engine block advice

[GYShah]

i am looking for some opinions on what to do and what considerations i need to make:

my 302 is probably going to be replaced this year

I have access to a '72 351w never been bored dont know how many miles but looks to be in good shape

should I hold out for a newer 351 with the potential for a roller?
do I even need a roller cam?

no plans for crawling or racing, just mainly town and some highway

 

[rockg]

I would have no issue with using the '72 351w, the older the better in my opinion. All depends on what you prefer.

 

[bad 68]

I have a flat tappet cam in a roller block. Becuse that's the way it came from Ford Racing. It runs so sweet I can't make my self replace the cam, lifters and pushrods for a little low end gain.

So I think getting a good seasoned block that hasn't been bored out yet is awsome. Flat tappet or not. But the heads will need to go. Really. I don't know what castings of heads are on the engine, but if they are true 1972s then they have small ports and large combustion chambers. Niether of wich are desireable form a performance standpoint.

 

[GYShah]

good to know about the heads
what will I miss without a roller cam? torque?, top end speed? mileage?

 

[vintage bronco]

if i were to rebuild a engine and i am, in no way would i use a flat tappet cam with oil the way it is flat tappet cams do not stand much of a chance another thing you have to ask yourself why would ford go to all the expense to convert the 302 to roller ? this in my own opinion.

 

[bad 68]

With a roller cam you can have a little more low rpm torque while still getting your high rpm power. The roller does this by getting more valve lift without any more duration. Exsessive cam duration hurts bottom end torque.
I can tell you that you can build a 351 without a roller cam that will pull hard from 1500- 5000 rpm.

 

[360 4V]

Hydraulic roller camshafts tolerate more ramp rate than hydraulic flat tappets do. In the old days of flat tappet camshafts there was zinc in the oil. In the '80s the EPA made manufacturers of motor oil stop selling motor oil with zinc. Hydraulic flat tappet camshafts and lifters did not survive this harsh new environment. Auto manufacturers began phasing flat tappet camshafts out for hydraulic rollers. Hydraulic rollers have existed for nearly as long as flat tappet but there was no need to resort to the expense of using them. Now engines have heavy duty valve train that can survive without zinc.

Now if I had a choice between the roller and non-roller 351W block I would choose a '69 to '74 high nickel block.

Build me some 351Ws nearly identical but for the purpose of comparing hydraulic falt tappet to roller. Tweak the valve timing around so we can see it from different perspectives. The roller has the edge. Now Put on higher ratio rockers on both and tinker with the valve timing and what do you find? I don't know how much of the friction I am going to do away with with my Schneider zinc formula but I would love to investigage this.

I do think the roller has the edge but I still would like to beat a dead horse on this one.

 

[addicted]

You could always just do a roller conversion. Couple hundred bucks and you have a high strength block with a modern valve train

 

[360 4V]

But is the base circle on the older block smaller than the base circle on the new block?

 

[DirtDonk]

Or use readily available zinc-rich oils or additives just for a flat-tappet installation.
You say you have access to this engine. Is it free? Does it come complete with an intake and oil pan you can use?

If it's going to cost you something, then compare it plus what you'd have to pay to make it ready to roll, vs what you'd be paying for a similar roller block with updated modern heads and choose which ever one makes the most sense dollar-wise.
If it's $150 or less, I'd go with the old one just because you can. If you've got to pay $400 to $500 to get this unmolested '72 though, I'd hold out.

Paul

 

[GYShah]

So I'm going to pay over $400 for the block and heads plus the machining and whatever else it takes to get it in
$2500 total including installation, tuning, etc.
Seems like buying a 351 roller wouldn't be any more $$ and if that's the case, shouldn't I just go for the roller?
Can I order one of these things all set up to drop in from somewhere?

 

[needabronco]

$400 is a LOT for a block! I'd say maybe $100-150 tops. I've was given a complete 351 a couple of years ago. They aren't really that rare...

As for the roller VS non-roller debate, I wouldn't worry about the difference. In reality you'd likely not see any real world difference in a Bronco. We simply don't wind up our mills like the Schmuckstain guys do.

Converting a flat tappet block to a roller is also cost prohibitive and severely limits your choice of cam's. It's simply better to get a roller block if that's what you want to do.

 

[Ranchtruck]

With the fuel injection keeping the mixture right, newer blocks often last a lot better. I've seen a bunch of 200k+ small block fords with the crosshatching still on the walls from the early to late 90's. All the older carbed motors I've torn apart have a good ridge at the top of the cylinders and no crosshatching left.

You could pick up a roller 351w from a 95-96 ford for pretty cheap from a junkyard, and if you bring a bore scope to check the cylinder condition through the spark plug holes before you pull it you'll get good results. If the cylinders are in good condition, you could do bearings, a re-ring and hone and get a rebuilt engine without all the machine shop costs.

I rebuilt the 71 302 and subsequently trashed it wheeling. This time I'm using a 96 351w out of a 250k F250 plow truck. I paid $150 for the whole motor at a u-pull it yard.

 

[GYShah]

I like the 351 roller option
I just need to find my way to a junkyard or else pay big bucks for a crate motor

 

[bad 68]

Don't forget that the 72 heads don't have hardned valve seats besides crappy flow charicteristics. $400 is way to much for these used parts unless it includes a good crankshaft, timing cover that works with the car style water pump, and 2 grove crank pulley. I'd still only want to give maybe $200 if it includes the crank and rods.

 

[360 4V]

I will gladly recieve unwanted cast iron small Block Cylinder heads with soft valve seats. I need sacraficial cylinder heads to screw with. I want to JB weld parts of the intake port with low velocity and open up areas with high speed air flow. This probably comes off as a crazy idea but with discarded cylinder heads why not?

As for not likeing soft valve seats, lead replacement (not lead) sells for $4 a bottle at most auto parts stores. How much do hard valve seats cost? I don't have them in my 351W.

Everything used to not be so heavy duty.