Right now I have an '80 F100 with the 300 Inline six. It works OK, but it only gets about 15 mpg. It has only 45 lbs inch^2 pressure on #4. Sounds like I need a leakdown test to determine why but it also puts oil into the coolant and has some sort of lifter clicking. I think I'd like to get a rebuilt long block and install it. Everything is stock on this truck. (3 Speed Manual)

Anyway I have been to several of the engine rebuilding shop sites. They list a 240 inch^3 inline six rebuilt longblock for about $500 less than the 300 inch^3. It also does not require a core. Could I install the 240 longblock instead of the 300 in my truck? It appears that the last year for the 240 was around '74. I now have the following emissions stuff on the truck. EGR that comes out of the exhaust manifold and goes into a fitting below the 1 BBL Carter carb. Air Pump that feeds into the exhaust manifold only. The usual vacuum lines & pcv system. Nothing into the head or block.

If I get the 240 longblock I have to pull the lifter covers, the valve cover, manifolds, carb, waterpump, pulleys, oil pan (stick goes into the pan), electronic ignition distributor, and timing gear cover off of my 300 and try to put it on the 240. Is all this stuff the same? I would hate to have to find new stuff for a 240 after the 240 has been out of production for so many years.

Does reading this know much about the 240? I have read somewhere that the 240 has a better head than the 300 and it has a shorter stroke otherwise the engines are identical. Any comments?

I'd like to get a Clifford setup but I must wait at least until '05 when emissions is no longer inspected on the truck (due to its age).

Thanks a lot
Irvine

 

Spend the extra $500 and get your 300 rebuilt or replaced. You'll spend a lot more than that trying to put/modify a 240 into a truck designed for a 300. The 240 is just as tough as the 300, just smaller cubic inch displacement...performance-wise they are the same.

 

get the 300 its much better. I have a 240 in my 66 f350 wich had a 300 in it. the 240 has not enouph power. Get the big brother 300 you will be a lot happier.

 

The 240 and 300 are basically the same engine, only difference is teh crank, con. rods, pistons, and in some of the older ones, the head has smaller chambers. The 300 is better if your gonna leave it N/A, but, the 240 is a little more rev-happier, has a better rod/stroke ratio, and can use 302 pistons, so it's better if you want to build a race only forced induction engine.
Evan MacDonald
82 F100 FlareSide ex. 2wd
MAF MPFI HD 300-6
Hedman Hedder
NP435(6.69 low)
NP205
3.55 Geared ARB'd 9"
Dana 44 TTB
31x10.50/15 Goodyear M/T's

 

i had a 300 in my one ton and it had plenty of power that motor was no good after a while an i put in a 240 this motor is old but it dosent have the same pep as the 300. and how would the pistons of a 302 fit in a 240 they are smaller the cubic displaqcement is 40 on a 240 and 37.6 on a 302 how would you enlarge a piston.

 

This is based on what Evan said about the 240 being able to use 302 pistons.

Don't remember the numbers off the top of my (pointy little) head, but the 240, 300, 302, and the 351W share the same BORE SIZE. That doesn't mean you can stuff a 351 W piston in a 240. Skirt lengths are different as are rod lengths. Crank journals are also different lengths.

Stroke length is different for all engines listed below.

BORE X STROKE = CYLINDER DISPLACEMENT

The stroke on the six is longer.

302 cid / 8 = 37.75 ci per cyl.

240 cid / 6 = 40 ci per cyl.

302 V-8 specs: BORE = 4.00; STROKE = 3.004

240 I-6 specs: BORE = 4.00; STROKE = 3.183

300 I-6 specs: BORE = 4.00; STROKE = 3.979

351W V-8 specs: BORE = 4.00; STROKE =3.491

Notice that the stroke on the 300 is comparatively longer than the other engines. That's what gives the 300 it's low end power. Long stroke inline engines will make torque down lower in the power band compared to a shorter stroke v-8 engine of the same basic displacement. The 240 with the shorter stroke (and same bore) will make power higher up in the power band, as it will generally rev higher.



Here's a link to a displacement calculator...

http://www.ihonk.com/h/speedcalculators/engine2.html


Larry

 

The 240, 300, 302, and 351W all have the same 4" bore, the 240 and 302 just happen to use the same piston pin height, and some of the early 240's I've seen use 302 pistons with 4 valve reliefs in them....
Evan MacDonald
82 F100 FlareSide 2wd
HD 300-6 9.5:1 CR
Clifford 270H cam
Hedman Hedder
SBC valved 66 240 head
Headlight Relays - Delanty Style
NP435(6.69 low)
3.55 Geared ARB'd 9"
31x10.50/15 Cooper Discoverer LT's