Seeing as how my WideBand O2 is not working and has been sent back to MSD for warranty replacement, I decided to take the car in to a chassis dyno for tuning. I beleive that the WideBand over time was inaccerate before it finally died. Come to find out I was right, I was not correct.
We did not tune for HP alone. I wanted fuel mileage to be more important than HP but not everything. Obvously I didn't want to give up alot of HP for a very small gain in mileage. We weighted the two goals at 65/35, mileage/HP, with mileage only a little more important. The uses of this car have changed and so has the setup.
A little back ground info:
Rear gear WAS 3.55 NOW 2.94 and soon 3.07
converter 3200 which I can foot brake when warm to 3200. Dosen't flash above that.
rear tire 26.1"
570 Carb jetting WAS 54s pri 58 sec NOW 59 pri 58 sec idle screws backed out about 3/4 turn. Purple secondary spring.
Timing WAS 25* total NOW 23* total. Intial on both is 19*. Note 25* made no more power than 23* but during heat soak seemed to be a very slite ping. 93 octane.
You may notice that the idle is a little on the rich side. It seems to like it. It dosen't start very easily leaned out.
Dyno sheets to follow:
This pull is as discribed above from an idle to full throttle. (pounding it to the floor)
page 1 idleing
http://tinyurl.com/267brg
page 2 Mostly idleing and the start of rpm climb
http://tinyurl.com/259bph
page 3 well into it
http://tinyurl.com/ypzucf
page 4 well into it more
http://tinyurl.com/yseooa
page 5 taper off
http://tinyurl.com/275n5r
page 6 max outputs
http://tinyurl.com/yuww9t

We only pulled it to about 4800 -5000 rpm because it stops climbing from there.

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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

Looks pretty mild mannered. You could probably go with a little lower stall converter looking at those torque numbers.

Does it seem kind of weird to rev it so much before it engages? What is like to drive around town? Do scare folks at a stop light?

What cam (lift and duration) did you put back in it and how much did you advance it?

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

did you notice much of a difference in acceleration after the rear end swap?

I'll start moving from a red light pretty good around 1500 rpm and at 2000 I'll pull away from the other cars. Of course if I nail it it'll jump up to 3200 and leave pretty hard.
There was a big difference between the 3.55 and 2.94 gears. The 2.94s where used and are noisy. They would be staying in if they where not nosiy but they are so if their coming out, 3.07 are going back in. It'll still cherp the tires off the line with 235-60-15s. It not bad at all around town but if I where to change the converter I'd loosen the idle up a bit and tighten the stall to 2800. I might not touch the idle spec.
My signature is correct and thats where you'll find the cam specs. Advanced 2*

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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

I'm still having a hard time believing either your dyno numbers or your buildup... (not taht I don't believe you, hope you got what I'm saying here, wich is that for that amount of work and money you should have a 320 hp - 350 lbs/ft peak torque engine)

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

How are you coming to this conclusion? I suspect its true, but I would like to hear your thought process.

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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

I really wish I had flow tested this head when I had it off during the compression reduction process. Its got to be the problem. I can understand that the exhaust setup is not ideal with the Dutra and cut manifold being wyed pretty close to the manifolds. http://tinyurl.com/328c2r But I can't believe thats killing it that bad. The rest of the exhaust is 2 1/4 all the way back. I don't beleive that adding a header and 2 1/2" exhaust will bring out the missing 100hp. I know that the Clifford intake flows a little more than the Offy. I really just don't know why. The head didn't look great but not hideous did it?
http://tinyurl.com/2rggyg
http://tinyurl.com/2sr8cy
http://tinyurl.com/2qdxen

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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

kinda ugly in my opinion,sent Dutra a head I did,thought it was a 10,he gave me a high 7,so this is just my opinion,mark

I think this is all pretty cool. I love your web site. And thank you for sharing the photos with us. Would you mind giving us a little tutorial on what the various colums on the dyno sheet mean? At the bottom it says max, but then as I look up the column I could not see that figure anywhere. Also, I don;t know what the abreviations mean in every case. Oil temp and lambda are pretty self evident, as are speed. What are the others? Thanks.
Sam

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Bren,
Some thoughts............
Looking at the torque numbers, you could go to a lower stall torque converter. They are fairly broad, and not very high for the stroker crank and the horsepower is low. My build is not too far down from these numbers. I am around 160 HP with a vary wide torque band that is very punchy.

I would think that tuning the exhaust to let it breath more and build another distributor to where it has more timing potential and advance would change your output allot. You mentioned you wanted some mileage. The way you have the distributor built is for drag racing, ... it just dumps all at once and thats it... So the engine is tuned for drag racing with that distributor, but you don't have the exhaust (flow) and carb to go with it.

If your going to run your exhaust system the way it is, build another distributor and put some springs in it and a vacuum advance and limit it if you want to 30 or 35 degrees and let the vacuum can kick in late to give you a little more extended punch. You could have a pretty snappy set up that way and get some good mileage too. Save your current distributor for drag racing.

This dyno is allot nicer than your first dyno runs and gives some nice real world numbers. Wished I lived closer so I could run my car on the same dyno and let you take mine for a spin. I just need to make the jump to a 4 barrel to unleash some of the hidden power.

I just thought your dyno numbers were off from all the work you have done to the engine. I seems like you have limited the output with your set up: with the carb, the exhaust and the distributor you built. It will be interesting to see your future modifications. Keep us posted. There is more hidden potential in your motor!

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Nice post Sam, And I agree Bren, even thought it may not always be a warm & fuzzy feeling when posting results, your info on your build is well documented & appreciated.


