Ok so got myself a full race stage 3 1400cc engine with kent 296 cam and 1.7 roller tip rockers, the rockers are sooo noisy though, they seem to wiggle on the shaft?? Anyone got the same?
Noisy 1.7 Rockers
Started by
LucArse
, Sep 26 2010 04:57 PM
2 replies to this topic
#2
Cooperman
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Uncle Cooperman, Voted Mr TMF 2011
- Location: Cambs.
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Posted 26 September 2010 - 07:22 PM
Full race engines ain't meant to be quiet. They are meant to give absolute max power at very high revs. The large valve clearances with that cam and rockers means that you have to accept the noise as it won't seem too loud with your crash helmet on.
#3
Lillee
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Just On Tickover
Posted 26 September 2010 - 11:13 PM
When you say loud, what do you mean? one of the rockers noticeably tapping or all rockers tapping in tune?
I'd check several things:
1.7's are pretty big, check that the rockers aren't hitting the rocker cover. Sounds silly but those after market alloy rocker covers don't give much clearance and need to be ground so they can be moved backwards slightly to miss the roller rockers. My 1.3's hit them easily so 1.7's would be worste.
296 is also a big cam with high lift, make sure your springs are not being coil bound. Turn engine over in 4th by hand and see if the springs aren't bottoming out. I've heard of heads dropping valves due to the incorrect springs being fitted to high lift valve trains.
IMO 1.7's are far too big, 1.5's on a large cam is more than enough to produce 150bhp and in fact 1.7's may be losing torque low and mid range, more so than they make up for in top range.
I run 1.3 roller tips on my 1330cc making 119.7bhp on the engine dyno. 1.5's lose out all the way up to 6000rpm, and only gain after 6500rpm which for a road engine is academic. I'd say even on a race engine building for power at 6000-7500rpm at the expense of 3000-6000rpm has to be questioned...
I'd check several things:
1.7's are pretty big, check that the rockers aren't hitting the rocker cover. Sounds silly but those after market alloy rocker covers don't give much clearance and need to be ground so they can be moved backwards slightly to miss the roller rockers. My 1.3's hit them easily so 1.7's would be worste.
296 is also a big cam with high lift, make sure your springs are not being coil bound. Turn engine over in 4th by hand and see if the springs aren't bottoming out. I've heard of heads dropping valves due to the incorrect springs being fitted to high lift valve trains.
IMO 1.7's are far too big, 1.5's on a large cam is more than enough to produce 150bhp and in fact 1.7's may be losing torque low and mid range, more so than they make up for in top range.
I run 1.3 roller tips on my 1330cc making 119.7bhp on the engine dyno. 1.5's lose out all the way up to 6000rpm, and only gain after 6500rpm which for a road engine is academic. I'd say even on a race engine building for power at 6000-7500rpm at the expense of 3000-6000rpm has to be questioned...
Edited by Lillee, 26 September 2010 - 11:15 PM.
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