This week I was able to tune my new 496 on an engine dyno. I was a little disappointed in the results as I expected about 25-30 more HP and torque. The test was run in warm conditions, high 80’s in Houston Texas so humidity was around 70%. Data is corrected.

Car is a ’70, auto, 3.42 gears, ~26” tires.

Engine specs:
454 .060 over
Forged crank, rods, pistons. Mahle file fit moly rings. Clevite 77 bearings
~ 10.25 CR
781 heads, port matched, runners & combustion chambers smoothed. 2.2/1.88 valves
Lunati Voodoo 60204 cam (hyd flat tappet)
Crane roller tip rockers
RPM air gap intake
800 CFM Edlebrock carb
Perf. Distributors custom curve HEI & LiveWire spark plug wires
Accel shorty plugs
2” headers
Timing - 14° initial, 38° total
Idle ~900 RPM - 14” Hg vacuum
180° t-stat. Water bypass closed.
93 octane pump gas

I was hoping to break the magic 1hp/cube and try and land around 525 hp 580 torque.

Output (max) – 565 ft lbs @ 3700 RPM
492 HP @ 5100 RPM

What I learned:
- 36 & 40 degrees dropped power
- Smoothing the intake with an airflow tube added about 5-7 hp. Need smooth air entry
- Cooling the engine to 100 degrees added about 20 hp & 25 ft lbs of torque!
- Valve float at ~5400 RPM

Plans:
Replace the heads with aluminum (rect. ports) sometime next year and shave the head to get to 10.5-11 CR. Move up to the Voodoo 60205 cam, single plane intake (like Victor Jr.), Holley or Demon carb. The street manners should still be good.

Engine builder agreed with the recommendations and added – “Just put it in the car and enjoy it!” Can’t argue with that advice. :thumbsup:

E.

Data (http://www.austintx.net/echristie/FTP/Dyno_Data.pdf)
Graph (http://www.austintx.net/echristie/FTP/Dyno_Graph.pdf)
Setting Timing (http://www.austintx.net/echristie/FTP/DSCF0604.JPG)
Ready! (http://www.austintx.net/echristie/FTP/DSCF0605.JPG)
Worth 5 hp (http://www.austintx.net/echristie/FTP/DSCF0611.JPG)

Still sounds like some good numbers. I'm in the process of building a 496 and plan on using a lot of the same parts you have. I've already planned on going with an air gap intake. How do you like it?

Still sounds like some good numbers. I'm in the process of building a 496 and plan on using a lot of the same parts you have. I've already planned on going with an air gap intake. How do you like it?

Seems okay. But...... it didn't set down flush on the heads. I ended up having to Dremel the outer mounting flanges about .06 on both sides to get it to fit. Tape the gaskets on the heads at the corners and place the intake down and make sure it fits flush. I don't know what heads you have, but on my 781s there is a ridge on the top of the intake side that was causing the interferance. Easier to grind aluminum than cast iron. Also easier to clean up afterwards. :)

Good luck,
E.

i figure a solid cam like it will give you more power EVERYWHERE b/c of it being a solid cam is all!

pdq67

Im planning to do something very similar as you. But after the recommendations by everyone here I went with the 60205 voodoo over the 60204. Wolfplace convinced me that almost 500 CI needs a lot of cam to breath right.

Im planning to do something very similar as you. But after the recommendations by everyone here I went with the 60205 voodoo over the 60204. Wolfplace convinced me that almost 500 CI needs a lot of cam to breath right.

My experience seems to support that. :)

Go for it!
E.

I wonder how much that carb is holding you back. torque looks great.

peak Hp seems a little low? Maybe the springs aint just right.

I wonder how much that carb is holding you back. torque looks great.

peak Hp seems a little low? Maybe the springs aint just right.

The carb is rated at 800 CFM. It has good drivability manners as well - very responsive. Top end might suffer. The dyno tech thought this as well, but mostly from a smooth airflow standpoint. We put an airflow meter on it and a WOT, it was right around 700.

