Just got off the chassis dyno today. Since the FI unit was heavily modified to allow it to flow required air for the race motor I really wasn't sure it would start let alone run well. I'm happy to report it will start without a choke. I'm using a solenoid in place of the cranking signal valve. Works like a champ. As you expect the factory setting wouldn't get you close so I used an instrumented chassis dyno setup to measure Air/fuel ratios. The procedure as suggested to me by Jim Lockwood and in Jerry Bramlettes web site, was to first set the economy stop at 2800 RPM to 14.5 ratio and then to set the WOT ratios using the power stop. I set these at 12.5. There was surprisingly good linearity throughout the range. There was a slight leaning at 7400 RPM. Earlier in the testing we had a richening happening at about 5000 RPM which we later attributed to a leak in the atmospheric reference tube on the bottom of the diaphragm. It was a LOT of work doing the porting and machining welding etc.to get this unit to flow around 700 CFM but I think it came out well. Thanks to the expert advice from several on the board. I'm off to the Portland historics next week and then to Monterey vintage races. Life is good. Jerry
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Re: Road Racing FI cars
Now I am dying to know whay the dyno results looked like. Just how mean IS that monster now? -
Re: Road Racing FI cars
jerry i would put a heat shield between the exhaust header and the air filter element to cut down on the heat to the FI unit as this will kill HP. outside air would even be betterComment
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Re: Road Racing FI cars
Probably one of the biggest power advantages of FI is the cold air induction. Power increases about one percent for every 10 degree drop in air temp, so if it's 80 outside and 120 in the engine compartment...
Assuming you don't have the radiator support with the opening for FI, I don't think they're too hard to come by being as how most service replacement had the hole.
Once you experience a properly modified and set up FI system, I don't see how a vintage racer would ever want to go back to a carburetor again.
Just make sure you frequently clean and lub the FI pump drive cable. I think broken cables accounted for more Corvette DNFs back in the day than any other cause.
DukeComment
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Re: Road Racing FI cars
Good idea. immediate problem was to see if it would run and have a stable A/F ratio throughout RPM range. I don't have inner fenders so there will be pretty good air exchange but I agree on getting cool outside air. I'm thinking this winter I'll work on a way to get intake air from the front high pressure area. JerryComment
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Re: Road Racing FI cars
i would use a magnehelic gauge in the area of the air cleaner to see what type of air flow you have to make sure you don't have a negative pressure area. you could also use a thermocouple in that area to see what temp the air intake is seeing.Comment
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Re: Road Racing FI cars
Drive cable housing. Clem remembers Doc Blatchleys Grady Davis Gulf research car. The 63 white/blue stripe one. So does Doc Mike. Rich Mason restored the car in the 90's etc.
When I was a young kid my job was to help keep the car running. I didn't like that job though as got all the grunt work. Anyhow we started out only using the bare drive cable as the race would be over if you had to change the housing.
One day at the Connelsville airport old Doc coasted off the track on a sharp turn. I said to the head mechanic-Timmy Grabiak. Now what the crap broke. Not my exact word. He said the drive cable probably fell out. And so it did. Doc was hollering at poor old JD as I recall. hahaha
So I got the hacksaw out (at Timmy's instruction) and cut the end of the housing off leaving only the stub that goes into the distributor. Then we filed the center to remove the burrs, used the round knurled note for a start (later we used the 57 hex nut to hold the stubby junk of housing onto the distr) Never again did the drive cable fall out. We NEVER broke a drive cable like guys do today.
Anyone here have a poc drive cable housing-just the very end-the distributor end that they can send to Jerry? I don't have any more junkers.
Lances #3 and the Purple People eater race cars both have the same set up as we are talking about. Just the bare cable, short stub, and knurled nut. As per the old original pics from the racing era.Comment
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Re: Road Racing FI cars
Jerry -
Does it cool OK? That upper radiator hose looks a tad on the small side.Comment
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Re: Road Racing FI cars
The 63 Grady car used the original air cleaner assembly sans air cleaner element. Yep no air cleaner element inside the can. Remember it like yesterday.Comment
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Re: Road Racing FI cars
this radiator was made for my car. It has extra rows of exchange tubing. it's also the oil cooler. it's acombined oil to water cooler. Heads are center taped to allow better cooling in this normally hot area and i run a 24 psi cap. Everything is very tightly shouded so air flow is directed/forced into radiator. Works great at race speed, don't want to sit around idling on the grid though.Comment
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