[DeTomaso] Pantera Problems for new Long Island ownwer

[Garth Rodericks]

Good approach, but I think many are not convinced it's a carb issue.  

Recap of what happened and what's been done:
- Car ran fine, but choke was wired open. Undid jerry-rigged choke wire and tried to adjust choke and car began running poorly.

- Messed with idle mixture screws to try to get car to stop chugging.

- Replaced spark plugs

- Carb  
  + Replaced the power valve with a 65. 
  + Cleaned all jets.
  + Replaced accelerator  pumps at each end of the magnificent holley 4779-7 750 cfm.
  + New carb to manifold gasket.
  + Check out http://www.bob2000.com/carb.htm for how to properly tuned your Holley.


I would also do the following in the order listed...

1. Not likely the cause of your problem, but simple enough to check... Test the Mallory Unilite to make sure that the module is not bad. Follow the procedure here: http://www.centuryperformance.com/mallory-unilite-and-e-spark-testing-spg-150.html

   Clean and inspect the inside of your distributor cap while it's off. Make sure the contacts are clean and bright, not burned. Same goes for the contacts on the rotor.

2. Replace plug wires - good idea anyway regardless of whether or not they solve your problem, unless they've been replaced in the last year.
   Double check the firing order: 351C firing order: 1, 3, 7, 2, 6, 5, 4, 8
      http://www.boxwrench.net/specs/ford_351C.htm

3. 

Check if the timing chain jumped a tooth:
   + Remove the distributor cap
   +  Rotate engine by hand until the rotor moves. Then
reverse the rotation by hand and see how far you have to turn the crank before
the rotor moves. If the chain jumped a tooth, it will be very loose. A few degrees means wear, which is normal (it's going to wear), but more than 1/8th turn may mean trouble, and a 1/4 turn means you most likely jumped a tooth on the chain, so start
pulling it apart. Disclaimer: I don't actually know what the tolerence is for slop in the chain; an 1/8th may even be too much. Does anyone on this list have an old or tired engine they can perform this test on and report?

4. Pull the distributor and verify that the shear pin has not sheared or
slipped. And if it hasn't slipped/sheared, add a smaller pin inside the
existing pin to double it up.


5. Check your Harmonic Balancer (Damper) as described in a previous
post to make certain the bond between the outer and inner ring has not
failed.

6. As for replacing the carb, I would consider Holley or Demon.
   I put a Holley 670 Avenger on my car, then had it dyno tuned. Runs well.
   http://www.banzairunnerpantera.com/updates_dynotune.htm
   
   If I were to buy another new carb, I would order from Chuck Nuytten (http://www.chucknuytten.com/). A fellow PCNC club member just ordered one and it's beautiful; very nice attention to detail; all flow areas cleaned-up compared to an out of the box Holley.

   Others on this list have purchased from QFT and been happy too:
   http://www.michaelspantera.com/Newcarb.html
   http://www.quickfueltechnology.com/home_2.htm

Good luck, and keep us posted!
Garth
#4033

Quoting boyd casey <boyd411 at gmail.com>:

> I have been thinking about your problem and I think before you spend
> $1000.00 ( and that's what it will cost you if you goo to a high end shop to
> diagnose your problem this is what I would do if I were you and I will help
> you do  it if you want. You can get a remanufactured carb right from holley
> starting around $250.00. You can also consider a used one for allot less or
> a brand new one for more. I also think (as I told you a 750 CFM is more then
> you need ,. A 650 cfm is good for a 351 cleveland of up to 500hp. I
> personally like a manual choke. One less thing to go wrong , very
 simple to
> operate and in warm weather you don't even need a choke.  I would buy a
 650
> CFM carb, and new wires, and check that you have the correct spark plugs. I
> would install the new carb and double check the base line settings for the
> timing and check the shear pin on your distributor gear.  Once you get it
> running I have a spare MSD 6AL Hi energy ignition set up and two extra coils
> so you can see if these things make enough of an improvement in performance
> to make the investment. NO ONE will lend you any ignition parts to "try out"
>  ( besides me) bbecause it is to easy to Totally F**K them up . Once we get
> your car running then we can work on "tweaking it" to get the maximum
> performance. If you want an electric choke or vacuum distributor
> or vacuum secondaries on your carb that is up to
 you. I think you should
> start with the simplest setup possible. This helps to
 eliminate other
> possible problem areas.  Let me know what you want to do. If you want to
> take a crack at my idea I will be able to help you.over the next few days
> and definitely over the weekend. His car has old wires. He changed the plugs
> to autolites, but kept the old wires. I have already told him that was a big
> NO NO.
>  Anyone who feels like  chiming in please do so. I am slightly above a
> novice and know next to nothing about carbs. Please voice opinion on 650  vs
> 750 for what is probably a stock engine and Holley vs Edelbrock or any other
> brand or model #. Also I Iknow there are lots of opinions on spark plugs.
> What is the consensus or the official position about the correct plugs to
> use
 ?
> Boyd
> So to put it in a concise
 list
>
>
> 1. Carbb Edelbrock or Holley ?
> 2. 650 or 750 ?
> 3. Choke electric or manual?
> 4. Plugs brand, and temp?
> 5. Wires Brand?
> 6. Vacuum distributor ?  ( opinion)
> 7. Vacuum secondaries? ( opinion)
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