The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Engine swap in a 1960 P-20 Van

I also have been brooding on changing my 235 to an early ( 1963 ) 327.

The Van is a 1960 P-20.

I love the 235 and I have nothing but praise for it. I did a lot of work on it and it starts and runs beautifully. I have no idea how many miles the 235 has on it, but, no smoke, runs 'strong'...and virtually no 'ridge' at the Cylinder Bore tops.

Odometer shows 120,000, but who knows how many times it has been around, or when the 235 was rebuilt last.

However, I can not get out of Town with it, since it is too slow an Engine for the Interstates. I hope to move Cross country early next Year, and I would rather Drive it than have it Transported.

I have a re-Built early 1963 327 which has been adapted to have a 350 Crank, which, along with being bored .60 over, puts me some ways above 350 CID then...and I think 10 to 1 compression ratio...and Hydraulic Valve Lifters and and Hydraulic Lifter type Cam.

I would be running headers and probably a Rochester 4 Barrel Carburetor...but maybe a Quadrajet...I do not know enough about them to make up my mind yet on the Carb and Intake Manifold choice.

Van has a 4-11 Differential.


I have the 'period' factory Engine Mounts and Cast Iron Bell housing, to marry the early 327 to my present Transmission ( which is Three-on-the-Tree ).

I understand one has to use a Shroud on the back side of the Radiator, since the 327 is a lot shorter than the 235.

The 327 is a lot lower than a 235, so I am hoping I will be Okay with the Engine 'Dog House' cover not needing to be modified.

I will need to find P-20 or kindred 283 option Throttle linkages and Generator Bracket, if anyone knows who might have those?

( The 283 was an optional Engine for the Van when new, and of course a 283 is the same Block and fit and so on as a same time era 327, as far as I gather anyway ).

What Flywheel would be good, do you think?

And, is there anything else I should be thinking about or scouting around for, for this Engine change? ( other than a LOW profile Air cleaner? Lol...)

Should I forget this idea and just leave the wonderful old 235 in the Van? And just have the Van Transported across the country, instead?

I am torn!

What do you all think?

All good discussion and questions. I would try the engine forum for an inspired response. Many have all of the details you need.
HB

The 4:11 rear end ratio is not going to help in the speed department no matter if you have a 235 or a 350. The 350 will certainly have more power than the 235. Your going to be working that 350 mighty hard if you want to run 65 down the freeway and your gas mileage will be poor. You might want to find out a price to have it moved, then compare the cost of gas for the trip figuring 7-8 miles to the gallon.(I think that may be wishful thinking) Then figure the cost to do the swap. If it was mine I think I would be looking around for someone to haul it for me.

Gears would be the cheapest option I think. 3.42's offer decent grunt with freeway cruising. I imagine you're running a 28" tire? Check out
WALLACERACINGCALCULATORS.COM
they have all types of calculators to help you figure rpm/mph with gear ratios and all.

You already have the highest gear ratio available for that housing, so gearing up is a pipe dream. Taller tires might help a little if something larger than what you have on the truck is available. The V8 will cruise at a little higher RPM, but it will be noisy. I ran a 59 Burb with a 307 engine, a SM420 trans, and a 3.73 gear ratio from California to Tennessee, heavily loaded and towing a small car, and averaged 10 MPG the whole 2500 miles. Your van won't come anywhere close to that MPG, even with the 350+ V8. Count on about 6 MPG on a good day with a tailwind. I'd choose to plan a route that takes advantage of as many secondary roads as possible, take some time, and enjoy the scenery going by at about 50 MPH as the 235 chugs along.
Jerry

Not sure what the Van had for Tires and Wheels when new...it had 15 inch Tires and Wheels on it when I got it, and they were old GM 3 piece Split Rims, so, maybe they were the originals.

They looked ridiculously too small to me, so I gave them the Heave-Ho and put on the 7:50-17s Rims and Tires, which look 'right'.


So, I am running 7:50-17 8 Ply Truck Tires, and ( being still close to new,) they are about 34 inches tall.

'Sweet Spot' cruising speed as is, with ther 235, seems to be about 45 Miles per hour.

It will do more of course, but, you can feel it is not liking pushing all that Wind!

So...the impression I am getting, as far as pulling the 235 and installing a 327 in it's place...is that the 327 may not really be able to comfortably manage Interstate Highway speeds, given the 4-11 Rear end ( and all that enormous Wind Resistence ) the Van has.

And that the 327 ( which has a 350 crank, so it is really a 350 of sorts ) would not give impressively 'good' Gas Miliage...or it may well be worse than the Miliage I am getting with the 235.

Which was around 12 MPG before I had the Head Rebuilt and before I corrected the horrible Intake and Exhaust Leaks and whatever else.

Which would then mean, 'Why bother?'


My only reason for thinking about the Engine change, is to be able to go on the Interstates, to Move across Country.

Once moved, I could care less about being on any freeways..I hate freeways/interstates ( as they have become, I mean ) anyway, and have avoided them - when possible anyway - for decades!

