Valve guide clearance...Is there a..
 

Consensus on how much? I am having my heads tuned up and my new head man thinks 4 thousands is too much.

He suggests 1.5 - 2 thousands of an inch

For those of you machinists and engine builders, what would you have in your marine application?

Also going to T&D shaft rockers and Inconel valves. Valves are 2.45 intake and 1.94 exhaust.

Re: Valve guide clearance...Is there a..
 

I agree with your head man that .004" is too much. Can't argue running .0015 to .002" regardless of guide material (you don't say whether they're bronze,etc). Some folks will aim for .001 to .0025" but your guy seems to be right in the ballpark. Just one person's opinion...

Re: Valve guide clearance...Is there a..
 

Just noticed the size of your valves. I'm curious about engine size, comp. ratio, induction,etc. Just curious...

Re: Valve guide clearance...Is there a..
 

Bronze guides

605 inches, 10:1 C/R Naturally aspirated (carb)

Have single 1250 dominators now. Considering using a tunnel ram and want to keep the midrange good. The tunnel ram is set up for dominators too but I think two small dominators (750s) may be better for my RPM range which is 6-6500rpms.

Any feelings there?

Re: Valve guide clearance...Is there a..
 

That's a lot of motor...and a lot of rpms. It wouldn't be appropriate to comment since the induction system, heads, cam,etc. need to be considered as a package. Cranks aren't glamorous things, but are critical with big inch, big power motors. You almost never see them mentioned when talking about motor buildups. I don't think you can go wrong with Lunati, Callies,etc. Twisted or non-twisted.

Re: Valve guide clearance...Is there a..
 

Just remember most shops do NOT have a dial bore gage to be able to measure the guild clearance correctly . They are expensive . And most want go to the trouble to measure them .Most I have watched broach them and they say they know what .002 -.0025 feel like :eek: .they may be close ?some will just hone them and get them closer.

I would think a alumium head will be differant??

I set my exhaust guilds at .0025-.0027 on my blower motors .We use manganese bronze guilds and we used the US seals blue seal.I have done this before and it does not smoke on start up.This is just my experance .ya know I am no head guy :drink: But I did stay in a Holiday Inn last night :evilb:

Goodluck

Rob

Re: Valve guide clearance...Is there a..
 

STRIP if the guy doesn't have a sunnen bore gauge he can use a plug gauge it's cheap and effective the clearance is about right I run .001 on the intake and .0015 on the exhaust with no ring on the exhaust seal and they don't smoke either you can get the plug gauges from ENCO MANUFACTURING or J&L shop supplies .

Re: Valve guide clearance...Is there a..
 

What about just measuring the "rock" of the valve just off the seat with a dial indicator?

BTW, I have the bore gauges but most ive seen just check how much rock the valve has.

Re: Valve guide clearance...Is there a..
 

Laz my guy has the bore gage from Goodson, I don't remember the name brand .He also has the plug gages .

Laz you run your exhaust that tight????


Rob :drink:

Re: Valve guide clearance...Is there a..
 

As a Quality Inspector, Calibration Tech, and an excellent machinist, if the machine shop does not have a proper bore gage there is no guarantee the job will be right by just using pin gages. Most shops don't want to spend the money to calibrate their tools. Pin gages wear quickly if not treated with utmost care.
Ever see what happens when one get stuck in a hole? Some people will take pliers, or worse, Vise Grips and pull it out. :eek:

And remember this, pin gages are usually purchased in what's called "Minus" sizes. That means that a .500 gage pin is actually .4998. A .500 pin will not fit into a .500 hole. That's a press fit.
So, if a "machinist" is trying to measure a .002 to .0025 hole with pins he'll never get it right. He could wind up being undersized or over.

Re: Valve guide clearance...Is there a..
 

Strip on aluminum heads with bronze guides I run everything that tight n/a blower and turbo depending how hot exhaust temps sometimes I don't run seals but everything marine I build with a seal and no tension ring on the seal for cast iron I'll run them .0015 int and .002 exhaust anytime you get the guide straight and round like it needs to be you'll never have any issues. By the way on my restrictor plate engines and sprint car alcohol engines I run .0007 on the intake and .0010 on the exhaust with no seals .

Re: Valve guide clearance...Is there a..
 

Ain't nothing like a tight hole ,Ya just have to keep her lubed so it want stick :evilb:

Laz thanks for the Info. Like you said if you get them straight and round they want have any tight spots .Its hard to depend on a local shop . I guess you have to trust them .It would not be cost feasible for someone like me to buy all these tools then learn how to use them .If I did that I couldn't afford all that BEER :drink:

Laz it sounds like you have done a little of everything with motors :D



Rob