Would this combo make a good daily driver

[maredlin1@hotmail.com]

Have a 1978 L20b in a 620. Want to bore to 86 mm and use 280z 10:90 dished pistons. Have a w58 closed chamber cylinder head, and use a 32/36 weber, or is there a better combo out there. I would rather not have to burn high octane, but will if I need to.

Thanks

[ggzilla]

Why is Premium so high in Colorado??? Generally speaking premium gas saves money. It costs 10% more but gets 15% better mileage. But when it costs 20% more then its losing.

[datzenmike]

Have a 1978 L20b in a 620. Want to bore to 86 mm and use 280z 10:90 dished pistons. Have a w58 closed chamber cylinder head, and use a 32/36 weber, or is there a better combo out there. I would rather not have to burn high octane, but will if I need to.

Thanks

That combo gives a 9.122 compression.

[MicroMachinery]

That combo gives a 9.122 compression.

 

If that's the case, you'll be fine. The closed chamber head design helps with detonation, and 9.1 isn't really that outrageously high of compression to begin with.

[maredlin1@hotmail.com]

Thanks for everyone's input. I think this combo is what I will go with, and let you know what octane gas it will run good at.

[Stoffregen Motorsports]

See? Someone here on Ratsun always has an answer.

 

Nice job guys.

[datzenmike]

Best mileage is high compression and high octane with the timing as advanced as safely possible.

 

 

Try just regular gas and adjust the timing by ear so there is a just barely noticeable ping under load. Maybe back off the timing just a hair to loose it. Run a couple of tanks and work out your mileage.

 

Now run some premium (or what ever you call it down there) and again advance the timing until slight ping and back it off. Run a few tanks and work out your mileage.

 

Now, does the mileage increase per gallon pay for the increased cost of the higher octane fuel per gallon?

 

Say you get 28 MPG with regular at $3.60 a gallon... that's 280 miles per 10 gallon tank

 

You get 32 MPG with premium at $3.80... that's 320 miles per 10 gallon tank

 

You go 40 miles further but it only costs you $2.00 more.

[maredlin1@hotmail.com]

Great information (and you're right, I always get an answer from Ratsun) p.s. Crow doesn't taste very good. I have a couple of annoying questions to some. Everything will be new. Cylinder head was milled 10 thousanth, do I need cam tower shims? Do I put the cam sprocket at the number one position or the number two with the 280z pistons. And as far as pistons go, I found original dealer pistons for around $65. each. They are probably the best out there, but I'm willing to settle for second, third, or what ever is a good piston at a reasonanable price. One more, what rings should I use (I know stock was chrome, but you about need to have a perfect cylinder for them to seat) I have read moly rings (don't know if they mean chrome moly or just moly). I've also read Hastings makes good rings.

Thanks for your time.

[maredlin1@hotmail.com]

Sorry, but I have more information. This might make a difference. I live over a mile high, (also in elevation 5,400 ft) Colorado

That's a joke son I'm quoting Fog Horn Leg Horn.

[Stoffregen Motorsports]

Hastings makes sprayed chrome rings as well as cast rings.

 

Cast rings seat quickly and will last a long time, but chrome rings will last a really long time.

 

Cast rings are easier to snap both on install and from detonation.

 

Chrome rings don't require anything special as far as the hone in the bore goes.

 

If you're having a shop hone the block then they will know what to do.

 

If you're honing it yourself, use a ball hone, lubricate it with WD40 (both in the bore and on the hone), use an electric drill (battery powered or plug in) set on the mid speed setting and for every one second count you should go down and up the bore two times (count "one one thousand"). ie - one one = down and up, thou sand = down and up. Run the hone in the bore five or ten total strokes.

[banzai510(hainz)]

make a good daily driver?

 

a stock L 20 with a weber 32/36.

 

cheap and EZ!!!!!!!!!!!!! forget the rest get more power just bolting a 38/38weber on there than getting bigger piston ect just to put a 32/36 on there.

 

just my opinion

[datzenmike]

AKA the point of diminishing returns. Stock is super easy to maintain and reliable. When building it up more and more goes into it and less and less is gained. The first 10 HP costs $150, the next 10 hp $200 more, the next 10 hp $500.... 

[Stoffregen Motorsports]

Man you guys are getting old. Where's your zest for life?

 

I say build the motor. Build it the way you described or a completely different motor, or even an engine swap.

 

I've got one word for you guys...Fahrvergnügen