I talked to both Lunati and the engine builder about the float problem. Lunati swears it is good fror 6400 RPM. The builder says he regularly sees BBC start to float at that point due to the weight of the valves. He suggested putting the engine in car and see how it does. He indicated many people reported to him that the problem is lessened in the car. He said he would loan me the spring tool to put .030 shim under the spring if I wanted later.

So, that's my plan.

E.

Eric,

I'm new to the site and live in Houston. While it's not apples to apples, I experienced something similar as well. The last engine I built for my old malibu, 400 sb, my first dyno runs were a little down. I was using an edelbrock carburator as well. After driving it a while, and it drove great, I decided to experiment with a holly DP. Just from bolting it on I picked up a full 20 horse power. These results were displayed, same day, on the chassis dyno. Maybe it was my inability to tune the Edelbrock.

P.S. did you have your engine built here in Houston? I'm new to the area and I'm in need of a recommendation.

Thanks,
Bill

Eric,

I'm new to the site and live in Houston. While it's not apples to apples, I experienced something similar as well. The last engine I built for my old

Snip...

P.S. did you have your engine built here in Houston? I'm new to the area and I'm in need of a recommendation.

Thanks,
Bill

Bill,

Yes. Send me a PM and I will forward you the details, who, where, etc.

E.

Eric,

I'm new to the site and live in Houston. While it's not apples to apples, I experienced something similar as well. The last engine I built for my old malibu, 400 sb, my first dyno runs were a little down. I was using an edelbrock carburator as well. After driving it a while, and it drove great, I decided to experiment with a holly DP. Just from bolting it on I picked up a full 20 horse power. These results were displayed, same day, on the chassis dyno. Maybe it was my inability to tune the Edelbrock.

P.S. did you have your engine built here in Houston? I'm new to the area and I'm in need of a recommendation.

Thanks,
Bill
I gaurantee ,the people at edelbrock (race enthusiest employees)use holley carbs!!!!

Eric,

I'm new to the site and live in Houston. While it's not apples to apples, I experienced something similar as well. The last engine I built for my old malibu, 400 sb, my first dyno runs were a little down. I was using an edelbrock carburator as well. After driving it a while, and it drove great, I decided to experiment with a holly DP. Just from bolting it on I picked up a full 20 horse power. These results were displayed, same day, on the chassis dyno. Maybe it was my inability to tune the Edelbrock.


Thanks,
Bill
=
Exact same experience, played with an Ede 750 on a 400sb half the day on my dyno, changing rods, jets, ignition timing etc,,,

Bolted on an old spider livin in, blow the dust out Holley I keep as a "test dummy" 4779 750
On the engine dyno, no other changes don't even know what jets were in the Holley.
15+ HP
To be fair, the Ede was very clean at low speed & the customer said it drove very nice right out of the box on his old engine.
But the Holley ran quite clean too (except for some unhappy spiders :D )so,,,,

I've got a 496 with the voodoo 60204 cam with 188 rectangle port heads. Max revs is about 5,100rpms. I'm happy with the results as a great reliable cruiser but if I had to do it all over again I would have installed the voodoo 60205. You will be happy with your motor either way.

Not to steal your post but, what does your motor sound like when the valves float? I have the same combo except with the 60204 cam and a 750 holley dp. My motor is crisp until 5000 or so then it breaks up. I have a msd 6al with a msd dist. My motor guy built the heads using the right springs, locks, and seat pressure.


Thanks Pete



PS what plugs do you use?

Not to steal your post but, what does your motor sound like when the valves float? I have the same combo except with the 60204 cam and a 750 holley dp. My motor is crisp until 5000 or so then

Snip...

PS what plugs do you use?
Imkman101,

Valve float sounds little like hitting a rev limiter, you can hear a rattle and the motor loses power quick and the revs climb slower.

I am using Accel shorty plugs - ACC-0576S.

