I am in the process of buying a 1990 motorhome on an E350 van chassis. It has a 460 V8 and I want to get a tachometer. I don't want one of these typical aftermarket 8000 rpm jobs as this motor probably dosen't go much over 5000, but I suspect the 4000 rpm tach I put in my 300 straight six is a tad too low. Also interested in the hp and torque, as with the E350 chassis, maybe they have a different cam or something?

Paul

 

I have a 94 F250 supercab 460 automatic with 4.10 gears. Anything much above 4,000RPM is pretty much just thrashing around. I have not noticed much additional range past that. The truck just runs out of legs after 4,000, I am not sure if I have ever gone past 4,500.

I don't know much about aftermarket tachs, but is a tach from a 6 going to work in an 8 without doing some conversions?

On my shop tach there are different scales for 4/6/8. They just basically take into account the different number of sparks per revolution of each engine. So just guessing, if you used the 4,000RPM tach that works on your 6, unless there was another faceplate or a switch, I would guess at 4,000RPM with an 8 you would read 6,000RPM on the tach. I could very well be wrong here, so don't take my word for it.

Jim Henderson

 

Cool! Another stump pulling grunt motor like my 300 I6. This motor has some pretty big intake valves though. I bet freeing up the breathing would make this one really go. I believe most tachs have a switch on the back to select between 4,6, and 8 cylinder. The problem comes in with the new V10 engines. Anyway, being a V8 I just thought a tad more rpm than an I6 and wanted a 5000 RPM tach just in case, though apparently the 4000 might suffice.

 

I first put a 6K tac on my 90 E350 and don't like the smaller divisions. Ordered a 4k tac from JC Whitney. Haven't got it put in yet. When I'm towing, etc, I haven't gone over 3300. If max torque is down around 2300, I don't see any reason to over rev. Bob

 

They are gutless after about 75 mph. Mostly newer ones. 87-97

[font color=blue] [font size=10] [b] [u]Take a big 'ol bite of Boner Pie

 

Elliott: The 4K tach from J.C. Whitney is great. It is a high quality tach with a calibration screw and terminals. You have to build your own wiring harness. Also you can call the manufacturer (Datcon) for advice on hookup. My only complaint, and it's a minor one, is that the lighting for night driving is a bit weak. But, it is perfect for my '95 F150, 300 I6:

https://www.ford-trucks.com/dcforum/User_files/3a55d02e3ce54623.jpg
I just wonder if the needle would keep going around the bottom if you needed to register up to say 5K.

 

Yeah. You should probably be alright with just a 4000 rpm tach. As said earlier, when your peak torque is down in the low 2000's, why the point revving to 5k?
In that motorhome, there arent any special mods to the engine that Im aware of.
You are gonna be looking at a rated horsepower somewhere around 260 and torque up around 360-380 foot pounds, ballpark. Somewhere in the back of my mind those are the figs for a stock '90 460.
You arent gonna want to run that engine much past 4800 rpm anyway, as the 460s have an outrageously long stroke, and at higher RPMs the connecting rod wants to separate from the crankshaft and send a piston through the side of the engine!
Groovy, huh? hehehe Good luck, and have fun.

J/.c

1965 Ford Galaxie 500 (okay, so not quite a truck)
460/C6 transplant @ 389hp/491 lb.ft.
14.29@103.8, 13-14 mpg heheheheheh

 

Proud Owner: If there is any mod to the motor for RVs I suspect it would be for more torque, not RPM. Anyway I found a torque curve for the 1990 460 V8 in "The RV Handbook." It gets about 350 foot pounds at 1000 RPM, peaks at 390 @ 2200, and tails off to 335 at the horsepower peak RPM of 3600. This beast should have no problem climbing mountain grades! Ha Ha, my wife, the first time she drove the motor home did a jack-rabbit-type start because she is used to having to really mash the pedal good on her 3.0 Aerostar to get it to go anywhere. This 460, ya hardly have to give it any pedal and it's movin along.

 

TallPaul:

Glad you found your info out.. Just like I suspected, around 380lb.ft. of torque, and right where it's useable.
I did some more digging around, and still cant find any mods to that specific engine in that specific chassis. As far as I know, all that torque is off a stock camshaft...Remember that notoriously long stroke(that has the tendancy to separate the con rods)? 460s are great!!
Have fun.....

J/.c

1965 Ford Galaxie 500 (okay, so not quite a truck)
460/C6 transplant @ 389hp/491 lb.ft.
14.29@103.8, 13-14 mpg heheheheheh

 

Wow! Just got back from a 700-mile shakedown cruise/ vacation to the Straits of Macinac (between upper and lower Michigan) and this 10,000 pound (loaded) beast really performed. I had no problem getting up and going and keeping up and, in fact, passed a few cars. Had it up to about 73 mph at one point. Gobs of power and it's really great to hear that intake sucking all those cubic feet of air. Bet a K&N filter would sound even better.