Looks to me like a .040 bored over 360/390 block, and the 3.80 stroke is close enough to 3.78 that it's probably measurement error. Or it could've been slightly offset ground, but I doubt that.

It's a 390. Actually a few more with a overbore. Where did you measure the bore, at the bottom or the top? That will make a difference if it is worn and tapered.

 

ok I retract... somewhat... I rechecked the stroke with another guage and it's 3.78 but the bore is definitely 3.09... I guess they bored it .040 over... but without the equasion to figure it out, what would the new displacement be and how much of a difference do you think it would make in the grand scheme of things.

Thanks,

Mark

 

Well the .030 over 390 I'm building will be, I think, 396, so yours is probably like 398 or something like that. It'll make a little difference, like the difference between a 410 and a 428, but not as much.

 

actually I measured it from the top and middle and got the same results... so the rebuild was done rather recently I presume. No scoring on the cylinder walls either.
Where can I find the block numbers as well as the crank numbers? The engine is covered in dirt and grease, so without getting out the pressure washer...

Thanks,

Mark

 

The casting number for the block should be on the same side as the left side of the block (same side as the starter), near the front, on the angled section. The crank number, although it may satisfy curiosity, doesnt really matter. It's a cast 390 crank. As far as I know, and someone correct me if I'm wrong, they're all the same, unless someone put a forged 427 crank in this 390, which I really doubt.

 

The only other "special" 390 crank that I'm aware of is the "Hi-po" cast crank with the fully grooved main journals, so it could possibly have one of those.

 

ok... I've done a little more measuring and have found that the heads have had a bit of work done to them. Although the valve sizes have not changed, I think, (approx. 2.03 intake and 1.55 exhaust) the intake ports have been enlarged.

I compared my heads:
old heads (C7AE-A) intake ports are 1.86x1.29
new heads (C4AE) intake ports are 2.22x1.29

I also compared the two intake manifolds I have:
old (C7AE9425-F aluminum) ports are 1.93x1.22
new (C5AE9425C steel) ports are 2.11x1.22

I would like to use the aluminum PI intake and there seems to be enough material to match the new heads.

I should have the rest of the motor apart by tomorrow afternoon and will hopefully have more numbers. The only thing I don't know how to measure is the cam to find out lift and duration. I would assume at this point that it is not stock. Would a machine shop be able to tell me it's specs if I took it in? I'd like to know so I can check it against the cam I've been waiting to install for some time. It's a CompCams 268H .494 lift / 218 duration @ .050".

I am planning on taking everything in for checking and cleaning at least. Freeze plugs will need to be replaced and all bearings will be replaced as well. Since this was a "Power-Pak" rebuilt engine, the rotating assembly may have been balanced already, but I will have them check that as well.

I really want to try the virtual "Dyno" check ratsmoker is offering. I'll soon have enough info...

Thanks again guys,

Mark

 

You can figure the lift by mic'ing the cam lobes on the base circle and then at the top of the lobes, but duration is another story. That 268H is really a mild cam, not much above stock. I'm running a Crane Energizer that's similar ( 272 duration .523 lift) in a 68 Monterey. Even a cold idle, the "lope" is almost non-existent. It does move the big Merc really well though. If your motor was a factory rebuild, then you may as well toss the cam in it in the scrap and use the 268H. The PI intake can be ported to match those heads but if you will look carefully, you will see that the extra area in the C4AE heads is at the bottom of the port and the bottom 1/8 inch is "wasted space". The C7AE head sounds like the same ports as the C8AE-H's on my Merc, which are basically Medium Riser 427 ports, they look smaller than the C4 heads but are actually a little bigger because they're fatter, the port floor is higher than the C4's which makes them flow better than the C4 heads

 

my vin # is -f14hrce0125
it is 4x4 and 'H' stands for 390?
But in the vin site Mil1ion has in his gallery.. it states a 351, which i know it is NOT.
Its also a 2v. The dude i bought my truck from says it has a 360, i never asked any more. Im startin to wonder now. Guess theres really only 1 way to find out. I will be stoked if it is a 390 rather a 360.

 

Here's your formula:

(pi) X (radius squared) X (stroke) X (number of cylinders) = CID

pi = 3.14
radius = half of the bore, 2.045
radius squared = 4.182
stroke = 3.78
# of cyl's= 8

.040 over 390 would be:

3.14 X 4.182 X 3.78 X 8 = 397.096 cid


a .030 over 390 would be:

3.14 X 4.162 X 3.78 X 8 = 395.197 cid


a std bore 390 actually is a:

3.14 X 4.101 X 3.78 X 8 = 389.405


Its a simple formula using pi to figure out the volume of any cylinder shaped object.

 

Longview, that vin says it's a '78 F150 4x4 with a 351m, what year is your truck?

Barry

 

Hmmmm...As far as I know its a 78. Its registered as a 78. Did 78/79's come with 360/390's?? I know for sure theres an FE in there. Original or not I am not too sure.

 

’76 was suppose to be the last year for the FE in pickups but I have heard of them squeaking through into the very early ’77 models and then that’s it.

Barry

 

Ok... I just got the cam out and checked the lobes which are all the same in dimension... 1.47 on the base circle and 1.73 at the top of the lobes. The only difference that I can see is that the intakes and the exhaus valve lobes have different centerlines. They're approx. .030 off from each other.

The cam has numbering on the back of it that looks like someone used an etching pen to write with. The info is as follows:

Cal Cams HF 30
254 - 264 - 10
RV - 1

Never heard of cal cams but it looks to me that 264 might be the exhaust lift...

numbers are coming slowly as I have time to tear it apart...

Also, wondering, since there was headwork done to the motor in the last rebuild, I'm not sure if the compression ration is still stock. Is there a way to figure this out now that the heads are off but the crank, rods and pistons are still in?

Thanks guys,

Mark

 

Based on your measurements, the cam you have is a .450 lift ( 1.73 ratio rockers) the 254/264 is the duration of the intake and exhaust. To figure the comp ratio, you will need to measure the deck clearance, dish ( or dome) in the piston tops, and what is size of the chambers in the heads. What are the casting#s on the heads ( between the middle spark plugs) Also what size are the pistons ( std or oversize) .