I just purchased a set of Aluminum rods and want to know what it will take to make them clear the block and pan rail. Any pics would be very nice. Also what does it take to internally balance a 455 with these rods? What are the advantages and is it worth the extra cost? I have only heard of one instance of the weight that has to be added to the crank flying out. What I am after is a light weight rotating assembly for less stress on the block even though I will not be turning it over 6000. I really do not want a stud girdle and the most HP would be less than 600 and most likely be 500 to 550. Thanks
I'm pretty sure that the aluminum rods will clear the block, and rails, unless you are planning on a big cube stroker motor, 494 to 535ci. I have GRP aluminum rods in my 470, slight offset grind of crank to run bb Chevy rods (7 inch), and there are no clearance issues, and no metal removed from the block for clearance. The crank seems to have some "heavy metal" added for balancing, but that's all I know about that. Gary G.
Internal balancing is a good investment in a race engine not needed in a street engine. Make sure the machinist installs the mallory parallel with the main journals not perpendicular. This is more time consuming but will remove the problem of flying out of the crank. Mallory that comes out of the crank at RPM will destroy the engine most likely. The balancer and flexplate will also need to be changed to internal balance units. You can use the aluminum rods and still go external balance if you prefer to save the money. A light rotating assembly, internal balancing and lower Rpm can be safe to much higher than 600 horsepower without block bandaids.
Yep thats 10000% true as mine flew out at Norwalk LAST year. We dropped the pan and there in the pan was the mallory in one piece and you can see the spot where it flew out. Bad prepping and welding by the machinist. Mallory plug did to my engine what a .22 cal does to the victim head of mob hit. Lot of damage as it bounced around.
You definitly need to check the clearances at the block/pan rails as well as the front half of the oil pan. Also the cam to rod clearance. On my motor I had to grind in all those spots and still had problems with the stock oil pan.
My rods are the stock length and the bore will be .038 over using JE pistons. I want to run the aluminum stage 1 heads with only mild port work to equalize flow. Find out what cam will work best with the heads flow numbers and then go with a smaller cam to be easier on the valve train. I can buy the aluminum heads for about the same price as it would cost to get a complete set of iron heads done and they will be lighter. How much does it cost to internally balance? What is the weight of a stock untouched rod?
Figure about $500 for internal balance job. The price will or should be an estimate + a specific amount for each hole and mallory slug to be installed, the mallory is expensive. I had over $150 in just mallory for the last balance, that was a steel rod motor so it needed more weight. If the slugs are fit properly they should not need welding, not just a drill it and go project it takes time to do this the right way.
Jimmy, Your engine goals sound much like mine on my first race motor. I did not want a girdle and its cost, and I wanted 550 to 575 hp. The horsepower goal was kninda backed into based on power possiblilties of a good set of iron stage 1 heads (no aluminum S1 heads at that time), and what the short block could take w/o a girdle. The light rotating assembly was accomplished w/ light pistons (12.4 to 1 Venolias) and pins, but we used stock rods and stock external balanced crank. Your aluminum rods may be overkill for the rest of your combo, but since you've already got them, what the heck. I turned this motor to 6000 rpm, and occasionally to 6300 testing gears and convertors. I was using a pretty big comp cams solid, comp pushrods, and KB roller rockers that I bought second hand (but unused). I had no problems with the motor, and it made 565 to 570 hp on the dyno. You are no Doug Hecker, as far pounding on your stuff, so internal balancing may not be the best use of your $$$$$ for this hp level. What do you plan on putting the motor in?
What do you plan on putting the motor in? [/QUOTE] The race car if I ever get it done! I just had the chance to get these rods cheap from the board. I am just collecting used parts now to build an engine for the future. I have the street engine in it now. It ran 11.30's in Alans green dinosaur at 3500 lbs. and mine should be 2800 or hopefully lighter and the computer shows it running 10.80's with the powerglide trans rather than a 400. I don't expect this engine to last forever and I would need to go faster to have a good chance at the Q16 in BG. I plan on selling my 70 GS stage 1 (cloned from a GS 350) soon and then get back on the race car. I would like to have it at BG next year and be competitive in the bracket classes. I am not bringing anything this year and just plan on helping Alan and visiting everyone. Good to hear from you Jeff. How are you and Melinda? Are y'all coming to BG? Is Mike coming? Drop me an e-mail and fill me in. And thanks for the advice everyone. It sounds like I will just stick with external balancing.
I would not recommend internally balancing the crank. Although a good Mallory metal installation should not be a problem, having to add too much is never a good thing, Consider it an "intrusive" process, and the less of these you do to any engine, the better off you are. At the RPM levels we turn these motors, I have never had a problem with a good quality external balance job, and I stress "good quality". That should cost you about $180-$200. There is only one guy I will let balance my stuff, he is good, slow, and expensive.. but worth the wait. He is known in the machining/engine building community around here as "the best". Funny thing is, he has an older SW balancer.. but really knows how to use the thing.. The only cranks we internal balance are billet ones, since they are much easier to do, not requiring heavy metal installation. JW
Thanks Jim I will stick with external balance and I hope that one of the local machine shops can do that right. I am going with the Aluminum rods cause they should be a little lighter and somewhat stronger but mostly I got them used and cheap compared to new ones. How much stronger are Howards alum. rods than stock and what other advantages are there?
