258 Dyno Run Pre 4.0 Head Swap

[captkhaos]

Hello,
I just ran my 258 on a dyno and thought I'd report the results. I have a Crane 753901 (mild) cam and lifters, a Hooker dual outlet header with a "Y" pipe into a single exhaust and a Weber 38 DGES carb. I made 2 passes and posted 131.91 horsepower and 367.57 ft.lbs. of torque. I backed off at 106 mph at about 6500 rpm. The numbers seemed to peak at about 95 mph. They guy said I tached over 7000 but the report doesn't show rpm. The dipstick blew out of the engine at one point. No problem except some spilled oil. The 4.0 head is at the machine shop now and I'll run it through the dyno again when I get it ironed out. The valves never floated but I am putting Crane's taller springs on the new head per their recommendation.

P.S. It was a lot of fun for 50 bucks!

[SIXPAK]

This will be great info if you are able to keep everything the same. Diff header of course.

[SilverXJ]

Are those figures uncorrect at the rear wheels? Those numbers seem pretty high.

[captkhaos]

I'm gonna try to post the data sheet now. I tried on a different forum and couldn't do it.

Dyno Run Specs 4Apr2011.pdf

No rpm data as I said but I've got a call in to see if there is another sheet they can print.

[captkhaos]

Hello,
I just got my computer set up here at my Mom's house in California and went to the forum. I went to the dyno shop just before I left and got the rpm data sheet. The guy explained that the rpm reading was intermittent and this caused the torque errors. The 258 did tach about 6,300 rpm. ( the guy told me he saw 7 on the screen!) I've attached the report here in .pdf format. The actual maximum torque however occurred at about 4,850 rpm and 142.24 ft.lbs. The horsepower, again at about 4,850 is 130.43.

I'm sorry for any confusion this may have caused. My only concern is to see the comparison before and after the 4.0 head swap. Obviously I'll use the same dyno. I plan to use the same intake manifold & carb so the only difference, besides the head, will be the header I use. I haven't bought it yet and am looking for something cheaper than Borla. Any tested recommendations? eBay has some stainless headers for $150!
Cheers,
Dan

Dyno RPM Specs 4Apr2011.pdf

[gradon]

I was gonna suggest not changing a thing if you actually had 367lb-ft to the wheels. . .