Engine Data 305E

[James]

I just got back from testing my truck on a chassis dyno. This will be my base line numbers. I am planning on installing the Holley carburetor and electronic distributor then do another engine test.

Max Torque: 140 @ 2000-2400 rpm
Max HP: 94 @ 3950-4000 rpm


The torque curve is very flat. Above 130 lbs ft of torque from 1400-3750 rpm. For an old truck that had no major work done on the engine it's impressive. No idea how many actual mileage it has, however I do know it been to Alaska twice from AZ in the early 70s. Once with a camper and once without the camper.

[AZKen]

I think this is in the wrong forum:

If "electronic distributor" means HEI, like a modified Buick dizzy, that's for reliability. A spark is a spark. As far as the holley, it's been dyno'ed and shown to have no effect. The science says the motor, as designed, can not use more than 300-350 CFM. It's volumetric potential is 300 CFM. The engineers who designed this fabulous motor studied every system and used carbs for maximum volumetric efficiency and overall motor performance. Which was the main goal as well as long life. If you are after more something, what is that something? An unknown motor should not be tested to max. Which is 3800 to begin with. Why are you testing at 3950-4000?

If you want more of certain things, get a SBC or BBC motor that will go 6000+ and save cutting up/modifying a 305.

The motor was built for reliability and torque. Built for highway speeds of the era. Built for heavy hauling. It is way too heavy. There are no speed parts made for it. It's limited but strong. It's not a "performance" motor.
The science/physics is real. You can not naturally aspirate more air thru this motor by just putting a bigger hole on top.

A chassis dyno measures drivetrain output not motor output. Changing differential ratio, tire size, trans and adding OD will improve drivability and some numbers on that test. Due to the many tolerances, variables and losses/resistance in the drivetrain/transmission, you can only extrapolate values assigned to the motor. This method is not used to compare motor part changes.

I applaud your ambition. Sounds like it's running good, enjoy it.

[James]

I agree with you Azken. I am not trying to make a high rpm motor out of it. I am trying to make it more reliable, by installing a HEI and a Holley carburetor. This will give me a peace of mind when I start my cross country trip in it, after I retire. While the engine might have been design back in the 50 and 60 what I am doing is applying a little modern technology. I have flow tested a 305 head and intake manifold. My results have shown several area of much needed improvement (lacking maximum volumetric efficiency). I believe the engine can make more torque in stock form, I don't care about HP performance or high rpm. This is why I had the truck place on the dyno, to establish a baseline. I know the chassis dyno is not the same as an engine dyno, pulling the engine and getting it to the dyno is more work and expense. With the chassis dyno there is no seat of your pant data. If the improvements I do make does not work everyone here will know about it, cause I will be posting my results. And if there is improvements it will also get posted here. As for the max rpm of 3800 rpm I can not find any reference in the manual or on the Internet that states this. And running it on the dyno to 4000 rpm for a couple of seconds (I believe) will not hurt the engine. Also I will not place a SB or a BB Chevy engine in this truck.

Now everything I have stated before and now is my own opinions. I also welcome your and everyone else opinions. A different point of view whether something will/will not work is how we all learn. And any mistakes/improvements I make hopefully help someone else.

[AZKen]

perfect reasoning. James, top of this page, dark blue banner, Jolly page, click engine data, scroll down to engine specs 305E.
Ken

[James]

Originally Posted by AZKen

perfect reasoning. James, top of this page, dark blue banner, Jolly page, click engine data, scroll down to engine specs 305E.
Ken

Yes I have seen that, but it does not states max rpm for a 305E. Now the HP rating is at 3800 rpm. Having the max HP and Max rpm the same (to me) is unusual, however could be possible for this engines. I still believe a couple of seconds (actually the dyno data says it took .6 seconds) from 3800 rpm to 4000 rpm (actually the dyno data says the engine didn't quite make it to 4000 rpm, the technician back off at approx. 3980 rpm) is not going to hurt the engine.

[bigblockv6]

[QUOTE=James; (actually the dyno data says the engine didn't quite make it to 4000 rpm, the technician back off at approx. 3980 rpm) is not going to hurt the engine.[/QUOTE]

With the Holley 500, 2 1/2 inch dual exhaust, Flowmaster 50 series mufflers and GM HEI ignition I found that the 305E in my 68 K2500 had no problem spinning 4000 rpms before shifting from 2nd 3rd gear on the granny low SM 465 transmission. I really seemed to make maximum horsepower for acceleration between 4000 to 5000 rpms though I wouldn't do that for any long period of time.

[bigblockv6]

[QUOTE=James;71703] I believe the engine can make more torque in stock form.
From all the mods that I mentioned I definitely experienced a noticeable amount of more torque over stock form.

[Quigley]

I certainly would NOT recommend it,but a friend of mine who was a lifetime pro mechanic had a 351M in a hot rod tractor and said he would run it up to 5000 RPM routinely and never did hurt it. Also said it took a good rat to out pull it. This was back when tractor pulling was in its infancy in our area. Dave