Stroking a 351w
 

I have a 1974 351w block that I am planning on stroking for my Classic Roadsters Cobra. The cylinders will clean up to 4.030". I hope to get 500-530hp from the engine. I am planning on buying a Probe Pro-Street 427 rotating assembly from CHP (forged crank & rods), and Vic Jr cylinder heads. I am also thinking of using a Comp-Cams Magnum 284HR or 290HR retrofit hydraulic roller cams.

I have a few questions.

1) Is this trying to get too much displacement from a factor 351w block? 427 cu-in is good for bragging rights, but the rod ratio is below 1.5 with these rotating assemblies. Am I sacrificing the engines ability to rev to 6k or higher? I am wondering if I should back off to a 408 or 418 stroker kit.

2) I am debating buying Milodon 4 bolt main caps to replace the original 2 bolt mains. I am not sure if this is necessary or if the smaller angled bolts are really that effective since the factory blocks don't have as much web material a the aftermarket Dart blocks. Am I is just as well off buying replacement 2 piece mains with high strength APR bolts and a main cap girdle?

3) I am planning on using Edelbrok Vic Jr heads & a Torker 2 intake. I think the extra height of the Vic Jr intake will cause clearance problems with my hood.

I think I have matched the components well, but I appreciate advice from those of you who have been there before.

Thanks

Your plan sounds fine, but you can get the same results with a 408 without the rod angle issues. If this is going to be mainly a street car, the two bolt mains on the existing block should be fine. Install a good new set of ARP bolts after having the block align bored and you're good to go. If you really want to push it past the abilities of the 74 block, you should probably be looking at a Dart or other aftermarket big bore small block casting.

The Vic. Jr. or Torker intake will hurt your low end but will be great at the top end. If street manners are important with this engine, a dual plane manifold like the Edelbrock Air Gap, RPM Performer, or Weiand Stealth would be a better choice. You'll get better low end and much better street manners.

Vic. Jr. heads are an excellent choice for your purposes and the cam you've chosen. They come with springs good for .650 lift so you're good to go in that regard. A good roller rocker, like the Comp Pro Magnums will top them off nicely.

Are you planning on going to roller lifters? Since the 74 block is a flat tappet block you'll either have to use tie bar lifters or have the block slightly modified (a small amount of grinding around a couple lifter holes) to handle the stock style rollers and dogbones/spider. If you use the spider, drill the holes in the valley to hold it down before the machine work as they line up directly over the cam bearings and you can easily go through and damage your cam and/or cam bearings.

I'm sure you'll get lots of other great advice here on your choices.

Bob

I've had a number of bad experiences after buying my engine and tranny from coast high performance, so I would not buy anything from them. Paid for a Bellhousing from them never got it called 3 times trying to get it always got the run around. Could never get any questions answered about the engine they sold me at least to calls about that. So just a warning before you buy from chp.

If that is the case..there are some things you should know.

First...I bought out my former partner about a year ago and have made a lot of changes.

Second..e-mail me some details at lmo@probeindustries.com and I will make certain that you are reimbursed for anything that you paid for but did not receive......and we'll happily answer any questions you have...if we have the answers.

If you don't wish to type....e-mail me a phone number....and name.

Third...we sell substantially more 427s than we do 408s. While I prefer the 408, for no particular reason, there are no issues with the rod angularity in the 427.

I personally used a 418 in our car...but we had it laying around from a magazine story.

Any of the three is enough to scare your wife half to death........

Stuart,


I see part of your issue.



I fired him......:3DSMILE:

I have had a 418 and a 408 stroker and both made the same power and torque and neither ever gave me any trouble. I never had a 427 stroker as I figured the 418 was pushing it the way I drove it. The 408 is just as strong and when built with good parts will take anything the others will. Just be sure to filter out any BBs that may get sucked into the intake as you pass them. :LOL:

Ron :)

CHP 427 stroker rotating assy
 

CHP sells a 6.125"rod length/22cc and a 6.200"/28.9cc rotating assembly. I was leaning toward the latter since it is a slightly higher rod ratio & lower compression ratio. The lower compression ratio should make it tolerant of pump gas. Do you have inputs between the two assemblies?

Unfortunately no as I put all the paper work with the cars when I sold them. I do remember the 418 was set up for racing and had a 10.8:1 compression and the 408 was for street and I believe the compression was about 9.8 to one. With aluminum heads you can run a little higher compression on street gas and get by ok.