I vote gears and the 10:1 - 327.
My '64 with a 327, th400 and 3.73 rear was a blast to cruise around. No where near 10:1 but it had headers, intake , full msd hei, dual 3" exhaust and a shift kit. Rpms depend on cam and heads, who knows what your 327/350 is capable of. My 65 gets 22mpg with 700+hp. It's at a neck breaking 55mph but it's all on the heads and cam and how much vacuum your pulling. 3000 rpm and about 55-60 mph I have 22 on the vacuum gauge. The truck is shaped like a barn door.
Put the motor in and have fun

I will have to find the Build sheet for the "327" to remember the details...I am not hip with the 'SBC's to have it all in the front of my mind.

But, 10-to-1, I am pretty sure...Powerpack Heads and all Chambers made to match for their volume...Hydraulic lifters, some sort of Cam or other for better torque at lower speeds...slightly larger exhaust Valves I think...

No Carb or intake Manifold yet...thgose are to be decided.

I had planned to run Headers.

With the 350 Crank fitted, and .060 over, likley CID I guess would be around 360 something or maybe 370-ish ( I have not tried doing the math ).

The Van is a light one Ton or a Heavy Duty 3/4 Ton, and I do not think I have any higher Gear Options for the Differential, than the 4-11s it came with.

Years ago I had a 1959 Dodge Pick up, which had a factory 318 V-8 and 4-11s far as I knew, and I would go from Las Vegas to Los Angeles and back, usually doing 85 and the Truck was happy to do it.

Miliage never seemed bad enough to bother noticing...whatever it was.

The Step Van of course has a BIG tall front and it has to push a lot of Air out of the way...much worse aerodynamically, than a pick Up Truck.

I know years ago guys would modify the ( or one of the ) 3/4 Ton Ford Rear Ends into a 'Quick Change' type. One can choose the final drive ratio one wants with that.

But, I do not know of anyone ever doing that with the Chevrolet 3/4 Ton Rear End.

The Machine Shop Engine Builder people who re-built my '327' said I would have no problem holding 80 with it in the Van...but, they might have been fibbing.

I do not really recall what RPM such an Engine is comfortable holding, on a Highway, and or with the vehicle weighing 5,100 lbs or so, and pushing all that wind in front of it!

I am sure that would take a lot of Horsepower though.

I will see if I can calculate Tire diameter with revolutions per Mile and that then with MPH and relate that to my 1-to-1 final drive, to see what RPM the Engine would be doing at various Highway type speeds.

Using this Calculator...

http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php


Unless I somehow did it wrong, according to the Calculator, my 34.5 inch Tires, 4-11 Rear end, 1-to-1 Drive out of the Tranmission in 3rd gear...70 miles an Hour would be 2,726 rpm for the Engine.

Would I be wrong to expect a 350 Crank '327' to comfortably hold 2700 RPM or even 3000 rpm, on a Highway?

"70" ( and holding 2700-ish RPM ) would be plenty fast enough for me!! ( And should be within what I could reasonably ask of my Brakes I hope, if I had to stop fairly quickly...whatever 'fairly quickly' would mean in reality with this old Beast at that speed...or what I mean is, I hope I would be able to come to an 'Emergency Stop' kind of Stop, before total gut-sinking 'Brake-Fade' anyway...maybe...won't know till I try it to find out! )

Your small block will manage 3,000 RPM all day without a problem, or even 4K with no concern other that being a little noisy. Pushing the barn door shape down the road will not win any gas mileage contests. I have run those engines from 6K to 7K RPM more often than I care to remember, but that was around a circle track and an engine with 1,000 miles on it was a worn out oldtimer. We built those engines with more clearance brand new that you'll find in a 100,000 mile street engine. They only had one purpose- - - -"Go fast- - - -turn left" and do it better than the other 20 or so guys on the track!
Jerry

50-60% of your redline rpm is fine. Even 75%. You wont have carbon buildup on the pistons at those rpm.

Well...if I do the 'swap'...I will keep the old 235 on hand, in case I later change my mind and want to put it back.

I am completely happy with the 235, it runs great, starts with a flick of the Key...has plenty of get-up-and-go for around Town, runs quiet-enough in it's way, does everything i would want it to do, and does it well.

The speeds one has to maintain now on Freeways and Interstates are the only draw back.

it depends how often and how far that you are going to drive on the freeways and how big a hurry that you are in. you can also realize the trucks expectations as how they are and drive accordingly. ther is always the right hand lane for slower traffic. you can also change the rear gearing and or put in an o/drive.
I wouldn't want to use it every day as a highway commuter no matter what
ron

Here in the Southwest, the Interstates, once out of Town proper, everyone pretty much is doing 85 or 90...Lol...there is no 'Slow Lane'!

Do yourself a favor and do some more research on putting a warmed up small block in a truck. You maybe can go out and run it 70 mph, but you are going to be disappointed in the long run. If your satisfied with the 235 other than your move you will be way ahead to either do as Jerry mentions and plan a route on 2 lane roads and take an extra few days or save a pile of money and just pay someone to haul it for you.

You know, I will see what I can figure out about the 'Two Lane' roads idea...that has a lot of appeal for me. I love driving, and I enjoy driving the old Van, and if I can find a route which would work, for the Van's cruising speed ( as is ) that would be really fun.

If not, then I will hire a car hauler and get it transported that way.