So my machinist started assembling my engine tonight and measured the deck clearance and he was WAY off from the numbers I was hoping for.

I calculated with the numbers I was shooting for 10.75 SCR and 10.008 DCR. With the new deck clearance I am seeing 9.061 SCR and 8.443 DCR. Do my numbers mesh?

Cylinder volume: 48cc
Gasket Thickness: .035
Gasket Bore: 3.525
Cylinder Bore: 3.440
Deck Clearance:
Actual: .161
Virtual: .071
Stroke: 4.125
Rod Length: 6.7
Intake Closing ABDC: 38

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2006 Jeep Commander
2013 Chrysler 200

1964 Valiant 4 Door
1965 Plymouth Barracuda
1967 Chevy Camaro

I got 9.037 and 8.421, but it's probably all in the calculator used.

Why do you want that high of a DCR?

The target SCR/DCR sounds like a boost alcohol number to me.


CJ

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Part of Tyrde-Browne Racing

Your numbers mesh with what I calculated. My target is not for boost or alcohol specifically but the idea of a turbo is not out of the picture.

The reason for the target is because I had to rebuild the engine and machine it so I decided to go ahead and over machine everything so I can cover anything I wanted to do now or in the future. I have a bit of a speed "problem". lol

_________________
2006 Jeep Commander
2013 Chrysler 200

1964 Valiant 4 Door
1965 Plymouth Barracuda
1967 Chevy Camaro

You will have a bit of a ping problem with that DCR and a turbo.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

You will have a bit of a ping problem with a heavy car and pump gas.

.....or a low geared car and pump gas

_________________
Yeah....Im the one who destroyed this rare, vintage automobile.....

Sandy are you referring to the target or the actual compression ratio?

The next question what does everyone think? Is this good enough or should I push to get to where I was shooting for.

_________________
2006 Jeep Commander
2013 Chrysler 200

1964 Valiant 4 Door
1965 Plymouth Barracuda
1967 Chevy Camaro

The compression that you have, and how the DCR computes out, should be good. Might need to play with the timing curve a bit. How much does your car weigh?

The target numbers would be off the charts high. Well, the DCR anyway. My Valiant is at 10.7:1 and runs on Premium. DCR is a lot lower. I think the Intake closing is in the 60ish degree range. My brain leaks.

What is the targeted use of this car?

CJ

PS If your going to put a turbo on this build to run on gasoline, you've already gone too far.

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Part of Tyrde-Browne Racing

I am shooting for a heavy streeter with some drag and auto cross. The car is a 65 Barracuda standing curb weight states 2850 from the factory.

_________________
2006 Jeep Commander
2013 Chrysler 200

1964 Valiant 4 Door
1965 Plymouth Barracuda
1967 Chevy Camaro

What cam do you have in there?

CJ

_________________
Part of Tyrde-Browne Racing

Oregon Cam Grind 791

Intake: 230
Exhaust: 230

_________________
2006 Jeep Commander
2013 Chrysler 200

1964 Valiant 4 Door
1965 Plymouth Barracuda
1967 Chevy Camaro

Got a copy of the cam card? Are you sure about the intake closing number?

CJ

_________________
Part of Tyrde-Browne Racing

I checked the card against the list and they are the same.
http://www.oregoncamshaft.com/Mechanical-Cam-Specs.html

But here is what they gave me.

Rocker Ratio: 1.5
Lobe Seperation: 108
Lobe Center Line
Intake: 104
Exhaust: 112

Duration
.015: In 284 Ex 284
.020: In 268 Ex 268
.026: In 257 Ex 257
.050: In 230 Ex 230
.100: In 197 Ex 197
.200: In 142 Ex 142

Valve Clearance
Intake: .015
Exhaust: .017

Cam Timing at .050:
Intake Open: 11 BTDC
Intake Close: 39 ATDC
Exhaust Open: 47 BBDC
Exhaust Close: 3 ATDC

14 degrees over*** at .050

Valve Lift
Intake: 489
Exhaust: 489

_________________
2006 Jeep Commander
2013 Chrysler 200

1964 Valiant 4 Door
1965 Plymouth Barracuda
1967 Chevy Camaro

Those are the .050 values for degree'ing. Your actual closing is probably closer to 56 or so degrees for DCR computation. That should put you in a better place for running pump gas, and your engine should scavenge.

I feel better.

If your going to boost this engine, your there. If your going to run it for a while NA, and your planning to run a big two barrel or four barrel carb, you may want to consider decking the block. At 48cc, you've already got a small chamber.

0.161" is way down the hole. Options are, deck the block or long rod the engine and install appropriate pistons for doing so. The K-1/Wiseco assembly is zero deck. That puts you in race gas land right now. With a 48cc head, it puts you into copper and O-ring territory, and no way would you be running anything remotely available at the local gas station.

I would deck the block if you want to be in the 9.5 or 10:1 range for a naturally aspirated build. To go with boost, you would be best served to purpose build another engine. You do have the option of installing a copper head gasket to raise the head back up.

Either way you may end up with custom pushrods. My latest purchase are mechanical pushrods with ball ends The cups don't work with the T&D rockers.

My latest build came out low on seven inch rods with a compression ratio of 9.75:1 SCR. Fortunately, that means I don't have to under-drive the blower so much.

CJ

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Part of Tyrde-Browne Racing

So lets talk about boost options. I am not interested in Nitrous but a turbo is something I could be interested in. What other boost option would you be available? Also where would I go from here with it? I definitely want an engine that kicks a bit.

_________________
2006 Jeep Commander
2013 Chrysler 200

1964 Valiant 4 Door
1965 Plymouth Barracuda
1967 Chevy Camaro

Try here.



CJ

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Part of Tyrde-Browne Racing