Date registered: Mar 2007
Vehicle: 1980 450slc
Location: Redmond, OR
Mentioned: 0 Post(s)
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That doesn't look anything like the throttle body that I purchased off of e-bay with the rest of the fuel injection stuff but it really looks like it has a good chance of fitting. I have never handled one of these throttle bodies.
I think using this throttle body sounds like a great idea but I do wonder about the vacuum ports. In my setup I am using vacuum ports off of the Mercedes throttle body for the MAP (manifold absolute pressure) sensor, the vacuum can for the door locks and the fuel pressure regulator. Do you know if the 65mm throttle body has any vacuum ports on it at all?
On my engine I have a large vacuum port in the intake for the brake booster and another one on the back (firewall) side of the intake. I can’t recall if there is a vacuum port in the middle of the intake or not. I will have to check.
I have found that my engine runs a lot smoother and is much more fun to drive with my 65mm Mercedes throttle body and the MegaSquirt brain. But I also notice that the low end acceleration is much more sensitive. i.e. I have to make a conscious effort to not peel out in my gravel driveway. I have not played around with adjusting the throttle linkage to make the low end less sensitive. With the CIS I used to floor it then have a smoke (I don't really smoke) while I was waiting for the engine to respond and start accelerating. With MegaSquirt the throttle response is instantaneous even without a functioning TPS.
What I am getting at is I wonder if a 70mm throttle body would be too large and cause a loss of low RPM pedal control. I calculate a 65mm throttle body to have an area of 33.2cm^2 and a 70mm to have a surface area of 38.5cm^2. That is a 16% increase in surface area. I don’t know off the top of my head how this relates to flow or CFM? My gut feeling is that a 65mm throttle body will flow plenty for the stock Mercedes 4.5 but when you start talking about headers the 70mm does sound tempting.
I also wonder about the overall width of the ford throttle body. My Mercedes throttle body is a pretty compact unit and a pretty tight fit in the intake already. I have a hunch we would have to do some modification on the throttle lever on the Ford TB to make it narrower. But this is just my speculation. Do you know if the throttle linkage on the Ford TB is held on with a nut or something more perminant?
The 65mm throttle bodies definitely seem to have a big advantage in the price department to me. That makes it a little easier to justify buying one to to mess around with.
What are your thoughts?
Last edited by oughtsix; 04-26-2007 at 12:16 PM.