ok, I ran this motor with no problems last year in my other car. i did a complete rebuild of a different car i pickec up. so most of this stuff is a straight up swap. it's got radically ported heads and a GM847 cam with manley race flo valves.. etc etc.
well it came time to start it and for the last few days it just wouldn't start. today i tried to start it and mashed on the gas while turning the key!
it started! I let off the gas and it runs, but it has a wierd stumble, a "clunk" (sounds like a midget with a hammer is sitting in the engine or tranny banging on something every 5 seconds or so) - I don't think there are any piston to valve problems. 847 cam with 1.5rr's flat top pistons, heads milled 10 thou. running on premium w/ 12:1 compression. like a miss or detonation maybe?? i dunno

it ran for a minute and then i shut it off when i noticed the water temp gauge was pegged out!... put my hand on the upper radiator hose and it was only warm. (i did just install a powerstat and it's not programmed for it yet, also have not bled out the lines b/c the car has not run up until today)
there are no check engine lights. i just didn't know if anyone has any ideas or has had something like this similar happen before.
I tried starting again afterward and once again... had to mash the gas to get it to start. It's real strange. A friend of mine is supposed to come down next week with his laptop and Lt1 edit crap and try to figure it out.
I just thought i'd post something here in an attempt to gain an educated guess at what could be the problem with it.
Bad sensor leaning it way out?
I have a MAF sensor installed of unknown condition, also a used blaster coil of unknown condition, but i bought it from someone who claimed it was great.
don't know about the "overheating" thing, i have heard of people installing powerstats and having them read funny when the computer is not programmed for it. (yes the spring side is inside the water pump)
thanks guys for any help

 

Leaky injectors? When you floor it while starting the injectors shut off, so you might be flooding the engine.

 

Just to clarify the situation with the coolant temp gauge, the sensor for that is in the driver's side head. It has nothing to do with the PCM. The PCM reads the sensor in the water pump housing. Is it possible the connector fell off the sensor in the head? It is possibl you have air in the head instead of coolant, so it may really be overheatnig as well.

 

Possible MAJOR vacuum leak (mine did this when one of my intake manifold gaskets didn't seal all the way) or you might want to consider readjusting the valves. What lifter and what preload did you put on them?

 

It would have to be a MASSIVE vacuum leak to make it do that. I would make sure the valves are all adjusted right, and I also think the leaking injector theory is interesting, you might wanna check that out. I had some FMS injectors that did the same thing to me, so now I am running the SC motor on the stockers waiting for some bigger ones that actually work!!!

Good luck Duane...

 

Make sure the electric optispark harness connectors are seated all the way.

 

I did a little more research today... found the leaky injector theory interesting and possibly the easiest to diagnose. I checked out the oil, which by the way this is brand new mobil 1, never been ran, so it should be perfect... YEP, it smells like gas. so, when i get some more time, i'm going to pull the fuel rail off and have a look to see if any injectors are leaking.

It's funny because the injectors were fine last year, (accel 30#) used them for 2 years so far, they sat in the garage still in the rail, in the intake, since last october. I don't know what could be wrong with them. can they go bad from just sitting?

I put new O rings on the injectors this spring when i repainted the intake and polished the fuel rail. I dabbed oil on the O rings when i installed them. If any oil got on the injector pintle could it screw up the injectors?

Say i pull out all the injectors: without dropping another $300 on new injectors, can i have mine checked out/cleaned/tested somewhere to know if they're bad? where would one go to have this done? machine shop?
thanks again!

 

I bet it is the leaky injector also..My car was hard to start for 2 yrs(would have to push the accelerator to get to start) and finally one day while I was driving it started running like crap-lots of smoke out the back and wouldnt idle..Low and behold I pull my fuel rail off and left the fuel lines attached, then turned the key to the "on" position and straight fuel was shooting out of cylinder #6..Oh and by the way..I had 30lb Accel's also
Get rid of those!!

When I put in Lucas injectors my car starts SOO easily now!

ps- I have 7 of them I will sell for $50

Cody

 

Have you checked the valves for overtightening. My car did the exact same thing as yours is doing with too tight valves. Gas in oil, I also had the funny banging noise, and if I pushed the gas to the floor the car would start right up. Maybe something to check out.

 

the valves were adjusted with the engine still on a stand. it was turned over and each valve was adjusted one by one. It would be pretty hard to mess that up. I was turning the motor by hand while my engine builder adjusted the valves. I have 1.5cc rr's with poly locks, and each one was turned 1 turn past zero lash, and then the lock was tightened. so maybe they have 1 1/6 turns at most.

wouldn't valves have to be drastically overtightened, like 2 or 3 turns for them to be screwing up that bad?

 

Accell injectors are most likely your culprit. They are CRAP. Look back in LT1 tech and you'll see many people having problems with them. I would also readjust the valves as they have way too much preload on them. Find zero lash and turn 1/4 for conventional lifters and 1/8 or less for Comp Rs.

 

Once your motor is running the valves will seat into the heads, and since you said you got new manley valves they are definately going to need to seat. I would check here I am running my comp r's at about a 1/16 turn so yes you could have gone to far with your type of lifter. (I am not sure of your type of lifter but this is what I used) And no they do not have to be 2-3 turns overtightened to open just a bit. When I set my comp r's at half turn past zero lash you could actually watch the valve open just a bit. Maybe something you want to look into maybe not if you think it is the injectors then try that.

 

I have Comp lifters, but they're only not comp R's, they're just a stock replacement. I have GM directions printed out from a GM dealership, on how to adjust the valves and it specifically says 1 turn past zero. I will look into this. Last year, i had the same lifters, 1.6rr's, same pushrods and everything with the lash set at 1 turn past zero and no problems.
I am leaning more toward a bad injector. I never knew that accel injectors were problematic.

 

We didn't really either until a short time ago. Do a search and you might find it interesting.

 

Do a search on "adjusting lash". You should get pages upon pages of information.
I also agree that more than likely it could be the injectors (accel = trash injectors). But I believe you have preloaded the valves too much. I have ALWAYS read on here (and by the engine building folks) that replacement lifters/stock lifters = 1/4 turn past zero lash, while Comp Rs are 1/16th to 1/8th past zero lash. On my little brother's cammed Formula using Comp Rs with a cc306 and 1.6rrs, we did 1/16 and that was perfect.