comp pushrods help!!

[mally69]

ok heres the scoop my grandpa just finished his 69 barracuda and put in a 440,, i am running the same heads and the same pistons in my 440 in my charger so i know the heads and pistons work together,,,, heads are 906 and the pistons come in the engine rebuild KIT that summit has from speedpro they are 10.34 forged pistons,,,,, well he ordered comp pushrods from summit their listed part number in the summit book is CCA-7840-16 supposedly the same length as the factory ones well (( it ran like a total dogg absolutley NO power )) well after his 440 blew up today with under 10 miles on this fresh 440 we tore it down only to find that every intake valve has rubbed all 8 pistons and number 7 piston swallowed the valve... has a huge hole in the #7 piston with a junk 906 head,,, i compared the comp pushrods to my factory pushrods and the comp ones are roughly 16th of and inch longer!!! HOW IS THAT POSSIBLE??? what would you guys do if this were you is there anyone i can call about this??? oh yea the cam is a comp Xtreme energy cam, lift is Int .477 Ex .480 duration @ .050 is Int 224 Exh 230

[aifilaw]

Well, you may be able to get some money out of them for misadvertisement...but good luck

really you should never crank and engine without measuring piston-to-valve clearance by at worst putting some silly-putty on the pistons, bolting 2 head bolts down and hand cranking it over once and checking the impressions.

Part of the problem may be that either the heads or the block has been milled down, a typical trick to raise crappy stock heads static CR's.

[mally69]

true,,,   but the pushrods being just that little bit longer would make a big differnce  i would think

[Just 6T9 CHGR]

Did you guys measure the lifter preload or just assume it was OK & put in a stock length pushrod?

After checking mine I wound up getting custom length pushrods to get the preload in spec.  Sorry for your misfortune

[aifilaw]

true,,,   but the pushrods being just that little bit longer would make a big differnce  i would think

Assuming 1.5 ratio rockers, 1/16" greater ends up being 0.09375in. instead of 0.0625in, 3 hundredths of an inch is not that much considering the standard piston-valve clearance you should maintain on any engine, i think you had bigger problems.

[firefighter3931]

From the sound of things this engine didn't have enough piston to valve clearance. As long as the plunger in the hydraulic lifter didn't bottom out then you would have been OK with those pushrods. Sorry to hear about the breakage. 


Ron

[jg68]

Maybe you got a funky batch of pushrods, but i just measured then installed my comp. pushrods in my 440, they were the EXACT same length as the originals, are you sure you measured them right, they've been selling these comp. pushrods for a long time & never had those issues, mine fit beautifully, now i did have to run .020 shims to get the preload right, but other then that, there great, i also agree with Ron, you must have had piston to valve clearance problems.

[idahogrumpy]

I have the same pistons in my 440 and I run a much larger solid lifter cam. I also run a modified 906 head. When I first built my engine I was breaking rocker arm adjusting bolts. Come to find out the valve spring retainer was hitting the top of the guides. Even after the machinist was ask to make sure there was enough clearance for use with my cam selection. This really pounded my spring retainers and did show up as wear on the valve keeper grooves in my brand new stainless steel valves. In my case it only happened at high rpms. I did not check the machinist work and ended up spending a lot of money before I discovered the problem. He did redo the heads, but I had to buy the gaskets oil, antifreeze and such. Plus all of the labor to put it back together.
CHECK EVERYTHING!
Were both cams degreed in the same on both engines?
                                                                                           Grumpy

[mally69]

well heres the scoop    yes the pushrods are slighty longer  than the 440 ones that we have   we did find out that the cam was 1 tooth off  which we think cuased the big problem    but its rebuild time

[Chryco Psycho]

I ALWAYS degree the cam on installation
Too bad about the problems