XXO/BVGC '38 Chevy Coupe Build

[38flattie]

Not as long as the Buicks, but still pretty long rods!

[desotoman]

Hey Tom . . . how the hell are yah!   Are you by chance going to make it to Bonneville this summer - would be great to see you again . . . has been about 20 years.   Let me know and we'll be sure to hook up.   We are planning to go to El Mirage in the spring - will keep you posted on that as well.   Who the hell would think I'd end up in Ohio - just so I could get back to racing on the West Coast.   But Hell . . . we now have the 'Wilmington Mile' -- out my way . . . gives us some new possibilities!

As far as the ports go -- given that we're blown,  the supercharger can overcome a lot of 'flathead sins' . . . the more port volume the better for what we're doing.

Dale

Hi Dale,

Good to see you posting. It has been awhile hasn't it.   I am doing good, thanks. Glad to see you helping Buddy on the Flatcad project. Yes I will be going to Bonneville this year, and will defiantly look you guys up, but if you are coming out to El Mirage, I will see you there first. Keep me posted. If you guys get the right cam in the Flatcad I think you will make some great Horsepower, and set many records.

I wish you guys the best.

Tom G.

[Milwaukee Midget]

Not as long as the Buicks, but still pretty long rods!

What kind of rod to stroke ratio are you at?

[38flattie]

Not as long as the Buicks, but still pretty long rods!

What kind of rod to stroke ratio are you at?

Chris, we're at 1.89!  Rod is 8.75", and stroke is 4.625"

[desotoman]

Buddy,

What is your deck height?

Tom G.

[38flattie]

Tom, Lately, I've seen deck height mention two different ways
.
What I call deck height is crank centerline to the block deck. That is 13.15"

The other reference to deck height I've seen is the space between the piston dome and the combustion chamber, at top dead center, without a head gasket.

That distance is approximately -.024"- -.020", with squish being .036"-.040", with a .060 copper head gasket. I say approximately, because we just had the heads and pistons coated, and installed the pistons. Dale has not yet had a chance to measure everything, after the coating and installation.

[gearheadeh]

Tom, Lately, I've seen deck height mention two different ways
.
What I call deck height is crank centerline to the block deck. That is 13.15"

The other reference to deck height I've seen is the space between the piston dome and the combustion chamber, at top dead center, without a head gasket.  is this called "compression Height"?
That distance is approximately -.024"- -.020", with squish being .036"-.040", with a .060 copper head gasket. I say approximately, because we just had the heads and pistons coated, and installed the pistons. Dale has not yet had a chance to measure everything, after the coating and installation.

[38flattie]

Well, I always thought compression height was from the centerline of the crank, to the top of a piston, if its a flat top, or the point on a piston where it starts to curve, if it's a dome piston.


However, with the recent articles I've read, I no longer understand what is being called what!

I've also seen CH referred to as the distance from wrist pin centerline to piston top.

I think Dale calls CH the distance from wrist pin centerline to the deck.

I guess it's whatever you want it to be!

[Stan Back]

Buddy --

Read the thread about roll bars mounted in unibodies if you really wanna get lost.  Least I did.  Almost ended up in Riverside.

Stan

[Peter Jack]

Ya gotta look up every once in a while Stan!!! 

Pete

[desotoman]

Well, I always thought compression height was from the centerline of the crank, to the top of a piston, if its a flat top, or the point on a piston where it starts to curve, if it's a dome piston.


However, with the recent articles I've read, I no longer understand what is being called what!

Buddy,

You gave me what I asked for, Thanks. This chart might help.

Tom

[maguromic]

Buddy, Your engine looks great, great to see the progress! Tony

[38flattie]

Well, I had the wind taken out of my sails today!
 
Chris had made a prototype head chamber, so that Joe Abbin could do the initial flow test.
 
Garry Odbert has been porting and testing his Caddy flathead, and getting 185-187 CFM at .500 lift, with a stock head, with the valve pockets cut to allow .500 lift. Garry offered to flow our head, for comparison.
 
Here are the numbers-intake side at .100 lift 64cfms lift, @.200- 123cfm, .300-150cfm, 400-163cfm, .450-166cfm, and .500-166cfm.

Garry reported a good, smooth airflow, which was about the only positive news!

In addition to disappointing flow, Garry did a dye test, and it looks like fuel is all in one 2'' spot, centered over the exhaust valve, unlike some heads, we placed the spark plug over the intake valve! Garry is going to send a pic this evening.


So, I'm pretty confident that no matter what the engine does on the dyno, we've left some HP out of the engine. Garry's port are not identical to ours, but that is only part of the equation.

We'll get it on the dyno, but I'll still be feeling disappointed in not getting more testing done prior to getting parts made. Ideas are good, but I'm kicking myself for not doing more testing! I'm definitely going to look at other piston/head options, for a major redo this fall.

[Jack Gifford]

Thanks for sharing those flow numbers. I had thought that the only meaningful testing would involve the block/head combination- how did you simulate the block/valve while flowing the chamber?

[38flattie]

Jack, Garry is building his own Cadillac flathead, and has it heavily ported-185-187 CFM out of a flathead is fantastic flow!

I couldn't get my block to him, so he used his. I realize this isn't the perfect scenario, but it's better than nothing.


I'm still sold on the roller lifter cam, and am working on getting the setup finished.
 
Josh is converting a lifter block for the rollers. He is adding an aluminum block, .300 thick, 1.4" wide, and the length of the lifter block, bolted to the bottom of the lifter block..He's use 82 degree counter sunk Allen heads to hold the plates on, then will drill and hone the blocks for a .0015 to max of .002 lifter clearance on the diameter.
 
After they are honed, he'll 't' slot a cut into the bottom of the aluminum lifter plate, and into the lifter block. The 'T' slot should allow the lifter to go up into the lifter block until it is flush with the newly mounted aluminum plate.