Finally all learning is over and I could squeeze another day into the Chevy's heads.

Just put both heads on the workbench and started to measure the ports. I'll need the figures to do some math to come up with a good estimate on valve size and how to continue porting.
The casting is very precise and may take only hundreds to be shaved off. At this time I also made some cardboard gauges which I plan to transfer to some aluminium sheetmetal. I want to use them to port the intake and exhaust ports and have a reference from one to the other.

The smallest port area has shown up as some 1.66 square inches

Interesting that the valve curtain area is in the ranges I'm about to research. The valve curtain area in this engine is not the restriction with the new camshaft. I'll see what some figure crunching in a comparative way (OEM vs. new camshaft) yields as results.

Looks like a 1.5:1 rocker arm is fair enough for the low end torque build I have in mind, paired with some undercut valves it will deliver a tremendous flow increase. The next step will be to figure out how to take advantage of that.

Finally had the time to download the pictures from my phone. Showing one of the cardboard cuts of the ports. Valves with a small piece of cardboard to determine diameter for unshrouding valves in the heads. Obviously some compromises needed here but still nice to see how good or bad the heads are. I think this is one of the main reasons for the L31 heads (heart shape). It retains a maximum of squish and unshrouds the valves nicely.

 

Follow-up on Jimspahr's post #31

Hot Rod Magazine has done a couple articles on the 4.3 V6

Making Big Horsepower With A 4.3L Chevy V-6 - Hot Rod Network

I guess the article you have been looking for is this one:

Chevy 4.3L 262ci V-6 - Engine Build

 

Not much going on. Finalizing my order for the remaining parts.

That will be:
ARP head bolt kit (black)
ARP accessory hex bolt kit (black)
Milodon 1.94 intake valves
Milodon 1.50 exhaust valves (both will have a curtain area with the new cam which is larger than the ports - not working them up this time as my rpm range will be below 5'500 rpm.)
Comp rocker arms
ARP rocker studs
Comp beehive springs (I think the same ones as for an LS1 - they will need minor machining on the guide bosses
Retainers, Locks, seals.
Main and rod bearings from Clevite in Standard and .001 undersize. (This will allow mix and match for clearance)
And small stuff such as freeze plugs

Stuff should be at my place mid April. Well - no - it will be end of May but shipping costs for overseas will be way down as I had a friend ship it by sea.

 

Finally my parts arrived. Took about 6 weeks to get the stuff from Summit via container to Europe.
Turned out to be a logistic nightmare. All container space being taken up. It was cheap shipping (some 75$) but took ages.

Well - all is here now and I'm looking forward beginning to work on the valvetrain.

Nice stuff.

Got Manley valves
CompCam Rockers and the other parts for the valvetrain.
I'll stick with Comp's parts as it seems that they work nicely together when being assembled outside of the scope of a "kit".

The last thing to order once test assembly is completed will be the lifter rods at proper length and the correct thickness of head gaskets.

With all the bearings available the next thing will be seating the crankshaft and rods.
Then I'll have to measure the block and determine machining operations.
Now that all the parts for the heads are available. The process is kind of an iteration.

Therefore it will be concurring tasks. I have to finish the heads to have the valves seating properly to determine how close the valves get to the piston.
At the same time I'll have to finish the block in order to be able to put the crank and rods and pistons in that will live in that engine.
Finally we can then determine which thickness of head gasket to use together with decking the block to achieve proper compression ratio.

Next step will be determining geometry of the rocker arms to have proper positioning of the roller on top of the valve.
Check for clearance issues with the rocker and the valve stem seals when at full lift.
Then figure how to machine the spring pockets and the guides.
Machine the valve seats to properly seat the valves at same heights.
And finally machine the rocker stud bosses to proper height for the geometry.

As soon as time permits, coming up next...

... test assembly of the block, and heads components.

 

I bet you felt like you were opening presents on Christmas, eh?

 

Indeed. Well might be all I will get for my birthday this year...

 

Not much going on. My machine shop has closed for a couple of days while I'm having my off-days which prevents me from a test-mount to determine deck height.

Just had a close look at the valvetrain stuff to make sure all parts are as required and the locks from COMP do fit the MILODON valves properly. Turns out the material is just perfect. I like what I got.

The pictures show:
The valves as pairs with an OEM and the new Milodon.
The valvesprings again OEM vs. new COMP beehive.
The lock groove with a valve lock under the microscope.

 

Cool!! Glad the parts are what you wanted!

 

Thanks,
Yes, the choice on parts is huge for the SBC, but you know that as you are building your own engines.

I wish I could build for the racetrack but it still has to be a daily drive.

Building all-out in some instances seems easier. Especially the fuel injection part. Building on the TBI is some challenge.

Slowly but surely coming together. Some problems are still unsolved, but I'll get there and tackle them once I'm there.

A nice venture into unknown territory for me. Up to now I've just built I4 engines and done repairs.

 

24 July 2018 update: (and 31st July - pictures as promised)

The crank is set!

Measured out within specs. No binding, no major hassles. Funny enough it had a very slight bind and it turned out that it was the cranks axial clearance being very tight. Finally had to grind the bearing to get it within specs.

It is now set and in the block with a rod and one piston without rings to determine deck height next week.

Pictures showing:

• The block prepared, cleaned and the main bore measured out to OEM specs. Upper bearing halves are in (upper is in the block as it sits upside down) and first cap set.
• The first cap in detail showing the Clevite bearing shells. The discoloration is from the manufacturing process.
• Caps set and bore gauge showing clearance. (Take smallest and largest measurement of crank pins and with the micrometer transfer to the bore gauge. What you measure now is clearance.) We never do plastigage as this method is more flexible and also accurate. (NOTE: I measure in mm this translates to 0.002")
• Now that I knew clearance is good, the block again with the caps removed to set the crank. Lubricant is just motor oil for test assembly.
• Caps and bolts ready with the torque wrench. (STAHLWILLE Manoskop)
• The crank is set and turns easy with just a very minor bind.
• Measuring axial clearance showed why it was still binding. The bearing was too thick.
• Next step was onto the horizontal grinder and cut the bearing down to reach proper clearance.
• And finally the #1 rod and piston goes in.

Next week I hope to get time off to measure the deck height and calculate how much needs to be machined off the deck. That will also require the cam to be set and cc'ing the heads again plus stick some plastiline onto the piston to determine clearance from valve to piston.