Maximum valve lift for 2.02 / 1.6 valves in 3.776" bore - Hot Rod Forum : Hotrodders Bulletin Board
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Old 02-28-2012, 08:56 PM
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Maximum valve lift for 2.02 / 1.6 valves in 3.776" bore

Anyone know the maximum valve lift for 2.02 / 1.6 valves in 3.776" bore. I have to pull the cam in my engine and would like to go back with something a little more aggressive. Heard it was around .490"

Thanks,

Isaac

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Old 02-29-2012, 11:51 AM
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Maximum lift will be dictated by individual cam specs, type of piston, i.e. dished, flat, domed, what valve reliefs and head restrictions. For the most part, you need to measure valve to piston clearance. You don't even tell us what motor this is or what heads you're referring to, without details, no way to tell.
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Old 02-29-2012, 12:37 PM
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I'm still trying to figure how you would fit 2.02 and 1.6 valves into a 3.776 bore and not have big time shrouding. What heads are you using?
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Old 02-29-2012, 01:31 PM
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I'm thinking this is a 305 chevy engine your referring to with a .040 overbore.
First of all, why would you use big valve heads on a 305? Did you bolt the heads on the bare block to check the valve to bore clearance? the 305 bore is barely big enough to clear the 1.94 1.50 valve combination.
Valves that size on a 305 presents two problems as mentioned, one is excessive shrouding, two is the possibility of the valves kissing the bore so even if it has enough bore clearance the shrouding will kill the flow so power gains wouldn't even be noticeable. Lastly is if this engine was built for street use it uses small valves for high velocity to help it develop low end torque. The big valve kills the velocity so it would have to be revved to stink before it started to make any power and that's when it would run into the next brickwall which is the excessive shrouding.
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Old 02-29-2012, 02:30 PM
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Bolt the bare block onto an engine stand. Put a set of valves into the head with checking springs. Bolt a head onto the block and look up the bore. Push the valves open with your fingers. You'll be able to figure this out pretty quickly.
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Old 02-29-2012, 03:31 PM
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Quote:
Originally Posted by TWIGDOG
Anyone know the maximum valve lift for 2.02 / 1.6 valves in 3.776" bore. I have to pull the cam in my engine and would like to go back with something a little more aggressive. Heard it was around .490"

Thanks,

Isaac

What is your power goal? in many cases STOCK valve sizes are more than adequate and in many cases near optimal, especially when considering a choked runner.
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Old 03-01-2012, 10:28 AM
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It's a street engine. It's a .040 over 305, flat top 4 eye brow pistons, zero decked. The heads are, I'll admit, a little big. 034 Phase 3 Bowties. Already had them and thought I would give them a try. If they don't work out, I'll port one of the sets of 416 I have give them a shout. I'm having issues with the current cam/rocker situation and I already have a thread started on that. Truck runs good with a hydraulic 454 lift cam in it now, but it looks as though I'm going to have to pull the current cam to fix the issue and was thinking about a little larger cam. Namely a comp magnum solid 270 or 282 grind.

Thank you,

Isaac
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Old 03-01-2012, 10:52 AM
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I would go with the 416's from the get go. Have them milled a little, fill the exhaust "y" section on the center 2 ports, and port them, valve job if you can afford it.

keep the stock valve size.

For a truck application I would run something like the XE262 cam, better yet a roller cam but that will cost more money.
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Old 03-01-2012, 04:16 PM
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If you are going to attempt the 2.02/1.60 valves you NEED TO TURN THE ENGINE OVER BY HAND and CHECK PISTON TO VALVE CLEARANCE before running it. I I'm curious if they will even be able open all the way without hitting the cylinder bores...

Either way, it's probably not a good idea to use valves that big.
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Old 03-01-2012, 07:00 PM
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The other problem you're going to run into if you use the Bowties is that the chamber is bigger than the bore by quite a bit. The top of the deck is going to encroach into the chamber leaving a healthy step.
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