Ok so this is a little drawn out and complicated but here we go... I have a 61 bel air that i decided to take my hencho en mexico gm goodwrench crate motor which has been sitting around for years (20+) and tear it down, clean it up (ball honed the cylinders to clean up some spotty rust) and put it together with new bearings and drop it in the car. Along the way I decided that I was going to drop a comp cams 262h cam in and a set of brand new vortec heads from a crate motor that got upgraded heads that were sitting on the shelf on along with a edelbrock epms intake and holley carb and cloyes timing set. I upgraded the springs on the head to ls beehive springs with new retainers and used the self alligning rockers from the heads with the standard push rods from the goodwrench crate motor since the others were shorter roller push rods from the vortec motor the heads came off of. I put in a new set of summit lifters since the other ones had been sitting for going on 2 decades. I get everything together get it in the car, wire it up with a modern starter, hei dist, and altenator and everything cranks over as it should after i primed the oil with the tool. As im trying to start it I see that im getting fuel spraying up instead of into the motor so we checked the timing repeatedly and not even a hickup of trying to start. I verify spark and im getting spark and fuel from the carb. The plugs are completely dry so it has me a little baffled at this point. I pull the valve covers and check the lash and several rockers are completely loose, so i set lash again and crank it overhoping to have something and no. I check lifters again and absolustely loose again. I completely loosen rockers again and then reset lash and still nothing. I check compression and it it barely budges the gauge. On cylinder 1 i completely exhaust loosen the rocker crank the motor a couple times and boom 90psi. So I set the lash to where the push rod barely spins and then only 1/4 instead of half a turn and check compression and still have nothing. I decide to check the opposite side of the motor and realize that every time i crank the motor only the exhaust valves are loose and every time i crank it it changes which ones are tight and which are loose. I notice that the threads on the nuts for the rockers are almost completely bottomed out on the studs now which they werent earlier. I still have no compression and no start or even a sputter. Im a motorcycle mechanic by trade but new to building car engines. Same principles but different techniques but im not afraid to try anything. I work for gm and one of our trades guys who is aprox 80ish yrs old said he thinks I have a bent cam which i will admit was used in a friends motor which wasnt running when we pulled it after sitting for a few yrs because i wanted it as a parts motor to rebuild the vortec heads which were on it but had a bent valve due to losing its spring. Does anyone agree with the bent cam? Ive thought cam and lifters personally even though the lifters were brand new and I bled them before putting them in after reading a post on here about doing so. Its killing me ive put so much money into this motor over the last 2 months trying to get it done for 2 big car events called back to the bricks and woodward dream cruise. I want to make it to one of the last events which is this weekend so any help is greatly appreciated. Thank you so much!!!
When you are adjusting the valves, you said something about pushrod spinning. This might be your problem...you need to back off all the valves, and adjust them to where there is just no clearance, then tighten the half turn. Instead of spinning the pushrod to check for clearance, wiggle the rocker arm up and down. It will be loose and rattle when there is clearance, and stop rattling when you take up the clearance. And you'll still be able to spin the pushrod. After you get them all to zero clearance (going through the firing order as you adjsut them, of course) then tighten them all 1/2 turn for the necessary preload. I don't know if this is your problem, but it might be.
Thank you I will try that. Im used to harley valves which is no up and down then do a fine adjust till it gets snug to spin and then lock it. So i will try this thank you!!!
The heads you are now using don't have press in studs, do they? You are not running into coil bind on your springs and pulling the studs out? I know nothing about your stuff. But I might look around at something like that.
Yes. If they have pulled out you can tell by taping them back in. If that is the case then you need to find why they are pulling out. And pin your studs or go to screw in style. I would think.
*again*--- here we go wonder how GM chevy ever got ANY engines ***embled and OUT the door....? I should make a vid, and do it JUST like chevy did...
...you say you put a new timing chain and gears in,....did you set the timing marks correctly?....or not?......I ask this because I did that years ago,...mistakes happen......miller
Yes i did and was verified by someone else to make sure. I know mistakes happen so i understand the reason you asked lol
Also. Exhaust valves are more likely to touch the piston as it comes up on the overlap. Your heads and pistons may not be happy with each other. Or maybe the cam is retarded. I hope it is something simple that I have not thought about.
stop... find TDC ...kinda like harmonic balancer *mark* (line) is --> on the tab the SAME time ---number 1 piston (and BOTH rockers) are *up* loose... if this TDC is NOT found to be CORRECT you MAY have camed it 180* out...(just a thought) pistons 1 and 6 are both up at the same time its just that the cam needs to be in the CORRECT position with the distributor (wiring order)
Harmonic balancer must be co-ordinated with the correct tab. The balancer inertia ring must not have slipped and must be in its stock location relative to the hub. Check with a piston stop and degree wheel. Also, multi-position crank sprockets have screwed up a lot of engine ***emblers. Triangle keyway uses the triangle mark on the sprocket to line up with the dot on the cam sprocket ---- likewise square on keyway, square on crank sprocket to dot on cam sprocket ---- likewise small circle on keyway on crank sprocket to dot on cam sprocket. If your cam is improperly timed, valves will potentially interfere with piston movement and can cause valves to push back and raise the non-pinned studs. Also when this happens, valve stems bend creating sealing problems.
Found studs are pushing out so heads are going to my buddies shop to have screw ins installed and valve seats cut. Debating on ordering new cam and lifters
When i pull the cam i will verify everything again. Thank you. Im debating on using the cloyes double chain i have i now or going to the stock one
Chain won't help. Use the soft spring method to verify valve to piston clearance. Or look at piston tops for marks from valves kissing them.
i had this same thing happen to me on a 54 chevy truck that sat for 20 years. when trying to start it i noticed a "cloud" of fuel/air over the carb. turned out the exhaust was totally plugged tight with thistle seeds and seat stuffing. try disconnecting the exhaust.
if you do the screw in studs and (guide plates) ditch the self aligning ROCKERS... your machine shop guy should be able to point you in the right direction.
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