help - i screwed up on my v8 - advice needed Options

[jimkelly]

last week we determined that some of my oil leak problem was 4 bolts holding my carb intake to the heads, so we applied sealant and 3 stopped leaking. on Saturday I thought i'd address the last one that did not stop leaking, so not only did I add sealant to it again, I decided to use a longer bolt because the other 3 were longer. I used a 1.5" bolt but it turns out the other were probably 1.25", the max that should be used. so anyway, monday go for a drive but power is weird, I figured it had to do with engine being cold and I just changed the fuel filter and thought maybe there was some starving going on, but 30 minutes later I decided to go back home and figure out what was wrong. anyway, yesterday I pull the valve cover off to find a cracked valve rod that I retrieved from the head with a magnet on a stick but I had to remove the intake to put the lifter back in the head. anyway, it is all back together but it revs ok in neutral but under load it is either valves or knocking. what you think? anyway, why does a guy with so little mechanical prowess own a 914, who the hell knows. i'd like to think the noise is due mostly to timing cause I of course had to pull the distributor. and I never put a tdc mark on my flywheel or crank balancer, need to, asap. I first thought it was vacuum advance problem but vacuum is pulling thru hose.


https://www.youtube.com/watch?v=tfKEa1-W0XQ


video is being loaded, pls check back and comment. pls pls.

[r_towle]

any local mechanic should be able to help diagnose that....
Its a chevy v8....so look for an older guy that works on trucks ...they know.

rich

[MJHanna]

Man I would just replace it with something more reliable like a 6 (IMG:style_emoticons/default/piratenanner.gif) (IMG:style_emoticons/default/beer.gif) (IMG:style_emoticons/default/beerchug.gif) (IMG:style_emoticons/default/happy11.gif) (IMG:style_emoticons/default/lol-2.gif)

[sixnotfour]

check compression on that cylinder ,may have a bent valve....timing,
advance till it pings under accel then retard, so it does not..............smblk chev no rocket science..

[bulitt]

I agree with Rich find a local Chebbie guy. It doesn't get anymore basic than a SBC.
So you used a too long manifold bolt and broke the pushrod.
Get a shorter bolt.
1) You need to replace the broken pushrod with another that has the same exact length.
2) Once pushrod replaced you need to set the clearance between the rocker arm and the Valve spring retainer.
3) Then find TDC on cylinder 1
4) Install your distributor so the points just open at TDC
5) Set your dwell on the distributor if it has points
6) Set your timing at idle with a timing light with vacuum disconnected and capped.
(usually 8 deg BTDC)

[Bruce Hinds]

I've heard of push rods bending, but not breaking. Looks like your long intake manifold bolt was interfering with the push rod. You don't say the you replaced that, but I'm assuming you did . . . It's kind of hard to tell what we're listening to. It should be quiet if the lifter is properly back in it's place and the rocker arm is adjusted properly.

If the bolt was interfering with the push rod, I'd had to think where the metal filings went. It's all pretty simple stuff, but don't drive it anymore until you find out what's up.

[screenguy914]

Since at least that valve with the broken push rod is closed, I'd perform a compression test (all 8 cylinders) as it sits now (no intake manifold, disconnect fuel pump source or wire, remove spark plugs).

If compression in all cylinders are within spec, it sounds like it's just a matter of careful visual inspection, replacing the broken push rod, reassemble engine, adjust the valves, then run engine. But that's being optimistic. It could also be less so.

It's possible that the longish bolt interfered with the path of the push rod, perhaps rubbing it until it failed. Confirm on forums catering to Chevy owners.

The internet and the world has all the info you need for the tasks at hand.

Sherwood

[BIGKAT_83]

check compression on that cylinder ,may have a bent valve....timing,
advance till it pings under accel then retard, so it does not..............smblk chev no rocket science..

(IMG:style_emoticons/default/agree.gif)

Good advice go to Autozone and loan out a compression gauge. Bet you got a bent valve.
Bob

[jimkelly]

shit.. sound like the consensus is I may have a bent valve.. shit.. did I say shit already? damn.

[Larmo63]

The problem is: You don't have a 914 engine. (IMG:style_emoticons/default/smile.gif)

[Andyrew]

shit.. sound like the consensus is I may have a bent valve.. shit.. did I say shit already? damn.

Do you have a engine rebuild shop locally? Then chances are you can get this done in a day if you pull the head yourself. Take it down to the engine shop, they can pull the valves and likely have the correct valves in stock to replace.

Get a scope, pull the spark plug and look at the piston, if it hit you'll see.

[rightpedal]

My bet its timing/vacuum leak. Bent valve??? I doubt it. In fact, I would eat brussels sprouts for a week if its a bent valve. Wiped cam maybe.

Start with the dumb stuff. The firing order 18436572. 5 and 7 get crossed up all the time. Sounds like its really advanced. Does it start exceptionally well. Spin the distributor counter clockwise (to retard it)till she just starts to slow down the engine. put it in first and stand on it. Improvement? spin a bit further. Improvement? you get the jist.

