question,I bent three rods in my 455 first time out. I have stock rods,11to1 compression,hyper pistons,runs on alcy and turned it 6500 rpm max. pistons or valves did not touch , as a result, burned up the crank and three rods. do i need lighter pistons or what? any help would be great.
Did you hydraulic the engine? Easy to do with methanol, especially the first time out if you just switched from gas. When I switched over, the methanol grabbed every piece of grit in the fuel lines and put it right in the carb, making the inlet needles leak by. Lots of fun, that methanol.
HI,I do not think I did. At least it did not show the usual signs of hydraulic. I ran methanol on car with another engine combo and it did great. My car made one pass at 6.08 then started slowing down.I was wondering if pistons were possibly too heavy with stock rod and alky?
Bent Rods Question, Anybody. If the engine beats out a bearing, will it bend a rod also? thanks for the help!
I'm a little unclear. What do you mean that you "burned up the crank"? Also, what do you mean by "beat out a bearing"? Do you have any pictures? -Bob Cunningham
Too Heavy.... I think those pistons are way too heavy for a stock rod at 6500. Check the edge of the piston for contact with the head. If you streched a rod, a piston when it rocks on the pin at TDC will start to contact the head. This would be your sign. I wouldn't worry about bending a rod off the valve but the head is a different story. I would throw away those pistons and get a good lightweight set if you want long-term survivability. I've seen too many motors have those pistons come apart and destroy everything. They are too brittle for a race engine. I would only consider running those pistons on a N/A street engine. I would race stock pistons before those Hyper pistons. :rant: On the bearings and crank, I would just chalk it up as luck as messed up as the rods are. You didn't ever over-rev it by accident???
Rods Thanks guys for the help. I think I have two problems. First I do not think I had enough oil pressure. had stock spring in pump with regulator turned in about half way. running pressure was 65 lbs. at 6000. second,do not know why rods were bent. cannot see where piston hit head. piston was .005 below deck, with TA .040 head gasket. have mufflers on car never made noise until third pass. I am like rick,I think pistons are to heavy for 6500 and alky. car made good power with converter too tight 2550 lbs 1.34 60 ft. and still ran 6.08 in1/8 mile. any help would be great. I would like to run this combo if i can get it to be reliable.
Oil Question, what needs to be done to crank or bearings or block to make certain that the rods get enough oil at 6500 rpm?
Detonation is what pounded out the bottom end. What size nozzles, main jet, high speed lean are you using. How much fuel do you use per pass.
I agree that detontation is what wiped out the bearings. I also would say it's contributed to the bent rods. I've seen it happen on a few bb chevy motors. 50 degrees of timing is not good on any motor for too long.
Rods My Nozzles are size 33 return pill is 88 has no high speed return. timming set at 38 degrees. exhaust temp at finish line was about 950. car did seem to use less fuel than my small block, but it made around 650 hp. can detonation be present without the telltell signs when you run alky?
950 degrees is way too fat. You should be around 1150 to 1200 peak. This is based on 1/4 mile racing, is the type of racing that your doing 1/4 mile?
How much fuel do you use from your trailer to the staging lanes, burn out, 1/8 mile pass, and back to the trailer.
What pump size are you using ? Do you have a shut off that returns to the tank ? Do you use it at the end of the run ? Is there a chance that you turned the ignition off while your foot was still on the throttle ?
Rods You know I never payed close attention to the amount of fuel used just that way,But I have checked my fuel after I put it in staging lanes befor and I do know it uses very little on the trip to staging lanes. When I ran this engine the first time I did not look to see how much fuel it used untill I got back to the shop and it was a little less than usual. As far as the shut off, it does have a shut off that i control inside the car, the only time I use it is when I get back to the trailer, thenI lean it out while it is idling then hit the kill switch. the pump is sold by rons racing, and is a (0) pump. Does detonation show heat on top of piston when you run alky like it does when you runracing fuel?
Is it possible that the shut off valve was closed halfway on that pass and leaned out the engine. Sounds like what happened. Another thing, I think the 33 nozzles are too small and that you should be around a 37 to 39 nozzle. As far as seeing signs of detonation on a piston, see if you have stuck rings in the grooves and the pins pounded out in the pin bores.
I'd be surprised if you got it to detonate at 11:1 were the bearings burn't or pounded out ? How bad are the rods bent have you measured them ? I assume your motor is around 460ci The nozzles might be a little (1-2 at most) small but your not that far off if the egt's are correct . You wont usualy see 1200 till the end of a 1/4 mile run . 900 to 1000 seems about right at the 1/8 , EGT's are dependant on your application . I've had egt readings over 1300 and still been able to wipe the pistons clean . Are you sure your timing was a solid 38 at speed ? Does your car drive well in pits and on the return road ? Wondering if the barrel valve is set up right ? I'd still side with hydraulic or something else over detonation .
Rods 434,to answer your question, If I shut the barrel valve off just a little bit it will build heat really fast,so I really do not think that was the case.I do not have any rings sticky, but do have 2 sticky wrist pins,#7 and 8. Dave,#7 rod bearing was completely gone and it is the one that is bent the worst. shaped like a bannana one way and like an S the other. I do have # 3 main in the brass but not spun. timming seems to be okay unless MSD is doing something funny. I think I am going to cross drill my crank,get lightweight pistons,rebalance and monitor my fuel closley and bump oil pressure a little and hope it does not happen again. Thanks for all the info it has give me something to think about.
