347 or 351???

[Simon]

Graham,

Yes, thats right. If you're block needs a +30 overbore (for example) the standard +30 pistons will be the same size as +30 331 stroker pistons.
Incidentally, I'd go for a 331 over a 347. the difference in capacity is minimal and MOST (but not all) 347 pistons have the piston pin intersecting the oil control ring. Some say it's not a problem, but why take the chance.
My 331 was significantly up on torque from a standard engine, it was really nice. I went with an edelbrock performer cam rather than the performer plus as I wanted it to be smooth and tractable which it was.
Have everything balanced together and you'll have a stunning engine.

Simon

 

[Graham]

Graham,

Yes, thats right. If you're block needs a +30 overbore (for example) the standard +30 pistons will be the same size as +30 331 stroker pistons.
Incidentally, I'd go for a 331 over a 347. the difference in capacity is minimal and MOST (but not all) 347 pistons have the piston pin intersecting the oil control ring. Some say it's not a problem, but why take the chance.
My 331 was significantly up on torque from a standard engine, it was really nice. I went with an edelbrock performer cam rather than the performer plus as I wanted it to be smooth and tractable which it was.
Have everything balanced together and you'll have a stunning engine.

Simon

Thanks Simon - that is top advice :thumbsup::thumbsup:

Graham.

 

[Mike Huddart]

Hi Simon,

Thats Interesting (and shows my lack of knowledge on these things). So you are basically saying that a 331 is a 302, with no bore change at all. It is simply the distance of the throw, i.e the distance the piston travels in total that makes up the extra Cubic inches.

If I/ve got this wrong, then please feel free to take the mickey out of me. I'm a TOTAL newb with V8's...

Cheers,

Graham.

Graham,
A 331 is a 302 block bored at 030 with an extra .250 ( 3.250 ) stroked crank ( actual size is 331.76 ci or 5438.7 cc )
A 347 is 302 plus 030 with a 3.400 crank giving 5689 cc
Mike

 

[Mike Huddart]

Whoops, sorry Simon, didn't see you're last post, never mind , he's heard it twice now!
Mike

 

[Graham]

Whoops, sorry Simon, didn't see you're last post, never mind , he's heard it twice now!
Mike

Don't worry Mike, It'll take me a couple more go's for it to sink in

 

[Gus Richmond]

Graham,
A rough guide to work out what dimensions are needed to get particular displacements. These are not set in concrete but fairly close.
B = Bore S = Stroke
All dimensions in inches
From 302 block
317ci B 4.000 S 3.100
331ci B 4.000 S 3.235
347ci B 4.030 S 3.400
355ci B 4.030 S 3.480
From 351 block
377ci B 4.030 S 3.680
408ci B 4.000 S 4.000
426ci B 4.000 S 4.170
435ci B 4.060 S 4.200
Cheers, Gus.

 

[Brett James-McCall]

Gus,
If you just have a +30 pistons in a standard 302, dioes this make it approx 306Ci (depending on cylinder chambers etc)? Thanks

Brett

 

[Jac Mac]

The alleged oil ring/piston pin bore problem only occurs where the individual selecting parts & or fitting them should NOT be doing so....get the RIGHT person doing both of those things & there will not be a problem.

 

[Ron Earp]

The alleged oil ring/piston pin bore problem only occurs where the individual selecting parts & or fitting them should NOT be doing so....get the RIGHT person doing both of those things & there will not be a problem.

Glad you mentioned it. The "347 bad" myth is so rampant it is hard to tell folks otherwise.

 

[Jac Mac]

Glad you mentioned it. The "347 bad" myth is so rampant it is hard to tell folks otherwise.

Yep, & there are a few 'myth' spreaders around here. I do not like the bore/piston wear patterns with the 3.40"/5.40" combo, & seldom reccomend it in a performance/race application due to the rod ratio, however as a torquey towing,fast road combo its hard to beat $$$ wise, is a bit harsher in the NVH dept than the 331-- the shorter stroke sounds & feels happier when revved, & isnt that the sort of thing we want in 'our' sports car stuff?

 

[Mike Huddart]

The alleged oil ring/piston pin bore problem only occurs where the individual selecting parts & or fitting them should NOT be doing so....get the RIGHT person doing both of those things & there will not be a problem.

Have to agree with you and Ron on this, the 347 makes a great combination particularly if you are running something like a hydraulic roller and limited to about 6500.
The bigest problem we have found is folk not paying proper attention to piston to bore clearance, if the short piston has excessive rock because of too much clearance then the rings can lose bore contact. Had a stroker in last year with about 4 thou too much clearance and carbon buildup half way down the cylinder ! But of course some " Old Joe" had bored it with a bit extra clearance because "thats the way I always do them" !
Mike

 

[Howard Jones]

Sorry but here I go again, My wife calls me the "Cheep Italian", and I do spend wisely.

At 400Hp (crank) and run mostly as a street motor I don't think you need to get too far from stock rotating parts or much bigger than 5 liters. Just good +30 pistons, rings and rod bolts. Find someone who will balance the works right and use ARP rod bolts. Set compression at 10 to 1 and use the stock block, crank and rods.

The power you need will have to come form the heads and valve timming. AFR heads with the CNC port job, 202 intakes and 160 exausts will be plenty of head for 400hp.

Call Comp Cams Tec line up and talk to them. I would run a HYD roller motor and limmit revs to 6300. Run as much cam as you can, The Hyd roller valev train will limmit the choices and keep you away from huge lift and radical cams.

400Hp should come pretty easy with a 750 DP Holley and a nice single plain intake.

Run advance curve at 34 degrees, all in by 2800 revs and tune the carb right and you should be happy.

You don't need to spend big bucks on special parts, they just need to be put together correctly, limmit revs, and get the performance gains you need from the heads/valve train.

