Intake valves to big? valve shrouding

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Cope

Cope

Fusing with fire
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My motor builder buddy showed up at the shop today and comments that my intake valves are to big.
He is saying I need to cut way more out of the combustion chamber, turn the valve heads down or stroke the motor. (440)

Now before you go and say this guy dont know jack, He builds very high end (30-50K) race motors that win races and He build them every day for a living.

What are your folks thoughts on this?



906 heads, 2.118 intake. I think thats what they mic out to. I will double check the size tomarrow.
He did say the exhaust valve size is fine.

Thanls again for the time and advice.
 
Are we supposed to know WTF heads and valves you have?
 
Cope said:
906 heads, 2.118 intake. I think thats what they mic out to. I will double check the size tomarrow.
He did say the exhaust valve size is fine.

Thanls again for the time and advice.
Click to expand...

It was below the pics.
 
My bad. The pics didn't come up for me at first.

I don't see any shrouding to speak of.
 
well it says right in the post?

Im not asking about distance between the seats, Im talking about getting the charge past that gaint valve head.

This may be the type of issue that I will never notice in this build bit I trust this guy and every little thing adds up when your trying to wring the power out of a motor.

Im gonna run these heads as I dont have the cash for aluminum heads right now.
I would like to hear form folks that know about valve shrouding and getting max performance oit of a build.

Thanks again.
 
Just short of hitting something, I can't believe a valve being to big :D
I believe the family friend that builds 30-50k motors is on a completely different level.
Ask anyone on this forum - they'll tell ya, I don't know much, but imo those valves look fine to small.
 
Mr. AJ, Im not sure I understand your question.?

Are you asking what lift I plan to run?

My buddy did mention possibly cutting the top of the bore back to allow the charge better access to the bore.
 
Sorry Cope, I missed the (440). My mistake.

I was interested to know where the valve edge was gonna be in relation to the bore as the valve opened; but with a 4.32Plus bore, my question is answered.I freely admit I know very little about BBs, but I'll throw my hat in with the boys here and say fogedabowdit!
 
If it makes any difference the bore is 40 over.

40 thousands is also the number he mentioned turning the valve head down.
 
I think you are worrying about nothing. No disrespect to your friend meant.
 
Turning the valve down 40 will pretty much eliminate the margin, necessitating a regrind, which will likely drop the valve some, which will increase the valve spring installed height which will require a reset. Now with the stems higher up, the geometry takes a dump, so the stems are usually shortened. Momoney.Momoney. Momoney.
 
Cope said:
My motor builder buddy showed up at the shop today and comments that my intake valves are to big.
He is saying I need to cut way more out of the combustion chamber, turn the valve heads down or stroke the motor. (440)

Now before you go and say this guy dont know jack, He builds very high end (30-50K) race motors that win races and He build them every day for a living.

What are your folks thoughts on this?



906 heads, 2.118 intake. I think thats what they mic out to. I will double check the size tomarrow.
He did say the exhaust valve size is fine.

Thanls again for the time and advice.
Click to expand...

Actually a picture of the valve removed,& and a picture of the valve job( and bowl work),would get an more honest response, IMO...(You're engine guy, might be right..The guy I worked for(Mopar exp. head porting 40+ years...),does do it to most of his high end builds) a picture of piston ,and how your head gasket: Will give us a better idea..
 
Abodybomber said:
Actually a picture of the valve removed,& and a picture of the valve job( and bowl work),would get an more honest response, IMO...(You're engine guy, might be right..The guy I worked for(Mopar exp. head porting 40+ years...),does do it to most of his high end builds) a picture of piston ,and how your head gasket: Will give us a better idea..
Click to expand...

Yep, them's good thoughts.

Also, his "motor builder buddy" still might be wrong.

I got a friend. Comes over and asks me what about this-n-that. I tell him........and he says, "That ain't what this magazine says!" Well then, why ask me? So go do what the magazine says.

906 casting uh? What does the seat, bowl and throat look like? What is the existing intake valve diameter? What lift cam are you running (big difference on how you set that head up)? With proper work the 906, 902, 346 & 452 heads are real happy with 2.14/1.81 valves. But you can put those size valves in and lose flow......you have to be smarter than your cylinder heads. I've run 2.XX* valves in 452 heads and 2.XX* valves in 906 heads.

*Sorry, need to know basis...........

And, I could be wrong..........what-da-I-know?

My ported 906 heads.............rats, never mind.
 
the answer is NO, but if you do anything the area in the pic between the 10 &11 o'clock position of the chamber could use a little grinding to open it up to the edge of the head gasket do to the chamber ceiling. that would help flow some, but do not grind the head diameter off the valve.
 
Thanks guys.

I have yet to decide on a cam or pistion combo yet.

