Well, I have a '70 LS5 454 in my '57 PU, going to pull it out this winter and freshen it up. My question is only regarding the bottom end and what are the RPM capabilities with it? See, I have a different intake setup I'm putting in, the intake is good for 6500 or so...years ago when I was younger and trying to impress folks, I always shifted at 5200-5300. My plan is stock main caps, stock rods with ARP hardware. Anything else I should be looking at? Thanks
A good oil pump would help... An AC PF-35 oil filter or equivalent... Double roller timing chain and gears.... And polish the journals on the cast iron crankshaft with 3M wet or dry 400 grit sand paper with WD-40 and using the old tried and true "shoestring" method....
Sooo , what are the rest of the particular's of the long block? Compression, head's, cam RPM range? Just because the intake is good for 6500, doesn't mean that the rest of the combination will support it. Tell us what you got, so we can really help.
I haven't gotten there yet, I may just rework the heads a bit, and will be running a full roller cam and valve train...thing is, that's not my concern yet. The concern is with running the LS5 stock bottom end with ARPs, is it safe to the 6500 range? The rest of the engine will come together.
I ran my old 2 bolt, cast crank 454 to 6000 rpm. Originally in my OT drag car, then became the engine in my 38 Chevy with only smaller carb and smaller exhaust. Still ran to 6000 rpm, just not as fast as the drag setup. No reliability issues, drove thousands of miles on street, and extended freeway driving. The short block was an old cast flat top piston. Just pout new bearings in before the racing and the big cam. Cam was capable of higher rpm, but it was not faster winding it higher rpm, even if it could have went more.
Not really familiar with LS5 spec's. But if it's a 2 bolt vs. 4 bolt dilemma, I wouldn't worry either way. If it's a 2 bolt main block, and you want extra piece of mind, put main stud's in it and have it line honed, and go for broke. If it's a 4 bolt block, Fuggitaboutit! Either way 6500 RPM is child's play for a Big Block. JMO
Was the rotating assembly previously balanced? Would be a good time to have it checked out. Scat 4340 6.135 rods are under 300 bucks. ARP stud kit instead of bolts is good insurance.
I would say a stock 2 bolt main cast crank is good for about 62-6300 rpm, as far as those rods go, by the time you buy the ARP hardware and get them resized you'll be really close to the price of a set of better quality Eagle rods.
Not giving advice, just my experience. I have been driving big blocks, mostly 2 bolt with cast crank, continuously since 1970, and used for my guidance, the bands on the tick-tock tach, that belonged with the engine. The amber band, was 5,000 to 5,500, and red band from 5,500 to 6,000. It worked well for me for almost 50 years. There is no question that the ARP studs will help greatly, but those valves are big and heavy, and swallowing one will ruin your day. It really depends on how much money you want to spend, and how hard you are going to drive it. My 454s, are two bolt engines, using massaged oval port heads, Comp springs and retainers, and roller rockers. I am also running a Comp, 280 Magnum, , double roller chain, with Rhodes leak down lifters. I readily admit, that I drive much more sanely than I used to, and now that I am running TH400 trannies, I am not revving the engines like when I was running the M21. I have a 427/425 four bolt, but haven't found the need to switch to it. Bob (77 now, and have become one of those old farts that content with going 10 over. Too much traffic to play sillybugger anyway).
By the time you have your old rods fitted for ARP hardware, you are close to the $$ of new Scat rods. Definitely have it balanced and a roller cam is the way to go. I ran mine in the stock cars up around 6300 RPMs.
2 Bolt 454 with ARP 3/8 rod bolts and stock rods here. Small 274H flat tappet with 840 rectangle port heads and a tunnel ram. Pulls hard to 6500 but I won't go past that. Usually try and shift at 6200
I thought the 1970 454 engines all came with a steel crank. I'd put new rod bolts in it when resizing the rods, forged pistons, and run it up to 6500.
Yes, thought a steel crank, but have never had the pan off. Lippy, the Chevelle was rated at 360, Vette at 390. Mines from the Vette, only difference is the exhaust manifolds (I think), but I really think GM just had to rate the Vette with more HP.
With good rods and good bearings, good oil pump, and a balanced job... you should be good. This is also taking in consideration you set everything up correctly. You have to really build your engine around the heads... you can have an intake that is good to 6500, but if the heads and cam can't hang... you're not going to hit 6500. Also, that 6500rpm capable intake is going to be good even if your peak hp is at 5200rpm. The 454 in my '55 four door has stock 4 bolt block, stock forged crank, good aftermarket rods, pistons, good bearings, and "ok" aluminum heads... oh, and a solid roller cam... and I shift it at 7500. I've ran it to 7500 hundreds if not a thousand times... on the track and on the street.
Well, the oval port heads I have can be opened up for some more flow. I might try that or spring for a few more bucks down the line for heads that can support it. When I say the intake will support 6500, and I want a bottom end to support it, really doesn't mean I'll twist it that hard, I error on the side of caution more so than not. My plan is to check the crank when I take the engine apart, if it needs to be turned, then I'll do so. After more good advice on this thread, something I'd (at my age-I give myself a pass) is have the rotating assembly balance. More good advice given here is may as well get better rods for the "for sure" factor. This engine will probably be the last engine I ever build to make some power...not talking 800-900HP, but I'd like to comfortably coax 600HP and be real safe with all of it. And that HP would most likely be at an RPM I wont go to (very often ) See the neighbor has a ChevyII that has a straight axle under it, I've been talking to him about it for 20 years, he keps pointing me to a Dart? I think it is, that had a wedge motor in it,,,he has a lotta cars to pick from, but he's more a hoarder than a seller...but every time I bring up the Chevy, he points me to something else. So, at soon to be 59 years old, I want a few shots at going fast in a straight line for a 1/4 mile. Other folks have seeing the leaning tower of piza on their bucket list, going to Paris and seeing the tower, ect...fastest I ever drove 1/4 was 13.86. Rode in many cars that were much quicker. Want to work up and do it myself while I still can. Yes, I can afford to go buy a newer vehicle that will do it, but wouldn't be the same. I guess to sum it up, I;m starting at the bottom and working my way up top. I'm not planning out the entire engine build at this point, but want to get the bottom end solid enough to please me...this isn't going to be a 3 month deal, just something I want to start on and work towards...hell, I don't even have the vehicle yet
We would have to get in a Hamb pissing match but I think 7500 was a good rpm area for a steel cranked BBC with decent square port heads and good Cam and valve springs, large holley and port work. You can twist a BBC tighter but to be reliable without going to race only parts I feel 7500 is about the safe limit. Everyone will tell you different , Oh yeah I twist mine to Blah blah blah. Your wallet will tell you when you need a dart block ect...
My 72 454 has a steel crank in it. I am loving this motor and am hooked on this thread. Some guys I really respect are interested and giving some good advice. Hope this keeps up for awhile.
I get the idea your going to drive like you stole it from light to light going to the Home Depot hoping to lift the right front tire.. If not, and being in a pickup, I’d build for low end torque and still shift it at 5200. I don’t have much experience with BBC’s but the engines I do that have 3-7/8” strokes made the highest HP at 6200 and were great from 4000 up. The good dual plane intakes today give great throttle response especially if sized with the correct carb with the accelerator pump cam dialed in. I’d rather be down the street with the other guy still winding out to 7500 rpm while I’ve shifted to 2nd pulling hard again and gone...Sounds like fun project...
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