 

[Ian K]

Gus,
If you just have a +30 pistons in a standard 302, dioes this make it approx 306Ci (depending on cylinder chambers etc)? Thanks

Brett

Hi Brett,

Yes, a .030 overbore with a stock 3.00 inch stroke yields ~306Ci.
.060 overbore with stock 3.00 inch stroke is ~310Ci.

Here's the breakdown (to expand on Gus's chart):

Block Stroke Bore Rod CI
302 3.00 4.000 5.09 302
302 3.00 4.030 5.09 306
302 3.00 4.060 5.09 310
302 3.25 4.000 5.315 327 *some use 5.40 rods
302 3.25 4.030 5.315 331 *some use 5.40 rods
302 3.25 4.060 5.315 335 *some use 5.40 rods
302 3.40 4.000 5.40 342
302 3.40 4.030 5.40 347
302 3.40 4.060 5.40 351

Ian

 

[Mike Huddart]

Mike I've heard a lot about the changes to the IVA recently from different sources. I'm looking to get mine through within the next 12 months. Do you think the test will change in that time ?

I'm running stack injection throttle bodies and motec on an eighties block so I'm hoping emmissions will be o.k. It's the Cats I want to avoid.
I opted for a 331 stroker engine for the reasons mentioned above. Rod ratio etc. The thing with a 331 is it MUST be balanced well, same for 347 i guess too with clutch and flywheel. It's critical. I'm getting just over 500Hp dynoed at the flywheel on mine but it did cost a bomb to get built.
Martin

Martin,
As far as VOSA are concerned the IVA requirments will not be changing but things may happen that are beyong their control . I don't think you will need to bother with cats just yet but I would not be concerned even you had to fit them. Sounds like you have a good EFI kit there and unless you have a rediculous cam in there it wouldn't be a problem. Typically we are getting fast idle HC figures of 10 out of 200 allowed with our EFI 8 stack motors even with 500 hp.
As you say, the balance thing with these stroked 302s is a constant battle for us. People presume that if they buy a "balanced " stroker kit from a US supplier that it will be OK. They are not, we had a US built 331 last year with four main webs cracked through to the cam journals, thing was , the balance wasn't THAT far out but it WAS out.
If you need any info on the IVA thing give me a call on 01270 811427. or E.mail me
Mike

 

[Randy]

love my 347, I track it hard . 435 hp and a 6500 rpm chip. lots of usable POWER.Not scared of my stock block. Ford racing is offering great deals on Boss 302 block. crank rod, and piston packages that are a great value.
Randy

 

[Gus Richmond]

I would like to know what the difference is between a "dart" (4 bolt main) and a boss block. I think the boss block has threaded plugs instead of the freeze plugs( has 4 bolt mains on 2,3,and 4th journals like the dart) . What about the head bolts/studs? do they pass through coolant passages on a boss block? or are they blind like the dart block? Where is the difference, to justify the additional cost of the dart block over the boss? Is the block material similar? What advantages does screw in Welch plugs have over the traditional press in plugs...perhaps a bit more rigidity but the block itself should bear the forces applied with no dramas (welsh plugs just being a necessity of production techniques)?
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com

Australia</st1lace> the 347 was an option in one of our falcons (like a mustang but slightly bigger and better :lipsrsealed. If there were longevity/reliability issues surely as a manufacturer it would not have been offered to the public? <o></o>
Sorry for babbling, but I am not sure which way to go in regards to powering my car. And don't ask about the trans axle....... Either way I would get one to suit.<o></o>
Thoughts please???<o></o>
Kind regards, Gus.<o></o>

 

[Mike Huddart]

Gus,
both blocks have siamesed bores so will go to 4.125 bore (Dart say safe at 4.185) Dart has steel main caps, Boss nodular. Top spec Dart comes with 4 bolt on 1,2,3,4,5, Boss and Dart Sportsman, 2,3,4. Boss and Sportsman will take factory roller lifters. Dart is about $4-500 more expensive. Weights are within 10lb of each other, big bore spec you loose 12 lbs
An alternative to Boss is the new Dart SHP, same deal as Dart Sportsman with steel caps on 2,3,4 but slightly cheaper than the Boss block.
ALL the above need finish machining so factor this into the cost.
The Boss and SHP don't come with any cam bearings, (special and expensive) or rear cam plug, dowels etc, so if you are ordering make sure you get these at the same time, standard parts don't fit.
Mike

 

[Gus Richmond]

Thanks Mike. I appreciate your input.
Regards, Gus.

 

[Bill Cooke]

I've got a 347 in my Daytona that I just love.Good AFR heads good cam that is not to crazy and a 650 double pumper on top.Just plain and simple that won't break the bank. I've got a 347 waiting to go into my Tornado.Again good heads and cam, 4brl on top.Dyno #'s showed max hp as 420 @ 5900 with torque over 400 from 3200 to 5500 with a max of 435 @ 4000rpm.As my Tornado is to be a street car I like all of those #s.
Bill

 

[Tony C]

All the guys are giving you great advice about the 331 as opposed to the 347. As for the 351 would that be the Windsor or Cleveland? For those you get about 100lbs increase and not alot of horsepower gains for the extra weight and heart achse of parts searching.
Over here 302 blocks are a dime a dozen. I run a twin turbo 302 with an AODE trans and thumper heads and trickflow efi intake and make about 450 to my rear wheels in my mustang.
If you want to make your target HP build a 331 with these things for realiablity.

DART 302 block or MAN OF WAR
AFR 185 heads
ARP STUDS
1.6 rockers
edelbrock dual plane manifold for carb.

Go to www.Stangnet.com for a good 331 recipe to make the horsepower you want and need.