March 2006 Feature Car

[sYc]

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What RPM's do you launch the car at Ken?

[/ QUOTE ]

Not for sure about Ken, but one year at the SCR I think Herb Fox left at about 10 grand. In fact, he had it wound so tight the car stumbled at the 60' mark due to fuel starvation.

[ORIGLS6]

[ QUOTE ]
I think Herb Fox left at about 10 grand.

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And that, my friends, is how you get to be a WORLD CHAMPION!!!!

[68TopStock]

Denis,

I will try and find the dyno sheets, pretty interesting as they also show fuel and air data during the 7-8 test runs. May need to send them to Rob to post, so they are more readable.

I have been launching around 5800-6000, however, am sure Herb did it a bit higher, with roller rockers, and stiffer springs, and a few other tricks. The dyno sheets show the current set-up peaks around 6200.

[Chevy454]

Send 'em, Ken...

[Denis]

Seattle Sam and I hung out a bit with Jerry MacNeish and Ben Wenzel when they were running their respective Z28's at the Indy nationals in 2004 -- Jerry drives a '68, Wenzel drives a '67. Both of those cars launch, and shift, at 8200rpm.

[mrrec]

Great car!!!

[Chevy454]

Here ya go folks, eat your hearts out...the much anticipated "Little Hoss" dyno session!

Here are 14 pages of the dyno break-in and 8 pulls for the engine that is in Little Hoss. Probably the only test ever done with a bone stock factory built 1967 Z28 engine with crossram, other than what GM may have done years ago, but never released. When Ron the owner of R&R Performance first looked at the motor with the crossram set-up, his comment was "I've done over 4,000 motors in 12 years, and have never seen much less done one of these, it will be interesting to see the numbers".

Here is a brief explanation of the sheets, which have the corrected power on the front and raw data on the back, I only sent a couple of the back sheets to show individual fuel and air flow for both carbs. Ron found it unusual that the manifold pressure was in negative numbers, and had not seen this before, and had no explanation. Maybe that is why the crossram required fuel splash guides (made up of epoxied wire in the prototypes, and became part of the lower manifold mold in production units like mine)?

The overall graph is for the last run, #8 which provided the best average power of 353.9hp and 332.1 lbs. torque, with a fresh .30/.30 lash setting and at 36 degrees timing.


#1-Cruise test, just that, initial break-in after setting float levels, with open test headers, which also recorded exhaust gas temperatures.
#2-Break in with timing set at 34 degrees, rpm up to 5100. Ron noticed low initial fuel flow on the rear carb and started making adjustments, based on fuel flow and exhaust gas temp. (fuel b on back page of next test). HP=311.9 @ 5100rpm.
#3-Near full pull to 5700rpm/352.4 hp, timing still at 34 degrees. See back page circled fuel and air averages. This is the only way to set-up a crossram, otherwise your just guessing. It really helped to see the exhaust gas temps while the adjustments were made.
#4-First full pull up to 6300rpm. This is where max 359.6hp @5900rpm was recorded, 329.6 ft lbs. of torque @5300. Ron continued to make carb adjustments, and set the timing to 36 degrees.
#5-Better overall average hp (322.6), with max of 358.7 @6,000rpm. Rear page shows fuel and air nearly the same at max power.
#6-Timing set at 35 degrees, average power down to 320.4 and hp down to 354.4 at 5900rpm. Reset timing to 36 degrees.
#7-The best average hp of 324, with max of 357.4 @a5900rpm. Ron reset the valve lash for one final pull. He was having fun.
#8-The best overall average power was recorded, of 324.3, with a hp of 353.9 at 5800hp, with the max Torque reading achieved of 332.1 ft lbs. @5200rpm.

When Ron was done with the session, he immediately called Gene Pearson, who reassembled the motor after it was dissassembled for cleaning and inspection. His comment was "it's a strong little motor, you won't believe what we got for numbers". I have an idea they thought I was pulling their leg when I first told them what I was bringing in to be assembled. The only thing Gene did was perform a micro-torque plate hone to the cylinders, the stock rod/piston/rings/crank/bearings were just cleaned, inspected, and reassembled, with the piston/pins untouched, so as to prevent breakage. The heads are stock 291 '67 heads, with possibly a mild clean up, with what I think is the 30/30 cam (I forgot to ask Gene to take the numbers off it, when it was out of the short block. I don't think it is the off-road cam, as the valve lash setting are different, and the lash setting we used (factory) seemed to help the overall average power.

I hope someday to build a motor like Fred and Herb had, which included 12-13:1 compression, and a .030-.060 overbore, with the crossram. When I calculated out the times and speeds that they were running, I think the projected HP was around 460-470 back in 1968. Best time was 11.75 and mph was 118.42 with a 3300 lb car.

Hope this is interesting for all to read.

Ken

[Seattle Sam]

Denis,
I forgot about those pictures!

Here is a shot of the Wenzel brother's trunk..



We also saw this 1957 "SS" Corvette

[DZ Fool]

Ken,
I am gratefull for you posting these sheets. I was wondering why the air fuel ratio was so rich ? I always thought 12.5 to 13 A/F ratio was optimum

Thanks again Dan

[SMGCO]

I've seen it in person. It's a real piece of history.