Mile High Perf Dyno Tune 340

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RLF Cuda

RLF Cuda

Barracuda Bob
FABO Gold Member
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Jan 7, 2012
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Location
Aurora, CO
This week I finally got my 340 dyno tuned by Mile High Performance in Englewood, CO. Totally satisfied with the work they did. The engine is a +0.020 1969 340 block with Sealed Power hyper-eutectic pistons at a measured 9.8:1 CR. Heads are mildly ported X heads with the factory cut undercut cleaned to the port, and port matching only. The engine has a MP 284-484 cam and Edelbrock Perf RPM manifold with blocked cross-over passages. The car has TTi headers and 3:55 gears with a 727.

I am now running a 440 AVS carb, but originally ran the 340 AVS. Prior to the tuning session, I tried to get the car running at 5800 feet with poor success. At Brandimere, it ran a 16 flat at 87. Quite poor for this combo. It pulled to 6500 rpm, but was really flat and lacked power most of the way up.

The before dyno run showed 241 HP at 5500 and 320 lb-ft torque at 3500-4500, falling off after that. Peak HP was 290 at 5300 with a sharp decline to 241 after that. I will try to attach the dyno chart later.

Jay at Mile High worked on the car for two days which include fixing a bad batter cable, dead batter and broken (literally) water pump due to a bad fan balance. The after tune HP was 335 at 55000 and good power to 6200, and a remarkable 360 lb-ft of torque from 3400-4500 and some decline up to 6200 where he stopped the pull.

Before, the carb had a very bad off idle stumble and the idle mixture was not responsive. After Jay drilled the cluster metering hole slightly, the carb was responsive to idle mixture and the stumble was gone.

I recommend Mile High Perf (aka The Carburator Shop) in Englewood very highly. First class work.

Regards,
Bob
 

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Your dyno was done in the car correct? So that means at the flywheel you are putting aout about 17-20% more than those numbers right? Also are the dyno #'s altitude adjusted?

Seems like a strong combo you got to get back out on the track!
 
Yes, it was chassis dyno, so the power is as much as 20% below flywheel power. And all power was corrected to sea level.

Bob
 
This is excellent, I was looking for a place to take my 1970 Duster with a fresh 360 Magnum for a dyno tune and I live in Denver. Mind revealing how much it all (or each service) cost?
 
dyno time was $550. this included multiple disassemblies and adjustments of the carb, and drilling the booster for proper fuel delivery. The drivability improvement and power increase were really worth it as I was not able to fine tune this much power into the setup myself. The car was on the dyno for two days (with some other repair work done in the mean time). They were really good to work with.
Bob
 
RLF Cuda said:
dyno time was $550. this included multiple disassemblies and adjustments of the carb, and drilling the booster for proper fuel delivery. The drivability improvement and power increase were really worth it as I was not able to fine tune this much power into the setup myself. The car was on the dyno for two days (with some other repair work done in the mean time). They were really good to work with.
Bob
Click to expand...

Cool thanks, looks like I'll be hitting them up here once I get my fuel delivery issues sorted out. BTW I'd like to meet up sometime and check out your Cuda, I could drive my Duster down to Aurora and show you that as well. I happen to have a 284-484 cam lying around and was curious to see how it might run in my 360 instead of the small Lunati Voodoo I have in it now.
 
Looks like a good runnin 340! My 340 also runs outta steam around 6200-6300. Natural rev limiter.
 
I will be taking the Cuda to Brandimere on Saturday, hopefully. Will let all know how it ran. But I only have 245-60x15's on the rear, so traction will be limited. And did I mention that these tires are about 20 years old as well? Hope they don't blow, but they did work last time I went to the track. Time for some slicks.
Bob
 
Sounds like the cuda will be running a ton better. I bought a 750 DP carb off Craigslist that was tuned by mile high perf, and I'll tell you what I bolted that carb on(off of a Chevy 383) my 360 and went from 95 to 98mph at bandimere with out no tuning. Are you going to the big mopar event on June 3? I will try and make it then. Saterday looks like good weather for you :)
 
Disappointing runs at Brandimere. Best was 15.4 @ 93. I suspect that sometime in the past the vibration dampener slipped as one last year I found the initial timing 20° retarded. I changed the distributor drive gear to compensate, but that was not the root cause of the problem, and probably masked the issue. I need a TDC tool to validate the timing marks on the dampener and do a root cause analysis to be sure all is well with the engine.
One clue is that I show 15° initial and 40° total with no detonation. The small blocks are supposed to run best with 35° total, so something is amiss.

Any thoughts out there?

Thanks,
Bob
 
OK, Time to figure out why things aren't working like I thought they should. The car has low vacuum, poor throttle response, and doesn't ET like it should for having 330 rear wheel HP. Time to do some basic investigation.

