I like the power I get at higher rpm but what's too high?
In other words what range of rpm is safe, and when does it become hard on the engine, and when does it get dangerous!

 

Don't wind it up before you shift as this is when valves can "float" at high RPM's and damage to pushrods, etc... can result. Do you have an owners manual? It should give you the approx. speeds as to shift.Shift out of 1st gear(low or granny) between 5-7 MPH. You can get away without using it if you're empty. 2nd to 3rd around 25-30 MPH and 4th around 35-40MPH. THese are approximate . If it seems to lug a little when you shift, try it at a little higher speed. You'll develop a pattern after a while. Just don't wind the **** out of it, someday you might regret it!

Barry

 

Barry,

I am assuming the max RPM for the 352 is around 5600rpm. What is good maximum cruising RPM in the highest gear (assuming no overdrive).

 

I beleive the max RPM for a stock 352FE is 4500rpm or so. I guess I drive a little different then some folks. I shift from 1-2 at about 4 or 5mph, 2-3 at about 15 and 3-4 at about 30. There isnt a set rpm to shift it, just dont rev it too 10,000 RPM and youll be fine, even if you do, I doubt youll be able to kill that old 352, they are tough sons of guns. Before I rebuilt my engine my bro drove my truck and he drove the hell out of it, he floored it in first gear for about a minute, we were going about 50 or so in in granny first! The engine sounded like it was going into warp drive. That engine didnt care, it ran like nothing ever happend. Needless to say I never let him drive my truck ever again.

 

I had a 75 with a 390 4v and it used to cruise along at 60 on the highway and it ran around 2900 RPM. It also got about 5-6 MPG at best! that was with a NP 435 4 speed tranny. Don't remember the ratio for the rear.

Barry

 

yeah, Im also trying to boost my efficiency as well as my performance. I heard a four barrel might be more what im lookiin for. Is this possible???

 

Dan, Mine can go as high as 44-4500 on it's own, with an automatic if I have it on the floor. I was testing mine the other day at 4000 rpms in second and it was running about 85 mph. It seemed to as happy as a fat baby with a big nipple in his mouth turning those rpms.

I am running a 3.00 gear presently, but ran it for a while with a 2.75 in it and it used all of the numbers on the speedo at 3800 rpms.

We just installed new heads after 24,000 because of a sorry machine job and no hardend seats. #6 valve was recessed about 1/8" into the head.

Rear gearing and engine size have a lot to do with the rpms that you have to use. Should you be running a 240 with a 3.00 gear you would have to wind the snot out of it to make power, while a 390 can handle it just fine.

Shift when you can catch the next gear without lugging the engine. The right 4 barrel can make a difference but the wrong one can cost you while using more gas. IMHO

John

 

What would be considered too high an rpm (or speed) if it is sustained over a long period of time? (352, 3 on the tree, 3.73 rear). The truck can go all day at 65mph. At 70 MPH the engine is definately working significantly harder.

 

Your max shift point should be at peak HP, not at whatever redline is considered to be. I think in the 352 it's around 4500 or so (don't have the Motor manual handy).
I get around 15 mpg with a 3 speed, 2v and 3.73 ratio.

 

My 352 runs around 3000 RPM @ 60 mph . After reading this post I guess thats ok. On my newer trucks / cars the tach usally shows 2000 rpm @60 mph. So 3000 is ok for this old 352 engine?

Does every one use the granny gear? Man, I rarely do . Too much jerking around .

see ya