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Discussion Starter #1 (Edited)
The problems are discovered here:
http://performanceboats.com//showthread.php?t=77198

Maybe this thread will inspire people to measure up their stuff and check other peoples work. Heads in question are Dart pro 1 310cc. Came on a motor in a boat I bought. I just had the heads all done up at a local "performance" machine shop.

I have several problems:

1: Valve stem heights are all over the place requiring different length pushrods on different cylinders...which prompted me to pull the heads back off and then I discovered:

2: Chamber CC's on cylinder head #1 are 116-117-118-119, and cylinder head #2 is in the 121-122 range across the board.

now the quest to figure out why, then figure out how to fix it.

Head #1. The chamber volumes are indicative of a resurface job that took place on an angle...but there are no visual indicators that this occured. Dart says 0.005" per CC. 0.015" should be visable on that little rough cast area between the intake valve and the surface...but all looks well.

I know for a fact that the valves are screwed up....but I wanted to measure things to see if there was a sloping pattern that might lead to the chamber volumes I'm seeing. I also wanted to see if there was any surface worth trusting as a reference point from which to work from. I whipped up this little tool:



A couple pieces of scrap. The round piece has a releif for the valve guide and about 0.002 clearance over the valve itself. Doesn't give you any real numbers, but gives a good comparison between all the valves. It measures the distance between the valve stem tip and the spring seat.

I first picked 1 exhaust valve used it in every hole to get an idea of seat depth variation, or more realistically, varation in the distance between valve seat and spring seat. The 2 center cylinders were the same, one end was +.011 and the other end was +.006. Same test on the intakes revealed only a .004" variation. Shitty work, but not the cause of my problem.

Then I grabbed all of the valves and stuffed them into one chamber to compare the distance between the valve sealing point and the valve stems. Intakes had a 0.012" variation and exhausts had a .036" variation. Once again, shitty machine work.

I then wondered if all the spring seats from which I'd been referencing were in the same spots....but measuring between 2 angled surfaces is tough...so I whipped this up with a piece of stainless rodstock from the scrap bin and one of the valves...



This gives me a measurement between the deck surface and the spring seat. I saw a .004" variation on the exhaust side and a 0.009" difference on the intake side, but with no real pattern.

I've still got to measure my total valve lengths, then scratch my head and put all these numbers together to hopefully come up with something meaningful that points me in a direction. I'm most likely gonna send these to Steelcomp to get done right, but I want to be able to know exactly what needs to be done before I hire someone to do 'em.

So far, I've found absolutely nothing on these heads that is halfway consistant.

More tomorrow....
 

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Discussion Starter #2 (Edited)
Spent last night making a tool to compare the relationship between the ground sealing surface of the valve and the face of the valve. This is what I came up with:



I machined a 45° seat in the bottom half and reamed it to 0.001 over the valve stem size. It's got a shoulder that centers the top half for repeatablilty. It works remarkably well. One of these days I'll put a block on the other end too to measure sealing surface to stem at the same time.

I found plenty of differences... +/- .010" measuring with this tool.

So, to determine the valve/seat height influence on my C/R:

I add all of the tolerances together

Valve seat to spring seat (measured using only one valve on all ports)
Spring seat to head surface
Valve face to valve sealing surface.

While I found that some chambers were affected up to 2cc by the valve/seat depth, they don't really coincide with my chamber volume numbers from before. Which leaves me to the conclusion that the chambers are cast with about a +/- 2cc tolerance, all other things being equal.

Every measurement I make points to the deck surfaces being level, flat, and true on both heads.

Next step is align the spring seats by either shimming or milling, then perform a proper valve job with all new valves. Once the valve/seat variables are taken out of the equation, re-measure the chamber volumes, match all the chambers, then resurface based on the new chamber sizes to get to 115cc.

After making all the tooling, I've probably got all of 45 minutes into measuring this stuff.
 

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Discussion Starter #3 (Edited)
Update:...things are getting severely out of hand

I've acqiuired:

- An old 1930s valve grinder/stem facer...original 6 ball quick-like chuck was junk so I converted it to a TG100 collet system, which still left me with .0008 Runout in the valve.....which pissed me off...I fawked with it and found .0004 error in the chuck taper, so I rigged up a mag stoneholder for a stone for my new sunnen valve guide hone and ran it for a couple hours to correct it, yielding less than .0002 TIR on a valve chucked up in it...which is more to my liking.

Sold my baby bench top mill and bought a big boy Tree 2UVR (coolest thing I've ever owned).....Last time I dislocated my shoulder was recovering my sunken shitbox boat...the second time was loading the mill onto the trailer....it still hurts.

