Just another 2056 build, Misc Questions Options

[76-914]

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[sdoolin]

Loving this thread! I have some 2.0 bus parts at the machine shop now for a 2056 build.
I was under my '73 the other day and noticed how close the engine bar comes to the 1.7 case where the bus oil fill would be. My bus engine came out of a '71, so the engine bar is smaller. I'm worried the block-off plate and studs in the bas case are going to hit the '73 engine bar, so I'm going to countersink the cover and use countersunk machine screws to hold the cover in place to try to get some clearance. Thought I'd give you a heads up about it. I saw the block-off plate in your pictures and the "1973 914" in your sig. Sounds like we're doing the same swap! (IMG:style_emoticons/default/smile.gif)

Thanks for the heads-up. If you get around to this before I do - post some pics please. My car has a running engine in it (I am still driving it) so I won't be sure if the engine mounting hardware will all bolt up until I am ready to install this thing.

[sdoolin]

Getting ready to measure Deck Height, and then set CR. Using a tool for Deck Height measurement made for Type I's. I will weld on an additional steel plate so that I will get even/appropriate clamping forces on all four studs/corners.



The screw in center(ish) of this plate is calibrated such that 1 full turn = 1mm. So with this tool I can use the calibrated screw to take a number, I can use feeler gauges to take a number, and I can also use a dial indicator (once I weld on the additional plate) to take a number.

I just hope (pray actually) that all the numbers are the same (or very very close).

That calibrated screw is not directly over the wrist-pin I know, but I am comfortable with this approach. No shim/gasket between jug and case, and a single piston ring installed.

[sdoolin]

Having measured deck-height over the weekend I (naturally) have questions. I used the tool pictured previously with the calibrated screw. The directions indicate 1 full turn = 1mm (which I measured and verified).

On cyls 1 & 2 I get a deck height measurement of 1mm using the calibrated screw, and some stacked up feeler gauges yield the same measurement. Did not measure the other side yet. I can tell that actual deck height is just a bit less since that calibrated screw (and feeler gauges) rock the piston ever so slightly. But - I am comfortable (for now) with a repeatable measurement of 1.0 mm (.039).

Plugging bore (96mm), stroke (71mm), deck height (.039) and chamber volume (55.2) into the CB Perf. engine calculator it yields a CR of 9.3 - 1. Is that too much?

When I first began this project a couple of months ago Jake posted a quick reply that I'm using pretty much all the right bits and pieces and I should se the CR at 9.0 - 1. I tend to believe that guy.

Without starting a flame war (if you are just going to bash JR, or this build don't bother posting) - how do we feel about a CR just a tad higher than 9.0 - 1? I'd love to bolt up the short block without any shims under the jugs and leave this CR alone, but am interested in experienced opinions from those who have done this (or a similar) build.

All meaningful replies much appreciated.

[wndsrfr]

Oil Dipstick Tube fitment. Bus engine cases need to be drilled. I am using 5/16" hydraulic brake line press fit into a 5/16" hole in the case. Will secure with some JB Weld (or other) when complete.

Anyone know exact height of dipstick tube from top of case to top of tube?

I'm seeing 85 mm on a known stock case....3 & 3/8" .....

Whoops....that 85mm is from the flange that the tin mounts against....from the case top it's 6 inches.....152mm. That's what I used on my 2316....

[Bleyseng]

Toss the VR rear main oil seal and get the Sabo seal from GoWesty as it actually seals the flywheel vs the VR seal which leaks.

[sdoolin]

More deck height and compression ratio questions (really the same one but I never got a response(?)).

I have measured and re-measured deck height on all 4 cylinders. All come up with 1mm deck height in the jug. I got sage advice from HAM that there is 1mm of step (deck height) in my cylinder heads. This gives me a total deck height of 2mm.

I am targeting 9:1 Compression ratio. Plugging the numbers into CB's engine calculator and solving for deck height it yields 1.28mm for a CR of 9:1.

So I need to remove 2.00mm - 1.28mm = 0.72mm.

I'm pretty comfortable with my measurements and with this math.

My question (finally) - can I remove 0.72mm from the jug, or do I need to remove it from the head?[i] It'd be much easier for me to remove it from the jug, so I'd prefer that, but if the conventional wisdom is against that, then I'll send the heads out.

If it is OK to remove this material from the jugs I could get it done this weekend and complete the short block...

As always - thanks in advance for all assistance.

[stugray]

I got sage advice from HAM that there is 1mm of step (deck height) in my cylinder heads. This gives me a total deck height of 2mm.

I am targeting 9:1 Compression ratio. Plugging the numbers into CB's engine calculator and solving for deck height it yields 1.28mm for a CR of 9:1.

If the heads have a 1mm lip, did you account for that in your combustion chamber number?
Or did you measure the comb. chamber volume?

