Monday, December 20, 2010

V4 Dimension (Error?) Question

Here's an e-mail from Patrick Lorenze.  I don't have an answer.  I'm sure Dad would have known, but in his absense, perhaps other V4 builders out there can assist:


I believe there is an inconsistency on the dimensions on page #7 of the plans and I'd like to make sure I understand which one is correct before I cut the Block.  The Oil Cover recess on the bottom of the Block is dimensioned .290" from the Oil Cavity wall which puts it at ".045" and .172" from the ends of the Block.  The drawing shows these 2 dimensions as .032" and .186".  I have triple checked and even scaled the drawing with calipers and I believe the intent is to meet the .045 and .172 dimensions.  I attached a pdf of the CAD file I am making so that I can create the CAM program to cut it on my CNC Mill.



Here is another way to look at what I am saying.
If the centerline shown for the oil cavity is also the centerline for the Oil Cover recess, then take the 1.540" dimension for the centerline......subtract half the width of the Oil Recess cavity (2.990"/2 = 1.495") .....and you get .045" .......not the .032" shown on sheet #7.
Hope this helps explain the concern.


There  is/was a problem with the dimensioning in the drawing. I brought this to Jerry's attention in an email. He corrected it in later drawing sets and sent me an update. Jerry scanned the new drawing and sent a PDF to me. 
I have drawing set #66.
Somewhere there is a web link detailing all the revisions. Maybe Allen can make that known to you.
 Allen should probably send you new copies of the sheets that have changed since your copy version.

Here is a copy of the email message he sent me. There were a couple of other issues I mentioned as well.
This may be confusing. There are my comments followed by his response (s).

I hope this clarifies the problem for you.

Dave Sage

"A couple of issues with the V4 drawings – errors - maybe not  - but anomalies none the less:

On sheet #6 the dimension of .307 should be .305 otherwise adding up all the given dimensions across the block comes out to more than the overall dimension shown of 3.285. I’m not sure how this could happen on a CAD drawing. (rounding errors ?) 

    You are correct, it should be .305".

On sheet #6 the width of the head deck (top of the block) can be calculated as 3.285 minus .077 giving 3.208. On sheet 7 the same thing can be calculated as 2.990 + .175 + .032 giving 3.197 a fair difference (11 thou). Not a biggy but still perplexing given it’s CAD. 

          The .175" dimension should be .186" instead, but if the other dimensions are adhered to it is moot. Granted

           the dimension needs to be correct anyway, or else just not included. I use the CAD for design as well as

           for output of the drawings. Some of these dimension errors are remnants of multiple design changes where

           some affected item dimension corrections were missed. Also contributing is 69 year old gray matter! All 
           the above will be corrected for all future plan sets along with a couple on Sheet #16 as well. The 3.210" to 
           3.208" and 3.080" to 3.078" due to assumed .002" added to the .128" for cleaning up the mill
           marks from Step #3 thus the .130" dimension. See below.......

If you look at the pictures of the finished engine, the heads seems to overhang the block an obvious amount all around which looks good. But given the dimensions above and looking at sheet 22 and 20 there will be no overhang on the ends and only 60thou on the top and bottom. The head is drawn as 3.200 long (only 8hou or so different than the 3.208 or 3.197 above)? 

          You missed the .128" of material milled away (plus .002" for cleaning up the mill marks) all around the gear 
          case cover on the flywheel end of the block in Step #3 on Sheet #16. This brings the length of the cylinder banks 
          to 3.078". With the heads at 3.200" long, there is .061" of head overhang on each cylinder bank end. 

Thank you for pointing out the dimension errors. I always want to know about them so I can correct them.


Jerry E. Howell"


Dad did maintain a revisions page.  It is referenced on the last page of the plan sets we distribute.



Hope this helps...



Thanks for the replies Dave and Allen.  I have plan set #188 and had already looked at the revisions page which shouldn't apply to the later set I have.  The dimensions still don't add up as I pointed out in my messages above.  I will do the best I can to figure out what makes most sense and go with that.

Dave.....Terry M. told me he saw you at the show with your V8 and said it was very cool. He also passed along some tips from your experiences which I appreciate.




Looks like you are correct. Those figures don't add up either. I didn't analyze your comment fully and just figured they were wrapped up in the complete block length issue I pointed out. As Jerry mentioned in his email - he probably changed something along the way and did not update all the incremental measurements. In any case it really makes little difference how big you make the opening as long as you keep it in mind when you make the cover. I would opt for enlarging the .032 measurement since .032 leaves a very thin edge between the recess and the outside of the block. I think mine is that thin and I'm always concerned with whacking it and bending or breaking it off.



Yes Pat:

Terry and I had quite along discussion. It's too bad this forum did not exist earlier - or better yet ,Jerry was still around to discuss the issues with.
 I believe we discussed the combined intake manifold / water passage issue. Since I have a temporary intake at the moment, I've pretty much decided to make the water passage (which is twice as long for the V8) a separate block below the intake that can be screwed down to ensure the water connection to the block without the balancing act of having the O-rings seal AND the intake runners line up at the same time. The intake will then be made slightly higher to clear the water passage block.
 The other issue with the current design is that it is generally a no-no to heat the intake manifold and the intake charge. Although it helps to get off-the-choke when starting it usually hinders performance to have a hot fuel intake mixture later.
 I had problems Sunday afternoon with my engine at Cabin Fever. The epoxy let go on the flanges of my temporary intake, probably because of the extra pressure on them caused by compressing (in my case) two O-rings which caused a water leak. The water collected and threatened to go inside the block around the lifter bushing. I stopped running it and mopped up the water.
 I'll fix this up and post another topic with my results. Not sure what to do about an intake since I still haven't decided if I need two carbs or not. I'll probably make one like Terry's. I like his work.




Thanks for the feedback on the design and sharing some lessons learned from your build.  Terry has done the same for me.  The Internet is great isn't it!  I decided I will probably transfer all the designs into my 3D modeling package (Alibre which is compatible with Solidworks) to reconcile all the dimensions and part fit ups, adjust the dimensions to the best of my ability and then buld the parts.   


I use Alibre as well, although I'm a rookie at it so I don't rely on it. I'm designing my new intake with it.
I do use AutoCad all the time for the simplist and since I'm building the V8 I've re-drawn a lot of the drawings to check dimesions resulting from the conversion to a V8.
I also use it a lot to solve trig problems. I find it easier to draw the problem and measure the unknown than to calculate and likely make errors.



I use Alibre to calculate trig answers too.

The program is really powerful and if you stick with it (I recommend the tutorials) it will suddenly click and you'll be able to use it for all its 3D power effortlessly.  Doing the assemblies is very powerful as is creating the drawings with no additional effort from the 3D models you create.  I use it to keep myself honest and find errors before I make chips.  I'll stop now because this is starting to sound like a commercial.


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