Thread: 383 Stroker Build

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Originally Posted by techinspector1

This should be the last time that happens. Get a 12" dial caliper as soon as you can. I bought a used Mitutoyo off ebay for 85 bucks.

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Big 10-4 on that Richard!

Gearing up for Saturday! Made this plate a while ago to rest dial indicator on and mocked up the dial indicator. Looks like i may have to take these springs out and replace with testers as they are stout. Also plan to clay the pistons as well. As to radial clearance which is something i'm interested in, any particular clearances i should need to know about other than just looking at it visually? Also, am i correct on .070 for intake and .100 for exhaust? Thanks!!

just remember that the closet spot isn't at TDC-the clay method works good for checking the radial clearance on the valves plus other tight spots of dome to chamber----I just spent a bit of dough($$$$$) for play dough at Toys R Us-----

Originally Posted by jerry clayton

just remember that the closet spot isn't at TDC-the clay method works good for checking the radial clearance on the valves plus other tight spots of dome to chamber----I just spent a bit of dough($$$$$) for play dough at Toys R Us-----

Jerry, I have found and others that I have talked to have found that Play-Doh will not hold its shape. All I have ever used, because I was taught this by an old timer, is oil-based modeling clay from a hobby or craft store.

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It wouldn't have been as funny if I said---spent a bit of dough($$$$) for modeling clay at Toys R Us--------

Altho I agree that play dough doesn't hold its shape as well---------its the thickness that matters here and it works fine for that-------of course if you want to make a casting or something similar-----there is a 2 part sponge stuff that works great for port shapes etc-you can slice a thin cross layer of it at any spot, lay it out on scaled graph paper and count the squares for the port area at any spot--Its sponge and you can work it out of the port after removing the valve stem thru it----

Robert, here's what Iskenderian says about valve to piston clearance.....
"Consequently, in today's naturally aspirated high-compression engines, we are settling for 0.125" V/P clearance, and in difficult situations, getting by with as little as 0.100" V/P clearance".

I don't remember anyone ever telling me the radial clearance of valve to piston, I have always just eyeballed it and made what I thought to be sufficient clearance based on the play of the valve stem in the guide, realizing that the head of the valve will move further radially than the stem does in the guide. Maybe Jerry or one of the other fellows can put a number on it for you.

Isky also says to look for 1/16" to 1/8" clearance between the bottom of the retainer to the top of the valve guide seal ........and 0.010" clearance between each of the valve spring coils at max valve lift, for a total clearance of 0.050" for the 5 coils.

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Because of radial issues plus the tightest spots being about 10* before and after TDC, is why I always do the dough thingiebob? Slice the squashed model clay with a razor knife and see the clearance------will also show the squash areas around the dome to chamber and spark plug--------do it and diassemeble , and measure without being disrupped by wife, friends, mowing yard or playing golf with bama---------

If

Thanks Richard! As to the clay, I was told this Michaels craft store a few towns over moved to an even further town. So my wife was out of town this week but did find a hobby lobby and picked me up some modeling clay a few days ago. They did not have oil based but reckon i'll oil the clay and valves real good before I turn the crank over a few times,

Thanks Jerry. In addition to claying, I'm going to try out the dial indicator as well and 10* is good information to know

Remember that on the overlap stroke(both valves open) The exhaust valve is closing as the piston chases it -sooooooooo, valve spring tension is critical so theres no float or bounce off the seat---The intake is opening and chasing the piston down from the top------I have and don't even squirm about as little as .040 clearance on the intake---Unless its a blown nitro engine--------------

Only turn crank over two rev and then check-many turns won't help anything
spray chamber with wd40 and clay won't stick

I stopped by a Hobby Lobby for some normal model clay----its too hard and I'm afraid would bend the valve stems plus not flow easily into nooks and crannies-Its going to continue to be PLAY DOUGH for my work-----

We measured P to V clearance today (without .028 head gasket) using both the clay and dial indicator method. Dial indicator results (without head gasket and with test springs) were as follows: Exhaust: 15*=104, 10*=88, 5*=90. Intake: 5*=75, 10*=70, 15*=76. Jerry Clayton was dead on, as 10* showed least amount of clearance. Claying the pistons (without h.gasket and with 1.550 springs), I split the clay in two and measured the thinnest area I saw on intake and exhaust. Results i got were around 0.160 on exhaust and 0.140 on intake. First time I've ever measured P to V but was a good experience and hope I did things right! As to radial clearance, eyeballing it, I saw no alarm bells (maybe someone else can confirm from pic). So I'm pleased with the results. Did have an issue with the pushrods I ordered (and posted a thread on the SBC section). I wanted to use 3/8 rods i ordered but found they would only work on exhaust valley, not intake. Would have helped if I'd read the doc that came with heads which stated, 'must use 5/16 rods.'

slice the clay thru the middle with an exacto or razor blade and you can see v to p clearance plus the radial clearance arount the edge of valve to notch circumference


I think some of the clays out there could bend the stems on some of these 6,7 mm stems--3/8 old school maybe not--------but I don't want to bend some $400 titanium valve

Originally Posted by NTFDAY

I've never seen one that wasn't tapped an threaded and it should be on every GenI small block starting in 55. Be hard to change fuel pump without that top hole tapped and threaded.

This is something we've still been thinking about and talked about today. If we'd caught it sooner, we'd had the machinest drill and tap a hole there for us. We'd rather test and tune this motor on our front motor mount engine test stand as opposed to dropping it in the car when the time comes and going from there. My Dad says he's never had much luck on tapping holes and I'm no subject matter expert on that area. We do have a tap kit and thought about doing a few test runs on a piece of iron. Any advice out there to give us or anything we need to know if and when we do tap for a left, front motor mount?

Originally Posted by jerry clayton

I think some of the clays out there could bend the stems on some of these 6,7 mm stems--3/8 old school maybe not--------but I don't want to bend some $400 titanium valve

The clay has to be worked with your hands to make it soft and conformable Jerry.

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I've always found cast iron to feel "sticky" when cutting threads. A good quality three-flute tap and some thread magic cutting oil will help.