Dumber than my engine block???

CurlyA6 · Dec 1, 2011

Twenty years ago, I turned in by tired old 289 as core to the engine rebuilder, who told me he only had a 302 to give me. No worries, I said.

Last month, researching my starter problem, I ran all the casting numbers of the various parts that now make my '68 Mustang run. Nothing is original, the engine, bellhousing, tranny (replaced a C-4 with a toploader), so I spent the time getting the numbers right. Now, I'm just more confused.

After 20 years of running my "302" I discovered that the block casting number is a '69 351W (C9OE-6015-C), but the motor otherwise appears to be a 302.

I know the 351 has a different firing order than the 289/302, and the crank pilot bearing o.d. lists in the parts catalog at 1 3/4" vice the 302's 1.37." Even though my block number is a 351, the firing order is for a 302 as is the pilot bearing o.d.

So, what exactly is my motor? Does the block number indicate a 351 cu. in. displacement, and the firing order indicate a 302 camshaft, crankshaft, and heads? Is that kosher?

Thanks.

mustangmike6996 · Dec 1, 2011

firing order should be on the intake if its original. google it.

also google the casting number on the block. the deck height is different so the intake is wider too.

69gmachine · Dec 1, 2011

302 and 351W cams are interchangeable, so you can't go by the firing order. It could have been swapped out at any time in the past. The Windsor is not only taller and wider, it has much larger main journals, 1/2 inch head bolts instead of 7/16ths and there is a rib beside the distributor hole that goes up to the top of the deck where the intake sits. If you pull the intake, there is "351 WF" cast into the lifter valley. It's hard to imagine you were given a 351W by mistake, but anything could happen. If he also gave you an original intake, it will have an extra pair of bolt holes at both ends where the water inlet mates with the heads.

65coupe408w · Dec 1, 2011

post picture...351 has a taller deck as already mentioned and it is overall a bit wider of a motor.

Hack · Dec 1, 2011

IIRC 302 is 8.2" from crank centerline to head surface, 351 is about 9.5" deck height (exact number depends on year).

dennis112 · Dec 1, 2011

Look at the distributor mounting boss on the block.

If it is parallel to the china wall that the intake mounts to, it is an 8.2 block (ie 302.)

If this china wall is raised nearly an inch above the distributor boss, then it is a 9.5 block (ie 351w.)

Take a photo of this area and the valve covers and we should be able to narrow it down for sure.

CurlyA6 · Dec 4, 2011

Unfortunately, the intake is an Edelbrock aftermarket add on, so no help there. I'll take a picture of the distributor boss tomorrow and load it here. If I'm reading the comments above correctly, it is not inconceivable that I have a 351 block and 3o2 head/intake/cam. Is that correct?

Loup-garou · Dec 4, 2011

Quick 302 vs. 351W ID tip: The timing cover and water pump assembly are obviously positioned the same on both engines. However, the 351's taller and wider block pushes the intake manifold higher. That's why the lower thermostat housing bolt on a 302 will be below the top of the water pump and you won't be able to put a socket on it. On the 351W you can remove the bolt with a socket.

The 351W intake manifold is around 11" wide at the widest point, while the 302 intake is around 9.5" wide.

You can indeed have a 351W block with 302 heads (if the head bolt holes are enlarged) and a 302 cam/firing order, but the 302 intake is too narrow. No way that'll bolt up.

2+2GT · Dec 5, 2011

Forget the numbers for a moment, and look at the front of the block. The deck on a 289/302 is even with the timing cover, while the 351 rises 1" above the timing cover, as shown here:

CurlyA6 · Dec 5, 2011

Hmmmm, odd. Here is a photo of the distributor mount area, looks the same as the photos above, rising about an inch above the timing cover. When I measure across the intake manifold, from front inner corner of the left valve cover to the front inner corner of the right valve cover, it looks to be about 9.5". The lower thermostat housing bolt, however, is definitely behind the timing cover...no way to get at it with a socket.

Sure seems to me that I have a 302 (judging by intake width), but the numbers and other hints seem like a 351. Please let me know if there are other clues I can look for.

Thanks.

KStang65B · Dec 5, 2011

I believe the B is a 351W and the C revision is a 302.

CurlyA6 · Dec 6, 2011

Interesting! I just rechecked Mustangtek and find that their listing for the -C revision shows 351W but has a small question mark icon beside it.

If I understand this correctly, when I tear down the engine I could simply measure the stroke (bore would be the same for both 302 and 351, no?) to determine which one I have. Is that correct?

65coupe408w · Dec 6, 2011

looking at your picture I would say thats a 302...the intake looks way more narrow than my motor.

Loup-garou · Dec 6, 2011

Given what you've described, I think it's safe to stop agonizing over casting numbers. It's a 302.

CurlyA6 · Dec 8, 2011

Thanks. Not agonizing, just making sure and trying to learn. The Mustangtek site seemed squared away, so I wanted to be sure before I discounted their citation.

Case closed, it's a 302.

Dumber than my engine block???

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