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D denney
Dodge Dakota
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3/13/2002
17:04:04

Subject: 4.7L OHC
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Wow, i did not know my dakota 4.7 was an OHC setup.I am familiar with how a DOHC system works,does the 4.7 have one came in each head or what?



CThomp
Dodge Dakota
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3/13/2002
17:11:18

RE: 4.7L OHC
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yes one cam per head.



Wcomea
Dodge Dakota
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3/13/2002
18:20:49

RE: 4.7L OHC
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Is their a DHOC head setup and would it help with performance?



Dave Mitchell
Dodge Dakota
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3/13/2002
19:12:09

RE: 4.7L OHC
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I would think a single overhead cam would have better performance than a double. Less complexity for more reliability. Probably alot less friction due to 1/2 as many bearings, less inertia due to one less cam sprocket, etc.

A double overhead cam is usually necessitated by having 3 or 4 valves per cylinder or the elimination of rocker arms.




kevster
Dodge Dakota
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3/13/2002
19:43:37

RE: 4.7L OHC
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The 4.7 has no pushrods, and uses one cam per head. pretty cool huh?



Clevite 77
Dodge Dakota
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3/13/2002
20:58:40

RE: 4.7L OHC
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I didn't know up until a couple of years ago but "most" OHC motors dont use cam bearings. The cams ride directly on the cam housing bore. It sounds crazy don't it?



CW
GenIII
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3/13/2002
23:16:23

RE: 4.7L OHC
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There are no cam bearings on the 4.7 either.

2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams.
Working on adjustable fuel pressure with return.

JoeC
Dodge Dakota
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3/14/2002
00:08:06

RE: 4.7L OHC
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No bearings on either end of the cams shaft??? Is it bolted/held down by the rocker arms?



CW
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3/14/2002
09:31:02

RE: 4.7L OHC
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No there are caps like on the crankshaft that hold it in place. Just no actual bearings.

2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams.
Working on adjustable fuel pressure with return.

robert
Dodge Dakota
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3/14/2002
09:54:20

RE: 4.7L OHC
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A SOHC setup is NOT better than a DOHC. The reason for a DOHC setup is twice as many intake and exhaust valves (normally -- but there are expections -- like a 5-valve head).

When we say that there are not bearings for the cam... that is half the explaination. The head itself and its cap are machined for the cam. They ARE the bearings. There just aren'nt any 'removeable' or 'replaceable' bearings. Because the load is minimal, you can get away with this. This is not a new concept.

The cam still rides on a film of oil like the crankshaft.



CW
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3/14/2002
14:36:03

RE: 4.7L OHC
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Like I said no actual bearings. Just a machined aluminum surface.

2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams.
Working on adjustable fuel pressure with return.

sandman
Dodge Dakota
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3/14/2002
16:49:36

RE: 4.7L OHC
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When they are casting the caps and the head they use an aluminum alloy high in silicone. The silicone creates tiny ultra hard spots in the aluminum. They then heat treat the parts and then finish machineing and polishing the area. The Japanesse have used this setup for over 20 years that I am aware of. They may have used it longer then this. It can repaired if it ever wears out of spec. This is done with some pistons(hyernetic) and some companys have done this on their engines. BMW tried this but it cost them too much money in Waranty repairs so BMW added steel sleves to the engines bore, GM still does this with the North Star. In reguards to DOHC or SOHC being supiorer I think that neither has a huge advantage over the other in our application. It would be nice to be able to individualy adjust the intake and exhaust cam but given our ECM's RPM and speed limitations as well as the injectors limits I doubt this would help us much. I just wish that Mopar would make some realy serious cams, vlave springs and a true performance ecm for the 4.7. I would be happy with the speed limiter removed and rpm limit bumped up about 2000 rpm. Their is no reason that this engine should not be makeing at least 1HP per cubic inch.



Dav
Dodge Dakota
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3/15/2002
16:16:13

RE: 4.7L OHC
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What year did dodge put the 4.7 in the dakota?



Muzzy
GenIII
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3/16/2002
04:28:03

RE: 4.7L OHC
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The advantages or disadvantages of DOHC is solely dependent on the port design. 4 valves per cylinder makes better utilization of the combustion chamber area. More air can be moved through 2 smaller intake valve openings than one larger one. The problem with most DOHC designs is the ports. Most heads have one port that splits into two for each of the valves. In most of these engines, the area where the split occurs is larger than the opening before the split. This greatly reduces port velocity. Your intake air charge slows down. This is sort of like taking a garden hose and putting you thumb over the end. By block part of the opening with your finger the velocity of the water coming out increases. While you don't want obstructions in your ports, you do want a gradual funneling effect as the air approaches the valve head.

We flow tested some Ford 4.6L 4 valve heads we ported vs. a set of 2 valve heads back at the performance shop I used to work at. The 2 valve heads had better port velocity than the 4 valve heads. The philosophies behind which is better has been a long standing argument since 4 valve heads were invented. I look at the racing industry for answers and to this day Top Fuel dragsters still use 2 valves per cylinder. Actually, most race engines do.

...my 1.9346 cents

2001 EC Dakota 4x4 - 287ci V8 - 5 Speed - 3.92 gears/w Sure Grip
Borla Stainless Steel Headers - IAT Adjuster
Flowmaster Force II Cat Back - Ported TB/Custom Cold Air intake
H&K USC Security System
Coming Soon - head porting/ install HO cams & valve springs

Graphite
DakotaEnthusiast
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3/16/2002
08:19:07

RE: 4.7L OHC
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Dav -2000

joe
someone pull me out please!
2002 club cab 4x4 Graphite /silver
2002 quad cab 4x2 Atlantic blue/silver

Brian W Bain
Dodge Dakota
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10/03/2003
13:16:53

RE: 4.7L OHC
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Does anyone know of an after market outfit that makes cams for the 4.7L.
I am towing a 3000lb trailer with 355 gears and want more torque, not high end revs.
brian



Jeep
Dodge Dakota
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10/03/2003
14:08:53

RE: 4.7L OHC
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Get the H.O. cams from the Jeep 4.7L Overland. You'll be pleased.



01Motorsport
Dodge Dakota
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10/03/2003
18:05:05

RE: 4.7L OHC
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3:92 gears would be a real plus pulling 3000 LBs. Usually less than 300 RPM difference on the highway, but the engine will love it.



Kowalski
Dodge Dakota
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10/03/2003
19:19:28

RE: 4.7L OHC
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The HO cams add great torque for towing.



RROD
Dodge Dakota
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12/23/2014
20:49:49

RE: 4.7L OHC
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I am looking to buy pistons and rings for a 2001 Dodge Dakota 4.7L DOHC std. I have looked everywhere and can't seem to find them. Suggestions???

Thank you.



George Frye
Dodge Dakota
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4/07/2021
17:41:13

RE: 4.7L DOHC
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I have an 04 Dakota with dohc and only 2 valves pe
cylinder. In need of pistons but 4.7 pistons are
93.00mm. The pistons that came out are 92.90. What
gives?



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