390 w/open chamber heads

[Treblig]

I've already purchased an RPM airgap as recommended by TXstang84. It hasn't arrived yet but I imagine it's for a square bore carb. I would rather not use a spacer so I'll be looking for a 800/850 CFM square bore carb. 340sfastback says not to buy the 750 Edel... but I do have a friend who has lots of Holleys laying around...maybe he'll trade me a square bore for my spread bore???
We'll see.


ANYONE AWARE OF CHRISTMAS DISCOUNTS FROM SUMMIT OR JEGS. I'd rather buy my 390 stroker crank at a discount if possible.

Thanks,
Treblig

 

[CPMotorworks]

Not to sound like a big dummy but aren't there any datum point on the block?? And also I thought the flycuttter was set parallel to the fixture that holds the crank (crank Center Line) or were talking about being out of square radially along a circle concentric with the crank center line??

treblig

Crank thrust and cam thrust face are the two reference points, but unless you have a 4 axis mill setup for blocks, you have limitations. You can reference bores from head dowels, but tolerance stack is the problem.
Most people that deck blocks float the block thru the mains on an adjustable bar, and level the block in X and Y with a machine level, and cut, parallel to the mains or not. That's part of the reason you hear this nonsense to mock up one rod and piston in each corner and compare before decking. Use the proper fixture and its done right without guessing.
Yes, you would think the cutter is set parallel to the fixture, but most automotive machinist don't have the training/understanding you do. That's why I recommended you have a good conversation beforehand.
If they don't use an indicator to check from the cutter to the block, or hone the block with a torque plate, find another shop.

 

[Treblig]

Many thanks for the advice=D>. I'll be sure and have a nice long talk with my machinist. I do know the guy from other builds I've done and they also race circle track (for many, many, many, years). they built they're own chassis and they get a chance to test (torture test) their own engine products.
I don't see any other way except to take an indicator reading and "average" across the face??? But that could be deceiving. I've programmed and ran CNCs, machined well heads, manufactured jet engine parts, worked in tool and die and designed and made custom fixtures but I've never worked in an (auto) engine machine shop. I would assume that they know what they're doing....but like you said, look before you leap!!

treblig

 

[Treblig]

Wouldn't the best time to surface a block be right after you bore and hone (with a torque plate)?? That way you can get an exact reading off the cylinders for being perpendicular to the bore in both axes. That should get you almost dead parallel to the crank if the bores were machined perpendicular to the crank. Isn't that the best way??
Using the bores vertically you would come out with the deck dead perpendicular to the cylinders...??

treblig

 

[CPMotorworks]

Wouldn't the best time to surface a block be right after you bore and hone (with a torque plate)?? That way you can get an exact reading off the cylinders for being perpendicular to the bore in both axes. That should get you almost dead parallel to the crank if the bores were machined perpendicular to the crank. Isn't that the best way??
Using the bores vertically you would come out with the deck dead perpendicular to the cylinders...??

treblig

No.
Your making the assumption the bores are perpendicular to the crank CL and to each other. This is production line machining that needs to be corrected.
Not a single automotive machinists is going to take the time to mount an indicator to the boring head, and sweep the bore top to bottom to align its axis with the boring bar. For one its time consuming and two its incorrect.
Your main line is your datum reference, with the crank/cam CL setting the angles. Thats why you do operations in the correct order to correct errors in the factory machining.

Also- simple formula to remember.
MPH*Final drive Ratio*336 (constant)
------------------------------------
Tire Dia
=RPM
ie 70mph*(4.10*.70 OD ratio)2.87*336
-------------------------------------
26" Tire
=2596 RPM @ 70 mph without slippage.

 

[moper]

"I understand what your saying about "zero decked" but then again, that's what it refers to, Zero decked for that particular application.
As for your underlined statement above, I'm a bit baffled. Its a simple fixture for older machines to set deck heights, and correct the 90° deck angles and crank/cam 45° to decks."

CP - You may be baffled because your assumption is the shops own one because it's easy to get. My assumption is they don't but still claim to be able to square deck. usually they are the ones that use a level to set the block's position... I knew one place that had a special mark on the level because the floor's slab had cracked under the miller and it wasn't level itself anymore... "as long as I level to that mark they're fine..."

 

[CPMotorworks]

"I understand what your saying about "zero decked" but then again, that's what it refers to, Zero decked for that particular application.
As for your underlined statement above, I'm a bit baffled. Its a simple fixture for older machines to set deck heights, and correct the 90° deck angles and crank/cam 45° to decks."

