So I have a 77' Camaro Type LT, nothing special but I love it. About a month ago I decided to buy a new crate 350 for it. The old motor would just diesel like there was no tomorrow, and after pulling it I could see why. But since I got the new crate in I have had nothing but problems. I have had 3 other people look at it and not be able to give me any hints. I made sure the timing on it is perfect but it still wont stay below 1k rpm without dying and then backfiring. If I can get it in gear as soon as I do it just dies. I have moved the distributor over a tooth to see if maybe that would do something but it just made things worse so I put it back.


290hp 350
Edlebrock 650cfp 4-barrel
Edlebrock Performance intake
Headman headers

Any suggestion please let me know and help me out

 

your problem may very well be timing related. it may be off a tooth on the cam gear but, sounds to me that it may be in the ignition itself. have you checked your ignition coil resistance? might be a good place to start. if it has an HEI distributor, i would also pull out the ignition module and have it checked somewhere like autozone. thirdly the problem could also be in your pickup coil. all three are relatively inexpensive and i would just about bet that the problem is with one of the three. one way you can find out if the timing is off is. get your number one piston up top dead center of the compression stroke. this can be done by using a straw ... placing it in the #1 spark plug hole and turning the motor over with a socket and pull bar on the harmonic balancer nut. the piston will push the strw out as it is coming up. be sure not to let it fall completely in the cylinder tho. use a long straw. you may also want to pull that valve cover to make sure it's on the compression stroke. the valves on that cylinder shouldn't be moving at all when it is coming up. when it has reached the top look on the harmonic balancer and see if the timing mark is on 0 degrees if not it is out of time. not on the distributor but out of time on the cam gear. like i said tho, i would bet it is one of the three listed above. good luck. sick

 

Since it is a new GM crate shouldn't the cam gear already be timed with it? Also I pulled the HEI distributor right off the old engine which ran fine, just had problems turning off. I just got done moving the distributor the other direction and got the opposite response; I couldn't keep it alive where as before it would go under 1000 rpm. I did in fact make sure it was at top dead center by using s very long thin screwdriver in #1 and got it to the top. I ended up calling GM to get the timing specs for it and they told me that it should be 8 dgr, before top dead.

 

the timing specs are right but, it should be 8 degrees before top dead center when timing it with a timing light. it should be at zero degrees when the motor is off an the piston is TDC. that 8 degrees is on distributor timing not valve train timing. if at TDC the mark isn't at 0 degrees the timing is off. is this a high performance crate engine? or stock? if it is high performance it may have an adjustable gear to degree in the cam. i still believe it's ignition problems tho. sick

 

Okay I will look at the ignition. Also when I got my new crate it came with 2 tabs for timing, would it have made a difference if I had used the other one. And if so, wouldn't I have been able to notice (I wouldn't be able to get it to run). But if it is the ignition then how would that affect it in gear, and why wouldn't it affect it while it was running at 1500 rpm. I'm not trying to be a pain in the butt for you; I am just trying to understand.

 

one tooth off on the cam wouldn't stop it from running but it would definately run like crap and you would never be able to get it timed in on the distributor. what is the difference in the two tabs? mounting bolt placement? the reason i'm thinking ignition is it was a crate motor, most likely dynoed before it was crated, the only parts you added was ignition right? and the dieing and backfiring sounds like a failing coil. when you say backfire, you do mean out the exhaust correct? sick

 

Well I looked at the two tabs and the only difference is the mounting position and only one of them will work, so I'm guessing I used the right one. Last night I hooked a vacuum gauge to it to find that I was only running about 9lb's vacuum. I did this before and thought that maybe I had an intake leak, so I changed my intake gaskets. But I am still having low vacuum. Once again, if it was my ignition (which I'm not deigning) how would it still be able to run above 1200rpm and sound great doing so? How would I go about changing/moving a tooth on the cam, wouldn't I have to pull it?

 

ok ... seems like for some reason we are on different pages LOL. you said it read 9 hg of vacuum. i thought you said it won't idle? is the 9 hg at a high idle? either way that is very low for your engine. if you had a very lopey cam i would say maybe. your gonna have take this problem on systematically. did you check to see if the timing mark was on 0 degrees at TDC? this you have to find out first. if not you will be chasing ghost and never find out what the problem is. if the timing mark is at 0 degrees at TDC ... the next thing i would do is adjust the valves and make sure one isn't too tight. if there is a valve that isn't closing completely, that would cause your low vacuum and it would also account for the backfiring and inability to idle at low rpm's. do you know how to adjust valves? if not let me know and i'll giva ya a quick run down. to your question about adjusting the cam gear. the only reason you should have to do that is if the timing mark isn't at 0 degrees at TDC. if it isn't you'll have to remove the timing cover, unbolt the gear move it over a tooth and bolt it back on. making sure that the timing marks on the two gears are aligned. the reason i keep stressing check your igntion parts is, you need to rule that out before you go internal. it still could be a bad coil. when a coil is going out. ( ignition or pickup coil ) it can cause several different symptoms. sometimes they just die and the engine won't start., sometimes the voltage will just get real low and cause delayed an detonation, sometimes they only work when cold, sometimes they make your engine spit and sputter.
it depends on what is wrong with the coil. if you have a voltage meter they are easy to test. sick

 

Just giving you the heads up on the timing. It turns out that the harmonic balancer I bought for it has the wrong timing marks. It is the right size and runs great now that it is actually timed. Thanks for the advice though, it gave me somewhere to start.

 

try out this http://www.users.bigpond.com/ergoff/vac1.htm