help please!!!!!!!
#11
Are you sure you got the timing chain installed properly? Intalling it a tooth or 2 off would be all it takes to cause the problem your having...Double check the timing chain and triple check the valve adjustment. If you have stock length pushrods then it will run fine but the length should really be measured. http://shbox.com/1/4th_gen_tech2.html#adjust_valves Method three takes the most time but is fool proof.
Last edited by skinut; 05-24-2012 at 08:34 PM.
#13
Join Date: Nov 2007
Location: Eastern PA,
Posts: 10,456
Copression test would let you know if the valves where to tight.
I had a customer once that had his car towed in. He had just finished his first tuneup and now that car would not start. He said car ran fine but it was due for a tune up so he thought he would do it himself. He even got me thinking he screwed it up. After about 30-45 minutes of not beable to find what he did wrong I decided to look at the car as if I hand no info on it. Step one for a no start. Check fuel pressure and if you have spark. No fuel pressure. This poor guy is beating hinself up and it had nothing to do with the work he did. It was just bad luck. It happens.
Having fuel and having good fuel pressure are two diffenert things just like having spark and having strong spark can be two different things. As a general rule if your valves are too tight the motor will spin a little faster. It they are to loose you should have noticed when adjusting them. A valve does not have to open very far to start and idle.
I am not saying you did everything right but you should do a little more testing before you pull it a part again.
I had a customer once that had his car towed in. He had just finished his first tuneup and now that car would not start. He said car ran fine but it was due for a tune up so he thought he would do it himself. He even got me thinking he screwed it up. After about 30-45 minutes of not beable to find what he did wrong I decided to look at the car as if I hand no info on it. Step one for a no start. Check fuel pressure and if you have spark. No fuel pressure. This poor guy is beating hinself up and it had nothing to do with the work he did. It was just bad luck. It happens.
Having fuel and having good fuel pressure are two diffenert things just like having spark and having strong spark can be two different things. As a general rule if your valves are too tight the motor will spin a little faster. It they are to loose you should have noticed when adjusting them. A valve does not have to open very far to start and idle.
I am not saying you did everything right but you should do a little more testing before you pull it a part again.
#14
what is brand and model/part number for opti, cam, rocker arms and timing gears? the push rod length does not effect lift or timing, it effects where the rocker makes contact with the valve stem.
#15
gm performance lt4 hot cam kit
One camshaft P/N 809-24502586
16 roller rocker arms kit P/N 809-19210729
16 valve springs P/N 809-12551483
16 valve caps P/N 809-10212808
16 valve keys P/N 809-24503856
16 valve spring shims P/N 809-10212809
GM Performance 12370835 lt4 extreme duty timing set
ac/delco optispark
One camshaft P/N 809-24502586
16 roller rocker arms kit P/N 809-19210729
16 valve springs P/N 809-12551483
16 valve caps P/N 809-10212808
16 valve keys P/N 809-24503856
16 valve spring shims P/N 809-10212809
GM Performance 12370835 lt4 extreme duty timing set
ac/delco optispark
#16
i contacted hawks 3rd gen and they said it could be one of 3 things, one but they said doubtful was the optispark, they say doubtful because all though it has happened it is rare for a good optispark to just crap out completely it should give you a heads up before it goes completely out, two would be not getting enough fuel pressure, or third, they said sometimes when doing a cam swap it has to have a base tune before it will start, they said some camaros start right up but they have had some camaros they had to get a base tune on before it would crank. does those sound about right, i know my fuel pump aint putting out the recommended fuel pressure that it should be but has always started it before, but maybe since the fuel lines were completely drained it aint up to getting fuel to the engine, any one know anything about the ''base tune'' before it will start, ive seen many camaros fire up after a cam swap before tuning but thats only what ive seen, anyone with experience on that?
#17
They're blowing smoke with those scenarios, as far as I'm concerned. A cam is a mechanical component. One thing it can change is how rich or lean your engine will run. There's no way for your computer to know what is what until after the engine is running. You never said, but is it safe to assume that you started out with a running engine? Do some mechanical work to the engine, and now you have a fuel supply problem? Not buying into that one either. But, go ahead and check your fuel pressure, since you think the pump isn't up to snuff. Have you tried priming into the throttle body, either with gas or starting fluid, then trying to start? If you get it to run that way and it quits, you have a fuel issue. If you get nothing, you need to retrace all your mechanical steps again.
#18
It's amazing how everyone has a different opinion on something they all have no experience with Lmao. I've never seen anyone just admit they don't know something here on this forum. Instead everyone just guesses lol. I don't know what all these guys are talking about. Your situation is quite common. Sounds like you should have more experience before getting involved in a job that requires some real know how lol. After hearing you discuss your fuel issue, now things are becoming clearer. You certainly DO have a lack of fuel problem that you carried over from before the swap. Why someone would spend the money to do that swap, and not replace the pump with a high volume pump either when you knew it was bad or after during the swap is anyone's creative guess. But untill you eliminate that pump from the equation, that is surely a contributing factor. You almost always have to go with a high volume pump. If your pump isn't putting out enough pressure to supply a stock pump, what logic are you using to justify that it would miraculously produce enough pressure for a more demanding cam? Start with a BRAND NEW...high volume pump. And then yes.....you will surely need to do a base tune. Any legitamite shop will perform a base tune. It is necessary to say the least. It is a must on these cars as well ad ANY computer controlled vehicle. Hope this helps you. I'm betting thats your issue in a nutshell. I can't tell you how many times I've seen this problem after a swap. I've lost count lol. Good luck though.
#19
It's amazing how everyone has a different opinion on something they all have no experience with Lmao. I've never seen anyone just admit they don't know something here on this forum. Instead everyone just guesses lol. I don't know what all these guys are talking about.
#20
on my behalf, i didnt go into this with no knowledge, i have been building engines for over 12 years just ive always stuck to the tried and true carb engines and have just recently started messing with fuel injected small blocks, didnt see where there would be much difference. i already had plans of putting in a walbro 255lph pump, i was just trying to get it running first to make sure everything would work out before i put the pump in, the pump that is in it now might be on the weak side but has always started her without fail so i figured it would be enough to start her for now until i got the kinks worked out, no hard feelings toward anyone and appriecate all the comments