When I moved to Colorado from Tulsa, the car didn't run well. I found the timing way off and thought the distributor had slipped. Reset timing about 20 degrees.

But the car acts like timing isn't right. Poor throttle response, overheats (runs 190 with 160 thermostat), and doesn't have good low speed power.

So, first thing to check is the timing mark. Purchased a piston stop and found the vibration dampner is off by 20 degrees. That explains the "slipped distributor". So, if the engine made 330 rear wheel HP with final timing of about 20 degrees advance, think of what it will do with 35 degrees!

Need to order a new SFI vibration dampner to replace the 40 year old one, and then see how it runs. Should be impressive with close to the right advance.

I will let you know how it turns out.

Bob
 
That's great you figured out the problem, did you try adjusting the timing by that amount to see if it ran better? I have the Summit damper on my 360 btw and it's pretty nice, timing marks all the way up to 60* BTDC and a removable counterweight so it can be swapped between internal- and external-balance engines.
 
Love this thread, thank you. I'm at 6250 ft. with a similar combo but a 360 in a duster. Ported X heads, 3.55s, LD340 intake which is similar to your eddy rpm,headers/H duels, 284/.528, but 11:1 comp and a 750. I say increase compression. I ran 14.7 at 96 and after 5500 rpm it gets a little flat.
 
I have a 360 dart with rhs heads, 9.5 compression, 219/221 dur cam, air gap intake, 750 dp, headers, 2 1/4" duals, 3.91 gears and a 1.92 60ft. I ran 13.8@98 at bandimere :)
 
I brought the car in with it running OK, so they didn't have the info to know that the dampener had moved. The mark was at 15 degrees before. It was my fault I didn't catch that the dampener had shifted. I had moved from Tulsa to Denver, and when they unloaded the car from the moving van, it didn't run right. Thought it was the altitude. Found the timing mark was way off, so I moved the distributor to compensate, and it ran worse. I got the carb adjusted so it ran OK, but I was fighting poor off-idle performance for a long time. I suspect that the ring was slipping on the rubber for a while and I kept adjusting the distributor to compensate, making things worse and not fixing the problem. So I can't fault Mile High for not catching this, but they are going to put it on the dyno again once I get the dampener replaced.

I should have the dampener on Wednesday, so I will report back then.
Bob
 
Well, work and business trips have delayed further testing and investigation of why the engine isn't performing as expected. Did a compression test and had varying results. ~120 PSI in most cylinders, but down to 107 in others. With 11.9 PSI atmospheric pressure at 6000 feet, probably not bad. But I needed to know why the low pressure in #7. So.....

I built a leak down tester (~$30 in parts from hardware store, I can provide details or build you one if desired). Using 80 PSI feed pressure, most cylinders had 79 PSI after the orifice restriction. Not bad. But #7 was 72. Oops, leak. Sound of air from exhaust port confirmed it was a leaking exhaust valve.

So.... I pulled the head. With tti exhaust, I wanted to not pull the headers. On the drivers side, if you remove the steering column, you can move the header enough to get to the head bolts w/o the hastle of removing the header completely.

Once off the engine, I put solvent in the exhaust ports and found leakage around the valve seats of several valves. Disapointed as I had a 3 angle valve job done (years ago when I lived in CA). I took the heads to Colorado Custom Heads in Englewood. They will inspect and report back. I will post what is found.

I inspected the FelPro head gaskets and found no evidence of leakage. I want to increase compression ratio to compensate for the high altitude, so I am considering 0.020" thick head gaskets. Mancini has several to choose from at 0.024" compressed thickness. Any suggestions from FABO memebers?

I also noticed that the bottom of the intake manifold gasket may not have been compressed against the head. The manifod is an older Edelbrock Performer. Small intake ports compared to my gasket matched 340 heads. I am seriously considering an RPM Air Gap to replace the old one. Thoughts?

With all these issues with the engine, I am surprised that the dyno showed 330 HP. Colorado Custom Heads said I should pick up 10 more HP with good compression in all cylinders. That would be great, especially if I get the low-mid range perforamnce back. I also want to see the vacuum increase from 6" when I took the heads off to something like 9-11". I do hope that the manifold leak was the cause of this, but I coulldn't determin if the gasket was really leaking or just looked like it was not compressed. I did seal the gasket to the manifold with Copper Coat to be sure it didn't move during instillation, and it didn't move. It came off the head cleanly.

Any other thoughts on this would be appreciated.

Bob
 
A performer rpm is the same as an airgap but without the airgap which will help keep your carb warm with engine heat due to how high your up there id go for the performer rpm
 
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