Bullshark

This sounds more like a timing/ ignition related issue to me. Have you convinced yourself everything there is correct?

Bullshark

shafrs3

It does sound like timing, the plug wire order is clockwise 18436572, the timing mark shows ~8 degrees BTDC with light, I'll recheck today.

shafrs3

Found the problem, my method for finding TDC failed me I guess. I've been using a compression tester to find #1 TDC, switched to the finger method and low and behold, 180 degrees out. Fixed that, fired right up.

Sounds good, smells good, life's good.

shafrs3

Thinking about this episode today finding the rotor 180 degrees out of phase, how in the SAM HILL is that possible, #6 should have gotten the spark. Well it was, I was seeing the spark pulse of the number 6 cylinder appearing on the the #1 plug wire.

shafrs3

Some of you guys wanted to know how much clearance I had between the intake and the hood, this is the method I adopted some time ago. I use clay and make some cones to place at the locations in question. Shut the hood and reopen to see how much the clay has compressed. In my case the closest the hood comes to the the plenum is about 5/8".

BBShark

Allan, Did you get it running? How is it?

shafrs3

Yes it's running, sounds & smells good. I can tune it in the garage now without getting asphyxiated. I need to finish the air cleaner before driving.

BBShark

Congratulations!!!!!! Again very nice work, very well designed and engineered.

shafrs3

Thanks Larry, I appreciate it.

Let me know if I can help you with yours.

442olds

Well this isn't exactly low profile but this is my version of a individual throttle body intake. Some of the parts are in pre fabrication mode but the intake is ready to go.

On the engine


compared to my previous Holley Strip Dominator and Holley Carb


And the throttle body models

BBShark

442olds: Nice setup and CAD work. That would be a very cool setup if you could make it work. I always thought the ASM manifold would be slick with 4 sidedraft style carbs with EFI (that would also help eith hood clearance). I'm thinking two (or four) sets of throttle bodys from a motorcycle?

Keep us posted on your progress. Looks like a very interesting project.

shafrs3

442olds, looks like you'd get some ram benefit from that intake, what are those throttle bodies modeled after?

Larry, good idea using motorcycle parts, you'd think the bores would be a little small though.

BBShark

You would think that motorcycle throttle bodies would be on the small side but they are actually pretty large for their displacement. I think the big Suzukis have 4 - 40 or 42mm throttle bodies. That's more area than most automotive stuff.

I work with a company that makes fuel injection setups for motorcycles and considered using 4 of these but I started thinking about the problems of synchronizing, hanging them over the top of the valve covers and how to make an airbox and decided to go the more conventional route.

It sure would be impressive though!

442olds

The throttle bodies aren't modeled after anything really. I guess if you had to say they were, then something like the Kinsler or Hilborn style. Really I was going to make a single plenum intake with an 80mm throttle body. But the mold was getting way to complex to make with my buddies homebrew 3 axis cnc. So I did some checking. Somewhere I read that individual throttle bodies need much larger throttle blade area than your typical single throttle blade/plenum intake. This is why motorcycles with multiple carbs/throttle bodies always seem to have rather large carb bores than would be expected. it has to do mostly with the standing waves and flow characteristics of a common plenum as compared to a single runner per cylinder. So going back to the Kinsler sight, the average throttle bore for a Big Block chevy is in the 2.25" to 2.38" diamter range. Which gives me a around 4.4in^2 of area. My throttle blade area is around 3.5". I just used the same shape as the inlet to the intake so I'm limiting myself in that respect. So hopefully its large enough but not to large at the same time. But the only way to determine that is to make them and see what happens.

Most of the parts are going to be cast from an expoy resin mixture that my buddy likes to use that will be fairly durable and pretty inexpesive to make. The molds will be made out of a combination of machinist wax and silicone rubber. Hopefully he'll have the molds cut in the next week or two.

I still have to make a new fuel rail that is a little closer to being flat. The first attempt tweaked when I welded the underside of the cross tube which isn't going to work for my purposes of mounting the center throttle shaft to the fuel rail. i'm still going to have to do a final machining pass to the pads for the shaft mounts but that whould be fairly easy.

Simmo

442 I love the plan.

Ive always been keen on long runner IR injection but the crossram Kinsler setup is fairly pricey. Yours keeps long runners and allows a cold air pickup from a hood scoop. You could see all those aircleaners whilst driving with a rear opening L88 type hood. The runner hits the head at a good angle too.

442olds

Thanks Simmo...I basically had three choices in intake for this project. Convert my Holley strip dominator and buy a $500 4bbl throttle body, a Ram Jet 502 intake ($1200 new from GM), or do something with a $200 mercruiser manifold. I can't say this adventure has been cheap. Piecing together a fuel injection system isn't cheap by any means. I'm going to be running a Megasquirt FI computer (already running the ingintion side with the carb, $300), 42 lb/hr Ford MSports injectors ($250 ebay), Materials and Tooling to make the throttle bodies ($350). So why spend all this money, bascially to have something different that no one else has. When people look under the hood of my car now, they know there is something different, this is just going to be icing on the cake when its done. And if it preforms half as well as I expect I'll be smiling from ear to ear!

Eventually I'll come up with an air box to draw air from the cowl, but as it is now the air temp I'm getting in my carbs air cleaner lid while cruising is only around 90 degrees on a 90 degree day. So we'll see how it goes with the itb setup.

shafrs3

If you could design the intake with a common plenum under the throttle bodies, synchronizing wouldn't be critical. What might be is throttle tip in, with eight 42mm throttle bodies tipping in all at once in a big block you could end up with a "punchy" engine, making smooth starts difficult.
But, I just had an idea here, a progressive linkage could be utilized. I once had a '65 GTO with a tri-power setup, similar to the 435hp Vette configuration. It ran on the center two barrel carb until about 2/3's throttle then the mechanical linkage would operate the two outboard carbs. Holley's ECU can be set to fire half the injectors until the TPS reaches a programmable value, then the other 4 will start to fire. So all you'd need is a linkage that opened four throttle bodies initially, I think you can see where I'm going with this, sounds like fun.

Are those motorcycle throttle bodies down draft? If they are something that looks like this first thumbnail could be done. I love that setup.

Second thumbnail is progress on air cleaner assembly.

shafrs3

Edit: that wouldn't work, unless I was trying to design an engine that ran on 4 Cylinders most of the time, and throttle bodies don't care how they are mounted, this is what happens when you put the first thing that comes to mind on paper, and you re-read it the next morning.

BBShark

I think what you described would work IF the TB's were progressive as you describe and all feed a common plenum. Imagine a LT1 style plenum with TB's mounted in the sides of the plenum and one TPS. It would sure take some tuning and a complex linkage and probably be a bear to work on, but it would be very cool.

There is a guy in Phoenix that makes billet TB's that mount to an old BBC crossover manifold for sidedrafts. He also makes some downdraft stuff also.

www.imagineinjection.com

stickboy

Looks great.