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Just had the combustion chambers cc'd on a properly set up rig to get accurate measurings.
Amazing that the stock castings have 0.2 ccm (which is nearly nothing) of maximum difference between them.
I could not yet get the block onto the stand to measure deck heights properly but.
The corners of the block are so square and the height differences on the four deck edges (from crank axis to deck surface)
within just hundredths (aka. thousandths in inches) that we probably have to machine just a minimum off the deck.
Then it will depend on the squish I'm aiming for if going with a 0.027" MLS or a 0.030" MLS.
It will either be the gasket thickness or shave a bit off the pistons. Gasket being my way of choice but that will come down to other factors, such as how much we have to cut the decks to get a clean gasket surface.
At this time compression calculates as being 10.7:1 which is high for use with pump fuel. The danger of detonation will be lessened a bit by the now available large squish area.
Still considering lowering the compression by at least 0.7 points with the valve job (cut seats deeper - valves go out and size of combustion chamber rises - grinding).
As nobody really has been messing a lot with the "pathetic" heads of the first Vortec's it will come down to how prone to detonation they are.
I hope to eliminate a lot of spots where detonation could be an issue with the proper squish.
The OEM head and piston combination will not create a real squish. Not sure what the engineers thought when they made the 94's V6.
No squish from the piston as they are dished. Even the small squish band around the pistons is way too far from the head to produce any squish.
The compression on the OEM measured out at 8.8:1, probably the reason why these engines are pathetic at best with the displacement at hand.
I suspect that they had lowered the compression so much, to cope with the inexistant squish on rather fast burning combustion chambers in order to avoid detonation at low loads with a lot of advance for fuel economy.l
Looking forward to next week. Employer assigned a week of vacation which will, hopefully, allow for some progress.
lots of good info, currently working on a engine build myself not quite to your extent mines a non balanced shaft block. it goes out next month for hot wash and bore and honing. Looking forward to seeing what numbers you get from this build.
Tanks, always nice to hear.
DonL that's for you, more pictures doing another step in the build.
Got one step further. Assembled all the rods and placed all the bearings. Then test assembled the block. Now it is ready to be measured for decking and honing.
A first measurement shows that the pistons are at the correct height below deck. (0.40 mm about 0.016")
With a 0.027" gasket it will create the right amount of squish. Have to check against rocking pistons but it is where it is supposed to be.
If we have to cut the deck further down, I have the option of using a 0.030" gasket giving us a lot of freedom to cut the deck.
With this setup which turned out nearly perfect for this block I have the option of decking again in the future. Eventually by shaving off a bit of the crown of the pistons.
For now it seems the right setup.
The assembly of the rods is a lengthy thing. First torqued a test rod and measured the bolt stretch. Turns out it will need more torque than indicated. So made a compromise in between stretch and torque to reach reasonable values. Disassemble again, then chamfer all sharp edges, wash, clean, dry. Wipe with a lint free cloth, set the bearing shells. Torque to specs, then measure the bore. The EAGLE rods are amazing and the bearing shells as well. Exactly within specs.
Then open up one bolt and measure how much it opens. This is an indication of bearing "crush". The shells are slightly larger in diameter than the rod big-end bore. This is the force which keeps the bearings from spinning. Simply crushing them into the bore with a given amount will yield enough friction to keep them where they should be.
Then take the rod apart, Re-apply ARP bolt lubricant and set ready to assemble.
The test assembly is made with all the rods and pistons in their correct place but without piston rings. Marked all the pistons with an arrow pointing forward to facilitate correct final assembly.
The V6 rod's are asymmetric and need to be placed correctly in order to be centered in the bore. With pistons such as I have, with a sliding piston pin, they could eventually be assembled in the wrong way which would cause all sorts of problems.
Pictures showing:
Rods with bearings shells. Unfortunately we could not get tri-metal bearings for the rods. But it's no race engine so the OEM stuff will do.
#1 rod with the bearing shells, the others ready after chamfering.
Picking the rod pin diameter and setting into the micrometer, then transferring into the bore gauge. Measuring proper bearing clearance against rod pin.
Measuring bearing "crush".
Asymmetric assembly.
