NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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- 1st Generation Specific (https://www.nopistons.com/1st-generation-specific-16/)

- - Engine Heat Problem (https://www.nopistons.com/1st-generation-specific-16/engine-heat-problem-39407/)

Quote:

Originally Posted by 83turbo' date='May 25 2004, 08:14 PM

Yes - idle and main are under the "mickey mouse hat". You can adjust the idle mixture screws (topmost in the pic) with a screwdriver, but the main and idle jets are sort of press-in things. When you remove the hat, you will see 4 screws (okay, so I'm referring to a Dell'Orto DHLA but it should be the same) - these are the jet holders. When you unscrew them, you will pull out the entire emulsion tube. Fuel jet is at the bottom, air jet is at the top - you have to pull off the jet holder to get to it if you are going to fiddle with those.

The brass screws to the left and right of "WEBER" hold the accelerator pump squirters.

I'm not sure what the others are - it's been a while.

To determine the cause of the 1500-2500 RPM hesitation, slowly tighten the idle speed adjustment screw, raising the idle. If it leans out and stalls, the idle fuel jets are too small (adjusting the screws won't help). If it continues to rev up okay, try different accelerator pump squirters. My Dell'Orto always seemed to have a problem there - I think because of the long, cold manifold.

Also I didn't see a cold start linkage in the pic. Do you have one?

Choke?

It does not have a choke that I know of, or I dont know what you are taking about.

To add fuel to maybe fix my heat problem, I need to adjust the idle screw or replace the main jets with the next size?

DCOE's never have a normal choke, but some have an extra third throat

which is very small and dumps a rich mixture below the throttle plates

for warmup without restricting airflow.

Main jets might fix it (if leanness is the problem). If it's lean now

and you up the jet size, you will likely notice an improvement in power.

I don't imagine the idle screws will have any effect on engine temperature,

although the idle jets (under the hat) might.

It is a "DCO 2 sp" if that makes any difference.

dude my car runs at 160 F , is that good lol ?

Quote:

Originally Posted by Hades12' date='May 25 2004, 06:07 PM

It is a "DCO 2 sp" if that makes any difference.

DCO stands for something like "doppio corpo orizantale" or some like that - Italian for "double throat horizontal". I don't know what DHLA stands for (Dell'Orto equivalent.

Check the transition as described earlier (slowly increase idle speed) to make sure your idle fuel jets are okay, then move on to the mains. Was this carb jetted for the 12A to begin with?

Also just wondering what you are doing for metering oil, as I didn't see a linkage.

The Engine was built for "KenA" by Downing Atlanta when he worked there, I bought the car from the guy he sold it to. Ken or Downing put the Carb on, So I would think that they jetted it to some baseline. It has run well but as the days have gotten hotter it has gotten hotter. I picked it up at Thanksgiving last year and it run at 1/4 guage all the way from Nashville to Atl. The header panel was missing at the time from a wreak by Ken. I had it pulled over christmas and put the header panel and lights back in. around the first of april is when it started running warmer and now a lot warmer.

I premix, I run 1 oz of two stroke to 1 gallon of fuel.

Do you have all the radiator sheetmetal intact? Make sure that engine compartment air can not get draw through the radiator and it has to pull fresh air.

What type of fan are you running? A good fan will draw some serious current.

Quote:

Originally Posted by falcoln0014' date='May 25 2004, 10:26 AM

as for running the car richer or leaner...My car is running EXTREMLY rich right now...so I don't think making it richer would do much good...more gas = more fire = more heat

"more fire" comes from increasing the amount of oxygen in the combustion chamber. When you lean out an engine (too much air) it begins to detonate (ping) because the fuel/air mixture is exploding rather than burning evenly.

Aside from that, have you thought about an EWP (electric water pump)?

These are much more effective than an engine driven pump as they vary the water flow based on temperature rather than engine revs. Also they prevent "churning" which occurs in normal pumps at high engine revs. The water is moving too fast to have any effective cooling properties.

There's no reason why that setup should run hot to begin with. The fact that it is running too hot indicates that something's out of whack.

Easiest way to prevent high RPM cavitation is to change the crank pulley.