Large intake valve small bore ???
January 12th, 2019, 11:23 AM
#1
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Large intake valve small bore ???
The 400 G is a small bore engine that used a D or C head from the factory with 2.067 intake.
The Canadian 442 400 G engine some times came with C heads with a 2.00 intake.
Would it be worth my time to try the smaller intake heads with the small bore?
The Canadian 442 400 G engine some times came with C heads with a 2.00 intake.
Would it be worth my time to try the smaller intake heads with the small bore?
January 12th, 2019, 02:19 PM
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January 12th, 2019, 03:45 PM
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Not all 1969 442 400 Canadian C headed cars had smaller intake valves. We just happened to have one, it was years latter that we came across this in print.
I do not have documentation that this was standard practice, my current Canadian 69 442 400 G has the larger intake valve.
January 12th, 2019, 04:04 PM
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The valve is shrouded so the larger intake may not be an advantage.
It might be a waste of time but we have two members that have lots of flow bench experience so I thought I would ask the question.
I know magazines always focus on max lift flow but what I found interesting is that the stock/super stock racer focus on low lift to max lift flow not just max lift flow.
That's one reason they do so much with so little.
Its just like rear gear ratio some times less gear makes the car quicker.
I talked to a few guys that ran the 400G back in the day and they said the car did not like as much gear as the 400 E.
It might be a waste of time but we have two members that have lots of flow bench experience so I thought I would ask the question.
I know magazines always focus on max lift flow but what I found interesting is that the stock/super stock racer focus on low lift to max lift flow not just max lift flow.
That's one reason they do so much with so little.
Its just like rear gear ratio some times less gear makes the car quicker.
I talked to a few guys that ran the 400G back in the day and they said the car did not like as much gear as the 400 E.
January 12th, 2019, 04:16 PM
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Optimum gearing has a multitude of variables. Torque curve of the particular engine, tire diameter and stickiness, trans gearing, etc. It's no surprise that the long stroke G-block would run out of steam and not want to rev. This is not an applicable example to the small valve discussion. In any case, do you know that the small valve 400 you had still had original heads, or even was original to that car? G-blocks in Vistas got small valves.
January 12th, 2019, 05:44 PM
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Optimum gearing has a multitude of variables. Torque curve of the particular engine, tire diameter and stickiness, trans gearing, etc. It's no surprise that the long stroke G-block would run out of steam and not want to rev. This is not an applicable example to the small valve discussion. In any case, do you know that the small valve 400 you had still had original heads, or even was original to that car? G-blocks in Vistas got small valves.
The 69 442 was a numbers matching original 400 G and had no problem revving past 5500 rpm until we spun rod bearings multiple times.
Last edited by Bernhard; January 12th, 2019 at 06:08 PM.
January 13th, 2019, 07:36 AM
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Im not sure. The best way to test would be to start with a small valve G, test the numbers, machine for the large valve and test again. Or I guess I could test the heads that I have on a small bore fixture and see how much if any that they loose.
January 13th, 2019, 02:15 PM
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Our 69 442 was not a turn pike cruiser it was a factory 4bl 325 hp auto bucket seat console car. We had a factory manual and the build sheet for the car. I still remember checking the carb, distributor, intake, block, heads, alt, trans and diff. When we pulled the heads and measured the valves we were surprised by the smaller 2" intake valves. It was only years later that we read about some Canadian 69 442 coming with 2'' intake valves. We had that car apart and back together and apart so many times.
Last edited by Bernhard; January 13th, 2019 at 02:17 PM.
January 13th, 2019, 02:21 PM
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January 13th, 2019, 02:36 PM
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January 13th, 2019, 05:28 PM
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One interesting thing the factory did to improve the flow of the factory 400 G block is that they finished the top of the cylinder bores with multiple angles like that of valve seat cuts. They used to angles at the top of the bore.
January 14th, 2019, 06:37 PM
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I know a few Oldsmobile engine builders that stated that they like to start with the small dia intake valve head then open up the throat with a cutter and cut fresh seats.
This way the valve is not sunken into the head do to previous valve seat cuts.
January 14th, 2019, 06:41 PM
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January 15th, 2019, 06:59 AM
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