1968 351 v 302

[x-codegtcs]

OK - decisions, decisions...I was going to rebuild a 302 that I have (not original motor) for this J code I am working on. I have the correct 302 F heads - although dated in June of 68. Now that I am over budget (no surprise) I wanted to save some $ and thought about buying an Autozone remanufactured motor although I was really against it, but wanted to save the $ and upgrade the motor at a later date - 3 years or so. But when I went in on Saturday, they said they are all sold out! (they had 5 the week prior). So, now with the finishing very close, if I send to the local machine shop, I am 4 weeks out. So, I check with Summit Racing - they have several selections available, and the 351W and 302 roller/non-roller blocks are the same price...HMM tastes great, less filling...Maybe. So, my questions are:

1) If I go with a 351W does that decrease the value as a GT/CS J Code (since this will never be a numbers matching car)? Do I keep the 302 and correct heads for future?
2) What can I use off my 302 on the 351 - timing chain cover, water pump, AC/PS/ALT brackets, oil pan, oil pick up, etc?
3) What would I have to buy? (exhaust manifolds, intake, carb cfm?, valve covers, etc)?
4) If I go roller over non-roller, I believe that the harmonic balancer needs to be changed - other than cam and lifters, anything else (see items in question 2)?

Rob - your input here would be very helpful. Thanks! Bryce

 

[robert campbell]

OK - decisions, decisions...I was going to rebuild a 302 that I have (not original motor) for this J code I am working on. I have the correct 302 F heads - although dated in June of 68. Now that I am over budget (no surprise) I wanted to save some $ and thought about buying an Autozone remanufactured motor although I was really against it, but wanted to save the $ and upgrade the motor at a later date - 3 years or so. But when I went in on Saturday, they said they are all sold out! (they had 5 the week prior). So, now with the finishing very close, if I send to the local machine shop, I am 4 weeks out. So, I check with Summit Racing - they have several selections available, and the 351W and 302 roller/non-roller blocks are the same price...HMM tastes great, less filling...Maybe. So, my questions are:

1) If I go with a 351W does that decrease the value as a GT/CS J Code (since this will never be a numbers matching car)? Do I keep the 302 and correct heads for future?
2) What can I use off my 302 on the 351 - timing chain cover, water pump, AC/PS/ALT brackets, oil pan, oil pick up, etc?
3) What would I have to buy? (exhaust manifolds, intake, carb cfm?, valve covers, etc)?
4) If I go roller over non-roller, I believe that the harmonic balancer needs to be changed - other than cam and lifters, anything else (see items in question 2)?

Rob - your input here would be very helpful. Thanks! Bryce

1) Value in my mind would be based on HP in your case so to speak. A numbers matching motor would be the most value, but you do not have it. Although a tasteful new fuel injected motor would be very valuable to a lot of people over the old cranky carb engine.

2) Some parts will swap. Such as the front and timing cover and accessory mounts. And if you get a 302 short block (non-roller) you can use your balancer and flex plate or flywheel and use your front end accessories and keep the engine in balance. You can use your fuel pump. You could use your heads but the J code heads have a very small combustion chamber than can run up the compression ratio. You could use your exhaust manifolds, but you will not be able to use any H-pipes sold for an original 302 or 351 configuration because of the high deck on the 351. And the stock manifolds will defeat the purpose of an engine that could develop more power if it had improved exhaust

3) If you go 351 you will need some stuff. Oil pan and pickup. Intake manifold. And in my mind shorty headers or correct 351 manifolds that do kinda mimic K code exhaust manifolds. A 650 CFM carb would be helpful. A new distributor as your 302 one will not work. A nice set of modern aluminum heads would be a huge benefit. I think the timing cover and water pump will swap as will the accessory mounts. Motor mounts are the same and the tranny will bolt.

4) Roller motors many times are built from the newer blocks that require the 50 vice 28 ounce balance. That means a new flywheel/flex plate and harmonic balancer. I am a bit fuzzy here, but I think you can get a harmonic balancer for a newer roller engine that will support your old 3 bolt pulley and accessories. If the company is a custom builder you may be able to get an old 28 ounce motor with a "retrofit" roller cam.

sooooo. If I was in your shoes and you can get a 351 Windsor "long block" for nearly the same price as 302 in roller or non-roller, I would get the 351 in a heart beat. I went on Summit and they have an 300 HP ATK 351 long block for $3k. 24month warranty and unlimited mileage. These are not Roush motors by any means, but Summit does not deal with losers in most cases. And it was a 28 ounce motor that will use your harmonic and flywheel or flex plate. All you would need is an intake, carb, distributor and I would recommend shorty headers.

All boils down to money. They have an ATK 50 ounce long block motor for $2.5k. But to be all it can be it needs a decent intake, carb, and exhaust. You can use your stock distributor. So about 700 more, but if you go short block you can reuse your heads if they are in good shape. If not, you can dump a bunch of money in heads before you know it!

The 302 short block with your heads and intake is the cheapest. Saw some in the $1,200.00 range. Redo your heads and off and running. Albeit not quite as fast.

Rob

 

[di81977]

I have done a 351W swap in a 68 HCS. Couple of other things to keep in mind:

1) I had aluminum heads on mine, but either way, you will need a special piece that bolts to the front of each head to allow you to reuse and align your alternator and power steering brackets. Basically these were aluminum bars that bolted in the accessory holes on the heads and provided a second set of holes for your accessories in the proper location to align pulleys. My local Mustang shop in Denver had them, so I assume they are pretty standard.

2) You will need special conversion headers with a 351W in a 68 Mustang. If you use 302 headers, the tubes will rub against the floor boards. About 6 years ago when I did this, the only conversion headers I could find available were Hooker Super Comp headers and they were not cheap. You might want to check this out.

Good luck!
David

 

[x-codegtcs]

Thanks guys for your time and experience! I am trying to nail down this week and move forward.

 

[di81977]

If you go with a 351W and need ignition parts, I am willing to give you a Duraspark II set up (distributor, ignition module, coil, misc connectors) that I used briefly on my 351W. Just pay shipping from Colorado.

There are lots of articles on the internet about how to install a Duraspark II. You will need to make some minor modifications to your wiring, maybe a trip to your local junk yard to pull some connectors.

I must say, though, that within a year I replaced it with a more performance oriented set up. I am sure Rob or others can provide an overview of the pros and cons of this system.

Let me know, it is yours if you want it.

David

Note - it has been sitting for at least 7 years. I went and looked at it again and think it is a Duraspark system, not a Duraspark II (which I believe has a wider cap).

 

[x-codegtcs]

David - Thanks! very generous. I decided to stay with the 302 and a fairly stock build with original F heads that I will port match and remove the smog pump "nub" to help with exhaust flow. Funny thing though, my wife couldn't believe that I spent that much time to go full circle...

 

[di81977]

Congratulations on your decision! 302 is certainly more period correct.