73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 4x4Cowgirl on December 30, 2009, 04:01:21 pm
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I have a bent pushrod in my 350 and I just pulled it out. I'm needing to order some new ones, but there are so many different measurements to choose from. I have a digital micrometer, and measured them. They are 0.315 inches in diameter and 7.796 inches in length. On Pace Performance, there are measurements such as 5/16"+.200" On the pushrods that came out of my truck, there is RP-3093 imprinted.
What I don't understand is how they got to that measurement? Is there a certain way I need to measure these pushrods? Any help would be AWESOME!
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5/16" = 0.3125, so 0.315 would be fine.
The +.200" means that the rod is .200" over stock length.
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OOOO ok. So that means that I have 5/16", so I need to look for some that say "stock length 5/16" ..... correct?
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Yes.
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OOOOOHH AWESOME! Thanks! I learned somethin new today! Appreciate it! ;D
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If your engine is basically stock you need stock pushrods however... I would question as to why you bent a pushrod.
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I don't know, I just got my truck and we heard a tappin noise and narrowed it down to the left valve cover, took off the valve cover and one of the rockers was turned almost sideways. Took it off, and that pushrod was bent... It's the only pushrod that's bent. It's supposed to be a rebuilt motor, I think whoever put it together was a shade tree mechanic and they didn't torque them down to the right spec... But we're about to pull my motor and go through it and see what else we can find. My rear main seal is leakin too... Hopefully that's all we find. It's supposed to be just a stock 350 though...
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7.796-7.800 is considerd stock lenght.. 5/16"
i would speing for a little stronger pushrod similar to these.. http://www.summitracing.com/parts/SUM-G6400/ for 26.00 buck..
i had a rocker nut back off on my 383 bent a push rod... the cause of it... the one that back off laid over and bound up its neighbor.. might have bent a valve as well... havent pull the heads apart..
IMO i only replace pushrods as a set.
i also upgrade the rocker arm nuts to these.. stamp steel version of poly locks and yes they will fit under stock valve covers.. the are basicly a nut with a locking set screw to keep them from backing off.. money i wish i spent went i built the motor..
http://www.summitracing.com/parts/CCA-4604-16/ fo 27.00
the std seld locking nuts are "technically one time use"... i have had them back off with stock springs
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Alright thanks! I'll look into those parts. Sounds like a good idea. Yeah, I'm goin to take the heads off and take them to go get the valves checked out because once I put this motor back in, I don't want to have any problems from it for a while! lol... I'm prolly just gonna throw all new gaskets on it. For sure goin to buy all 16 pushrods. I might go ahead and buy new rockers. It all just depends on what we find when we start tearin it apart. But I appreciate the info! Thanks a lot! :)
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As far as what caused the pushrod to bend it may depend on the quality of parts used in the rebuild. As I mentioned in another post my 79 Jimmy ran an Autozone special $799 rebuilt 350 I pulled from a parts truck. I'm guessing they use cheap foreign parts because that motor would bend pushrods from time to time,
To make adjusting the pushrods easier I cut a 1" strip out of the stock valve cover so I could get to the rocker arm bolts. When it came time to replace a pushrod I would throw this cover on so I could adjust the pushrod with the motor running.
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Whoa that's a pretty nifty idea!!! You should like, patent that hahahahah!!!
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if your going to go through it.. i would check/verify/replace the following
cam shaft
oil pump
fuel pump.
bearings
springs
valve seats
valve geometry
gaskets i like felpros..
oil pan i splurge for the 1 piece.. with the alluminum gromet inside.. (no pinched gaskest to leak or fall into the oil pump...) and like 30.00
check out the balance... if the rubber is cracked... theres a posibility that it might have spun or will spin.. easy check verify TDC mark with TDC #1.. stock replacement is like ~60.00
6-3/4 od http://www.summitracing.com/parts/SUM-161350/
8" od http://www.summitracing.com/parts/SUM-161358/
fuel pump i run both a SBC and BBC variants and they are good to about 600fwhp for fuelling.. running out of fuel can cause detremental damage.. pending engine setup. from the motor going too lean..
http://www.summitracing.com/parts/SUM-250000-1/ 45.00 runs 8psi
i would look into some shim Head gaskets.. usually they are good for ~.5:1 compression raise.
rocker arm torque specs is till the push rod stops moving(vertically) then +1/2-5/8 turn. you spin a pushrod by hand with lash is set right.. they are suppose to spin naturally anyways..
quick way to figure out rough compression.. http://kb-silvolite.com/calc.php?action=comp
not trying to nickle and dime you.. just things i look at.. if $ is limited i prioritize... oil, mechanical(timing chaing oil drive shaft, cams, balancer) fuel, then everything else.
