gretchen/jason Posted January 27, 2008 Share Posted January 27, 2008 So im getting my engine back after being rebuilt twice first time i got screwed by a machine shop . Anyhow im running the short sbc 400 rods and 400 crank with forged pistons that work with the setup . Question is what is the rpm range with the short rods . Everything is completly balanced using top of the line rod bolts etc . Ive had some people tell me oh 6 grand is the limit some have said between 7-8 thou rpm but of course none of them aparently ever owned a sbc 383 hmmm . So i figured id ask and see if anyone who has run a 383 knows about rpm limits of the short rod 383 . My cam has a range of 2,200-6,200 rpms " comp cams" lifters to match and springs that are rated for the supercharger ill be using and roller rockers no roller lifters . 2,400 rpm stall converter and not sure if ill keep the R200 3:54 gears or use my R180 4:11 gears . Jason Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 28, 2008 Share Posted January 28, 2008 Well, that is a debated subject. OEM rod strength is typically not a concern as the rod bolts fail long before the rod itself. I have seen OEM 400 rods live for long periods of time on the dirt track with 14 to 1 compression and big solid or roller cams. Keep in mind that if properly prepped with proper machine work on the block, crank, rods, etc. you probably won't have much of a problem IMHO. Aftermarket rods are IMO insurance and well worth the additional $350 cost over the rework cost ($180) for stock rods which includes aftermarket bolts. If your going to add NOS or some other power adder the life may be shorter than if it were NA. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted January 28, 2008 Author Share Posted January 28, 2008 Well no NOS but just 7 lbs of boost from the super charger i had on it before i went from a 350 to a 383 . The machine shop builds boosted and NOS powered engines they said as long as i dont use over 11 lbs of boost i will be just fine . Heck if i end up with the 440 horses they say ill have who needs NOS . The stock crate 350 put 290 to the tires the engine was only rated at 290 to the crank shaft . My compression before boost will only be 8:1 as it was all measured out . Jason Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 28, 2008 Share Posted January 28, 2008 440 horses rwhp or fwhp? rwhp I'm assuming. Yeah, your probably going to get a taste of that HP and want some more, kind of like JNJ boys. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted January 28, 2008 Share Posted January 28, 2008 valve control issues are a more likely problem above 6000rpm but the lower rotating assembly with stock rods is not the ideal as IM sure you realize, piston speeds over about 4000 feet per minute are pushing things pretty hard if your useing reworked stock rods with 3/8" ARP bolts, so that equates to 6400rpm and Id be very reluctant to exceed that rpm. Quote Link to comment Share on other sites More sharing options...
Guest oes03 Posted January 28, 2008 Share Posted January 28, 2008 I have a 383 (in my truck) afr heads a roller cam and eagle crank and rods I had the thing balanced but during the build the cam hit a couple conn. rods so I had to grind on them a bit (on the shoulder). Anyways I did not rebalance the motor just took about the same amount off ea connecting rod. I was not aware this is a common practice. I shift @ 6500-7000 and knock on wood have not had issues yet. On the other hand I had a 350 stock rods w/ARP bolts balanced I ran that up to 7000-7500 after 3 years broke a valve. The conn rod bearings were loose on on rod but had not spun. It was a matter of time. Long story short i would stop @ 6500. Oh yeah all the rods I run are 5.7" (short rods) Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 28, 2008 Share Posted January 28, 2008 I have a 383 (in my truck) afr heads a roller cam and eagle crank and rods I had the thing balanced but during the build the cam hit a couple conn. rods so I had to grind on them a bit (on the shoulder). Anyways I did not rebalance the motor just took about the same amount off ea connecting rod. I was not aware this is a common practice. I shift @ 6500-7000 and knock on wood have not had issues yet. On the other hand I had a 350 stock rods w/ARP bolts balanced I ran that up to 7000-7500 after 3 years broke a valve. The conn rod bearings were loose on on rod but had not spun. It was a matter of time. Long story short i would stop @ 6500. Oh yeah all the rods I run are 5.7" (short rods) Yup,when using the 350 rods you have to grind on the rod bolts for cam clearance. Rods 2 and 5 are the culprit, but you have to do all 8 for balance reasons. 400 rods 5.565 have shorter rod bolts and the rods are different on the big end, which is why they work as is. Bottom line is that the internal forces basically double with every 1000 rpm, so 7000 has about 2 times the internal stresses as 6000 rpm, so you be the judge on what you feel comfortable with. Next time, spring for eagle rods in the 5.565 length if you still have concerns. Quote Link to comment Share on other sites More sharing options...
