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Nil Bastardo Carborundum
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Vh Agent Orange
I'll try to clear up a few questions for you regarding heads, manifolds etc.
The early red Holden engines (149 and 179) shared the same design cylinder heads but they had different sized combustion chambers. The 179 chambers were larger. Valves and springs were the same. The 179 was simply a larger bore 149. I think the 149 was about 3.25 inch bore and the 179 was about 3.5 inch bore. There was a low compression version of the 149, which ran the standard 179 head, with its larger combustion chamber. Compression ratios were around 8.8:1 for the high compression engines and 8:1 for the low compression 149.
The 161 and 186 were simply bored version of the smaller earlier red motors. 161's had a 3.375 inch bore and the 186 went up to 3.625 inches. Again, the cylinder heads for both engines were the same arrangement - if you wanted a Low Compression 161, a 186 head was fitted. Unfortunately, my records don't give any indication how to tell one head from another. Compression ratios were 8.2:1 for the low compression 161 and 9.2:1 for the high compression motors.
There was also the X2/186S head assembly but these were identical to 179/186 heads, according to my records. (Surprises me actually - I thought they had larger inlet valves.)
The 202 was simply a stroked 186. It would have used similar heads to the 186 but the compression ration was up again. I can't recall the figure but it was around 9.8:1 or 10:1.
Early heads had siamesed intake ports which were very inefficient. Blue and Black motor heads had 12 ports, with separate ports for inlet and exhaust for each cylinder. They are much more efficient and you would be better off trying to get one of those for your 186 block if you can, if you are after performance.
If you have a twin stromberg manifold for the 149 head, it will have had twin BXUV-2 carbs from the factory, which were actually 149/161 carbs, to increase bottom end torque. You can run twin BXV-2's from 186's but because of the larger venturi, they tend to reduce bottom end torque but increase top end breathing. The choice is yours. The carb model number is cast into the base of the carby. Make sure you use identical bases and carb bodies.
Early manifolds will interchange between 149 right up to 202 red motor. Once you get to blue and black motors, you need the manifolds designed for them.
I'll try to clear up a few questions for you regarding heads, manifolds etc.
The early red Holden engines (149 and 179) shared the same design cylinder heads but they had different sized combustion chambers. The 179 chambers were larger. Valves and springs were the same. The 179 was simply a larger bore 149. I think the 149 was about 3.25 inch bore and the 179 was about 3.5 inch bore. There was a low compression version of the 149, which ran the standard 179 head, with its larger combustion chamber. Compression ratios were around 8.8:1 for the high compression engines and 8:1 for the low compression 149.
The 161 and 186 were simply bored version of the smaller earlier red motors. 161's had a 3.375 inch bore and the 186 went up to 3.625 inches. Again, the cylinder heads for both engines were the same arrangement - if you wanted a Low Compression 161, a 186 head was fitted. Unfortunately, my records don't give any indication how to tell one head from another. Compression ratios were 8.2:1 for the low compression 161 and 9.2:1 for the high compression motors.
There was also the X2/186S head assembly but these were identical to 179/186 heads, according to my records. (Surprises me actually - I thought they had larger inlet valves.)
The 202 was simply a stroked 186. It would have used similar heads to the 186 but the compression ration was up again. I can't recall the figure but it was around 9.8:1 or 10:1.
Early heads had siamesed intake ports which were very inefficient. Blue and Black motor heads had 12 ports, with separate ports for inlet and exhaust for each cylinder. They are much more efficient and you would be better off trying to get one of those for your 186 block if you can, if you are after performance.
If you have a twin stromberg manifold for the 149 head, it will have had twin BXUV-2 carbs from the factory, which were actually 149/161 carbs, to increase bottom end torque. You can run twin BXV-2's from 186's but because of the larger venturi, they tend to reduce bottom end torque but increase top end breathing. The choice is yours. The carb model number is cast into the base of the carby. Make sure you use identical bases and carb bodies.
Early manifolds will interchange between 149 right up to 202 red motor. Once you get to blue and black motors, you need the manifolds designed for them.
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