CP - You may be baffled because your assumption is the shops own one because it's easy to get. My assumption is they don't but still claim to be able to square deck. usually they are the ones that use a level to set the block's position... I knew one place that had a special mark on the level because the floor's slab had cracked under the miller and it wasn't level itself anymore... "as long as I level to that mark they're fine..."

Depending on the block, the machinist, and the milling equipment used this could be a good or bad thing as there is no reference to setting a deck hieght or correcting any relationship of the deck to anything else.

Well, honestly I'm not baffled, just seems odd you would imply there is no way possible to reference deck height or squareness when you obviously have the knowledge and awareness of how to do this stuff correctly.
A simple process of indicating in the plate and a measurement to it does both of these things.
Yes, I agree and am aware most shops that make claims dont have the skills or equipement to do this. My block fixture was the first thing I made when I bought my surfacer.

 

[Treblig]

Well at least I have a very good idea about what questions to ask and what answers to look for. If you're not a machinist, or at least someone who has dealt with this sort of thing, I can see how you could be easily fooled into thinking that you have a deck and bores that are parallel and perpendicular to the crank CL. I truly wonder how many guys are out there thinking that their engine is correct when in fact it may not be. Wish I had a computerized laser measurement system like the one we used in the aircraft industry, that would make it a piece of cake.
Oh well, I'll talk to the machinist in the engine shop and hear what he has to say. Like I said they race their engines on a weekly basis so get to test their own products.
Just so everyone understands, I'm not going to get my block zero decked. I'll get it squared up, parallel to the crank and perpendicular to the bores. I'll zero deck only if I need to based on the pistons and the heads.

thanks again for the nice easy RPM formula,
Treblig

 

[moper]

Well, honestly I'm not baffled, just seems odd you would imply there is no way possible to reference deck height or squareness when you obviously have the knowledge and awareness of how to do this stuff correctly.
A simple process of indicating in the plate and a measurement to it does both of these things.
Yes, I agree and am aware most shops that make claims dont have the skills or equipement to do this. My block fixture was the first thing I made when I bought my surfacer.

I would call it vague - not odd. My apologies if I appeared vague. Again - I'm approaching my posts in this thread as I'm looking in on a local shop and assuming worst case - they don't have that fixture. I did not intend to assert that there's no way to accomplish it. I should have clarified.

 

[Treblig]

Well here's a BIGGIE!!!! I remember reading the STICKY about "SB engine rebuilding got ya". As I was fitting the TCI adapter to my 318 I thought I would check for the oil hole that is recommended for lubrication of the distributor drive components. This 318 was completely overhauled and was ready for install. I had planned to make it into a 390 stroker so I haven't torn it back down yet.
Anyway, I checked for the lube hole recommended by CPMotorworks and you can see what I found. First pic is of how it should be and second is what I found. Third pic is the TCI adapter on engine.
This will be the 390 stroker I'm building. I already have the SIR rods, 750 Holley carb, RPM intake, 2.02/1.60, 360 heads, 340/360 Mag Truck exhaust, adjustable rockers, 200R4 trans, TCI adapter, Stainless Ferrea valves and many other items.

Treblig

 

[64 SRT8 Dart]

Are the first two pics swapped?
The 2nd pic shows a plug...which is the way it should be, 1st pic looks like someone drilled a hole in the plug and its pushing oil through it.

 

[Treblig]

According to CPMotorworks the plug (threaded plug) should be drilled for a lubrication port. It only makes sense, if the distributor gears don't get sufficient oil they will fail prematurely. So the first pic is how it should look when the engine is running. The second pic is how my overhauled 318 looks right now. If I drove it this way the distributor gears would wear at a faster rate than they would if they had extra oil. This is very important for those Mopar folks out there looking to build a long lasting engine.

I'll go back and find the size of the hole you're supposed to put in the plug.

Treblig

 

[Treblig]

The hole in the plug should be between .030-.050 inches. But .030 is sufficient. A .020" hole would probably work as the oil pressure would simply spray out of the hole onto the shaft but a hole that small would really be hard to drill by hand!! Just remember that when you drill a hole that small there is a risk of breaking the drill bit so drill very carefully and take your time. I would recommend that you drill the hole in the plug before you install it. That way if you break the drill bit in the plug you can still fix it without getting metal particles in the engine. Drill bits are made of hardened metal and you don't want any hardened metal particles floating around inside your engine.

Treblig in Tex