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1964 Chevy C10, Cummins ISB170, Allison 1000 5 speed, full float 9”, ECU Tune, 5/7” static drop
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Discussion Starter #1
Does anyone know what engine type Cummins part number 4939973 exhaust manifold was used on?

looking for round port exhaust manifold options
 

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That manifold comes on the ISDe 4.5 engine. May also fit the ISBe 3.9 or QSB 4.5 16 valve engines but won't swear to that. Appears to place the turbo a good distance away from the head. Turbo was mounted in a down position. Manifold 4946654 is one found on the QSB 4.5 and mounts the turbo up top.
 

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1964 Chevy C10, Cummins ISB170, Allison 1000 5 speed, full float 9”, ECU Tune, 5/7” static drop
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200 Posts
Discussion Starter #3
That manifold comes on the ISDe 4.5 engine. May also fit the ISBe 3.9 or QSB 4.5 16 valve engines but won't swear to that. Appears to place the turbo a good distance away from the head. Turbo was mounted in a down position. Manifold 4946654 is one found on the QSB 4.5 and mounts the turbo up top.
Thanks. The ISDE manifold would be ideal. I’ll look into the ISDE and see if it’s similiar to the ISB
 

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1964 Chevy C10, Cummins ISB170, Allison 1000 5 speed, full float 9”, ECU Tune, 5/7” static drop
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Discussion Starter #4
Char, you have a reference for 4892480? Is this the same as 4939973. I found the 4892480 on quickserve and it looks similar to 4939973.
 

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4892480 appears to be identical to 4939973. Could be an earlier number for it or a different manufacturer. That one is strictly coming out of China. The diagram below shows all the parts. If you need numbers on the bolts, spacers, etc let me know. One thing that is not mentioned is the turbo flange. Most all these have a T25 flange but there could be others which would create a new part number.

PS. In case you don't have enough numbers to confuse you here's yet another that looks the same. Part 4897792 which is an earlier number for 4939973.
 

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1964 Chevy C10, Cummins ISB170, Allison 1000 5 speed, full float 9”, ECU Tune, 5/7” static drop
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200 Posts
Discussion Starter #6
4892480 appears to be identical to 4939973. Could be an earlier number for it or a different manufacturer. That one is strictly coming out of China. The diagram below shows all the parts. If you need numbers on the bolts, spacers, etc let me know. One thing that is not mentioned is the turbo flange. Most all these have a T25 flange but there could be others which would create a new part number.

PS. In case you don't have enough numbers to confuse you here's yet another that looks the same. Part 4897792 which is an earlier number for 4939973.
Thank you very much. Looks like this will work for my engine placement. I did notice on quickserve that manifold has a note, RPM LIMIT >1800 rpm. Long runners higher rpm, if I read that correctly.
 

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Never really hear of an RPM note on an exhaust manifold. However, longer runners may lose some thermal efficiency. Having the weight of the turbo hanging that far out could also stress the manifold. Of course the HX27W or HE221W that was used on these isn't a very heavy turbo.
 

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Rough guess is they may have designed that manifold as a "tuned" system the same as a hotrod gas engine. The 1800 limit would suggest Genset application. Not as much vibration as a mobile unit.
Cheers Steve
 

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In doing some more checking, the road use ISB engines used manifold 3948477 shown below. That long runner type was not used on anything but industrial applications. Same goes for the short runner center mount which placed the turbo up top. Also, manifold 3948477 has the T25 flange because the turbo used was the HY30W instead of the HX27W or HE221W used on other engines.
 

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1964 Chevy C10, Cummins ISB170, Allison 1000 5 speed, full float 9”, ECU Tune, 5/7” static drop
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Discussion Starter #10
In doing some more checking, the road use ISB engines used manifold 3948477 shown below. That long runner type was not used on anything but industrial applications. Same goes for the short runner center mount which placed the turbo up top. Also, manifold 3948477 has the T3 turbo flange instead of T25 because the turbo used was the HY30W instead of the HX27W or HE221W used on other engines.
FYI, manifold 3948477 is T25 flange. Also the HY30W turbo is T25. I currently have this manifold and turbo
 

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Thanks for the correction. I corrected that post. The specs I found said T3. However, that is not shocking because I have found many errors even on Cummins Quick Serve site. Even found one spec that said it was aluminum. So there is not a T3 manifolds for the ISBe 3.9. I guess if you wanted one you'd need to take a Dodge common rail manifold and chop off 2 cylinders. It would look like the 3948477.
 
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