What an experience! Should have brought ear plugs and a heart monitor.

(see sig photo with spec info below)

Today the 1970 Corvette was put on a dyno after a number of engine mods
were done earlier this month. The dyno work was at Schatz & Krum in
Sacramento. This is my first experience at a dyno test. My heart was
pounding most the time. Bizarre/wicked to stand next to your car with
it "going" over 110MPH (automatic with 3.55 gears) and making very loud
noise out the exhaust - that's what those rustangs hear as I zip by....
Stu was super to work with.

"As arrived" I knew the car was not right. I had the timing VERY
advanced. At full advance it was 44 degrees, idle was 27 degrees!
Why? Trying to get a good idle. Learning experience. This is the
first car I have owned with a serious cam. Until today, I did not
realize how it was supposed to "idle". "As arrived" the car put out
244HP at the rear wheels at 110MPH. I was not pleased with the numbers
although the car was running pretty nice (I thought). The good thing
is the sensor showed the carb was dialed in, but a suggestion was made
to change the metering rods one size.

So, it was time to address the timing. Testing in 1 degree increments
showed the best performance was at 31.5 degrees of full advance.
Horsepower rose to 274 at 112MPH and 5200rpm. The curve is very
interesting. The HP is climbing all the way to red-line - not flattening
out yet! So the engine is at about 365HP. (Hmmm - a roller cam and
stiffer valve springs = higher rev....right?)

Now I have a cammy idle and some work to do. During one of the pulls
the A/C belt came off, tangled a bit, broke, kicked off the power
steering belt. A scary moment. I need to get a 59.5" belt and remove
the valve cover to get it installed. And the alternator mounting needs
to be improved. I was aware of both of these issues but did not expect
it to bite the dust like this.

So, a fun day. Good investment for getting 30HP, more torque, and
knowing it is set up optimally. Dyno was also reading 445 on torque.
Wonder what it will do in the quarter mile?

And of course I asked, "What should I do to get more HP?"
Answer: smaller carb or get a TBI system.

I also drove a C3 with an 1800-2200 stall converter today. I want
such an enhancement! Hello tax return (I hope!)!

:D Go fast :D,
Jim

 

Jim, that´s something on my to do list for the future.
Did you operate the car during the dyno run? or did sombody pull the throttle cable of the carb while the hood was opened?
Did you make a motion picture of your dyno run?
Any photos that show the car on the dyno?
And most important, how much noticeable was the improvement after adjusting the timing and carb properly?
Markus

 

WOW! That is amazing to get 30 extra RWHP by optimizing the timing!!!
I guess it is a lot more efficient (and accurate) to make those adjustments on the dyno rather than at the strip. You would have needed quite a few 1/4 mile passes, adjusting for your launch, etc. MJ

 

Markus,
I have photos of the car on the dyno - will post tomorrow.
The car is operated by someone inside the car - I did a few during the timing checks which were done at 80MPH. The whole thing is incredible.
Off the street, if you just come in, do 3 pulls, and leave, the cost for this is $65. With the added effort on timing and carb setting/verification it cost me $150 - worth every penney.

My camera does small video clips- I did not do this - too focused on the activity. I do havea video fo the start up after the top end rebuild - dang loud - as I just ran headers - but that clip is 10MB.

Jim

 

Wow sounds like you had a good time at the dyno session. I wouldn't be surprised if you pick up another 10 horse or so after your motor loosens up a little more. Remember to change oil after runs like that, to get all the little bits out. :cool: :cheers: :seeya ..........

 

Awesome results. I hope to get something like that out of my rebuild. Congrats. :smash: :cool: :smash: :cool:

 

I ran my car on a dyno last year. Yes its loud. I never knew my vette could sound like a race car! I had never reved the car above 4000rpm until the dyno. Took it all the way up to 5500rpm. I'll have ear plugs next time. I was a little nervous that something was going to fly off the engine or my rear end would come to a grinding halt. After a couple of pulls and more confidence that my car was up to the challenge, I really had fun. I picked up about 20hp and 15lb-ft torque by dialing in the carb and timing. I also found that my fan, fan clutch were robbing me of power and torque. I was running the car myself on the dyno for about 2 hours. All for about $60.00. The best $60 I ever spent.