I you get it running well enough to get it over to me, we can tune it, check it over, and put a timing mark on it. I'm around all weekend. Second exit on the western side of the bay bridge.

Steve

PS if you do a compression test make sure you didn't collapse the lifter setting the lash.

[76-914]

Don't feel bad Jim. I'll bet there were a thousand guys that didn't pay attention to which hole the short bolt went into (the one right in front of the #1 cylinder wall) when removing the alt bracket on a 327. Any old timers here remember that fiasco. When I saw your pic I remembered that when I was a kid I had that intake off 3 times one weekend. The last time was to get my mom's paring knife that I left sitting on top of the lifters. Scared the shit out of me when I started it. (IMG:style_emoticons/default/headbang.gif)
Jim, most of us have fuched up more times than we care to remember but that is part of the learning process. Keep on keeping on. (IMG:style_emoticons/default/beerchug.gif)

[jmill]

Wiped cam maybe.

PS if you do a compression test make sure you didn't collapse the lifter setting the lash.

(IMG:style_emoticons/default/agree.gif)

Chevy's wipe cams pretty easy. Doesn't take much. BTDT with a new cam and solid lifters. It's also fairly easy to collapse the hydraulic lifters during adjustment. Other than that they are tough to destroy.

[jmill]

Oh, if you don't know already, don't use the rubber intake gaskets. Toss them and just use a thick bead of permatex ultra black.

[veekry9]

The truth is the engine,is a write off,total rebuild.
(IMG:style_emoticons/default/happy11.gif)
Many questions.
Because you have metal in your oil.
Murphy lives inside engines.
Did you compare the new pushrod's length with the others?
Did you remove any metal from the pushrod's guide hole?
Did you inspect(microscope)the flying lifter?
Did you inspect the valley for metal fragments?
How badly damaged was the stamped rocker arm?
Any nicks on the valve tip?
Appears to be a bone stock iron head,with an ally intake and headers,and I presume,a stock cam.
Factory valves and guides?
What head castings are they,compression and squish?
How many hours old is the cam chain and sprockets?
Any indications of knock or ping under load?
What are the compression and leakdown readings?
Have you had the valve seats scoped?
Have you ever pulled the pan to check rod and crank clearances?
What is your oil pressure and temperature,idling while hot?
Any sign of scoring in the bores?
Have you pulled a piston to determine running clearances and wear?
Many questions,for a sbc lump,the beauty is the price to fun ratio.

https://www.google.ca/webhp?sourceid=chrome...-8#q=find%20tdc
https://www.google.ca/webhp?sourceid=chrome...+aluminum+heads
https://www.google.ca/webhp?sourceid=chrome...t%20chevy%20350

The truth is we have to make mistakes to learn "do not do that again",at times,that can be very costly.
(IMG:style_emoticons/default/dry.gif)

/

[jimkelly]

don't know what's worse, bent valve or cam wipe which I never heard of before now. geez. wish I have more tools here, engine stand, torque wrenches, timing stuff, and know how, most importantly know how. thanks guys for not laughing at my pain (IMG:style_emoticons/default/hissyfit.gif)

[Bulldog9]

If the intake manifold bolt put enough pressure on the pushrod to cause it to break, there will likely be some sort of problem, damaged lifter/cam lobe, or bent valve because the valve couldn't close, or both.... As far as 'wiped cam' that means the cam lobe is worn out or will give less lift. You can run on that for a while. Not optimum, but not unacceptable either. You could have also destroyed/collapsed the lifter which I assume is hydraulic or bent the rocker arm . THIS is your best hope.

I agree with the comments above, check/replace the lifter, replace the pushrod, and do a compression check. IMO, if its a damaged cam lobe, DRIVE it..... Take your time, Save your $$ plan a build, do it right. If a bent valve well..... (IMG:style_emoticons/default/mad.gif)

[rick 918-S]

The good thing: Your working on the most common V8 engine on the planet. The second good thing is they are easy to work on.

Start systematically. You can first check the valve lift with a simple metal ruler. First check to see you have not set the lifter too tight. At bottom dead center see if you can just spin the push rod with your fingers. I think you can go 1/4 turn tighter but don't take my word for it. I haven't built a Chevy for 30 years. Check the internet sites for SBC engines. Just leave the pushrod as is for the test.

Next rotate the assembly through one revolution. Measure the amount of travel from the bottom of the motion to the top at the nose of the rocker.

Then check another exhaust valve and compare. Who cares if your not dial indicator accurate. With the intake on you will at least know if you have enough of a difference to dig deeper into the engine. Lifter or cam.

Ya, Another thing. Watch the bolt that can come in contact with the push rod for the mechanical fuel pump. That will wreck a cam also.

[TargaToy]

Jim,

How did you set the lash when you installed the new pushrod?