You comb chamber number seems smaller than a stock head.
I had to shave my heads down significantly to get below 55 cc.

Stock is almost exactly 60 cc.

[sdoolin]

I got sage advice from HAM that there is 1mm of step (deck height) in my cylinder heads. This gives me a total deck height of 2mm.

I am targeting 9:1 Compression ratio. Plugging the numbers into CB's engine calculator and solving for deck height it yields 1.28mm for a CR of 9:1.

If the heads have a 1mm lip, did you account for that in your combustion chamber number?
Or did you measure the comb. chamber volume?

You comb chamber number seems smaller than a stock head.
I had to shave my heads down significantly to get below 55 cc.

Stock is almost exactly 60 cc.

I did account for the 1mm step in the heads in my combustion chamber number, or rather Len did at HAM. I did not CC the heads myself, that was done by Len at HAM. The spec sheet that came with the heads says the chambers are 55.2 CC. I am pretty sure Len's number is accurate. Much more so than mine.

[sdoolin]

I am taking .72mm off the top of the jugs today. Should be a good time.

[sdoolin]

Toss the VR rear main oil seal and get the Sabo seal from GoWesty as it actually seals the flywheel vs the VR seal which leaks.

Ordered Sabo seal from GoWesty last night - appreciate the heads up.

[MarkV]

Are you sure about the size of your chambers? When I did mine they were in the 59cc range. Did you do the whole clear plastic disc and burette thing. It's been a while since I did mine but I had to use spacers that I ordered from aircooled.net under the cylinders. I ended up with 9.5 : 1 compression and it runs fine on regular fuel.

[sdoolin]

Are you sure about the size of your chambers? When I did mine they were in the 59cc range. Did you do the whole clear plastic disc and burette thing. It's been a while since I did mine but I had to use spacers that I ordered from aircooled.net under the cylinders. I ended up with 9.5 : 1 compression and it runs fine on regular fuel.

I did not CC the heads myself - but have been through the process for other engines. These heads are the RS+ specification heads from HAM (Len Hoffman). They came with a spec sheet that includes the combustion chamber volume. I trust the numbers from Len.

[MarkV]

Len did my heads too. I measured them to make sure everything matched on all 4 cylinders. My finished deck height with spacers was .014 with a combustion chamber of 59cc my exact compression ratio is 9.3 to 1.

[stugray]

So I did the calcs myself and got 8.37CR with a 2mm deck height which agrees pretty well with the CB calculator.

on the CBPerf website, When I plug in 96 bore, 71 stroke, comb chamber 55.2, compression ratio 9.1, and click solve for deck height I get 1.17mm.

So your target of 1.28mm will get you to 9.0:1 CR.

And sorry if I missed it, I assume you will run with no head gaskets?

[stugray]

Len did my heads too. I measured them to make sure everything matched on all 4 cylinders. My finished deck height with spacers was .014 with a combustion chamber of 59cc my exact compression ratio is 9.3 to 1.

Are you certain your final deck height was .014?

From what I recall from research is that you should not have a deck height of less than .025 (.65 mm Min) to allow for piston expansion.
I am sure it depends on the specific piston material, but that was a rule of thumb that you supposedly should not cross without knowing what you were doing.

I was trying to get maximum CR on my build and had the engine assembled with .024 DH, and chickened out and tore the engine back down and increased to more like .030.

[sdoolin]

No head gaskets...

[MarkV]

The deck height of .014 was before I added a .020 spacer. And my 59cc was before I decided to send my heads to Len to have them rebuilt. He welded up the spark plug holes and changed them to 12mm. I can find my notes for the finished head combustion chamber after Len rebuilt them. I know my compression ratio is a little more than 9:3 and I was worried about it being to high at the time.

[sdoolin]

I decided I always need to know where my crank is - I mean - that's just a good idea...



Degree wheel is an old Ducati piece. Where we say "degree wheel" the Italians turn it into a song and say "goniometro per messa in fase dei motori a 4 tempi". I mean, it says it right on there. Rough translation = "goniometer for commissioning phase of the 4-stroke engines".

"Commissioning phase" - I like that...

[MarkV]

So disregard pretty much everything I said. I found a photo of my heads after I got them back from Len. When he finished I had a 60cc combustion chamber. Jake bored my factory jugs to 96mm and with KB flat top 96mm pistons the deck was .014 and with a .020 spacer and no head gasket that put my compression ratio at 8.8:1. My OEM cylinders must be shorter than what you are using. I used short peices of tubing and snugged the head bolts to hold the cylinders in place before I took measurements. I had to swap cylinders around and clean some minute gasket material off the registers until I got both banks to have equal pre and post spacer deck height. I also had to sand the spacers with oil and wet/dry sand paper. Both banks weren't the same but both pairs matched when I finished.