|03-02-2012 01:27 PM|
While the bowties with 2.02's will fit the 305 cylinders with a +.040" over bore you'd do best for your truck using the 416's. If you fully port the 416 w 1.94x 1.50 valves you can actually make these lowly heads flow better than the bowties do in in stock as cast form.
As stated I would check bore clearance and VTP clearance when using those bowtie heads.
The 416's once fully ported will work very well, flow decent and make lots of power.
don't be shy with the die grinder. Use a felrpo 1205 as a guide, the meat and potatoes is deep in the port. Don;t be shy. Needs more than a simple pocket port.
mill as required to get the required chamber volume (51cc to 64cc)
When you cam up a 305 its critical to get the cr correct.
When you cam up a 305 the power range moves up quite a bit so don;t be shy with the converter and gears as it will loose low end torque and want to rev.
You want at least a 3000 real stall speed when using any of the cams you suggested. (A "10" 3500 stall converter will give you the desired 3000 stall behind a 305 motor) And lots of gear.
If you are not going to change the gears and converter , keep the mild short duration cam. 1.6 rockers will increase lift while retaining the short duration
its very easy to over cam a small cid motor.
|03-01-2012 06:00 PM|
|engineczar||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.|
|03-01-2012 03:16 PM|
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.
|03-01-2012 09:52 AM|
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.
|03-01-2012 09:28 AM|
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.
|02-29-2012 02:31 PM|
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.
|02-29-2012 01:30 PM|
|techinspector1||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.|
|02-29-2012 12:31 PM|
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.
|02-29-2012 11:37 AM|
|engineczar||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?|
|02-29-2012 10:51 AM|
|68NovaSS||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.|
|02-28-2012 07:56 PM|
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"