Blown 526 HEMI over rev

Hi guys,

I broke a trans input shaft at the top of first gear. The engine hit the rev limiter (9500) for just a second before I caught it and clicked it off.

Is there anything I need to double check to be sure nothing got hurt?
I was told to check the rod bolt torque to be sure that hasn't changed.
Anything else????

Thanks in advance.
Frank

 

RPM's

Don't know who's rods you have, but 10000 + is not uncommon for the Blown TAD cars. If you don't feel comfortable take the out and check them. Rod not forked C/C etc. Don

 

I have overrevved mine lots of times when it rolls a sprag in the trans or spins the tires. I wish it only went to 9500. Mine has seen 11,200-11,400 several times without any significant damage. Check your valve train includiing spring pressures. A freewheeling overrev loads the rods the opposite that running them does so check bearings and if you have questions about piston to head or valve clearances check those also. Dave Germain

 

Typically when that happens by the third run it'll toss a rod or two. I would change the rods if it were mine, and check the lifters along with keepers and retainers and everything else mentioned here.

 

I agree ( even though it hurts to throw new rods away) but if you roll a sprag and send it to the moon, take them rods out before it cost you a block/cam/heads, etc when those rods decide to part ways

 

rods

Sorry, but 9500 main't shit. Don

 

Take it apart and check EVERYTHING and put it back together again.

Extra attention to Center to Center on the rods.
Check the rods for big and small end bore distortion
Check every rod bolt for stretch or feed it a new set.
If checking fails on any one of these above feed your money eating monster a new set of rods to prevent wallet pains.
Check piston ring side clearance. Really do this one. If the clearance grew feed it a new set of pistons.

9500 under load is nothing. But 9500 free rev is ouch.

 

I broke a transmission joke at the starting line and free rev the engine to 8800 . So I took everything apart and checked the rod bolts and if the had been out of round at the big end and pin clearance ....Everything ok.....just as it left the line the very next run a week later it threw 6 rods out

Now I know, it will hurt less to throw a set of rods to the trash can , that let the engine throw them out , along with a block, cam and crankshaft

 

I've heard several people say this very same thing. Why does this happen? There has to be an explanation.

 

Over rev

Thanks for the replies guys.

The rods are Brooks B2's. The engine (including rods) has 5 runs on it (including the over rev on run 4).


Hi Don,
It was nice to meet you. Next time we'll have to catch up with each other BEFORE the staging lanes .

Thanks again guys.
Frank

 

The reason is that combustion pushes back against the piston and rod. Close the throttle and create a vacumn and bam....it will sometimes break a rod if it is suspect. Boggs told me one time he didn't like our 4.500 stroke because if we over reved it it would pull the cap and bolts out of the rod. Went 10,400 once on the 2-3 and next run at 400 feet.....well rods would have been cheap. Same as free wheeling.....no cushion! I know the dragsters turn way higher than this but with a short stroke!!

When I was an apprentice tech a long time ago, we used to sneak a head off just wedging up the intake with the bolts loose on the opposite side. An old journeyman asked if I wanted to see something neat. He held a piece of cardboard over the open intake ports. He made sure the choke was not on step. Start if up but don't ever touch the throttle as the rods will come out he said!!!! All you saw was the piston at the top and the bottom like it was on a strobe light. Randy speaks with authority......change the rods. If you roll a sprag......you have lots of work to do and don't take a chance. I have rolled one in 25 years and that was in a dragboat at the hit and that was before the dual sprag deal for boats. Keep a close eye on them or figure out why it shakes and rolls the sprag.

Sad but the cheapest route is new rods. The best rods won't take a freewheel in my opinion and survive the next couple runs.
Thanks. That is my free advise......for what it is worth
Dale

 

You might get away with it...you might not. Rods are cheap. Blocks, camshafts, cranks, titanium valves, liners, pans and fires are not.

 

i dont thinks it that big a deal check every thing if it looks good run it 9500 dont seem that bad to me i would run it

 

FLIP A COIN...if you like to gamble..if you were in the finals, then I would say go for it..best of luck.Dave

if I remember rite the last cam I got was around $500.00

 

Broke a gear set in my glide at the hit and sky'd the motor 9,000 plus BBC. 4 run BME's. My friend who runs N/TF strongly suggested not making another pass (replaced trans) without replacing rods. We only had 2 more passes to make and our season was over. We were getting a little bit of $'s per pass. Decided to try it after checking oil filter and valves. Car ran a solid 6 and kicked a rod out the side of the block as soon as we lifted in the lights. Block was fixable, crower crank junked, took out 3 pistons, both heads were hit and needed welding, lost 3 valves, oil pump broken and steel stoker pan was totally wasted. oh yea it also needed new rods

 

I would also very much like to see an explanation to what really happens to the rods. It seems people have checked their rods for big end roundness etc. and the next pass they still exit the block, is there no way to tell if a rod is ok or not after a free rev like that? Pweefe forgive me for my fpelling, im not used to wright in english