This summer I posted a couple of messages about my 400 small block.

I have a 400 small block with a tpi that has some issues.s

The main problem is when the car is running and you try and do a hole shot from a stop the car jumps up and breaks the tires loose for a split second and then falls on its face dead silent like the motor is off. when you let off the car comes back to life. The really wierd thing was one day i wet the pavement down and did a hole shot and the car did not stumble because the car was not under so much load?????????? I bought all of moates hardware and tried to program this out with no luck.

Next the motor would not start when it got up to operating temperature (like a timing issue) once it cooled down it started just fine.

last the blm would not go above 108 I programed that so it would read 128 but it did not help the situation.

I am wondering if anyone else has a 400 small block with a tpi
the motor is bored 30 over and runs 10:1 compression.
the cam has 480 lift and 230 duration.
I have 24# ford svo injectors.

before I go back together I want to know if it is possible to run a 400 with a tpi or if anyone has any other suggestions on what the problem could be.
I am at a loss I spent all last year trying to get the car to run correctly but cam up with nothing

 

Trever I have a 406 in my vette running a Superram with the GM computer so a TPI system can run a 406. Your description of the problem makes me think it could be one of two possible problems. Either you have an ignition problem where you are lossing spark under WOT high acceleration (loss power wire, bad coil, bad ignition module or ??), or you have a fuel pump pickup that is uncovering under high aceleration causing the engine to fall on its face.

The 108 BLM numbers mean you are running rich. You need to reduce your fuel in your chip where you are seeing these numbers. Did you change your injectors and reset your injector constant for the new size?

 

Yes, the changes I have made are:

changed the injector constants to match the 24# injectors.
changed the cylinder volume to match the 406.
reduced the fuel in the chart to make the blm read between 126-130

I hooked a fuel pressure gauge to the valve on the rail and had someone watch it and it did not appear to lose fuel pressure.

The no start when hot sounds like a motor with a timing issue correct?? The car once started runs and idles perfect.

Is it possible to have the injectors leaking extra fuel in the cylinders when the car is off and creating a vapor lock when warm.

Do you know if my cam is too big. someone said because it is not a fuel injection recommended cam it may be losing too much vacum and stalling the motor. I have very good vacum when idleing however.

 

The not cranking when hot sounds like heat soak on the starter solenoid. How close is your headers to the solenoid? If it's tight a $10 heat shield can help and or header wrap on the pipe by the solenoid. Also, it could mean that the solenoid is weak and about to go out.

 

Yes I have have some pretty tight headers that go almost against the starter. I have gone through 2 starters last summer thinking that the other one was going out finally I took some heat wrap and wrapped the starter with no luck. Do they make actual heat sheilds as well.

another thing I am doing is sending out my headers to Jet Hot to have them coated. This is suppose to disapate the heat and make the header not get so hot.

Like I said before I am looking for a good recipe for a 400 motor before I go back together. I have had many people tell me the cam is to big but it runs and idles to well for me to think that.

 

I do not believe the cam is too big for a 400. My 400 is running a cam of 240/240 at .050 with .595 lift and 112 lobe seperation and it works well. My idle vacuum is 11.5 inches at 800 RPM. You have not listed your lobe seperation?

The no start when the engine is warm, does it crank or just click? Does it crank very slowly or kick back against the starter?

Where do you live, your profile says WI, I live in WI, if your are located near me I could try and help you out.

Brian

 

Hey Brian,

I live in Janesvile WI. That would be unbelievable if you could help me out. I spent the last two years driving the car like this and would like to get it so it is a reliable drive. I don't believe elkhart lake is to far away.

The motor kicks back against the starter when it does turn over. Most of the time when it is warm it is just locked up tight. In the event that I can get it to turn over it will kick back. I have taken out two flywheels with the starter knocking out teeth.

I will get you the lobe seperation tomorrow I have to call the machine shop that has the motor.

Do you have any ideas on the stumble when doing a hole shot??

I would like to have some fun in the car but I am a little frustrated after 2yrs of messing with it.

Here is the car:
http://students.uww.edu/brandenbtl16...edprojects.htm

 

Sounds like your base timing is set too high if it's kicking back. Set it back into a reasonable range (6-12 degrees base), and see.

Your other problem (going limp on throttle snaps) sounds like an AE (acceleration enrichment or "pump shot" as some call it) problem, and perhaps the VE table is not calibrated well enough. COULD also be some problem with a wire or something in the ignition setup that gets tweaked when the engine twists, or some other gremlin.