Premo tuned = happy roadster

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Young-gunroadster
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Premo tuned = happy roadster

Post by Young-gunroadster »



Big shout out and thank you to Dave Premo for jetting my Mikuni 44's on my rebello 1750cc; He also fixed a bunch of issues i didn't even know i had such as cooling system not holding pressure and gas pedal being bent such that pedal to floor was not giving me full throttle on my carbs.

Check out the pictures and short video of the car revving.
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Last edited by Young-gunroadster on Mon Apr 19, 2021 11:39 am, edited 1 time in total.
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Gregs672000
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Re: Premo tuned = happy roadster

Post by Gregs672000 »

That's great, no bog even off idle, not easy to accomplish. The pumps look like they are set well. Hard to read your meter, but I'm glad you have one!
Greg Burrows
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Solex68
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Re: Premo tuned = happy roadster

Post by Solex68 »

David Premo is the best. Funny I have that Stant test kit based on Premo's suggestion. He's tuned my cars as well. No one has driven my car faster than Premo. Nearly pooped in my pants at Solvang :) as we tuned and test drove down curvy single lane roads.
Greg a.k.a SOLEX68 - http://www.datsunvents.com/
Laguna Hills, CA
68 2000 U20
Always willing to help another Datsun Roadster owner
Pending installs: SS brake lines, Stan Stealth Dizzy, Denso TT plugs
david premo
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Re: Premo tuned = happy roadster

Post by david premo »

Sorry Greg, never intended to be a substitute for a good laxative. I was just trying to get the best out of your car when tuning it. FYI I recommend presser testers to all the people I work with. It’s so important that owners make sure the cooling system holds pressure to prevent engine damage. So what the big deal is radiator pressure is critical to not causing head gasket and cylinder head damage. Early pressure caps on cooling systems were an improvement over no pressure caps seen on many early auto’s. However, it was not until the advent of higher 12 to 14 pound caps that engine performance and fuel mileage improved. The reason it was important to get cooling system pressure up has to do with the boiling temperature of water. By raising the pressure cars could run higher temperature thermostats and have more complete combustion with a leaner mixture. Engines like running lean and mean, they make much better power than when they are overly rich. Over fueling an engine is the slow death of the engine. Racers used to call it black death, because the incomplete combustion would clog the ring lans in the pistons and the rings would no longer move in and out freely and compression would drop. Engines like running hot, I run a 190 degree thermostat in my roadster and it runs great.
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Skyman
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Re: Premo tuned = happy roadster

Post by Skyman »

Dave knows his s#!t. That's for sure!
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Gregs672000
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Re: Premo tuned = happy roadster

Post by Gregs672000 »

Right now I'm tuning my EFI system and working on acceleration enrichment. Gotta say, if the video is an indication of the whole tune, Dave is as good as a computer for carbs. It is not easy to set up a system that will not stumble when hitting it hard at 900rpm and revs buttery smooth to 5000+, believe me. Well done Dave.

BTW, Dave took me on a similar run as Greg described in my own car at Mt Shasta many moons ago that also showed me its potential, and failings... remember the railroad tracks at the end of the hill Dave? That's when I/we discovered I needed to improve my badly fading brakes... Brakes, WHAT BRAKES?!
:smt006
Greg Burrows
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Daryl Smith
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Re: Premo tuned = happy roadster

Post by Daryl Smith »

"..it was not until the advent of higher 12 to 14 pound caps that engine performance and fuel mileage improved."
Dave,
If I remember correctly, the roadster engines are running about 6-7 psi cooling systems? Do you have a part # or place to look for the caps to increase it to the 10 - 12 psi range?
I've been running 180* with no problems, but, would go to 190 with the proper caps in good condition for the new engine.

Thanks,
Daryl
'66 2065cc Stroker "Frankie", EFI and GM D585 ignition
she aint pretty, she just looks that way...
david premo
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Re: Premo tuned = happy roadster

Post by david premo »

Daryl,
The factory manual has a 13 psi cap listed as standard. On factory cap is stamped .9, meaning .9 kg/cm2 or about 12.8 psi (13 psi) from what I can tell.
Dave