# Gear driven cam?



## pandrad61 (Jul 8, 2015)

on many internet photos I only see a single cam for the head driven by a belt and next to it the belt driven fuel pump. in my head maybe the second cam is gear driven and makes contact on the belt cam so that way there is only a single cam gear for space savings.


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## pandrad61 (Jul 8, 2015)

no ideas?


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## Aussie (Sep 16, 2012)

In that picture you can see the second cam with no belt attached, so it has to be gear driven, possible from the other end.


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## pandrad61 (Jul 8, 2015)

that's what I figured. its a clean et up ill say that much


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## NickD (Dec 10, 2011)

Talking about basic engine design? Only choice we have is to learn what's in there with the option of staying far far away from it.

For years, the camshaft was in the engine block and gear driven, very reliable with constant engine oil lubrication. Overhead cams sure changed this, now using chains or rubber bands that stretch with age.  Good question, could overhead cams be driven by gears? Seems like it should be possible, but probably too expensive.


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## Aussie (Sep 16, 2012)

I am just happy that my CTD has chain driven cams.


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## pandrad61 (Jul 8, 2015)

> For years, the camshaft was in the engine block and gear driven, very reliable with constant engine oil lubrication. Overhead cams sure changed this, now using chains or rubber bands that stretch with age. Good question, could overhead cams be driven by gears? Seems like it should be possible, but probably too expensive.


. yes they where simple using push rod single cam but they suck in performance. 2 valves per cylinder are no where as efficient as 4 and with DOHC you can add VVT, and a more efficient cylinder design. DOHC is the future and pushrods have no place in it. push rods while cheaper and simple in its design just cannot compete with DOHC or SOHC. you can add bigger ports, don't have to shape the dome with thinking about the push rods so better had design.


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## NickD (Dec 10, 2011)

pandrad61 said:


> . yes they where simple using push rod single cam but they suck in performance. 2 valves per cylinder are no where as efficient as 4 and with DOHC you can add VVT, and a more efficient cylinder design. DOHC is the future and pushrods have no place in it. push rods while cheaper and simple in its design just cannot compete with DOHC or SOHC. you can add bigger ports, don't have to shape the dome with thinking about the push rods so better had design.


Very true, but have to live with a belt or a chain, wonder why they don't use a tensioner sprocket inside of a guide that wears out. Least a chain is engine lubricated, don't get this with a belt. Also with a belt, get camshaft seal leaks, don't need seals with a chain.


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## jblackburn (Apr 14, 2012)

pandrad61 said:


> . yes they where simple using push rod single cam but they suck in performance. 2 valves per cylinder are no where as efficient as 4 and with DOHC you can add VVT, and a more efficient cylinder design. DOHC is the future and pushrods have no place in it. push rods while cheaper and simple in its design just cannot compete with DOHC or SOHC. you can add bigger ports, don't have to shape the dome with thinking about the push rods so better had design.


Honda has been doing VVT with SOHC engines for years (J series V6 and D/R series Civic motors)


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## Tomko (Jun 1, 2013)

GM has done VVT with cam in block designs for what seems like a decade now.


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## oilburner (Jun 13, 2013)

the intake cam is geared to the exhaust cam , several engines use this design, saves space. easy timing belt to change.


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## pandrad61 (Jul 8, 2015)

> GM has done VVT with cam in block designs for what seems like a decade now


we have mny 6.2 with it and many problms, dopped lifters is a big one in that system. esspecially with the cyliner deactivaon systems

exactly, the industry has moved on to DOHC and SOHC vs push rod. i think the only production motor still using push rods are the corvetts LS and Lt series blocks. since the 90's push rods where getting phased out


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## pandrad61 (Jul 8, 2015)

> Also with a belt, get camshaft seal leaks, don't need seals with a chain.


in DOHC i do love chains. unortunatly GM wen belt with th CTD america.


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