zmann69 Posted January 31, 2008 Share Posted January 31, 2008 must agree with Dr. Hunt. for what you are already spending, another $350-400 for rods and bolts that you will not have worries about, should be a no brainer. i used to have a 383 also and 6200-6500 with a blower on top was the most i was spinning. also if you are worried about rpm's them buy a matched f/i cam to match your heads and rpm worries. there are alot of good companies out there that are only a phone call away and willing to lend some help. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted February 2, 2008 Author Share Posted February 2, 2008 So i talked to the machine shop and they used i quote " a stock style forged rod " not a eagle h style forged rod but it looks like the stock rods as one of the rods from the 400sbc was 25 grams to light to work with . Then i decided do i really need to go to 7 grand i said not really when i had a stock 350 with the supercharger i rarley left second gear and i allready beat who i was racing . That was with only a 330 horse engine . I was told with the 383 the cam i selected and the heads i shold at least hit 400 horses with 4 lbs of boost . So i went with the basic forged rod they recomended for what i would be doing with my z . Oh and they are the 5.565 rods i thought they were the 5.7 i was wrong . Thanks for the replies . Jason Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 3, 2008 Share Posted February 3, 2008 , I know I could easily be wrong here,but, I can,t help feeling that it sounds like they gave you a good snow job to justify useing crappy reworked stock rods with crappy 3/8" rod bolts and less expensive pistons, to make the job cheaper and easier to assemble. Id be surprised if the shop used aftermarket forged rods at all in the short length. WHY? well most aftermarket pistons and rods are fairly expensive compared to stock rebuilder, style replacement stuff and the use of short stock rods , stock damper and flywheel,allows the use of 350 pistons to build the 383 which is the least expensive sbc piston easily saving the builder a couple hundred in ballancing and machine work to produce a functional 383 Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted February 3, 2008 Author Share Posted February 3, 2008 Well i do know the pistons are forged pistons from speed pro as i had them leave the heads off so i could verify they installed them and they did . I had the " stock 400 rods " marked before i gave them to the machine shop and i recieved the rods i gave them in a box when i paid my bill . The pistons ran me 530$ i ordered them my self for the short rods 5.565 and had them sent to the machine shop after they located them for me .One reason being i had allready orded gapless rings that fit the 5/64 3/16 ring grooves as i didnt want to spend anothe 350 $ on rings as i couldnt return the ones i had ontop of a set of pistons so i hunted down forged pistons that fit my rings and the short rods . The rods they took care of cost me just over 200$ through the machine shop so i cant say much for the rods as i dont know where the aquired them . I ordered the rod bolts myself from JEGS and bought the other parts my self also from JEGS , aka the flex plate i ordered SFI aproved and the damper i ordered SFI aproved 200$ damper 120$ flex plate ARP head bolts timing gears etc etc . They charged me 1,220 to assemble the short block 220 was for the rods plus machine work . they installed valve seats valve springs complete balance of the rotating assembly etc etc . All i did was put the heads on myself and install rockers and push rods at work . I cant say anything about the rods hopefully i didnt get riped of twice as the previous machine shop didnt balance the crank and i had a bad rod i wasnt told about untill the second machine shop told me about it . And the heads didnt have and valve seats installed in them from the first rebuild . I spent 700$ at the first machine shop and they didnt assemble anything so i sent it to a different machine shop to be " checked out " And bang another grand latter. So far ive used 3 different machine shops in this town that were highly recomended and got taken twice once was on the L28 3.1stroker . They didnt tighten down the camshaft towers and i broke a camshaft and smashed a few valves . The other being the 700$ for my 383 . Hopefully the third time was a good one as this 383 has been built twice assembled once and hasnt been in my z for over 7 months man what a drag . Jason Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted February 3, 2008 Share Posted February 3, 2008 , I know I could easily be wrong here,but, I can,t help feeling that it sounds like they gave you a good snow job to justify useing crappy reworked stock rods with crappy 3/8" rod bolts and less expensive pistons, to make the job cheaper and easier to assemble.Id be surprised if the shop used aftermarket forged rods at all in the short length. WHY? well most aftermarket pistons and rods are fairly expensive compared to stock rebuilder, style replacement stuff and the use of short stock rods , stock damper and flywheel,allows the use of 350 pistons to build the 383 which is the least expensive sbc piston easily saving the builder a couple hundred in ballancing and