355 circle track engine problems

[dgordner]

I race a 355 chevy circle track pro stock. I rebuilt the engine at the beginning of the race season. The first time out we finished 6th with the car and no problems. The next three times we had to load her up and bring her home before the feature. My son tells me that if he just eases into the throttle the engine seems fine but if he floors it the engine seems to vibrate like an asphalt roller with the drums on vibrate. I can't distinquish if it is electrical or fuel. We have replaced distributor and all components, coil, wires, carb. Compression is 150 therabouts. Any ideas???

[dparker]

Have you checked the universal joints.

[dgordner]

Yep. It is not in the driveline. It is in the engine as we are in the way!!!!

[dparker]

When you rebuilt the engine did you change the crank or any internals.

[dgordner]

Not the crank. New eagle rods and Ross pistons. All ballanced. The engine worked like a top the first race. The only thing I changed from the first race to the next was the battery. Since then I have changes all the cables as well.

[MEMRACING62]

VALVE LASH?

[dgordner]

The first week we ran it at 14 and 16. I have had it at 18 and 20. No difference.

[lookingaround]

my truck done something close to that. felt ok driving but when you put a load on it it shook like crazy. come to find out the bellhousing was broke almost all the way off. not saying this is your problem but thats how mine acted
http://i83.photobucket.com/albums/j289/ProBlaze/tranny005.jpg
http://i83.photobucket.com/albums/j289/ProBlaze/tranny004.jpg

[dgordner]

Nope!! I nut and bolt the car before every race. I am a safety nut!!! I do not rely on anyone but me to find those kind of problems. I don't want my son hurt so I am a fanatic. Seeing your transmission reminded me of the one I discintegrated on the quarter mile in Pa. I broke it so bad I didn't need to unbolt it to remove it!!! COSTLY

[TheYellaBrick]

dirt or asphalt ?

manual or auto?

Is there any vibration with engine at idle when the car is NOT moving?

Have you eliminated any sort of electrical miss ? plugs / wires / dist cap

Is there vibration when the engine is revved up when car is not moving ?

If vibration is present ONLY with car in motion,
- at what speed,
- under load,
- gliding with clutch in or in neutral ?

[dparker]

There's a big diff between a miss and a vibration. If the vibration is actually coming from the engine, I'd have to say you may have a bent or crack in your crankshaft. There isn't any chance someone put a external balanced flywheel or balancer after rebuild is there? I've also seen a vibration if your flywheel is cracked.

[cepx111]

Not the crank. New eagle rods and Ross pistons. All ballanced. The engine worked like a top the first race. The only thing I changed from the first race to the next was the battery. Since then I have changes all the cables as well.
Sounds like a high rpm dead miss.
I'd pull the plugs and look hard at the
porcelin on the exterior of the plug or around the center electrode.
I miss like that will make it vibrate like the dickens, especially if its more than one.

[dgordner]

The miss fire does come and go. The last race we couldn't stay out of the way so he brought her in. When it came time to load her in the trailor, the miss fire was not there. I am possitive it is a miss fire, I just can't figure out what is causing it. My son told me when he eases in to the throttle it is fine until he floors it for the straight. It is almost like it is ok in the two barrel but when requiring the four barrel it misses. However, do not take that last comment out of context as we only have a holly two barrel on the engine.

[dgordner]

What would I be looking for around the porcelin on the plug?

[BEAST477]

You havn't added any new electrical components have you? I did a couple years ago took me most of the season to find it. I only had a miss under load and at higher RPM's. Do you run MSD stuff? If so get your hands on a MSD tester you can test everything through the entire RPM's you run without running the motor and not spend money on parts you don't need. Just a thought.

[dgordner]

No new electrical components. Even unplugged the tach and still had it. I am going to replace the entire electrical in the car. Switches and all. I guess at that point I will know if it is electrical or fuel. Speaking of fuel, how would a fuel pump act when it starts going bad?

[bjuice]

what kind of Pump..mechanical carter ?

