|02-12-2009 05:18 AM|
Not to hijack your thread, but the chinese made American engine parts are kind of hit and miss, with "Cat" being the bottom of the barrel. Be careful where you drop your money on "good deals". I purchased an "SFI approved" BBC flexplate made by Cat and luckily I inspected it thoroughly before I installed it and found 2 of the welds that attatched the gear to the plate to be cracked but still attatching the 2 pieces together. I contacted the internet seller from whom I purchased the part. The guy I talked to said he would send me a Scat brand replacement instead of another Cat, I asked him what the difference was and he said that their company recieved about half as many returns on the Scat brand compared to the Cat brand. I said no thanks and just asked for a refund, he then tried to give me a set of free chinese roller rockers along with a new flexplate if I "would like to give em a shot". I still said no thanks and got my $45 back. Maybe I'm being a little "glass half empty" but I'd be willing to bet those rockers were yet more crap they had recieved on a return.
Unfortunately, unless you have mega-bucks lying around, if you want to build a stroker you've got about 3 options Cat, Scat, or Eagle. I havent heard too many horror stories about Eagle, and they seem to be pretty common place in stroked motors, along with the 4340 scat's. I don't know of anyone thats used a Cat crank personally, but if the quality in their cranks is anything like the quality in their other parts I can see why. Do a little research on their reliability and quality before buying such an important part. It may sound like a good deal, but I'd hate to see anyone throw the money it takes to build a BBC down the drain because they were trying to save a couple hundred bucks on a crucial engine part.
One problem that you run into when using a short rod on a stroked engine is the rod crank angle. To simplify it as much as possible a longer rod is beneficial in two ways as it relates to the effeciency of an engine. The first being the amount of time the piston spends at TDC. A longer rod is going to spend more time at TDC than a shorter rod allowing for more pressure to be built up in the combustion chamber before the power stroke. The second benefit of a longer rod is the amount of force that gets exerted on the cylinder walls. The longer rod gets to spend more of its energy moving up and down in a cylinder bore instead of pushing the piston against the wall of the cylinder creating more wear and friction, which in the long run equates to an engine not lasting as long do to higher stresses in the rotating assembly and an unevenly worn cylinder bore.
|02-11-2009 02:58 PM|
|CNC-Dude||Do a search, there are several very recent posts about building a 496 and all thats involved! Too many things to relist....|
|02-11-2009 10:53 AM|
your right i jsut yped them wrong ... you on top of these around here lol thanks
would i have any issue if i go wit this crank and rods any modifing need to be done to the block ??
|02-11-2009 10:44 AM|
|68ss||check that number again. I think it should be 6.385|
|02-11-2009 10:37 AM|
|454cutlass86||well i just got off the phone with the company who makes it he said they are balanced forthe 6.835 rods|
|02-11-2009 10:32 AM|
here is the info on it
AISI 4340 FORGED STEEL CRANKSHAFTS
CAT forged 4340 steel crankshafts have been tested and proven to excel in engines producing 1,000 horsepower and 10,000 RPM. The premium 4340 aircraft quality steel with vacuum degassed forging process creates a clean and pure crankshaft. The state-of-the-art CNC machine centers provide superior tolerance.
CAT 4340 crankshafts incorporate these features:
- Computer designed counterweight to reduce main bearing loads.
- CNC machined to provide superior tolerance and journals micro polished to 5 RMS.
- Generous 0.125" journal radii to disperse stress under high loads.
- Each crankshaft has been visually inspected, X-rayed, magnafluxed, and ultrasonic tested to ensure perfection.
- All cranks are heavier at counter weight for easier balancing with various applications.
- Journal surfaces are treated with plasma gas nitrite to HRC60 hardness for superior wear resistance.
|02-11-2009 10:29 AM|
|454cutlass86||thanks alot yeah i can get all info on it he posed it with the info|
|02-11-2009 10:16 AM|
|CNC-Dude||Only the bore and stroke determine the cubic inch of an engine! Not saying you shouldn't use the stock length rods in your build-up, but typically, most 4.250 cranks have a lot more couterweight structure added to them to aid in the balancing of the added stroke. The shorter rods will require you to remove most of what was added, and in doing so will require you to add back about $600 dollars worth of Mallory metal to bring the rotating assembly into balance. Generally, these crankshafts have their counterweights cut for specific rod lengths, so if its still new,as you say it is, then you should try to find any paperwork or contact the manufacturer, to get their recommendations on what rod lengths they made the crank for....especially before you buy some aftermarket pieces that might not be able to be returned.|
|02-11-2009 09:19 AM|
how to make a 496 bbc
i have the 454 andi found a guy that has a 4.250 stroke crank for dirt cheap breand new if i bore the block .60)already.30 over)
if i use the stock rods i have will it make it a 496 or do i need longer rods