If given a choice which rods would you run with, 5.7" or 6" ??? I was just pricing out pistons and i realized that ones for 6"ers are pretty close in price, and i kinda was tossing around a set of rods too since gm pink rods arent that common anymore. BTW, i know new rods are big overkill for a street motor(it'll be my overbuilt as hell daily) Thoughts?
i have a 6 inch rod 355 that is the best performing street motor i have owned---J&E pistons,Summit H beam rods ,510 solid roller...
Given my choices and having already used my last set of pinks (still using them) I would go with a long rod. They work well and cost isn't nearly as much to run 'em today as it was say 20 years ago.
Ok. What difference would that .30 make. I understand some issue with piston scuff, but what else? I am sure p-n-b can help.
Oldolds, it affects the rod-to-stroke ratio. This also gives a different thrust angle on the crank and the time for peak cylinder pressure vs crank position. In general longer rod is better as it keeps the piston at the top a little longer. So you maximize the pressure from combustion to push the piston down. it also helps reduce the side forces on the piston some. Shaggy, given you are buying new pistons anyway, and you want an overbuilt engine, go with the new lighter, stronger and longer rods. Seems that new rods are almost as cost effective as rebuilding a set of used rods nowadays. Plus you get a better rod in that it is potentially a better shape in profile, lighter weight and stronger material. The longer length is just that much better benefit. I say go for it and build it to be able to withstand a lot more than you plan.
Interesting topic for discussion. If I was building a 327, I'd stick with 5.7 rods; 350 would like the 6.00. I know some folks that have NHRA National record certificates hanging on the wall that actually ran a rod that was shorter than 5.7 in their 288 engines. And I think Jenkins ran something like 5.85 rods in his 331 ProStock engines. Bottom line is one size doesn't fit all.
6 inch. Its a pretty standard set up anymore. The pistons are proven technology and the cost is about the same. Only way i'd run 5.7 rods is if I had a set sitting there fresh that didn't cost me anything. Take a look at using 5.94 powdered metal rods out of v6's, interesting stuff there for a low buck alternative. I forgot the engine designation, I'll try to update this post.
The rods stay straighter, meaning the piston pushes straight down, the pistons are usually lighter, and the rods stay at tdc/bdc longer, the only tradeoff i know of is increased piston acceleration/deceleration Basically it's mostly a traditional build, forged large journal 327 crank, 11 to1, l79 cam, 2.02 camel humps, holley 600 dp, edelbrock c4b, mallory dual point(old style), 11" clutch, t-10 in a '65 el camino... Probably a 3.73 or mabey a 3.90 gear if i can get one, but i havent got that far Thanks guys, basically i was just making sure there wasnt an obvious downside to one of these
i would rethink the compression ratio unless your running racing gas or e85 you should use something around 9.2-1 for a daily
I've done a lot of thinking on it, and things like the slow ramp on the old style cam, and it's decent amount of overlap should work to my benefit, by bleeding off some of the compression at low rpms, i'm pretty sure i want over 10, but i'm still debating 10 1/2 or 11. E85 isnt out of the question, but there isnt any pumps locally Also i did cc out my heads(really 62cc), and will do my pistons too to make sure of my real compression so there arent any supprises
If you have iron heads I wouldn't go over 10:1. Aluminum heads can get away with more. I am running 10.8:1 with aluminum Dart heads on 93 octane pump gas with a well chosen cam (late closing intake) with no problems. Running this much compression you must be sure of your tune at all times. I wouldn't go any higher than 10.8 or so and be comfortable. What if you get a bad load of gas?
I have a circle track engine Bore 4.155 and a 3.25 stroke [stock on a 327] 6 inch rod around 352 cu in .. I had this engine assembled for all of the above stated reasons plus I could run very large valves. And last stay within rules on max engine size. Oh yes this thing pulls very hard from 3800 on.
Try Googling E-85 gas stations for your area. It may not be current but it is a start. Just start looking for those yellow nozzles. Some of them are diesel. Bob
Their is two different schools of thought here. Smokey Yunick (you knew it was coming) always said use the longest rod you can reasonably fit into the engine for all the reasons stated above. The other is that shorter rods are best it all depends on what fuel and CR you plan to run. In a PHR Engine Masters Challenge engine for example a lot of guys use shorter rods to snap back the pistons to help prevent detonation.
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