Regards,

Jim


[Modified by Jim73, 10:37 AM 1/25/2002]

 

Jim,
How did you get the Edelbrock Air Gap intake under your hood? Is the Edelbrock carb shorter than the Q-Jet? I have read many posts that say because our model years have the wiper door/hood config we lose just enough clearance to make using anything other than a Edelbrock Performer intake nearly imposible.

 

Where are they located?

 

KLJ,

I don't have the air gap, I have the vortec performer intake. Sure wish I had the air gap on the car. I have read of a few people who were able to make the air gap fit, but with the performer I only have about 1/4" clearance. No way will the air gap fit.

Regards,

Jim

 

What i would like to do is set up an appointment for next week weather permitting and cruise over. Why is it that they have you run it in higher gears? I didn't take the time to figure it out, But I guess that you have a auto running in third gear is how you got 112 mph @5200 rpm. Would that mean that I would need to be in lockup 4 gear because of my 3000 stall converter? I would worry about trying 4th gear because the dyno would be exceeding 200 mph way before red line. 2.86 gearing with 7600 rpm

 

George, They need to make the run in the 1:1 gear. When I had mine dyno'ed, he asked me what top speed in my 1:1 gear was. I'm not sure exactly what they do if it gets to be too much speed, but I got the feeling that they try to avoid getting too much speed on the dyno. Unless someone is running a 2.56 gear, I don't think it will matter much.

Tom

 

jimbr, Those are pretty good numbers for your combo. I'm hoping to get back to the dyno soon. The last time out I got 250rwhp with the hyd cam and questionable lifters. Now with the solid cam and roughly 10:1 comp, I'm hoping for 270-280, but i'll need to tune the carb and advance curve. What are the specs on your cam and are you running an electric fan or crank driven fan? Supposedly, getting rid of the engine driven fan will be worth another 10-15rwhp.

Tom

 

Great results! What cam are you runnin? With those RW torque numbers that car should pin ya to the seat like a big block (ask me how I know :D )! Curious why he advised you to go to a smaller carb. Did they monitor air/fuel mixture? Also was wondering why you didn't rev it higher; I would think you would be good to go up to ~6500 with a small block. I've run mine also and it is a blast, especially when you get a group of C2,3,4,&5 guys together like we do every couple of months to check progress on our mods. :cheers:


[Modified by Marks69BB, 10:36 AM 1/25/2002]

 

gkull: I'm not exacly in the 200mph club, but when I went for a dyno run, my tires really werent up to the task. Redline in top gear on my car is 153 but my tires are only S rated (112 i think) The car got really unstable about that speed, tires folding a bit, so I had them do the next run in 3rd gear. It made the numbers lower across the board, but it let me see the entire curve. 263rwhp@5300 or something close to that in 3rd gear, I need to go out and get some Z rated 17"s :yesnod:

 

Bob - It would make more sence to use my third gear. so with 4.11's it would be around 130 mph.

I just need a telephone number and give this place a call. I would put in my best guess sea level jets. my max timing mechanical is already at 34 @3000 rpm

 

I too would like to Know why he said to go with a smaller carb for more HP.

I would think a 600CFM carb for your setup would be the minumum you would need, this kinda makes me happy though cause that''s what I have. :D


[Modified by MotorHead, 11:38 AM 1/25/2002]

 

Folks, Here's answers tolots of questions:

1. This place is located is South Sacramento
http://www.schlatzandkrum.com

2. The manifold is the PERFORMER AIRGAP which is .27" taller than the std Performer (this is a new model Edlebrock offers and has better flow numbers.

3. I have no idea what cam I have!!!! It was undocumented when I got the car but it is clearly NOT stock. :D

4. The FAN is the stock clutch fan thing

5. The carb is a 600cfm. If you take 5200RPM times 350cu in and assume an 85% effeciency, that means about a 500cfm carb for this.

6. Why only to 5200 rpm? You'll really wonder when you see this graph below. The dyno guy asked how high I take the rpm when I'm on it - 5200, so that is what he tested to. It was exciting. I have no idea what I really should consider red-line. When local clubs to a dyno day, I might go back and take it to 5700??? Look at this:



I'll post the graph in a new post just because it is so cool! Clearly it still wants to make ponies. Love it.

Jim