The dumb question is, What does it mean to "stroke" an engine, and why would you? Sorry. Just thought I'd ask.
Sarcastic answer, It's where you go into your garage, pop the hood and pet your engine over and over. Serious answer, Is making the piston move farther up and down in the block. longer rods and a different crankshaft are needed along with some machine work. By making the piston travel farther you get more cubic inchs and in return will give you more HP and TQ. Hope this helps!
...... Ok that's cool thanks for the quick reply! Sounds like something I may want to do when I get my next project. Now when you say machine work... what kind of machine work needs done? Also, does it use the same heads, rocker arms?
Wouldn't it be shorter rods that are required? With a longer stroke from the crank the piston would move too far up, so the rods need to be shorter, don't they?
No...longer (actually...it depends on the exact combo...some probably are shorter). Usually the piston is "shorter" from tops to bottom of skirt though. I'll try to see if I have any pics when I get home later...a visual is a lot easier
Stroking it is something you do when you run out of better things to spend money on to build your car. $1500 for 30 or so Hp is not worth it to me for a street/strip car. Been there done that, wont do it again.
I had a friend who turned his 302 into a 347. He installed the new crank, rods and pistons and when the crank turned it would hit the side walls of the engine. He had to get the walls shaved down some so the crank wouldnt hit it. Other than that basic machining, making sure everything is flat and even. As far as the heads he used the same twisted wedge heads he had. The rockers are the same I think the push rods had to be longer if Im not mistaken.
The stock rods on my 9.480" deck 351W are 5.95" long, the 408W stroker kit from Eagle has rods that are 6.25". I think that is because the shorter stroker piston must clear the crank counter Balance lobes at the bottom of the stroke. The stroke of the crank on a 351W is 3.5", the stroke on a 408W crank is 4", that .5" more travel in a complete stroke might require .25" extra inches of Rod. But hey Im no engine builder Im just looking at numbers trying to figure out what they mean. The main reason Im planning on a 408W stroker Kit is because the 351 block I have needs Boring, Decking, Line Honing and all that goes with freshening an Engine block. I wanted a Forged Internal Balanced H Beam rotating lower end anyway so for probably 500 dollars extra I figure to get the extra power, make more torque and make the torqure earlier in the HP curve. But I need some good flowing heads to make it work. Figure on spending $8000.00+ if Im not doing the assembly. Not everyones cup of Tea. But it should be a Fun Car to drive. IF I CAN EVER GET ALL THIS BODY WORK DONE!!!!!
What really makes me nervous is that every time I hand my wife a reciept she asks "Is This For The Maverick"? Then she gets out a ledger book ans records the amount, she keeps a running total of the money I spend on it. I told her I would sell my Electra Glide this fall.
If you're going to spend $8000, you're not so far away from the cost of one of these. http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=23023
I looked at those, but I found a 1969 9.480 complete with a standard bore for 300.00 and decided to get a little crazy with it. Im looking at making 500 HP with a 150 shot if I get bored.
Rod length depends on the sepcific combo WRT piston and crank stroke. In example, I think old school 393 stroker (351Wbase) uses a stroker crank with the stock rods and 302 pistons. I don't think a 393 needs much if any block machine work (for clearance issues). If you are rebuilding a 351, you are going to get new pistons anyway, so a new stroker crank is the only major cost for the 393 setup. If you are going pretty high performance, then stock crank might not have be in the plan anyway, so going 393 vs. 351 is not that much more money. Someone correct me if I am wrong on this 393 setup and relative "cheapness" of it.