Ball drive tooling for valve seats...I had a hard time deciding between this and the grinder setup, but figured both would be best.

Sioux valve seat grinder setup....but all the tooling was junk so I got a few new stone holders and after playing with HSS pilots, determined that they suck....so I bought solid carbide tapered pilots...and they still sucked, so I had a bunch of pilots special ground for myself at the tool grinder down the street that hold seat to guide concentricity within .0001"....

I've built plenty more measuring fixtures and played with my swap meet tools and I'm blown away by the fact that I can produce valve to stem + seat to guide concentricity within .0008 (no, that's not an extra zero) with archaic equipment while my ex-machine machine shop with their 30K$ seat and guide machine can't hold .010"

...Oh, and after deciding on the ball drive tooling, I started looking at cutters for the seats...hundreds of profiles...which is best? So I built a flow bench. Still waiting on a couple pieces to show up to get the electronic manometer working, but we're close. I've been turning out different profile "mockup" seats on the lathe for the last few nights to test different concepts on the flowbench and see what works best....

Some say I'm going a little overboard on this. :)



Stay tuned for the rest of the "I've got half a years salary in a set of shit heads that are gonna be perfect" story ....
 

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Stay tuned for the rest of the
"I've got half a years salary in a set of shit heads that are gonna be perfect"
story ....

That could be a Country song... lol

Butcha gotta do it yourself sometimes to have it be right. Spare nothing building and blueprinting your motors, cause that's what make's good motors ~GREAT motors~
 

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What shop messed them up? My dad brought his heads to a very popular shop in OC and when he brought to the engine builder, installed height had to be redone. Its water under the bridge now but might prevent others from having problems with them.
 

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These guys?

Our Services

We are a full service machine shop able to handle all of your automotive, hi performance, marine, mill, lathe and fabricating needs, including:

CYLINDER HEAD
Valve Jobs
Head Resurfacing
Valve Guides
Valve Seats
Hardened Valve Seats
Magnaflux
Crack Repair
Screw In Studs and Guide Plates
Porting and Polishing

CYLINDER BLOCK
Boring
Honing
Torque Plate Honing
Align Honing
Deck Resurfacing
Block Hot Tanking
Cam Bearing Installation
Block Magnaflux
Cylinder Sleeving

RESURFACING
Flywheels
Intake Manifolds
Exhaust Manifolds
Plus Miscellaneous Resurfacing

CONNECTING ROD
Recondition Large End
Balancing
Small End Re-Bushing

CRANK SHAFT
Regrind and Micropolish
Balancing
Straighten and Weld

COMPLETE ENGINE
OEM Stock Replacement
Car, Truck & Light Diesel

HIGH PERFORMANCE ENGINE
Early/Late Models
From Mild to Wild Performance
Stroker Kits

MARINE ENGINE
Cabin Cruiser, Ski Boat or Off-Shore Racing

WELDING
Mig, Tig, Heli-Arc and Oxygen Acetylene
Specializing in Aluminum and Stainless Steel Welding
 

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Registered
Joined
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1,591 Posts
These guys?

Our Services

We are a full service machine shop able to handle all of your automotive, hi performance, marine, mill, lathe and fabricating needs, including:

CYLINDER HEAD
Valve Jobs
Head Resurfacing
Valve Guides
Valve Seats
Hardened Valve Seats
Magnaflux
Crack Repair
Screw In Studs and Guide Plates
Porting and Polishing

CYLINDER BLOCK
Boring
Honing
Torque Plate Honing
Align Honing
Deck Resurfacing
Block Hot Tanking
Cam Bearing Installation
Block Magnaflux
Cylinder Sleeving

RESURFACING
Flywheels
Intake Manifolds
Exhaust Manifolds
Plus Miscellaneous Resurfacing

CONNECTING ROD
Recondition Large End
Balancing
Small End Re-Bushing

CRANK SHAFT
Regrind and Micropolish
Balancing
Straighten and Weld

COMPLETE ENGINE
OEM Stock Replacement
Car, Truck & Light Diesel

HIGH PERFORMANCE ENGINE
Early/Late Models
From Mild to Wild Performance
Stroker Kits

MARINE ENGINE
Cabin Cruiser, Ski Boat or Off-Shore Racing

WELDING
Mig, Tig, Heli-Arc and Oxygen Acetylene
Specializing in Aluminum and Stainless Steel Welding
Ah T.I.G. ( tungsten, inert gas) and heli-arc are the same process. Just thought I would point that out, no malaice intended.
 

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Discussion Starter #9
I'm impressed. How'd you guess?
 
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