Finished assembly from below. (crankshaft side)
And the assembly seen from the deck (or cylinder head) side.
Very nice progress, it bring me back to my high school days in shop class(when I decided to attend). I used to spend my time tearing down, port and polish, rebuild the engines for my credit. Unfortunately, I didn't attend enough class to pass lol. But all in all, the experience is all I wanted.
The rocker stud bosses have been machined and tapped for screw-in studs. These heads are the same as for the TPFI the little dome on top of the runners is for the injectors spraying to the valves. 19.14 mm is roughly 3/4"
Things tend to go way slower than one expects. Especially if there is no hurry in completing them. The more important to keep going and adding step to step - even if it's small steps.
Work started on the heads.
To determine the quality of the seats I have measured the valves protrusion above the machined surface where the valve-spring will sit.
Simply by using a piece of steel tube that has been ground to exact length (70 mm - roughly 2 1/2"). The tube is longer than the valve stem when sitting on it's seat.
Measuring the distance down into the tube and subtracting from the length I know how far the valve stems protrude.
Mind you! The 1994 has rotator-caps on the exhaust valves. In order to achieve the same spring pressures GM has machined these spring seating surfaces deeper than the intakes.
Therefore I will have less spring pressure on the exhausts without shimming. Now the shims need to be about nearly 1/4" on the exhaust springs and 1/8" for the intakes.
More work on the lathe.
I found the seats to be OEM spec from manufacturing. They have never been reworked and we should have enough depth to cut them down a bit which will add about 2 ccm to my combustion chambers.
At this point I'm getting a little itchy about the compression wich at this time calculates as 1:10.2 - A bit too high to run on 95 octane fuel (our "regular") but will be safe with 98 octane (our "premium").
We'll have to bore the valve guides and insert K-Line guides before machining the seats. Still to be determined and maybe a tool being fabricated to enlarge the valve seat pockets in the heads.
Images show one of the heads, my machine-shops special tool to measure depth and the Manley valves with K-Lines ready in their box.
Not much done on the Blazer. Heads porting has been completed. Mind you, no porting in the sorts of widening up passages and such but just getting rid of all aerodynamic restrictions, casting bosses and numbers inside the channels.
Smoothed the throat area but kept the venturi just above the valve seat. Short bend radius just cleaned up, valve guide bosses rounded. The matching of the intake and exhaust ports will be done once I can assemble the whole engine.
In the meantime been looking into several options of swapping in an aftermarket fuel injection. It turns out to be an expensive thing for a PnP thing like the TBI injections from known manufacturers such as Holley, or EZI. With the required harness and such up to 4'000 $. Been looking into the Megasquirt Project for years (other project car) and the evolution 3X will be the next thing to buy. Will cost me about 1'000 $ (aka 900 Euros). Again steep learning curve. I plan to get the ECU and then will fit all additional sensors to the Blazer with the OEM engine that I'm running at the moment. So I can figure out how it works, how to tune and as a by-product figure the VE and other tables from the factory.
Have to fix my phones USB plug. Charges but unable to connect to computer. PITA to get the pictures out of the phone but found a solution now.
Ive used mega squirt before on a mazda Bp-t from japan in an AWD kia rio. Its not to bad there are a couple Build yourself kits you can get from a couple dyi shops for fairly cheap. I know there are a couple tuning shops that that will tune the stock ECU. The same company that make the roots style super charger for the 4.3L does ECU tuning. I donmt have the link on my phone but when I get home will attach it and they may be able to help you out for a cheaper price. A mega squirt kit if you put it together yourself should be around $600 U.S. The mapping program was pretty easy to use I was running an MS-2. Heres a UK shop for MS ExtraEFI Engine Management I got mine back in mid 2000s think I paid 300 for everything I needed, you should be able to contact MS directly if you have any questions and they should be willing to help. I know they were helpfull ack when I did mine. Heres some more info for ya https://www.diyautotune.com/support/...t-your-sbc-v8/. If you can solder the DIY kits are the way to go your looking ant a couple hr job. mostly just to double/ triple check you putting everything where it needs to be the soldering is the easy part.
10-26-2018, 04:17 AM