machine work to produce a functional 383 Sad, but so true Grumpy, seen it waaaaaaayyyyyyyyyyyy to many times! I was going to comment earlier on the HP numbers. A well built 383 will net 400 HP being NA. Under boost, I wouldn't be suprised if you get 550 horses at around 10 psi. I would expect 500 HP from around 7 to 8 psi. But that is my opinion. Back in the days, grumpy can remember I'm sure, aftermarket rods were a luxury item that cost alot of $$$$. Hank the crank was the primo crank manufacturer and carillo was the rod man to beat. A set of sbc rods would back then if I remember correctly set you back $1500 and so would a crank! Not so today, Eagle cranks can be had for around $400 and rods for $350. Cheap insurance IMO when coupled with a 4 bolt block and ARP studs. If you ever get the chance, buy a set of JE pistons and eagle rods. The pistons rarely require any balancing and are spot on dimensional wise piston to piston, real quality pieces to say the least. I have carillo and Eagle rods and both are fine pieces with the carillo having better quality and higher HP rating. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 3, 2008 Share Posted February 3, 2008 I hope it all works out well for you, but I don,t think the odds flow in your favor if its like my area,I have about a dozen "MACHINE SHOPS" in my area, Ive seen the work most of them do... and I know of only ONE that can be SEMI TRUSTED to do decent work. I was FORCED to learn how to do most of my own work and inspections as I found repeatedly that I was being charged for work that was either not done or done in a slip shod manor by people that could give a s$%%^^ less about doing the work correctly as long as they got paid. one shop that gets good reviews from the guys that can,t tell a port from a valve, with stickers being the main speed part on thier cars, charged me to install a splaid main caps and tried to give it back with a $1200 machine work charge and STOCK 4 bolt main caps, even thou Id paid for and supplied milodon splaid main caps, and it was obvious there was no hone work, or any of the other work that was listed and prepaid for, done, when I complained they admitted that they were trying to give me the wrong block back and could not find mine, and they would not return the $1200 Id paid up front or the supplied main caps as they insisted ID already picked up the correct block, (SOMEONE HAD BUT the signature was not mine or even close to the correct name) I eventually got $1200 in (FREE) machine work, but was out a good block, but only after lawyers got envolved (a loose/loose proposition I detest some machine shops employees I learned to take detailed before & after pictures of all parts and document EVERY LITTLE BIT of the work to be done,costs envolved, too stamp parts with ID numbers and get detailed reciepts and set dates for work completion, I learned to carefully inspect the work, and learned I needed to do as much as I could myself, and understand EXACTLY what needed to be done and WHY it was being done, and that every hotrodder needs measuring equipment like mics and dial indicators, calipers, magnifying glasses, degree wheels,etc. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted February 3, 2008 Share Posted February 3, 2008 Fortunately, here in NM we have 3 quality machine shops IMHO, Mauldin super service in Las Cruces area, Edwards Racing Engines (alb.), and Budlong motorsports in Alb. Edwards is pricey, but do good work and spit it out in a timely fashion doing famous name sprint car engines and high HP special engines. Keith Mauldin is a wonderfull person and record holding drag racer building and driving dragsters these days, and Tod Budlong has done top quality work on many of the fastest turbo ford mustangs in the country. The rest of which you are on your own. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted February 3, 2008 Author Share Posted February 3, 2008 Well im hoping all goes well . I did stamp id numbers on the block and the end of the crank to make sure i got back what i gave them and i did . They do work for my company HYUNDAI as im a mechanic there we send oure heads to them and sometimes short blocks and they run fine . hopefuly i recieved decent machine work . Only time will tell Jason Quote Link to comment Share on other sites More sharing options...
lsdengines Posted February 11, 2008 Share Posted February 11, 2008 Not trying to beat a dead horse here, but the combo you went with will probably be okay if revs are kept to 6500 (your cam will probably actually top out closer to 6k, tho), and boost is kept to 6-8lbs. That is a good truck combo. You added stroke and shortened rods(based on a 350) which makes for a much less than desirable rod/stroke ratio. What does this mean, higher piston speeds at any given rpm and less dwell time at tdc/bdc, and therfore less piston acceleration. What you do get to get away with though is not running a small base circle cam or grinding the rods. I wouldn't be worried about power, the engine will make plenty. I'm just nitpicking and pointing out that the combo is less than ideal for a performance, high rpm engine. Quote Link to comment Share on other sites More sharing options...
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