Well I guess you already know my thoughts on the head. In the last 10 years there has been great advancments in the combustion chamber & ports. And a lot of times it was a surprize to see what works & what doesnt. It really is almost unbelievable to see some of the very small changes that made hugh improvments, or even losses in performance.

You would not believe the number of heads that have surfaced with a lot of major porting & chamber work just to find out they didnt even work as good as the stock casting, much less work anywhere near a head that was done by someone knowlagable with the correct tools to know when they get it right.



Its hard to look at pics on the internet and know, or make a judgment on what is being looked at. But a few things do stand out, and I am sure there is much more going on than I can see. For instance, the pic #52. The chamber at the far left you can only see the intake valve. That valve is sunk very deep in the seat & you can see rough gring marks at the upper edge above the valve. There is no way for that to flow any kinda even or desent flow, much less have any good wet flow characteristics. In pic # 54 as you look down in the ports it is easy to see the bowl work, and the short turn radias is just a mess.
When looking at the ports its hard to judge the size to know if there is any kinda possiblity for any good air velocity, but from just looking at the pics it looks like they would be very lazy ports to me. This is something that is hard to achieve even with the right tools, so a judgment from looking at pics is not anything to really be going by. One other thing to piont out about the head, is the inconsistancy I see between each valve & port. Trying to tune a engine with a head that is that defferent between ports & chambers will drive you nuts.



The bottom line is that it takes very skilled people to pull off what is needed when taking a head to the levels you are needing. There is no way a cut & gouge job like this is going to work on a N/A engine that has special needs such as yours. A turbo engine could get away with a little bit of this type thing just because it can force the air through even though its not efficiant.


You ask about headers & your Y pipe. This setup would be great for most /6 engines. Infact the DD exhaust may be more than most /6ers need. But your trying to feed a lot of CID (bigger engine) than most. A good header & exhaust design will create more intake flow (thats what I said, More Intake flow). This is what is so important about exhaust when trying to feed a high RPM, or big cube engine, and even cams with overlap. Head port design & a good exhaust "CAN" add 100hp in many cases. This combined with the right camshaft can really make or break a engine. No I dont think with these changes you will gain 100hp, but 50 to 75hp may be possible plus a insain torque curve.


You need to be talking to people at the level of such places as Modern Cylinder Heads, or Best Machine Shop when looking for good cylinder head work. I am sure there are many others that can do the job, but when working with local people you have to know who can & who cant. I have a real good guy here local in my town, but its easy to see when you go to his shop that he is able to do the job. One thing right off you look around and he has many NHRA trophies setting around & a shop that is to dream about. Now it doesnt take someone with multy dollar setups to achive good port work. But you can bet that the ones that have the skill will have many other racers running around with there work on there cars to prove that they know whats going on.


It gets expeincive to ship heads around for good work, but if it was to come down to that there are quit a few guys in reputable places with the reputation to back there work, that can supply great head work that will incress the power on your setup, and at a affordable price. If it was me, I would get a good header for the engine & take it from there and see how things go. The exhaust effects things much more than just getting the exhaust out. I feel like it will help your setup a whole lot, and change the tuning needs, plus pull more upper RPM power into the mix without loosing any low end at all, infact it will probably incress the low end also.


As far as the dyno sheet, you might want to remember that you have installed a higher stall convertor. This will make a engine show less than it would before. Although it will show less HP, it is still good for tuning and finding the right timing & fuel needs. But even then more tuning is always needed when you go to the track, the dyno gets you close, but not exact. MPH is the best guage of power you can have when tuning. ET tells you nothing about the engine, just the car & suspension, always go by the MPH when tuning. Plus when you make ajustments to the car to leave the line better, the MPH will always drop when you incress the 60ft time from things like convertors & tires.


I wish you would of had the head flowed when you was part last time, but I understand you was hoping to find all the improvments when you got the engine to quit detinating from the high compression. The truth is you might gain more detination resistance from a good header & exhaust than you gained from lowering the compression, but that depends alot on just how good the head works also. If the ports are prone to reversion the header will still help alot, but the ports will hold it back alot also. Its not just all about big open ports in the head, ports like that will almost always kill power.



Jess, hope this helps.

Thankyou about the website. I just cut and paste pictures in an Album directory and hit Publish. My brother saved all the password/location stuff and if the computer where to crash or something I'd be clueless as to how to make it work again. (fingerscrossed)

1st colunm is Engine RPM
2nd Chassis/Wheel HP
3rd Estimated Engine HP based on 18% drivetrain loss.
4th Chassis/Wheel Torque in LbFt
5th Speed calculated from the dyno's drum speed.
6th Oil Temp. (no sensor was hooked up)
7th Air Fuel Ratio (sensor was installed in head pipe in a bung that I provided)
8th Boost (I don't have forced induction, so no sensor was hooked)
9th Fuel Pressure. (no sensor was hooked but I was running at 4.5psi)

The Max values can be found on image 70 http://tinyurl.com/ypzucf These high max numbers I feel where a result of the engine "bouncing" off the stall of the converter.

Lucky13
Your post has been very informative and helpfull. I am sure you have told me most of this before, but sometimes one needs to increase ones knowledge to a certain level to begin to understand, and some of it rejected because I may have felt that my goals/needs where not being taken in to concideration. ie - street driven, ect.

I can't bring myself to "throw out" this head and start over. If the head gets thrown out the rest of the motor goes with it. But lets say that something could be done with this one. What would something like that cost roughly? I mean it s allready got oversized valve and fits my bore. I realize that it may not beable to be saved completely in that it may not be as good and a virgin core being worked, but I am sure it could be made better, maybe even alot better.

What header would fit my car and what one should I get? (long, short, brand). Anyone want to trade an Offy and Dutra/Cutoff setup for header and Clifford manifold.

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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