351W Rebuild or Crate Motor?

[rmarks 20]

Tough day returning from a cruise in the other day.  Ran over some debris on the highway in traffic which took out half my front spoiler, the speedo no longer works (bounces), and my car started running rough and now it's difficult to keep it running.  The later may just be coincidental as I saw no damage underneath the car except the spoiler.

Anyway, while troubleshooting the rough running engine, I pulled the spark plugs and did a compression check and discovered oil on some plugs and low compression on a couple of cylinders.

So, what is your recommendation on tackling this ... rebuild the original 351W, or drop in crate motor?  Any idea on what a typical rebuild would cost?  Recommendations for a crate motor if I go that route?

[rwcstang 201]

3 hours ago, rmarks said:

Tough day returning from a cruise in the other day.  Ran over some debris on the highway in traffic which took out half my front spoiler, the speedo no longer works (bounces), and my car started running rough and now it's difficult to keep it running.  The later may just be coincidental as I saw no damage underneath the car except the spoiler.

Anyway, while troubleshooting the rough running engine, I pulled the spark plugs and did a compression check and discovered oil on some plugs and low compression on a couple of cylinders.

So, what is your recommendation on tackling this ... rebuild the original 351W, or drop in crate motor?  Any idea on what a typical rebuild would cost?  Recommendations for a crate motor if I go that route?

if I were to do this all over again, I would rebuild locally with an experienced machine shop, they can do the same build and you can buy parts and have them install it.

Most online crate engines are affordable but some companies use a mix of off-shore/brand name parts to keep cost down. 

only issue I have with online crate motors if something goes wrong with the engine, you have to take it out (or pay someone to take it out) and ship it back to them for repair, which takes more time and money.

 

[rmarks 20]

Follow-up question.  Would a valve job help with the oil  and compression issues?

[Mach1 Driver 560]

9 hours ago, rmarks said:

Follow-up question.  Would a valve job help with the oil  and compression issues?

unless its the rings

[Boss429Dreamer 18]

If it's the original matching numbers engine I would rebuild it. Just depends on how original you want it to be.

[RPM 1,190]

You should have several top shelf machine shops in the Houston area from which to choose. 

[Vicfreg 771]

I rebuilt mine and had did the disassembly myself, then had a local engine shop do the machine work and balance the rotating assembly.    While I was at it, I had them install 393 stroker hardware.

I put the rest of the engine together myself.   I used bolt on Edlelbrock top end (Performer RPM) parts.   All you really need is an engine stand (they are cheap, find them used everywhere) and a engine lift (you can rent those).  Not many specialty tools except a couple torque wrenches.

I used a high volume/high pressure oil pump and upgraded shaft, and edelbrock double roller timing chain kit.   This is a good time to look at your harmonic balancer, mine was dried out and needed replacement.   It's a fun winter project and there's nothing like starting up an engine you just built!

I had a little extra fun and found a cheap engine test stand and modified it so I could break my engine in, since my car was undergoing some sheet metal surgery at the time.   That allowed me to try a couple different ignition system options and time/tune the engine, check for leaks, etc.     Also a ton of fun.  (the neighbors were not impressed...)

Before and after pictures.   I wound up adding a CVF pulley system and had to go with a reverse-rotation water pump in the end.

 

[Phils69 27]

I would go local like I did before. I used a guy that some friends recommended and could not be more satisfied. He is a small father/son shop and has helped me out a lot. He even came to my home for the first start on my engine after I installed it. Having said that a friend totally switched to crate morors at his shop. 

[1969_Mach1 333]

What kind of Mustang is it?  If that is an original 1969 351W that hasn't yet been rebuilt, I'd rebuild what is there.  The 1969 351W motors are not that easy yo find any more.  In the end, if it were mine and that's is the original 351W motor, I'd do a mild performance or relatively stock build using what is already there.  I say mild performance or stock because you can easily go down a rabbit hole with a performance build.

[rmarks 20]

3 hours ago, 1969_Mach1 said:

What kind of Mustang is it?  If that is an original 1969 351W that hasn't yet been rebuilt, I'd rebuild what is there.  The 1969 351W motors are not that easy yo find any more.  In the end, if it were mine and that's is the original 351W motor, I'd do a mild performance or relatively stock build using what is already there.  I say mild performance or stock because you can easily go down a rabbit hole with a performance build.

It's a stock convertible with the original stock 4V motor.  Used for cruising, cruise ins and car shows.

[Alan_Mac 48]

If you want your original block stroked and a performance build you could send it on a skid to Coast High Performance.   

[1969_Mach1 333]

20 hours ago, rmarks said:

It's a stock convertible with the original stock 4V motor.  Used for cruising, cruise ins and car shows.

It's your car and ultimately your decision, but for that I would just do a mild performance build at most.  The static compression ratio on stock 1969 4V 351W motors is pretty high, 10.7:1, so maybe a little more camshaft than stock to help reduce the dynamic compression ratio.  Not too aggressive because then manifold vacuum drops, power brakes won't work as well, the stock torque converter won't be compatible with the higher idle RPM.  And also as manifold vacuum drops, potential for oil leaks seems to increase.  You wouldn't think so, but there seems to be a correlation between the two.

[LoneWolf2U 136]

20 hours ago, rmarks said:

It's a stock convertible with the original stock 4V motor.  Used for cruising, cruise ins and car shows.

Research local shops for rebuilding your engine.  Save yourself the headaches that could follow if any problems arise.

[rwcstang 201]

23 hours ago, Mach1Rider said:

Research local shops for rebuilding your engine.  Save yourself the headaches that could follow if any problems arise.

agreed, rebuild your 351w into a nice stroker locally and enjoy it. 

[SM69Mach 68]

On 10/11/2020 at 10:10 AM, Vicfreg said:

 

IMG_3042.MOV

That is a good looking motor right there!  Nice job!

[rmarks 20]

What are your thoughts on adding an aluminum intake and heads such as Edelbrock Performer RPM or AFR?  Worth the money?

[rwcstang 201]

let me ask you this, what do you want out of this engine and whats your budget?

[EastYorkStang 63]

Come up with a plan, your ideal engine. Then work towards it. 

[1969_Mach1 333]

On 10/13/2020 at 7:03 PM, rwcstang said:

let me ask you this, what do you want out of this engine and whats your budget?

I think rwcstang hit-the-nail-on-the-head.  Without knowing these two things you'll basically keep "floundering".  You need to get this sorted out first.  If you're like me the budget will limit what can be done.

[smh00n 87]

Build it yourself. Then you know what parts went into it and you choose the quality. 

So many stories around about crate motors that are junk.

[fvike 173]

On 10/11/2020 at 4:10 PM, Vicfreg said:

 All you really need is an engine stand (they are cheap, find them used everywhere) and a engine lift (you can rent those). 

Use a chain block. The Mustang got a long nose.

[barnett468 418]

On 10/10/2020 at 4:44 AM, Mach1 Driver said:

unless its the rings

lol

[barnett468 418]

On 10/13/2020 at 4:43 PM, rmarks said:

What are your thoughts on adding an aluminum intake and heads such as Edelbrock Performer RPM or AFR?  Worth the money?

if the bottom end is good and you can get at least 9.0:1 compression ration, the heads will help if you also install a bigger cam but then you may need to change the gear ratio.

[1969vert 55]

Plan within your budget.. Stock rebuild would be easy.. Modifying with cam and heads may need a new converter and gear change if you go a little wild.. It can be done but what do you want to achieve with it..