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Discussion Starter #1 (Edited)
I am still at Al Mitchel's place after running my Spider on his dyno today. I will post the graphs when I get back to Columbia. We did 13 pulls while we tinkered with the ignition timing and the carburation and we got just over 143 HP at the wheels at about 6200 rpm with a very wide power band. That equates to about 169 HP at the flywheel. The drive up to Al's is about 380 miles and I got 23 mpg while running at 75 - 80 mph for most of the ride.

More to follow.
 

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Discussion Starter #4 (Edited)
Here are the charts for the final run in 4th gear. I believe that the rule of thumb to convert wheel HP and torque to flywheel is to add 15%. So Peak HP is 165 at 6200 and peak torque is 151 at 5400. The HP was 158 or over between 5400 and 6600 and the torque was 138 or more between 3800 and 6300.

I built the motor during the winter with guidance from Richard Jemison.
The lower end is from an 85 Spider that I bought for $100. The only modifications were to the oil pump - eliminating the end float and I fitted a small diameter, aluminum crank pulley that I bought from Gordon Raymond. The flywheel was lightened by Richard.
The pistons are 85mm Venolias, machined to give 10.6 to 1. Richard got a set of liners bored to the correct diameter for the pistons because there is some variance in the size of various pistons that are nominally 85 mm.
Richard prepared the cylinder head. It was originally a Spica head.
The camshafts are RJ136 intake and RJ785 exhaust with 104/104 lobe centers.
The carbs are Weber 40DCOE116/117 with 34mm venturis, F34 emulsion tubes, 150 main jets, 210 air correctors and 55F21 idle jets. Fuel is supplied by a Carter vane pump and is regulated to 3 psi.
The intake manifold is from a Euro 1750 and was matched to the head by Richard. The air box is from the same 1750 Spider.
The distributor is a 123ignition running "D" curve with 13 degrees advance at idle and 34 max at 4000 rpm. It fires an MSD 6AL, an MSD Blaster coil and NGK BPR7EIX plugs gapped at .045" the wires are Taylor 8mm, metal conductor.
The exhaust is Shankle headers, Shankle cat replacement tube and stock CISAM center and rear mufflers.

I broke in the motor by running it at 2000 rpm unloaded for 30 minutes then 1 hour at 5000 rpm in 4th gear. I did a hot torque to 70lb-ft after the 2000 rpm run. The compression was 180 psi on all cylinders after 80 miles of running. I have not checked it since.
It used about a quart of oil to drive 760 miles and do the dyno runs.

I will be happy to answer any other questions.

Al, Richard and I are pretty sure that peak HP and torque is limited by the small carburetors but this is a well mannered road car that my wife and daughter also drive and I want to retain the flexibility and ease of driving. The two OEM mufflers may also be a bit restrictive but I don't want a very loud car.

We would have tried leaner idle jets if I had any. It was running pretty rich below 5000 but we had to use relatively large main jets to keep the AFR safe in the power region. Al thinks that there could be more torque at lower rpm with a leaner AFR.
 

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why go back to carbs? fi is much easyer to work with, no jets,elumsion tube, etc..even if you got it perfect acroos the board( unlikely) once you go up 1000-2000 feet or higher, all bets are off.. but 165 hp is very good.
 

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Discussion Starter #6
I like carbs on my Spider. I have FI on my GTV6. I appreciate them both.
 

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Discussion Starter #7 (Edited)
a few more notes

The first run on the dyno before we changed anything yielded 136 BHP. So all the trials changing timing and carburation got us an extra 7 BHP.
I had set the spark advance at 34 based upon advice that I had received. It turned out to be spot on. We retarded the spark to 30 and 32 degrees and we lost power. We advanced it to 36 and it was essentially the same as 34 so we left it at 34.
The 7HP that we gained came from increasing the main jet size and weakening the idle jets. We tried to fatten up the AFR in the power region by reducing the the air correctors but it was not effective and we had to use the main jets. This fattened up the "idle" region and we got a bit back by leaning the idle jets. But remember that we were only gaining 7Hp from significant carburation changes.