[DMotorsports8]

I HAD A NEW RACE CAR DO THE SAME THING AFTER I CHANGED ENGINES, THE ENGINE DIDN'T HAVE A GOOD GROUND, MY BATTERY SAT AT THE BACK BY THE FUEL CELL AND THE GROUND WENT TO THE CHASSI AT THE REAR SO THE ENGINE WOULD BREAK DOWN FROM 4000 UP IF YOU JUMPED ON IT. WE TOOK A GROUND WIRE WENT FROM THE BACK BOLT ON THE INTAKE TO THE CHASSI AND PROBLEM FIXED!!!!!! WE LOST 4 RACES OVER THIS........


BUD

[dgordner]

The fuel pump is mechanical. I am not sure of the make. However it is not stock. It has been on the car for God knows how long. As for the ground, I ran all new cable on the negative side of the battery.

[DMotorsports8]

DO YA RUN A FUEL PSI GAUGE? WHAT CARB IS ON IT?

[dgordner]

No fuel psi. carb is a holly 2 brl.

[DMotorsports8]

I HAD A 4412 WITH THE WOODEN SLIDE PLATE IT WARPED AND GAVE US A HIGH RPM SKIP ONE TIME AT A RACE TRACK, WE ENDED UP MACHINEING IT DOWN ON THE CEMENT BLOCK WALL AT THE RACE TRACK. IF IT'S THE WOODEN ONE CHECK IT OUT, WE HAD TO RUN THE THIN GASKETS HERE IN FLA. SO THE PLATE HAS TO BE FLAT.

[dgordner]

I will look at that tomorrow. Thanks

[stickshift70]

my truck done something close to that. felt ok driving but when you put a load on it it shook like crazy. come to find out the bellhousing was broke almost all the way off. not saying this is your problem but thats how mine acted
http://i83.photobucket.com/albums/j289/ProBlaze/tranny005.jpg
http://i83.photobucket.com/albums/j289/ProBlaze/tranny004.jpg

[MEMRACING62]

looking at that bell housing gives me a chill !!

[JimmySmith]

I once had my car to run smooth until wot, then would pop and act ugly , MSD dist was corroded inside like it was 50 years old ,cleaned and eliminated problem. also BAD GAS will make one do this Later J.Smith 4621 racing :D

[cepx111]

What would I be looking for around the porcelin on the plug?
Cracked porcelin on the exterior of the plug will make it arc or ground (dead-miss) to chassis under a high load, I.E. WOT, that's when the ignition is at its weakest and we all know electricity always finds the path of least resistance and it's much easier for it to ground to chassis than ground through the plug.

A cracked insulator can cause a miss fire, it will not arc at the tip or on ground electrode but rather on the inside body of the plug making it have a miss fire.

You might just be a tad on the lean side if at WOT you aquire a mis-fire, you could have some trash inside the main jets, I've actually had this problem before on a 1966 mustang 289 2 barrel I had, it ran like a devil till you got in it ( WOT) then it would miss like crazy, that one little piece of thrash in one jet cost me a couple hundred dollars worth of ignition parts till I figured out it was the carb.
Cp

[dgordner]

Is it possible that my mechanical Barry Grant fuel pump is going bad? And if it is, would it be shoving to much fuel into the carb as i have noticed at idle the butterflys (throttle plates) are saturated and I can see fuel running off of them.

[dparker]

Is it possible that my mechanical Barry Grant fuel pump is going bad? And if it is, would it be shoving to much fuel into the carb as i have noticed at idle the butterflys (throttle plates) are saturated and I can see fuel running off of them.

The pump going bad won't cause that but a regulator might. Try not to run more than 7psi to the carb.

[Bubstr]

I would have to go along with the thinking of Beast here. when you load the engine it is easier for a wire, coil, plug wire to jump to ground. These are hard to find sometimes, because your circuits will test ok with no load. Try using a fine water mist and put a load on engine in garage and turn off the lights. A lot of the time you will get a light show to point you in the right spot of trouble. The misting should keep you from burning up the clutch. It helps the jump to ground with less load. It's like a coil breaking down, they run at an idle but load them and watch them fail.

I had this after an engine change once and it was a slightly pinched wire off the distributor. Couldn't see it or test it till the water and light trick. Must have done it taking it out or putting it in.

[MRichardson43]

I have a new GMPP 355 circle track crate motor for sale if anyone is interested, click on this link, looks like it may go cheap:
http://motors.shop.ebay.com/merchant/rollinritas