Ratbones2002,

I agree. I think I will like it. :)

E.

Eric,still good power/trq #'s even though your not happy but i think there is more left in your 496 if you dial it in better esp on the timing side.

You stated your inital timing is set at 14 deg btdc which is too retarded for that cam by easily 4-5 deg.

Also,you stated you lost power at 38 deg total per dyno results.

So what i would do is bump your inital up to 18 deg btdc and get the mech adv recurved/limited to 18deg max for a 36 total to keep total under 38 where you said it begins to loose power.

Dialing in the additional 4-5 deg btdc intial timing with get you more low end to mid range power & reponce and keep the total below 38deg which will keep you from loosing power as you stated was seen in dyno testing at 38 deg total & above total.

The 496 with that cam should really like the additional 4-5 deg inital timing but the 14 initial your currently running is too retarded for that cam IMHO. I bet you had to back off the initial to get the total down to 38 deg which is not really the best way to go to avoid having to pull the dist to recurve the mech so you can run the correct amt of initial,you loose power & perf this way.

I would also have a vac adv installed (with 10-12 deg max advance) that is fully activated at approx 2 inches less then the lowest idle vacuum the motor has with 18 deg inital (not the retarded 14deg inital your currently running) and auto trans in gear. The additional timing at part thorttle cruise will help your motor be more respnsive down low,use less fuel,and maybe even run a couple deg cooler too.

After getting the mech adv recurved to 18 deg & adj the inital to 18 deg btdc you should then try hooking the vac adv to the ported/non vac port off the carb 1st ,then road test, then also try it from the full vacuum on all the time port to see which works the best. But listen for detonation esp when lightly accellorating from part throttle cruise at a steady speed when the motor would be more prone to detonate from the additional timing due to the vac adv. But the vac adv of 10-12 deg all goes away when the throttle is wide open when the intakevac drops below the activation point of the vac adv which leaves you with the 36deg btdc total which is below the 38 deg total that looses pwer according to your dyno results.

Try this this setup and i think you will gain some more low end to mid range umph and get some of the power/torque back you think your lacking.

Scott

What are the specs between the 60204 and 05?

60204- 276/284 233/241 .554"/.572" 110/106 2200-6400



60205- 284/292 241/249 .572"/.590" 110/106 2500-6600

Eric,still good power/trq #'s even though your not happy but i think there is more left in your 496 if you dial it in better esp on the timing side.

Snip...

Try this this setup and i think you will gain some more low end to mid range umph and get some of the power/torque back you think your lacking.

Scott

Scott,

Thanks a bunch for the advice. I put some thought into what you suggested and I think based on the dyno runs, you might be right. Since the engine isn't yet and I have to pull the distributor anyway to install the engine, I'll send it back and have them modify the curve to keep me at 38 total.

There is a vacuum advance on the dist but I don't know how much it advances.

Once I have the engine in the car, I will try your suggestions.

I really appreciate your feedback!! :beers:
E.

Eric,the dist shops can tell how much the vac adv is giving you and if its too much they can install a vac ad with only 10-12 deg additional adv thats fully activated at 2 inches less then the lowest idle vacuum with 18 deg initial and auto trans in gear.

Let me/us know how you make out with this timing setup,it will be very interesing to se how your motor responds to the addtional initial timing when it comes to the bottem to mid range power.

Scott

Eric,one more thought.

Your running alomst 500 cubes which is a big motor with a conservative 800fm carb.

I built a 469 Poncho with poterd ram air heads,11:1 comp,292 comp cam,edel trq intake and 750 holley,headers in a 69 bird with 4spd & 373 gear.

At his 1st time ever to drag race it with headers still hooked to ex and having traction issues and learning curve he ran 12.6's.

I felt it was under carbed for opt perf so i suggested he buy a 1050 dominator (no choke) and man you could really feel the power/trq gain in the seat of our pants on the street,it was substantial for sure.

