XXO/BVGC '38 Chevy Coupe Build

[GH]

Buddy, I wouldn't  call me one of the BIG BOYS. We showed up with a big Buick and lucked into some open records. But we sure had a lot of fun doing it.

[Dr Goggles]

Actually I like anyone who doesn't use their head for just a hat rack.........

Ha!

I like that.

[SPARKY]

BUT,  But, but--- some of us like to use our heads for a ---HAT rack 

[38flattie]

Aero mods are coming!

From Randy: Well folks hope everyone had a good christmas just thought i would do a little update on progress. I fitted the new hood top so john (wzjunk) can get the new hood scoop fitted to the car. I will be taking it to him over the weekend sometime.

..and from WZ JUNK:I am laying up some of the flat panels today. Hardest part is keeping the shop warm enough to cure the fiberglass.

[Glen]

Buddy, looking good.

[38flattie]

Well, While I explore ways to blow the engine up, others are actually making progress!

From WZ JUNK:

Attached is a picture of the first mock up for the outside of the scoop.  I will be looking at the shape some.
 
Most of the fabrication of the air intake is done.

[38flattie]

Gotta give WZ JUNK props- He's a helluva craftsman!

From WZ JUNK:

Attached is a picture of the two fiberglass panels I made by laying up resin and fiberglass on a flat sheet of plate glass.  I will cut the flat areas of the scoop enclosure out of these panels.  That starts tomorrow.

Attached picture is of the completed air duct.  Note the rubber collar near the Enderle injector.  The air duct is in two pieces under this flexible rubber collar.  This will allow the engine or the body of the car to flex or move some without stressing the hood and scoop.
 
Most of the green tape you see in this picture is my way of making a flexible tape measure so that I can keep everything straight or aligned as I build the enclosure for the air intake.

 
John

[fordboy628]

38Flattie,

Currently reading through your build diary for nuggets of info, I'm up to page 91.   I am very impressed by the quality of the work, the dedication of you, your crew and the suppliers/fabricators/etc, the amount of forethought, testing & machining, AND, the outstanding results you all have achieved.  Bravo to all!!!

Will wait to request any info until I've finished your complete build diary.

Also, if gear split ratio graphs of engine rpm Vs. mph are of any help, I can create graphs that show the rpm drops between gear shifts.  I have found this type of information to be useful.   Inputs are for tire dia, diff ratio, diff split gears (quick change), trans ratios, and engine rpm range.

Congrats on this special project & Build Diary.
 
Fordboy

[fordboy628]

38Flattie, Bored & Stroked,

How is the crank drilled to feed oil to the rod bearings?  That is, which main journal feeds which rods?  Is the crank crossdrilled?  If not, consider fully grooved main bearings, so that a constant supply of oil & cooling reaches the rod bearings.  If the center main feeds 4 rods by itself, consider enlarging the center main bearing oil feed passages, as was done on Milwaukee Midget's 3 main BMC engine.  This increases the oil flow to the main bearing which feeds 2 con-rods Vs. the others which feed only one rod.  See his build diary for details.
 
Fordboy

[manta22]

Crossdrilling the crank is a good way to create a fatigue failure. Grooved main bearings are FAR better if you want the engine to live.

Regards, Neil  Tucson, AZ

[fordboy628]

Crossdrilling the crank is a good way to create a fatigue failure. Grooved main bearings are FAR better if you want the engine to live.

Regards, Neil  Tucson, AZ

I agree.  IMHO, crossdrilling is not a good idea for a crank that probably has high(ish) bend loadings.

After going back to look at the jpegs of the rod bearings, I am convinced that the combination of the wear & the heat discoloration point to an inadequate amount of oil flow to the rod bearings.  Notice that the majority of the wear & discoloration is on the rods fed by the center main and the #7, which is further from the rear main than the #8 rod.  Also consider that the oil pressure in the gallery (& @ the gauge) has NOTHING to do with the amount of the oil flowing to the bearings.   More bearings fed = more flow required......

Many racing engine designers have gone away from the idea that high pressure/high flow is needed to have bearings survive, ie: the Cosworth DFV.  In original spec it required 90/100 psi of high flow oil pressure.  In generation IV (I think...) alternative crank drillings allowed the oil pressure to be reduced to 55/60 psi & retain high flow.  This netted a bhp gain as the power to drive the oil pump was reduced & then that power made it to the flywheel........   Nascar V-8's typically run 50/60 psi high flow oil systems which also results in a net bhp gain.......

I'm not saying you should reduce the pressure just yet.  Consider thoughtful mods to increase oil flow where needed, if possible.  Maintain the oil pressure you had, and then determine if there has been any improvement in the bearing wear and coloration at the next teardown.
 
Fordboy

[38flattie]

Fordboy, the mains are crossed drilled now, but I don't remember which ones feed what rods. I'll have the crank back in my hands next week, and I'll check it out. Dale may weigh in here, as he now has the crank.

Last year we ram Mobile one racing 0W-50 oil. I've been convinced that it is not the right oil for this application. We'll be running a straight 50w synthetic oil this year.

In addition, Barnes is going to add another suction and pressure stage to the dry sump. This will be dedicated to the piston oilers and lifters.

I believe we will 'half shell' the bearings this year, to aid in both oiling, and clearances.

[fordboy628]

38flattie, bored&stroked,

Sent you an info request & some preliminary speadsheet analysis of your dyno sheets.  Look over what I sent & figure out what questions you have.   I have a couple more questions.

1/  What std is dyno data corrected to?  SAE J1349?  STP (SAE J607)?
2/  Boost psi is on top of what atmospheric pressure?  Is this corrected?
 
Fordboy

[fordboy628]

38flattie, bored&stroked,

Are there any clear close-up photos of the oil drillings in the crankshaft you can post up?  What I want to see is the 'phasing' of the oil flow with respect to each cylinder's individual TDC.  How the delivery of the oil supply is 'phased' determines if you must run relatively high pressure or if you are able to run relatively low pressure.

In "low pressure" cranks, the oil delivery hole for a particular con-rod/cylinder, is 'phased' to 'lead' TDC by 50/60 crank degrees.  This allows the oil film to be 'distributed' onto the crankpin prior to the highest load period, (20/25 degrees BTDC to 50/60 degrees ATDC) during the ignition & combustion phases.  There are SAE papers about this subject, although I have not read them in a while.  Oil delivery to the con-rod bearings, with crankpins drilled @ either TDC or 90 degrees BTDC, was judged to be less effective, at lower pressures.  Keith Duckworth came to the same conclusion.  There have been some other technical articles on this subject over the years penned by, I think, Smokey Yunick & Bill Jenkins.   So the bottom line is: how the crank is drilled dictates how much oil pressure you have to run.

If you guys ever have to order a replacement crank or build up another complete engine, you may want to consider this effect.
 
Fordboy

[38flattie]

FB, thanks for all the great info. I'll review the spreadsheet when I get out of this hellhole they call work! I'll have the crank back in my hands Thursday night. I'll take a series of pics and post them.



Pops29 has been busy! Great job Don!

From Pops29:

Here is an update on the new main caps.
(both mains) This shows the increase width on the new front cap compared to last years!

(maching center, machining center 1) Here is the new center Cap being machined -- big difference

(centers) here it is with the old cap over-layed on top of the new design

next step is to drill the bolt holes and alignment pins, then set up and do the final fit grind and off to Boyd enterprises for the line bore and valve grind