The Stovebolt Site Forums The Shop Area Engine Shop How should it run?

Am I expecting to much from a 250 cubic inch engine? Should it be able to spin the tires with a automatic transmission? Should it run faster than 72 mph in the quarter mile? Anybody have any '60s magazines around with factory road tests? How fast were the trucks new? Is 140-150 horsepower about right? Joe

I don't know Joe,seems like it should run in the mid 16's, but as you said in the email,your carbs may be too small and you may need to rev it much higher to make use of the cam.I remember at the drag strip in the 60's-70's mom and pop 6 cylinder cars ran in the 18's.There are fast Chevy 6 cylinder vehicles, but they are all out drag cars, unstreetable.How does it run on the street, drag strip times aren't always a good indication of street performance where are more interested in passing power and roll on performance.

There are a lot of factors that come into play. What tranny? Gearing ratio. Tire size and tread. Have you done anything to the engine? What vehicle is the engine in?

Back in the '60s, they were just trucks, the only mags writting about them might have been Field and Stream or some ag magazine. As for Horsepower I believe the 283, V-8 in my '61 panel was only rated at 140HP, and would only spin the tires on ice with its 3-speed. How ever the fastest factory production auto/truck in the early 70s was a shortbed with a 454ci. and would smoke those polyglass tires .

With proper gearing and enough low end torque you should be able to spin the tires in almost any passenger car or half ton truck. I have a new 292 straight six and 4 speed in a 1966 half ton pickup. It also has a new Luk 11 inch clutch set. The truck has a low geared rear end (3.73) and a rather low first gear in the tranny (3.09). I can turn tires on pavement without much effort or engine revving at all (about 1500-2000 rpms).

Unless you have a 700R4 (or one of its newer computerized derivatives) you probably have a taller irst gear than I. What's your rear end ratio?

-ftyler

Ftyler; I think we talked cams once and found we are using the same one only mine is in a 250. The truck weighs 3280 with me in it, I had it up to the scales today. Its a '37 set at factory height meaning lots of wind resistance. 250 with turbo 350 and stock 6 cyl conveter. It seems pretty tight, not much stall speed at all. The rear axle is a 3.42 with 235/75 R 15 radials. On the street it runs great. Very smooth and able to pass with out down shifting. I really thought it would run quicker due to how it feels out on the road. It could be the tight quarters and wind noise that makes it feel fast.

The three caburators are most likely the problem, to small, only 80 cfm each. The Corvairs ran four with 190 ci or less. They really look good and run so good I not going to worry about it. The fuel milage is 19 on the road so thats good. I do have a 3.08 ring and pinion I am going to swap in. After that I may have to do some more engine tuning. Most of my driving is on the high way and at 70 mph, the rpm's are to high.

I was just curious if any body ever ran trucks or dyno'ed one. I have all winter to decide what to do to it. Since getting it together and logging 3000 miles I am ready for something to do. Maybe three model B's Joe

Yep that is the same cam (if the duration #s are 194I/204E @ .050). I have a 500 cfm 4 barrel with the settings unchanged out of the box and the response is crisp. No bogs and no hesitation. My idle is smooth, no lope. How's yours?

You will never turn good quarter mile numbers with a highway rear end. If you want to improve #s then a 3.73 (better yet, a 4.11) or lower is what you'll need. What I like most about my setup is that I keep my stock lower geared rear end for great takeoff acceleration, but run a 2.75 final overall ratio in overdrive. Turning 2200 rpms (literally cruising) at 70 mph is great.

-ftyler

If I was after quarter mile time I would go with a 3.73 and more carburation plus a looser converter. This was a one time only for and idea on how its running. The 3.08 will hurt it but the overall results will better. I might keep the 3.42 and go with a lock up converter in the 350 if I can find some spec's to look at. Anybody use one of these?

Mine has a slight hesitation off idle from being to lean. Just turning out the idle screws makes a difference. One jet richer will cure it, I am just to lazy to do it. I am saving it for mid winter when I really run out of things to do.

I am looking hard into replacing the carbs with bigger ones. I have three NOS model B's just waiting for something to run on. They are the same number and year so it should work OK. This weekend I'll take one over and put it on dads flow bench and see how much air we can get through it compaired to what I'am running now. I might even take along the OEM Mono-jet. Joe