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Alright thanks, I appreciate it.
So far I have replaced the oil pan and bought a reusable rubber oil pan gasket. Did an oil change on it. Changed spark plugs. Adjusted timing. That's about it. It's been sittin ever since. But I am lookin into a RV cam... But $$ is limited so far... I will definitely look into getting some of those priority parts you suggested thanks a lot for the input! ;D
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What kind of rocker arms are they? If the rocker walked sideways check the tip of the valve to make sure it's not mushroomed or it will happen again. If they are roller rockers they should have guide plates and hardened push rods. The other thing is there is no torque specs for sbc rockers they need to be adjusted according to the cam.
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They're just the stock rockers... But the tip of the valve is a little worn away. I planned on replacing them too. I just got a new cam today so I will have the torque specs for the rockers. Im just shoppin around right now for the parts.
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what camshaft did you get? also timing chain is almost require swapout as well with new cam
BTW rocker on SBC do not have torque specs.!!
what did you set timeing at? at idle or max timing?
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I got a cam from Engine Tech with an overall duration of .443 on intake and .465 on exhaust
A buddy of mine thats a chevy nut gave it to me today for free ;D
So timing chain too? Man lol it keeps addin up!
ok rockers on sbc... no torque specs LOL :D
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I got a cam from Engine Tech with an overall duration of .443 on intake and .465 on exhaust
A buddy of mine thats a chevy nut gave it to me today for free ;D
So timing chain too? Man lol it keeps addin up!
ok rockers on sbc... no torque specs LOL :D
.443/.465 is lift not duration ;)
duration would be some were around 200-220* @ .050" lift
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lol i am still learning the engine talk. I only know 4 wheel drives so far hahah.
ok on the box it says .214-.224 at .050
does that sound right?
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yep :) thats duration the valves are open in realtion to crankshaft rotation ;)
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ooooooooooo!!!!!! ok cool! i learned somethin new again! :P
so with that size cam, do i need to like upgrade any other parts to coordinate with it?
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unless you know what springs are in there... my first thought woudl be to up-grade the valve springs.. so you know whats in there..
stock lift was less then .400" on alot of these engines..
http://www.summitracing.com/parts/SUM-174001/ these will allow you to handle up to .490" lift
and yes this stuff adds up.
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Shoot, I have no idea. I'll have to get my boyfriend to check it out when we pull the motor I guess. LoL. I was really only wantin to fix what was wrong with the motor such as the pushrods and the rear main seal this way I don't spend an arm and a leg.... But with this new cam, I don't know now. ???
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understood..
i woudl get the push rods and oil leak fixed.. save the cam swap for a later date.. give you time to get springs and other stuff linded up and your truck back up and runnning.
oil pan gasket can be swap in truck if its 4wd.. if its actually the main you can do it in the truck.. though it will be a $#@%.. doing it on your back..
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Yeah I have done the oil pan gasket 3 times already. 1 with just a new gasket. Didn't work. Bought a new oil pan. Didn't work. Then used silicone and new gasket and loc tite on the bolts. Didn't solve the leak. So it has to be the rear main. Yeah, I don't think I want to do it since my trucks so high off the ground it would be a b*@#! to do. So we were just gonna take it out that way I can go ahead and repaint the block and heads and go thru the motor to see what all is there and if anything else is screwed up. But I really don't wanna have to screw with this motor again for a while after we put it back in, that's why I was contemplating goin ahead and doin it all at once but man it's addin up. Might need to get a loan out LMAO.
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your looking at close to 600-700 in parts roughly...
bearings,
gaskets
timing chain,
valve spring set
piston rings
push rods
granted it can be done for less.. pendign what make the priority list and what doesnt.....dont for get to add 100-150 or so for broken/loss stuff, fluid and gernal misc stuff, new plugs/wire be a good idea pending condition of current set.
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Yeah, so far I have replaced the oil pan, oil pan gasket, spark plugs, oil change, and that's about it. Set the timing where it lopes pretty decently. But shoot, All I wanna do is drive it again LOL. I got it in October, drove it for a few days and its been parked ever since. Pissed me off to see it just sittin there! So hopefully we can get this ball rollin before too long! :)