Thats a really nice tool to have!

I'm sure you know this already, the readings at idle will likley be rather rich since there will be unburned fuel in the exhaust with a hotter cam at idle because of the overlap. It will not end up in the 14 plus range that it will at cruise. So that reading you have may not mean the idle is too rich but may just be raw fuel in the exhaust.

11.7:1 seems really, really rich for an idle. My EFI idles at 14:1. 12.5:1 is what they recommend for WOT under boost. I would think 11.7:1 would put out the flame and kill it.

What kind of wide band O2sensor and gauge did you get? Can you supply us with a link or a dealer? What kind of gauge face does it have? Is it round or square.

Sam

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Link is provided 3 posts back.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

Thanks, I did not realize what that link was for. So kind of ignored it. Does your A/F gauge start to give you accurate readings right away after you start up the engine, or does the sensor and gauge have to warm up? My somewhat quirky wide band gauge does not read anything for about 25 seconds, and then seems to give questionable results until the engine has run a bit. This makes tuning during warm up a bit of a guessing game.
Sam

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Its a heated O2 sensor and gives readings after about 10 sec.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

So, how is this car coming? Any info or work been done lately?


After doing some studing & research, I feel sure you are going to have trouble. 230 psi is just to much for pump gas by a long shot. With some of the best combution chambers & preperations for high CR pump gas engine 200 psi seems to the pushing limits. I supect that the little /6 is not going to manage that much.

One thing that was adviced about earlier IMHO is the wrong direction. Retarding the camshaft has the possibility of helping alot. I not only think that it being advanced is hurting your power, but I think it is adding to the high CR psi & det problems.

Personally I think a new cam grind from the right person will bring your engine to life. Maybe as much as 50 more hp. But it will also tame the engine down & make it live on pump gas,get better milage, and have a much better power curve. There is very few people I trust with this type of grind, and the big companies are not one of them (uness you have good connections within the company).

I would try retarding the cam, it can be done & do cranking CR checks as you try deferent degrees of retard, without putting the front back on the engine. Alot of work I know, but I feel something is going to have to be done. Running race fuel is a very expesive thing to get into, and will take away from the enjoyment of the car.


Jess

Retarding the cam will lower the cylinder pressure (CP) but not by 30 to 50 psi.
I have set cam timing by the CP check method discribed above and you can see anywhere from 10 to 30 psi, depending on the cam and static CR of the engine you are working with.

Resetting cam timing would be worth a try but I suspect that you will have to retard the cam timing a bunch to get the CP psi where you need it for pump gas. Remember, a retarded cam looses a lot of off-idle / low RPM responce but picks-up high RPM abilities, not really what you want with the stroker SL6 running on the street.
I do agree that a well engineered cam could be the solution but you will have to find a knowledgable grinder willing to work-out the lobe profiles and grind. If it were me, I would get a different cam and try an in car cam swap... do some cam degreeing and run the CP tests before and after the cam swap. In the end, you may find that you still need to take some static compression out of the engine.
DD

While the right custom grind might make it work with pump gas, it would have to trade off something, somewhere. To get it right you would still need to know what your compression ratio really is to get the cam designed.

You have put so much into this at this point that it would be a shame to do and spend more on a patch job type of repair. No matter how much another cam might help most of the time, it will at some point be in it's peak torque range at full throttle and will need octane to match the compression ratio. The cam can only negate the compression by letting pressure bleed off or not letting as much charge in, that means a lower VE percentage. This is totally against the whole goal of building a high performance engine.

If you look at it from a blank sheet point of view you would never consider a too high compression ratio and whatever the cam grind that is supposed to fix it as part of your planned combination.

I would gather all the hard facts you can. Find out what the real compression ratio is even if that means pulling the head. It's not that big or very expensive and you will be on the road to a definite fix, not another expensive experiment. Then take a hard look at actually fixing the actual problem in the best way. Best case would be some chamber work. Next best some piston machining and new rings (but would still need a teardown and honing) Worst case would be another block, machine work, rings, cam bearings, gaskets etc. and some assembly work.

