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Head Port Advice Old 409

General engine tech -- Drag Racing to Circle Track

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Ishiftem
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Head Port Advice Old 409

Post by Ishiftem »

These are some original hi perf 409 heads that I ported. The intake flowed 323 cfm at .700 and were pretty quiet. Valve size is 2.275. Anyway, now that they have been run, there is a white residue in certain areas of the ports. All 8 ports have the residue in the same spots. I’m thinking these are areas of lower flow. Is that correct? What could be done to help even the flow more through the bowl area? Is the guide boss acting like a dam?
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536A3408-CE3D-42A8-AE60-6951BAD17A43.jpeg
0E93828B-D94A-4FE4-B116-3ECE35DD2A81.jpeg
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vortecpro
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Re: Head Port Advice Old 409

Post by vortecpro »

Nice to see a set of production heads with the valve guides done right
Racing a NA NHRA stocker should be mandatory before any posting.
1980RS
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Re: Head Port Advice Old 409

Post by 1980RS »

If I ever get time I want to try some experiments on my 340hp 409 heads I have laying around. I have one more 409 I can build now that i welded one block. I always love messing with 348/409 engines. Great job on the heads.
Ishiftem
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Re: Head Port Advice Old 409

Post by Ishiftem »

Thanks. I’ve run a best of 10.13 in a 3850 pound ‘63. Not bad for a antique!
JoePorting
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Re: Head Port Advice Old 409

Post by JoePorting »

I'd guess the white stuff is ash from reversion. Exhaust gases are going into the area just below the intake seat and burning any residual oil deposits in the area.

Nice port work btw. :D
Joe Facciano
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Re: Head Port Advice Old 409

Post by KnightEngines »

Yeah, reversion.
You need to look at cam events.
mag2555
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Re: Head Port Advice Old 409

Post by mag2555 »

Your intake valves should not have a angle on there chamber side face, they should be a chisel.

A angle on the face is the start of low lift low velocity reversion.

What is the current ID of the valve bowl and what is the port area on the crown of the short turn, and what is the minimum port area ?
CGT
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Re: Head Port Advice Old 409

Post by CGT »

Id be interested to know cam specs and valve seat angles.
mag2555
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Re: Head Port Advice Old 409

Post by mag2555 »

I would like to know also what the average Exh to Intake flow ratio is within his range of valve lift from his Cam?
Ishiftem
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Re: Head Port Advice Old 409

Post by Ishiftem »

Well! After some more of investigation, it is exhaust but not reversion. The valve seat is slightly sunk where it is next to the exhaust valve on each cylinder. So basically exhaust was blowing past the closed valve at that spot. I posted a picture. The port area at the short turn is 3.135. The smallest port area is at the pushrod pinch and is 2.7. The highest point of the short turn is .600 above the valve seat. The throat is 2.04. The valve job is a standar 60/45/30. The intake valves have a 30 back cut. Exhaust valve is 1.75. I lost the flow numbers for the exhaust side. Anything I can do to improve these things or just leave well enough alone? These are my first full port job. I tried to follow basic rules and do no harm. Thes best numbers I’ve heard from these heads is around 330-335 @ .700 so I don’t think I did too bad. Just trying to get in the 9’s!
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vortecpro
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Re: Head Port Advice Old 409

Post by vortecpro »

What MPH do you run?
Racing a NA NHRA stocker should be mandatory before any posting.
Ishiftem
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Re: Head Port Advice Old 409

Post by Ishiftem »

My best is 132.2 mph when I ran the 10.13.
mag2555
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Re: Head Port Advice Old 409

Post by mag2555 »

Well if your running enough lift to access atleast 310 cfm from your Intake ports and in that same lift range your Exh flow ratio is averaging 68% you should beable to make 700 hp, which should get you into the 9s if the intake manifold your running can pass that much cfm! ?
Powertrip
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Re: Head Port Advice Old 409

Post by Powertrip »

Those are real good numbers, especially since it looks like there is NO short turn height whatsoever.
Would love to velocity probe that port.
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dfarr67
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Re: Head Port Advice Old 409

Post by dfarr67 »

Always surprised at the number these kind of engines put out and in factory trim- what killed them in the day?

- just a stop gap engine on the way to something better?
- cost of engine?
- dead end due to rotating assembly weight?
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