When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Making progress on the engine overhaul. I have come up with a question: I am looking at purchasing 2 rebuilt heads(both of mine were cracked). One set of heads I am considering mentions 7 mm springs. Is this the proper size for my 3.0 flex fuel engine, or is there another size valve spring I should be looking for?
Thanks for reading this.
You mean 7 mm valve stems... Later heads had 7 mm stems as apposed to 8 mm, the springs were more conical for the 7 mm stems too.
The 7 mm valve with the smaller spring retainer made for less moving weight so better all around design.
For your Flex Fuel, you want the heart shaped combustion chamber in the heads (that's what's important), the valve stem size and for that matter the spring type doesn't matter.
Mentions and shows the valve stem difference and also flex fuel difference for heads
Overall the 3.0l Vulcan was the same from 1986 to 2008(production run) but there are some differences that need specific year of engine to address
Big one is head bolt length, pay attention to that one
Jeff,
I went and checked the heads on my engine; they are NOT the heart shaped ones. They are the regular oval shapes. Can I put heart shaped heads on my engine and not create any problems; I am thinking head bolt lengths, for example.
My Ranger was produced 12/99 and the VIN has the V. Here is a fuzzy image of one bank of my heads:
The block dictates what head bolts are used.
The longer bolts are also thinner.
On my 99 (as in the link) my thread holes in the block were recessed, indicating that the longer bolts had to be used.
However, the longer bolts did not fit, the block was threaded for the shorter and thicker bolt size.
Someone at the factory goofed.
If your block has recessed thread holes, are threaded deeper for the longer bolts and are smaller in diameter when compared to the shorter bolts, then the longer bolts are used.
(when I tried to thread in the longer bolts on my block, they were really sloppy and way too long. They would have bottomed out by a good inch before they even came in contact with the head, I had no choice, but to use the shorter bolts)
The bolts are not interchangeable, it will be either or...
When dealing with the bolts, the head thickness remains the same.
Only the block was changed to accommodate the different bolts.
Note that the torque sequences are different between the two styles of head bolts.
It will say in your manual.
If your engine is indeed a flex fuel, then someone probably changed out the heads at one time and put the wrong ones on.
If yours is a flex fuel engine, it will have this sensor on it.
I have never worked on a flex fuel engine, so I don't know where that sensor is located, but Ron would probably know.
He has much more experience then me.
Last edited by Jeff R 1; Oct 29, 2017 at 02:20 PM.
Yes, if 8th digit in VIN is V then you should have a Flex Fuel 3.0l Ranger, "U" was gas Only 3.0l model
Flex fuel engines had larger injectors because more ethanol is needed with air mix than with gasoline, 9.8:1 vs 14.7:1 air:fuel ratios
And different shaped head chambers
Heart shape head is 47cc(Flex), oval is 49cc(gas only)
So you actually get a bit more power from heart shape with gas only, slightly higher compression, lol
But not enough to go out and get new heads
And that's it for the difference in flex fuel and gas only as far as engine is concerned, injector size and head shape
Either head can be used on any 3.0l Vulcan block, won't matter, flex or gas only, from an engineering stand point the heart shape was better for using/burning E85, but in practical, real world, use it doesn't matter, either shape works for either fuel
Fuel sensor was only used for a few years, under drivers seat area on fuel line, by fuel filter.
Very expensive sensor, so much so that you can buy Flex Fuel sensor by-passes, if sensor fails and you don't want to spend the $500-$750 to replace it then you can plug in it's wires to the By-Pass unit so computer stays happy.
You should run gas only after installing a by-pass.
Sensor was not used/needed after a software update to the computer, computer was allowed to increase fuel trims for ethanol without setting Lean codes, not sure you can update earlier computers to that version but I don't see why not.
I think(and I understand, in my case, how dangerous that might be) that my Ranger, 12/99 build date, with the V in the VIN, came without the heart shaped heads. But the valve stems are 7mm. This indicates to me that perhaps Ford dropped the heart shaped chambers and simply used regular heads with the 7mm stems. I will have some time later today to research this more. But unless I find evidence to the contrary I will stick with the regular shaped heads and the 7mm stems.
Spoke with Ford tech(?) support. Their records show only one cylinder head for both regular and flex fuel engines; part number 6U7Z-6049-A. This indicates to me that Ford abandoned the heart shaped head and went back to the original head shape, albeit with the 7mm valve stem.