Another option might be to get some good money out of your head on ebay and build another one, leaving the engine in the car and saving all that work. You could get the new one done first and it might even be better and less expensive than the first if anything you learned along the way can be incorporated. Your out of pocket might not be bad at all with this route.

Trying to take the easy way out is fine if you will be happy with it. It looks to me like you did not make this effort just to settle in the end. I would also look at doing the work yourself if you can. Spend money on tools, not someone elses half hearted labor. At least you will always know what you have then and doing it yourself is half the satisfaction.

You have large valves in that head. Were the chambers swept araound the valves?

If this was not done I would consider radiussing the chambers around the valves and increasing chamber volume. Its your best shot at lowering compression and increasing flow.

My machinist buddy and I swept all 6 chambers and balanced chamber size in 6 hours on an old Victoria vertical mill. ....then I sent it to have the valve work done.....

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Not sure I know what you mean. The cambers where cut bigger to match the bore size. Behind the valves where enlarged to match the larger valves, but this is behind the valve and should'nt effect CR. The head was shaved only .012 to true it, so a new head likely could not be shaved less to give lower CR. If I pull the motor part and measure it again it won't lower the CR. It has 65cc cambers and its 7 in the hole. If its not 7 in the hole its at least a zero deck. There is light under the straight edge at TDC.
Moving on a bit. I am not totally against running some mixture of 110 and 93 octane. Total timing is set at 27 degrees and the carb is now very close on its tune. I install Autolites 64 which are 2 ranges colder then the stock pluges that I had. I am going to start mixing back in the 93 to see if the detonation returns.
By the way I just got back from the dyno. I still have some off the line richness to work out (carb cams). After grinding the only cam I had its alot better. Not right but better.
The results:
http://tinyurl.com/2tnqw2
http://tinyurl.com/357lmo
http://tinyurl.com/3apxmm

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

The lastest FX1 performance computer results.
1/4 mile 16.05 at 87.6
1000ft 13.47
1/8mile 10.42 at 69.8
330ft 6.9
60ft 2.47

Alot better but still have start bog and a little vac secondary bog.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

You are making progress now.

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Official Cookie and Mater Tormentor.

YouTube Chassis dyno video.

http://www.youtube.com/watch?v=DKIXT_0v2TA

Notice the spray of coolant from the bursting heater block off cap on the water pump.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

If your having trouble read the dyno sheets, I have at the wheels, 158HP and 227 ftlb torque. Adjusting for drivetrain loss of 25%, it puts me at 210HP and 302 ftlb torque.

I am suppost to have a 2500stall convertor. Can someone tell me how to determin the stall?
Idling at 1000rpm and in gear the car tries to move forward. A little gas and at 1500rpm its really hard to hold back. I haven't stood on the brakes and watched the tach, well I have but I don't remember what it read, but it was well below 2000rpm. I'll have to try that tomorrow and take note.
Shift points:
Letting the trans do the shifting is the slow way down the track. (shifter in D) The dyno guy and I went for a test drive on there semi closed "drag strip" which is basicly a dead end street. We did a couple of passes with the shifter in Drive and thought it was eghh good, just OK. He said it would be nice to extend the shift points out a bit. I said I should be able to do that by manualy shifting and we went back for another run. A bit of a hesitation of the line, at 5500 and still pulling I shifted to 2nd, the 1st to 2nd shift has a little delay in which I hit the rev limiter at 5800rpm for just a split second and then 2nd came in which barked (not chirped) the tires and ran 2nd gear out half way before the public "drag strip" was entering well, the public. The tuner guy said "well you got something here now!!".
I cruise around on the highway at about 3000-3100rpm. I am thinking that a 2800 stall convertor would be right for me. If it where going to be a drag only car I would think higher but it is driven on the street.
On the dyno using there simulated 1/4 drag strip, the best time was 15.3 at 90.2mph. We let the trans do the shifting during these runs. I/we didn't think to shift it manualy at this point. Keep in mind there is no air resistant in this simulation.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

See, now you are learning more.

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Official Cookie and Mater Tormentor.