1964-1979 head variations/variants

Hello everyone, I hope everyone is doing fine. I'm back at the board after some time.

I have some inquiries to make in regards to head designs in AMC six cylinders from 1964 through 1979. I hope anyone can help.

I have been requested advice many times in recent days in ragards to medium and small sized VAM six cylinder engines (199 and 232) from some friends at the Guadalajara and León VAM/AMC clubs.

Before I start, I'll share some background.

Virtually ALL 1964-1970 199 and 232 engines produced in Mexico are exactly the same (spec-wise) as their American-made counterparts. The first difference I know of comes in 1971, where AMC's original 244 degree camshaft was replaced in favor of VAM's inhouse 266 degree cam.

The 232 six cylinder engine series was introduced in the United States in the 1964 model year, and it was introduced in Mexico in 1965.

The 199 six cylinder engine series was introduced simultaneously in the United States and Mexico in the middle of the 1965 model year (replaces both the L-head and OHV 195.6 six cylinder series).

The first VAM engine to differ from AMC's original engineering and specifications is the 252 cubic inches inline six cylinder introduced in 1969. It is characterized by a new 266 degree camshaft, a 3.91 inch bore, flat pistons for a 9.5:1 compression ratio, a new head with 3.91-inch-diameter combustion chambers and the stock 232 crankshaft (same stroke).

The second VAM engine to differ from AMC's canon was the 282 cubic inch six cylinder introduced in 1971. It kept the same bore, pistons, camshaft and head from the 252 six plus the notable improvements of an all-new larger steel intake manifold, large-diameter Carter ABD carburetor and the stock 258 crankshaft (same stroke).

The 258 six cylinder was introduced in 1971 in the United States and in 1973 in Mexico (replaces 252).

As far I know, the Mexican 258 is virtually the same as its American counterpart, variations mainly being limited to the camshaft, compression ratio and carburetor type.

The 199 six cylinder was discontinued in 1970 in the United States and in 1969 in Mexico.

The 232 six cylinder was discontinued in 1979 in the United States and in 1976 in Mexico.

All AMC and VAM engines up to 1972 have a flute-type shaft over the head holding all rockers in place. It was replaced with the independent rocker design in 1973.

Between 1964 and 1979, What I need to know IS:

1.-

From 1965 through 1970, the 199 heads and the 232 heads are the same? Are they interchangeable? Or are there any differences (valve diameters, port sizes, etc.)?

Between both engine series, they only difference I know is the stroke (longer in the 232 and shorter in the 199). They share the same bore.

2.-

In 1971 the 258 was introduced, since it also has the same bore as the the 232 and 199, its head is interchangeable with these two series? Or are there exclusive characteristics to the 1971-1972 258 head?

3.-

I know the crankshaft was different between the 232 and the 258.

Was it different between the 199 and the 232?

4.-

How different or interchangeable are the 1973-1979 232/258 heads (independent rockers, flute-type shaft gone) in regards to the 1964-1972 engines?

5.-

The 1975-1979 gas emission regulations resulted in different head designs from the ones in the 1964-1974 period?

Frequent Problems:

Here in Mexico obtaining a replacement/new flute-type shaft for the 1965-1972 199/232/252/282 engines is almost impossible now. Everytime the shaft wears out, the engines become pretty much useless.

Constantly, Mexican owners of mainly 1969-1972 Javelins ask me what can be done to solve the issue.

In all cases, the first thing that comes to mind is to tell them to replace the original head with a 1973-1986 VAM 282 head. In the Javelin's case (a performance model), the real advantage is not just solving the flute shaft issue but also obtaining the larger valve diameter (2.02 inches intake, 1.68 inches exhaust), since all 1969-1972 252/282 head still have small valves (virtually the same size as the stock AMC valves).

I do know several cases in which Javelins get their heads swapped like this, as far as I know there's no need to change or modify anything, it's virtually just a bolt-and-unbolt/plug-and-play operation.

Here comes the second problem.

Owners of 1965-1972 VAM cars with the 199 and 232 engines that have the same flute shaft problem, I do not have certainty of answering them like I do with the 252/1971-1972 282 cases.

The first thing that comes to mind would be telling them to replace the original 1965-1972 199/232 head with a 1973-1986 258 head, since it has the same bore as the 199/232 units.

Is this possible/correct?

How interchangeable are the 258 heads with the 232/199 engines?

VAM engines from 1975 through 1986 were not as chocked from gas emission control devices as the AMC units, making them more similar spec-wise to the 1964-1974 AMC engines.

Thanks in advance.


Edited by Rambler Mexicano - Dec/18/2017 at 12:08am

I have a worn rocker shaft that I have been attempting to drill through with a cobalt bit to the other side so that it could be flipped over. It's been a long slog drilling for less than a minute, then resharpening the bit. There are still 3 or 4 holes not all the way through and my second bit is becoming quite short. I have heard that a carbide bit is harder but they are about 3X the cost of cobalt. There is also the danger of them breaking off as they punch all the way through.One thing I have noticed is that the shaft is harder on the ends than in the center.

When the 6's went to the Delco alternator in 1975 the alternator mount bolt holes were moved to accommodate it.

FSJunkie wrote: pacerman wrote: When the 6's went to the Delco alternator in 1975 the alternator mount bolt holes were moved to accommodate it. Perhaps so, but the alternator does not bolt to the head...at least the Delco doesn't. I have a 1977 232 with a Delco alternator. It bolts to the timing cover and the side of the block near the fuel pump.