, using a Holley 2300 carb.  I wish I knew what ever happened to that intake!  To say it woke up the 258 would be an understatement.  Very very good flow, well in excess of the RPM potential of a stock 258, yet had really good low-end grunt as well.  Was truly excellent around town, on the highway, as well as for autocross and road-racing duty, which it saw plenty of in that car.
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