70 340-no power

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dart gt

dart gt

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i have a 70 340 stock block, j heads,268 comp cam,edelbrock performer intake with 800 thermo quad carb.Motor was rebuilt and have no more power than a 318.What could be the problem.Distributor was curbed,running no vacum,coil shows 9.95 volts at distributor.Timing is at 14 degrees,36 initial.It has a 4 speed and 323 gears.Any help would be greatly appreciated.Thanks David
 
Just reading the information you provided, I would be concerned with the cam, and how it was degreed in. What is it ground on? Was it properly degreed in?

9.95 volts? Is that on the output side of the ballast resistor? You do have a full 12 on the battery side, correct?

Did you run a static compression test? Leakdown?

Never been a thermo quad fan, but plenty people are.
 
Sent you a P.M.
The Dart in my avatar is in Trenton.
 
It's all in the tune....not many know how, I run into them frequently.

You can throw all the parts at you want, but that won't make you as fast as you could be...

If you want to start off good, lose the thermoquad and buy something more readily available 'parts wise' and with literature a plenty to help you tune it=holley carb.

make sure the cam is degreed in right too, most are 4-6* advance when you stick'em in straight up, thats a lil excessive especially when the cam is already kinda small.
get the timing [initial] up to around 18-26* or whatever it'll still start with fully warmed up and not kick back the starter...then limit the total/ful adavance to 30-35* [what ever it'll run with best] you'll have to find out.

Just a start.
 
had a brand new 600 eddy on it but didnt help,thats why i tryed the thermo quad.The cam is set on the stock mark,could that be a problem?Did a compression test and got 160 on each cylinder with 4 cranks on starter.I never had 12 volts on any side.Top pins were 9.5,bottom left was 0,bottom right was 10 on resister.
 
FIRST thing I'd would be hook up the vacuum advance unit.
 
you may have some old wiring issues if you can't get 12 volts to the ballast.


If you have a 160psi, good.

now ...on the eddy carb, what model? 1406? or 1405?

If ti was the 1406, it was probably too lean, needs to jet like the 1405
The real deal is no spread bore is gonna meter the fuel for power as good or better than a square bore carb, only the primaries get any credit jmo in metering decent.

Get a 700-750 double pump holley.jmo
 
1406 carb,changed metering rods and springs,didnt help.Have more snap with thermo quad.I checked voltage with just the key turned on,should i start it and try it or will it make a differance?
 
No but to lean is a real killer,do you have a vacuum guage?
 
dart gt said:
1406 carb,changed metering rods and springs,didnt help.Have more snap with thermo quad.I checked voltage with just the key turned on,should i start it and try it or will it make a differance?
Click to expand...

thermos have this 2 step booster in the primaries which is like 2 stages of excelleration=lots of mixing, thats good.
The down side is the very lil total cfm coming through around them-primary side.
The secondaries on a thermoquad have no boosters while 'holleys do'.., instead the thermo have spray bars/piss tubes that give this sprinkler effect to 'as best as they can' to mix fuel for the 600 or so cfm that flows through the secondaries alone..
And now that you might see how much bigger the secondaries are compared to the primary, you may also understand there are WAY different amounts of a/f & a/s in relation to the 4 conners of the plenum..-very crude in my description but the idea is easier understanding of this.

all this is related to the 'snap' you are talking about, but may not exactly be the reason why. Another reason could be simply be wrong pump shot/position shooter size, main jet too lean will make it real lazy right after xcelleration.
 
BTW If the heat range of the pug is too hot, it will have a white porclin meanwhile a tiny ring of black where the ceramic meets the inner base, which is where you should be reading the plugs to begin with.
How is the metal ring looking?
 
David,the Dart looks amazing who did the body/paint?was it a local car?have you had any others I might recognize?
 
metal ring is good.I am running 1 number down from stock plug.Was trying to stop deiseling but didnt work.Car still runs on after shot off.
 
my nabour and i did the body work and paint.all my other cars i had out west in brooks alta.The only other one i had here was a 72 torino,34 years ago and a 72 demon 25 years ago.
 
If you are pinging,running on and no power then you have a timing issue.
 
i had an issue before with pinging and black smoke coming out when you tramped her down.The guys on here helped me fix that problem.Just one thing after another
 
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