Perry, Having worked with a couple '94's, and after turning one into a 525 with a billet crank alum rods and 4.360 pistons, I can honestly say that I really think the extra cost for the crank is well worth the performance and reliablity gain. That being said, I have a Supercharged street 494 going together shortly here, and we are pondering the idea of internally balancing it. I did hurt one offset ground crank at the 760 HP level, that tweeked the number 7 rod journal radius, and there certainly was discussion on that external balanced motor if we would maybe not have seen that. It was an existing shortblock that we freshened, and added HP to with Alum heads. External balance puts more stress on the number 2 and 4 main, and it's tough to say if that tiny rod journal was just not up to the task. Motor had light pistons, pins, but the heavier billet rods. So, yes, going the extra mile to internal balance on a '94 is not a bad idea, but personally I tend to shy away from them now, and just go headlong into the billet stuff. More bucks, but I beleive the payback is there. Up to 750 HP, I beleive even an external balanced '94 will be ok. The supercharged '94 was something that was brought to me to build, with parts already in hand. Had that been a "clean sheet motor" it would have a crank in it. Actually, the customer is considering upping to a billet crank after a year or so, just talked with him this evening. Jimmy, Have the machinist check those rods carefully.. for both big end size, and stretch. Used aluminum rods are not used steel rods.. what I mean by that is the alum rod is a much more delicate piece, and a "throw away" item after they are used up. If they are in good shape, they should easily handle 700 HP. JW
Thanks Jim Sounds like Aluminum rods are not necessary but still will help keep the weight down on the rotating assembly. The rods were already sent back to Howards and checked before I bought them off the board. I will still have them checked Thanks.
Aluminum roded motor is alot easier to internally balance since it has less rotating weight to balance. If it was my motor, I would internally balance it and run with what you got. It can be a vicious cycle spending money on durability and deciding where to draw the line. Wear out your buget combination figuring out what you want to run and how far you want to go. Then put your money in a more thought out combination after you learn from any mistakes you make. It will give you more time to collect and get deals on good parts not to mention time for better parts to come out. :TU:
Hey Jimmy, I would like to add some information to this thread. To keep it simple I will just use bullet points so you can follow. I may not be able to explain in writing as easy as I can verbally so look me up in BG so I can explain better. 1. Aluminum Rods.... until recently I have been a believer in steel rods. But over the winter I spent a great deal of time trying to reduce the rotating mass all in an attempt to make my engine LIVE. To give you an analogy... Take a 5 lb weight in your left hand and spin your arm around like the crankshaft. The 5 lb weight will want to pull your arm out of its socket. Then put a 10 lbs weight in your right hand. Again spin your arm. I have a feeling it WILL pull your arm out of its socket. All I am trying to say is less rotating mass will reduce the amount of stress on your crankshaft, lower end of your block, and the cylinder walls. 2. Internally balancing...... In my opinion this is the only way to balance an engine. Since you are going with aluminum rods and a lighter weight piston your rotating assembly (also known as bob weight) will be lighter than the stock assembly. In this situation there should be NO need to add weight (mallory) to your crankshaft. In fact they should have to remove weight. When they do this make sure they remove the metal from your crank on a lathe. This is called lathe balancing. DO NOT let them remove weight by drilling holes in the crank. If you replace your stock connecting rod with a heavier connecting rod then you would have to add weight to the crank. Again.. this is just my opinion but if you have to add weight to a crankshaft its better to add the weight near the center of the crank or even spread the weight out in a few strategic places on the counterweights. 3. Block and component clearance..... Make sure you check your rod big end to the block and OIL PAN for clearance. If the big end of the rod is much larger than the stock rod then you will have issues. If your not using a girdle then I know you will have modify the oil pan up in front on rod journals 1 thru 4. I think the minimum clearance should be .060 to .080. 4. Cost of Int vs. Ext balance..... there shouldn't be that much of a difference in cost as far as labor goes. It will take them about the same amount of time. I pay around $200 to have this done. Do expect to pay more if they are adding mallory. Its about $45 for a slug. But again... your rotating assembly will be lighter and should eliminate or minimize the need for mallory. Perry, There are two ways to reduce the stresses on a crankshaft. 1. Less rotating weight.... I can tell you that my present engine has a bob weight of 1674 grams. If your running a heavy steel rod and a piston that is over 600 grams then longevity could be an issue. 2. Camshaft.... I have spent a great deal of time over the winter talking to camshaft experts across the country about the effects that a camshaft has on an engine. I am now a FIRM believer that if you have a camshaft that is creating more than 220 psi of cranking compression then you are going to ABUSE THE CRAP out of your crankshaft and bearings. Higher cranking compression is caused by a camshaft that is too small. Hope this helps shead another perspective on this issue. I also believe there are many different ways to build an engine and my ideas are certainly not the only way. Thanks
Hey Guys, Another note.... You can still internally balance an engine using an external balance flywheel and damper. They just balance the assembly as if the two pieces didn't have the extra weight. Take Care
Perry, You guys really know how to make the cars absolutely fly!!!! And they are some of the best looking cars to boot!!! How far into the 9s are you looking to put the car? Keep us up to date on your progress. Also Perry, what was the trick you were discussing on keeping the tire rubber off of the rear quarters? Take Care
