The 5 ltr engine.
Discussion
Any thoughts on this pondering? As I understand it, the 5 ltr is fond of eating its cam lobes in a short time and this is less than ideal.The engine has double valve springs which presumeably are meant to prevent valve bounce which occurs at high revs, the downside being a great mechanical effort is needed by the cam to lift the valves on double springs (hence the wear). A 5 ltr motor is especially torquey and is not too keen on high revs anyway being longer stroke, so why not ditch the extra springs?
I know i'm wrong but would like to know why, plenty of proper engine bods on here to put me straight.
I know i'm wrong but would like to know why, plenty of proper engine bods on here to put me straight.
Sorry for the delay, had to do some jobs on my needy moggy minor while it was daylight. Thanks for the input chaps, as ever it's an education on here.
Spend that's 5 reasons for double springs you reeled off - outstanding. All sounds fair enough. Don't know if any of the 400s with 500 cams used twin springs too. Finding it hard to get my head around the idea of greater lobe wear at lower revs, but high rev base circle wear makes sense to me. My car is low geared so higher revs comes as standard so a good thing maybe. Perhaps the keys to the variation of wear rates between different owners cars is the oil type used, warmup habits, driving habits, matallurgical and hardening variances in manufacture, component tolerancing (are 500s blueprinted) and as you say, over/under revving.
Spend that's 5 reasons for double springs you reeled off - outstanding. All sounds fair enough. Don't know if any of the 400s with 500 cams used twin springs too. Finding it hard to get my head around the idea of greater lobe wear at lower revs, but high rev base circle wear makes sense to me. My car is low geared so higher revs comes as standard so a good thing maybe. Perhaps the keys to the variation of wear rates between different owners cars is the oil type used, warmup habits, driving habits, matallurgical and hardening variances in manufacture, component tolerancing (are 500s blueprinted) and as you say, over/under revving.
Will the cam last longer ? and can you run more of a radical cam .
http://www.thewedgeshopstore.com/products/Roller-C...
http://www.thewedgeshopstore.com/products/Roller-C...
black and green said:
Sardonicus said:
They are out there for the RV8 at a price 
check out those cam lobes 
$1050 - about £1100 by my reckoning by the time duty, VAT and shipping go on. check out those cam lobes Hmmmmmmmmmmmm..............
I think I would be going down the roller rocker route also if I was getting this stuck into the RV8 now your into plastic melting territory 
the RV8 is certainly not cheap to get serious with hence why so many on here have defected 
Sardonicus said:
h I never said it would be cheap I think I would be going down the roller rocker route also if I was getting this stuck into the RV8 now your into plastic melting territory the RV8 is certainly not cheap to get serious with hence why so many on here have defected
Looks flawed to me... the ties between the lifters, unless they have some lateral freedom engineered in that is not obvious from the pics, will pull the pairs together or push apart as they prescribe their strokes. It's perfectly possible to run cam durations that take you well into reversion problems with a single plenum on hydraulic, and ultimate lift is limited by the head/guide dimensions that, again, is quite attainable on a hydraulic set up. Run outriggers on the rocker shafts, keep the idle up to prevent scuffing, use decent oil and the job's a good un without all this I think I would be going down the roller rocker route also if I was getting this stuck into the RV8 now your into plastic melting territory the RV8 is certainly not cheap to get serious with hence why so many on here have defected The bars do let the lifters move up and down, there just there to stop them rotating so the roller stays rolling on the lobe
I think the reasoning behind roller lifters and cam is to enable you to run steeper lobes allowing them to open and shut the valves with more lift in a shorter time, if you did this on a normal flat tappet lifter/cam the lifter would get its self wedged on the side of the cam lobe
I think the reasoning behind roller lifters and cam is to enable you to run steeper lobes allowing them to open and shut the valves with more lift in a shorter time, if you did this on a normal flat tappet lifter/cam the lifter would get its self wedged on the side of the cam lobe
GasMunkey said:
The bars do let the lifters move up and down, there just there to stop them rotating so the roller stays rolling on the lobe
I think the reasoning behind roller lifters and cam is to enable you to run steeper lobes allowing them to open and shut the valves with more lift in a shorter time, if you did this on a normal flat tappet lifter/cam the lifter would get its self wedged on the side of the cam lobe
^^^ This.I think the reasoning behind roller lifters and cam is to enable you to run steeper lobes allowing them to open and shut the valves with more lift in a shorter time, if you did this on a normal flat tappet lifter/cam the lifter would get its self wedged on the side of the cam lobe
Simply; a more radical profile can be achieved without the lifters binding on the camshaft, and causing massive wear. Which is indeed what many early drag racers suffered with (intentionally) before the advent of the roller camshaft.
The valves reach maximum lift sooner, and hold the lift for longer. Most of the benefits of a higher lift, longer duration camshaft are achieved without the [need for] a lumpy idle and poor low rev. driving characteristics caused by the extended overlap used to achieve this using flat tappets, with longer slopes/ramps.
A side benefit that is often overlooked is the reduced 'rolling' resistance offered. This is usually referred to as 'free horses', because you were already making them [the horsepower] to turn the standard camshaft.
I have seen these used in street rod BBCs to great effect, where the maximum safe lift for a reliable street car using solid lifters was suggested to be around .600. One chap was managing nearer .700.
Of course, with steeper ramps and heavier lifters, normally comes the need for even stronger springs, placing even greater stress on the valve gear overall. At this point a good set of roller rockers become almost essential, and lighter, stronger valves are to be seriously considered.
Pupp said:
Sardonicus said:
h I never said it would be cheap I think I would be going down the roller rocker route also if I was getting this stuck into the RV8 now your into plastic melting territory the RV8 is certainly not cheap to get serious with hence why so many on here have defected
Looks flawed to me... the ties between the lifters, unless they have some lateral freedom engineered in that is not obvious from the pics, will pull the pairs together or push apart as they prescribe their strokes. It's perfectly possible to run cam durations that take you well into reversion problems with a single plenum on hydraulic, and ultimate lift is limited by the head/guide dimensions that, again, is quite attainable on a hydraulic set up. Run outriggers on the rocker shafts, keep the idle up to prevent scuffing, use decent oil and the job's a good un without all this I think I would be going down the roller rocker route also if I was getting this stuck into the RV8 now your into plastic melting territory the RV8 is certainly not cheap to get serious with hence why so many on here have defected a non-hyd cam with adjustable push-rods is probably my budget quite frankly 
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