With just the carb change the car went from 12.6's to 12.2's and went 12.00-12.10 with open headers and street tires . With slicks,open headers,and more experience he could maybe do high 11.90's.

We got the 1050 dialed in well and it runs fine on the street too.

Point here is i think your under carbed for your 500 cubes/motor setup even on the street.

I think a 900-1050 cfm dominator dialed in correctly along with the ign timing curve i suggested could conservatively gain an additional 50-60hp/40-50 lbs trq for you motor.

Scott

Eric,one more thought.

Your running alomst 500 cubes which is a big motor with a conservative 800fm carb.

Snip...

I think a 900-1050 cfm dominator dialed in correctly along with the ign timing curve i suggested you could conservatively gain an additional 50-60hp/40-50 lbs trq for you motor.

Scott

I like the way you think Scott!!!! I will put that on the to-do list. I think I will get the engine in the car and running, make some baseline chassis dyno runs, and start tweeking. Seat of the pants will tell me if I am on the right track and then back to the dyno for fine tuning.

Based on feedback from many on this thread, the 800 is going to have to go. They run great on the bottom end where most of the driving is, very response. However, in the quest for the almighty HP..... Somethings gotta go. :)

I've got this thread copied to a document so I can find it easily later on.

E.

Looks like Westside...I've dyno'd several motors there. Good folks.

You're right in that area where you've found out how hard it is to feed a big motor. A REAL NICE set of oval ports with good porting will handle it pretty well, but it would have to be a nice set.

When you move into the 500"+ territory, everything you've learned about cams and heads and intakes ahs to be re-thought. It takes bigger stuff and it will still drive nice.

Those two cams are WAY too small to work in a 496 to me unless you're happy with the RPM range you're dealing with. I would do something about the valvefloat issue now, not later...because it is easy to overrev a BBC and hurt stuff when playing on street tires. BBC's don't like have valves bouncing around..stuff breaks.

I'm not a hyd cam lover at all for toys like this....I'd go with a good flat tappet solid. You won't ahve to adjust valves very often if you get one that isn't too crazy and it will defintely run stronger. I'd be in the .620-.640 lift range at least and in the 255-260* range with a solid cam.


I woudl throw a Holley HP 1000 on it and it would run great. I have done it several times on this type of motor and it works great.


JIM

I gaurantee ,the people at edelbrock (race enthusiest employees)use holley carbs!!!!

I used to know a gentleman I say used to cause he passed on last year. He was great with eddy's had been useing them on his motors for years. He could tune them and make them run better then anyone I knew but he was older and had been useing them for years since before I was even born he was also good with Q-jets. I tried to learn from him but never could get it right. So I would say it is all about the tunner and what he knows best. his dual quade setups and tunnel ram cars ran great I seen ppl bring him small blocks and big blocks alike that others couldnt get right and he would tinker and tune them changine rods jets and tweeking springs and linkage and the things would just scream. So like I said I believe it is all in what you are use to tunning.:yes: just my 2 cents.

A cam in the 260's @.050 intake and 1000cfm carb will put your combo around 600, CHP built very similar engine and put up over 600HP,

Please consider this solid lifter cam by UDHarold made for my about 9.8 to 1 CR., 496.

It's a max midrange grunt cam is all!

278/249/161, 110/106, .618" and need's .018" lash on both sides!

I'm figuring above 600 hp....

Imho, Harold FLAT know's how to create a max. GRUNT cam like this!

pdq67

Agreed. I am probably going to be happy with the 60204 for a while. I knew after I dynoed, I should have gone with the 60205. But, oh well.

Maybe a roller or solid lifter will be next. I have only dealt with flat tappets up till now. My recently rebuilt '93 LT1 has a roller in it from the factory. It's a nice set up.

I did a lot of reading and wanted something reliable, good street manners, good vacuum. Now I have a benchmark with this engine, I can move up as I see fit. I don't pretend to know more than UD or some other folks on this forum, but I am learning. :hurray:

E.