If I were building another motor and did not have access to a dyno, I would go conservatively low on ignition advance and conservatively fat on carburation knowing that I would be unlikely to damage the motor and I would only be missing out on a few BHP.

Compression ratio, cams and porting seem to have the most impact. Bigger Webers are probably the way to go if you want a more powerful motor with less flexibility.

Here is the amusing story. Al told me to drive the car to 3000 rpm in 3rd then floor it. The computer would then take care of the test, increasing the rpm all the way to 7000 when it would shut it down. I was sat in the car watching the tach, oil pressure and temperature. I watched the revs go beyond 7000 and almost hit 8000. The car and the dyno were making a lot of noise. I feared that the computer had farted and I was about to lose my motor and have to figure out how to get back to Columbia SC. I panicked and got off the gas. Al then convinced me that his computer tach was accurate and my Alfa tach was wrong. I watched it indicate 7800 on the remaining runs. The rear wheels were doing 108 mph in 4th at peak rpm.
 

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Ed,

I think your results are outstanding. Your car is as docile as my s3 at low speeds but comes alive in a way an s3 owner could only dream of. Thanks for confirming and quantifying the results of your engine build and sharing the results here.
 

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Discussion Starter #10
Here is the AFR curve added to the torque and HP curves. The drop in torque below 3800 rpm corresponds to the drop in the AFR from 11 to 10. I have ordered some more type B idle jets to try to lean out the mixture in this region and hopefully extend the plateau of the torque curve down to 3200 or so. Tuning emissions Webers is a bit more involved than tuning classics as there is more interaction between the progression and main circuits.
 

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Richard Jemison
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Adjustments

Ed, my suggestion is AFTER you get your AFM changed over to a wideband unit, and have a chance to establish the AFR from idle to 5000 RPM, have a muffler shop build you a 2 1/4" (minimum) exhaust system from the header collector out. Using larger internal muffler and resonator will not cause noise. The stock sized parts are too restrictive.

Then start serious tuning.
The RjR136 intake cam was the earliest of the faster ramp rate cams but isn`t as fast/low overlap as the newer cams. The cam timing may well improve the entire power curve. Key will be finding the happy place for both of the LCs and I suspect that will reflect a wider LSA than 104 which is very tight for engines with as long a runner system as these.

Getting the 2000-5000 power band higher is more important than the very upper limit but typically my cams don`t fall off as much after 5250 due to the valve event timing and duration above .250 lift.

Did you try 220 air correctors?
 

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Discussion Starter #12
Did you try 220 air correctors?
210's were the biggest that I had.

Maybe this exhaust stuff (and the upcoming GTV6 work) is an excuse for me to get a MIG welder and learn how to use it.
 

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Outstanding! 150 mains, very interesting. Great build and fun to drive! Congratulations
 

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Discussion Starter #15
Thanks. I will buy a wide band sensor and see if I can lift the torque curve at the low end. I suspect that I could have left the CR a bit higher, but maybe I have a bit of insurance against getting some poor gasoline or driving in a State where they don't sell 93. I was influenced by your posts about engine builds. I ran my liners in the dish washer!

Emissions Webers need larger main jets than classic Webers. It is because the progression circuit rolls off as the main circuit comes in. The progression circuit is always contributing with classic Webers.
 

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Discussion Starter #16
Engine pictures

Some pictures of the motor.

It seems that 15% is the rule of thumb for transmission loss in 4th gear so my peak flywheel HP is about 143.8/0.85 = 169 HP. I re-read Murray's black spider thread and my dyno numbers are very similar to his before he modified his exhaust system and tinkered with the cam timing. So I want to see how close I can get to his 160 HP at the wheels with my small valve, small carburetor motor.
 

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Discussion Starter #17
Pistons

I found some pictures of the pistons before they were machined. #2 was damaged and the blank was machined to match it. Later on, they were all cut down to give 10.6 to 1
 

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