what to set my valve clearance at.
Joined: Apr 2004
Posts: 1,151
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From: Center of the Sun (Phoenix)
Here's a few items to consider. Valves need to fully seat to prevent burning. Valves need to fully seat to maintain good compression. Loose valves have large gaps, don't burn and seal the combustion chamber during the compression stroke. However, with a tighter gap, the valve lifts off of the valve seat further than with a large gap; sort of like having a slightly higher lift cam lobe. The higher lift adds power (maybe too little to measure) until the lift is so high that the valves don't seat, the engine loses power and subsequently the valves burn. So the issue is finding the sweet gap that maximizes lift without burning valves. Billman has noted a preferred gap for DBW engines to enhance longevity.
Joined: Jul 2013
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None, my personal experience is if it's in spec that's it, out of spec causes problems. The closer you get to the specs on the hood the better, that is the ideal spec for power and throttle response.
If it's too tight the car will sound like it's missing, and idle like crap. It will be fine at higher rpms. Too loose and it makes a horrible clacking sound from the valve train plus it throws the timing off.
If it's too tight the car will sound like it's missing, and idle like crap. It will be fine at higher rpms. Too loose and it makes a horrible clacking sound from the valve train plus it throws the timing off.
Joined: Apr 2004
Posts: 1,151
Likes: 118
From: Center of the Sun (Phoenix)
None, my personal experience is if it's in spec that's it, out of spec causes problems. The closer you get to the specs on the hood the better, that is the ideal spec for power and throttle response.
If it's too tight the car will sound like it's missing, and idle like crap. It will be fine at higher rpms. Too loose and it makes a horrible clacking sound from the valve train plus it throws the timing off.
If it's too tight the car will sound like it's missing, and idle like crap. It will be fine at higher rpms. Too loose and it makes a horrible clacking sound from the valve train plus it throws the timing off.
Joined: Sep 2014
Posts: 11,395
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Maximum lift height is critical --- AFAIK, the duration of lift is just as important. Too loose valves will have less duration of lift.
The duration of time the valves stay closed is essential for the transfer of heat. So, too short of a duration may lead to heat damage.
The duration of time the valves stay closed is essential for the transfer of heat. So, too short of a duration may lead to heat damage.
Last edited by windhund116; Feb 23, 2024 at 06:44 AM.
Joined: Jul 2013
Posts: 5,735
Likes: 632
The valves remain closed for a split second longer than they should, works great for low rpms, not so good for high. Basically tighter or looser than spec on intake or exhaust is almost like using cam gears. Tighter to advance timing looser to retard it. As a general rule of thumb advancing intake timing to a point will improve torque across the board, but only to a point. One you won't exceed until you have beyond toasty tight valves.
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