Ron

FWIW I am off to dyno my 408 stroker next week (finally my turn). Keith Craft built the top end (Heads-Cam-Intake) and my local machinist Stanley Morton did all my machining. I went with the Eagle Forged Rotating assembly that is zero balanced. I expect to make at least 500 hp at 5800 RPM (maybe more). I went with the comp cams girdle, scorpion roller rockers 1.72, Ford roller lifters, Comp Cam retro fit spider and dog bones, Performer RPM Intake (helped a little by Keith Craft), Pro Comp Distributor, Srp pistons, H-beam rods, SRP forged pistons, etc.

I expect to track and drive this engine on the street.

Good Luck with your decision. By the way counting machining, parts, etc I have about $6500.00 plus the $300 I am going to spend on the dyno in my engine. That includes everything from the billet flywheel to the water pump pulley, and includes a high torque starter. No labor because I did all my own assembly.

Clois

Clois,

I had much the same things in my 408 as you do and when they dynoed it I had 527HP at 5900 RPM and 526 pound torque at around 4300 if I remember correctly. I may be off a ways on the torque, but I am sure of the horse power. My 418 put out around 530 horse and over 500 pound torque but at a higher RPM as it really wasn't built for the normal street driving. Good luck and I hope that your numbers come out where you want them.

Ron :)

With that cylinder head I'd run the 22cc dish. With .010 deck and .041 gasket and the head at 61ccs that's only 10.25:1 compression.

You would lose enough horsepower dropping to 9.62:1 to notice and the 10.25 is livable with the aluminum head.

I wouldn't do this. At the horsepower/rpm levels you're running it simply isn't necessary. I kinda draw the line around 650, because that is where I see the main caps start walking around.

The girdle is optional as well.

I've always used the Victor Jr with these engines, but I am not familiar with your car. We used a low air cleaner, but we've never had clearance problems with the Backdraft or Superformance cars.

Of the two cams I'd pick the 284HR. The 114 Center is far more friendly than the 106 on the 290HR. A TFS with about the same lift and duration and a 112 LC would be even better.

You should have no problem getting your 530 horsepower with this combination.

It was recomended by our builder and long time freind at K&M machine that we go ahead with the Splayed main caps on our stock block we run it hard alot under track conditions and thats were my ?????'s are what are you planning to do mostly street and occational track days I would rather go overboard on the rotating ass. than not,and girdles are for collecting broken peices in the pan when it goes booom.

mark from chp called me and if they follow through with what they said then I will be happy and would recommend doing business with them.

No knock on CHP, but I've had great service and great prices from adperformance.com. Talk to Brian, he'll answer every question you've got and a few you don't.

Bob

351 Stroker
 

I am building a street car. The consensus seems to be that the 4 point main may be overkill compared to a 2 point with a main girdle, but not necessarily a bad idea. Let's face it, if I thought overkill is a bad Idea, I wouldn't be putting 500+ hp in a 2,200lb car. This would also leave the option to add NOS if I ever decide to (even though it is unlikely).

Has anybody heard of cracking in a stock block from the added holes? Beefy 5/8" steel girdles with high strength bolts get close to $300. Rather than spend this much I think go ahead with the 4 point main. This way I leave the option to add boost at some point (even though I doubt I ever will).

I would like the Vic. Jr intake, but I don't think I have the clearance under my hood. Once I have it all assembled, I will check my clearance and perhaps upgrade from the Torker II.

Thanks far all the advice !

I like a girdle on a 302....because the block is really weak and the girdle will keep the crankshaft from ruining your tires.

And I sell a lot of them for the 351W. But...at 530 horsepower you are well withing the capabilities of the stock block.

I don't mind the add on 4 bolts......if you have a very, very good machinist.

Brian is a Probe Dealer, a buddy, and a very bright kid. I like him too.

soooo on your build -- how much vibration , oil consumption and engine wear are you willing to tolerate>?

with the rod ratio and required pistons-- a 427W can lead to cylinder bore wear issues and oil consumption over the long-haul.

For instance - I am not a fan of ANY stroker piston where the OIL CONTROL RINGS intersect with the piston pin hole/bore, this leads to oil consumption and dirtier than needed exhaust. ( Note: I am not a treehugger by any means but in automotive engineering this is the equivalent of using match-heads for sparkplugs. )

a 402-408W (still with a 4.030 bore) might be a healthy long term , powerful alternative that would run cleaner, burn less oil, and last longer.

My 5cents worth.

Steve