I have an opportunity to pickup a complete 1971 Super Cobra Jet 429. These motors allegedly make about 375 HP in factory trim and come standard with 11:1 + Compression, screw in studs with guide plates, HUGE ports and 4 bolt mains.
My question is this. Does anyone have experience in boring and stroking these engines to 540 + cubic inches? I have heard of this being done using the stock crank with an offset grind and aftermarket rod/ piston combination but would like to get feedback from anyone with info.
Thanks
Andy
Andy,
I to have a 429 Super Cobra Jet motor. 4-bolt main. I bought it from a guy for $800.00. The block is the same as a 460. I used my 460 steel crank and bored it over .60 making it a 472. I would change out the rod bolts and go with ARP. Are you putting it in a boat?
Goa,
I rebuilt a 1970 429 Cobrajet this winter and like big block ford stuff. This new engine is currently in my 78 Glastron Carlson CV 23 jet, and I just have an opportunity to pick up this Super from a guy that lives about 3 blocks away. It's currently apart so I've had a chance to take a look at all the parts.
There is a different guy in a small town near here that alledgedly has a simple combo to build a 540 cu in big block ford with readily available commmon off-the-shelf type parts. I guess the real thing is that this combo will give BIG hp and torque numbers, hold up over time, but not break the bank to build.
It just almost sounds too good to be true, but I thought that with the massive ports, valve sizes, and small combustion chambers, along with a good old 4 bolt block, I would have a great foundation for a big cuber even if the rods and crank weren't needed or coudn't be used.
I just wanted some back up knowledge before I go talk to this other guy about his combo. wink
The block can be bored pretty big and stroker cranks are available. 540 with a stock block is pretty big. It's easy to get 514-525 out of them. I would snatch it up quick. These motors make sick amounts of torque/horsepower!
Android,
You have the best Ford OEM cast iron 429/460 block for building the stroker motor.
Grinding the crankshaft's rod journals in an offset manner (to increase stroke) is a popular way to increase displacement in those engines. If you must have 540 cubes, then you will at least need a 460 crankshaft that has a 3.85" stroke (your 429 crank has a 3.59" stroke).
The 2.5" rod journals on the 460 crankshaft can be ground off-center and down to 2.2" so as to accommodate a Chevy rod. You can get up to a 4.3" stroke this way. This stroke, along with 4.44" bore (.080" over) will give you a displacement of 533 cubic inches.
A 4.46" bore (.100" overbore) will give you 537CI and 4.47" (.110" overbore) will get you your 540 cubes. Please note that you are boring your SCJ block significantly with these last two options and, although your's is the best OEM block for overboring to this extent, you would be well advised to have it sonic checked before doing so. (Sonic checking will most likely determine that your SCJ block can handle it, but better safe than sorry, right?)
I would recommend going with the 4.3" stroke and 4.44 bore to get 533 cubes, and leave material in the block for future overbores. Also, since you already would need to acquire another crankshaft, you may want to consider buying an strong, aftermarket 460 stroker crank (with the Chevy rod journal sizes already incorporated).
Your heads are awesome and have HUGE intake ports and good flowing exhaust ports. Intake valves are 2.25 inches. Combustion chamber volume is 72cc's. Compression will be high with increased stroke, so choose pistons accordingly.
To get an idea of your intake port size, below is a picture of my stock 460 heads that have had the intake ports matched to my Super Cobra Jet tunnel ram. Stock 460 intake gasket is below cylinder head for port size comparison:
[img]http://www.***boat.com/image_center/data/506/350Kaned3_flange-med.jpg[/img]
Your heads can be ported even more so and it would be best to first port the exhuast before the intake since this is where your greatest flow restriction currently is. Research everything before cutting or grinding anything.
An excellent link (and a guy who really knows how to port your heads): http://www.reincarnation-automotive.com/
Some info on your engine internals: http://429mustangcougarinfo.50megs.com/components_3.htm
LO
[ April 17, 2003, 08:12 PM: Message edited by: LakesOnly ]
Wow, thanks for all the input guys. Sounds like I had better get down the street and pick up that engine.
I've got an Austrailian guy coming to Illinois from New Jersey next week to pick up an '80 Honda CBX and a parts bike next week. I guess my wife isn't going to see all the cash from this sale huh?
Now if I can just find a crank on e-bay for a couple Hundred Buck$, and we'll get this ball rolling!
thedroid:
I've got an Austrailian guy coming to Illinois from New Jersey next week to pick up an '80 Honda CBX and a parts bike next week. I guess my wife isn't going to see all the cash from this sale huh?
Now if I can just find a crank on e-bay for a couple Hundred Buck$, and we'll get this ball rolling!
Trick stuff can be found on eBay. Here are some OEM ford rods set up for a 540: http://cgi.ebay.com/ebaymotors/ws/eB...&category=6770
Here's a stroker crank. This guy probably has H-beam rods, too:
http://cgi.ebay.com/ebaymotors/ws/eB...&category=6770
LO
I am convinced that lakesonly knows his shit wink He just dropped a book load of info in a few paragraphs. I would take more with him.
By the way lakesonly, I love that tail pic wink
396
I read an article a few years back on a bbf 540 stroker it stated that the crank was offset grinded and inline 6 cylinder rods were used!drew marine did the motor and seem to be the specialist at it.Also newer blocks cant be bored much but the early 70s blocks are prime candidates.
Lakes only =A walking BBF information guy who obviously knows alot.
andy...another way to enhance your big block ford marine situation is to sell the 429 SCJ to some numbers matching ford restorer that needs one of these rare engines more than you do (hopefully at a good mark-up) and build a 460 based stroker with parts that are a lot more suitable for marine use...the SCJ was a great musclecar motor but it was ill suited to the marine enviroment...consider the following...locate a bare 429-460 block from 1968 thru 1972..buy a cast steel 4.3 stroke crank from one the ford performance suppliers...use a good 4340 forged con rod at 6.7 long and the probe forged pistons and top it off with the blue thunder cj head with the chevy exhaust port and the blue thunder dual plane intake..this makes for a great 527 cubic inch marine engine package and it is very reasonably priced...the 429 SCJ has a good 4 bolt block, but the forged high compression pistons and cast iron old design cj heads are best left to a restored musclecar instead of a boat....from mike at C.T. Marine. In.
Posting Permissions
Reply With Quote