Im looking at Lunati-30230743. Its the largest cam i can find with what I think is some what streetable power band.

Advertised intake lift, .589
intake lift at 50 not listed?

I'll be down at the shop in a bit and pull a valve and get.some picks for ya.

Thanks again for the time and advice.
 
Shhhh, it's a secret performance enhancing process overlooked by the majority of people. Unshroud both valves. Slap some blue die on the deck surface, bolt the heads onto the gutted block and scribe the piston bore opening onto the deck of the head. Make sure your head gaskets are not too small and protruding into the chamber. Use a carbide bit to open up the chamber edges on the heads to the bore size. Be sure to focus on matching and carefully blending the scribed bore circumference on the head at the deck surface, blending into the chamber and unshrouding both valves.

Measure the installed height of your top ring in the bore near the valves, and mark it with a sharpie. Use a large stone or carefully use a bit to relieve/ notch the top of the bore near each valve to match the newly unshrouded valve reliefs and head gasket notches. Be careful not to get real close to the top of the ring travel.

You don't want to negatively affect the swirl into the chambers/bore, so don't get carried away. Limit the process to unshrouding the valves and chamber to removing just enough to get the head and top of the bore so they all match; the head gasket, the top of the bore and the unshrouded valve and combustion chamber edge in your chamber. That will unshroud them nicely. There's a lot of flow enhancement, improved flame travel and reduction of hot spots that can lead to detonation to be had there.

You may want to cc each chamber as you get them close to finished and adjust your compression ratio to suit your needs. It helps if you can visualize what your compressed volume looks like in 3D as the piston approaches the top of the stroke. It should have no sharp edges on it, and ideally, the majority of that chamber volume will transition from a round flat, pancake shaped object into a 035" to 040" thin circular object that is only thick in the roof of the chamber. In other words, it should be high quench with the majority of the swept volume being squirted into the small heart shaped roof of the chamber in the head at the last split second. That violent movement of the compressed volume in the last split second before the spark lights it off is good stuff.
 
..............No matter how much u stroke ur motor it won't have any bearing on unshrouding the valves........Ur builder doesn't make any sense by making that comment...............kim..........
 
Kim is right, and;
I read that too, but I understood it a little differently.
Reading between the lines; If the valve was shrouded enough to be handicapped 10% in the charge density, it could be recovered with a 10% larger cylinder. And as a bonus the longer stroke would allow a bigger cam, before running into a Dcr issue.That was my conclusion.
Kindof a band-aid on an open wound idea, and an expensive one at that!
 
There is enough work under the valve to not have lost any flow with the larger valve and bOb and others are correct, you don't have excessive valve shrouding. Leave it as is.
 
You mean we weren't so stupid after all? Well hell's bells.
 
Well never having met you I will refrain from posting my judgment or opinions on that topic...


;)
 
jbc426 said:
Shhhh, it's a secret performance enhancing process overlooked by the majority of people. Unshroud both valves. Slap some blue die on the deck surface, bolt the heads onto the gutted block and scribe the piston bore opening onto the deck of the head. Make sure your head gaskets are not too small and protruding into the chamber. Use a carbide bit to open up the chamber edges on the heads to the bore size. Be sure to focus on matching and carefully blending the scribed bore circumference on the head at the deck surface, blending into the chamber and unshrouding both valves.

Measure the installed height of your top ring in the bore near the valves, and mark it with a sharpie. Use a large stone or carefully use a bit to relieve/ notch the top of the bore near each valve to match the newly unshrouded valve reliefs and head gasket notches. Be careful not to get real close to the top of the ring travel.

You don't want to negatively affect the swirl into the chambers/bore, so don't get carried away. Limit the process to unshrouding the valves and chamber to removing just enough to get the head and top of the bore so they all match; the head gasket, the top of the bore and the unshrouded valve and combustion chamber edge in your chamber. That will unshroud them nicely. There's a lot of flow enhancement, improved flame travel and reduction of hot spots that can lead to detonation to be had there.

You may want to cc each chamber as you get them close to finished and adjust your compression ratio to suit your needs. It helps if you can visualize what your compressed volume looks like in 3D as the piston approaches the top of the stroke. It should have no sharp edges on it, and ideally, the majority of that chamber volume will transition from a round flat, pancake shaped object into a 035" to 040" thin circular object that is only thick in the roof of the chamber. In other words, it should be high quench with the majority of the swept volume being squirted into the small heart shaped roof of the chamber in the head at the last split second. That violent movement of the compressed volume in the last split second before the spark lights it off is good stuff.
Click to expand...

That's what I did. First pic in looking up the bore with the crank out up to a head bolted on with dykem blue painted around the bore. You can see the scribe line of the cyl bore with the chamber massaged out to meet it in the second picture.
 

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