I have a 69? 340 in a 71 duster 4sp. I know it has a cam but not sure of the bore. Holly strip eleminator high rise singel plane?, 750 vac holly, tti headers, 3in flowmasters. I am not sure if it is a good combo. carb to big? exhaust to big? I just dont think the car runs strong enough.it came off the dyno at 265hp 280 tq. secondaries were not opening. made them mechanical but have not had it back on yet. know that is not enough info, but it is all I have. thanks
new member help
- Thread starter RICHSIMP
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Burntorange70
Well-Known Member
Welcome to the site. Good to have you. You are right. Not enough info. Will need more.
fishy68
Tyr Fryr's Inc.
Well I haven't seen a Holley Strip Eliminator intake but I'd assume it's a large plenum single plane intake. Those are only good for 3000 rpm and above so you need decent gears with them. What gear ratio does your car have? Gears can have a huge impact on how a car runs.
Making the vacuum Holley mechanical (I assume you put a screw in the linkage) is generally a big step backwards cause they don't have a secondary accelerator pump and go real lean when opened up fast. Why do you think the secondary wasn't opening? You generally can't see open it just standing beside the car cracking the throttle open. If you do see it open it's probably opening too soon. When your driving the car and punch it it under a load it'll open the secondaries a lot faster than when in neutral. Remember there is a spring in the secondary vacuum pot that you can change to change the opening point. Put a lighter spring in it and the secondaries open faster. Too light of a spring will make it bog down cause their opening too fast. The 750 isn't too big but it's on the edge.
BTW: Was that 265 hp at the wheels? If so that's about 315-325 at the crank. Not fantastic but not terrible.
First thing I'd do is check the timing curve. Most likely it'll respond best with 15-18 degrees of initial timing and about 34-36 total all in by 2500 rpm. Remember when it comes to tuning do the ignition first then the carb. The ignition affects the carb but the carb doesn't affect the ignition.
Then I'd pull the plugs and have a look at them to see how the mixture is. If their old cruddy plugs put new ones in it and run it for a blast through the gears (approx. 1/4 mile) wide open and quickly shut the engine down (don't let it idle down) and pull to the side and pull the plugs and have a look at them. Of course do this in a safe place such as the track or nice smooth fairly long back road where you have a place to pull off the main road and make sure no other cars are around. Safety is paramount.
Oh yeah, the exhaust should be fine and welcome to the board.
Making the vacuum Holley mechanical (I assume you put a screw in the linkage) is generally a big step backwards cause they don't have a secondary accelerator pump and go real lean when opened up fast. Why do you think the secondary wasn't opening? You generally can't see open it just standing beside the car cracking the throttle open. If you do see it open it's probably opening too soon. When your driving the car and punch it it under a load it'll open the secondaries a lot faster than when in neutral. Remember there is a spring in the secondary vacuum pot that you can change to change the opening point. Put a lighter spring in it and the secondaries open faster. Too light of a spring will make it bog down cause their opening too fast. The 750 isn't too big but it's on the edge.
BTW: Was that 265 hp at the wheels? If so that's about 315-325 at the crank. Not fantastic but not terrible.
First thing I'd do is check the timing curve. Most likely it'll respond best with 15-18 degrees of initial timing and about 34-36 total all in by 2500 rpm. Remember when it comes to tuning do the ignition first then the carb. The ignition affects the carb but the carb doesn't affect the ignition.
Then I'd pull the plugs and have a look at them to see how the mixture is. If their old cruddy plugs put new ones in it and run it for a blast through the gears (approx. 1/4 mile) wide open and quickly shut the engine down (don't let it idle down) and pull to the side and pull the plugs and have a look at them. Of course do this in a safe place such as the track or nice smooth fairly long back road where you have a place to pull off the main road and make sure no other cars are around. Safety is paramount.
Oh yeah, the exhaust should be fine and welcome to the board.
As for the general description, it all sounds good. Now, if you knew what the cam was or the specs to it....or your compresion ratio (Actual) What gear ratio and tire size does the car have?
Just focus on having it be a good running car. Everything else will come later.
I see Fishy has a good handle on things. Welcome aboard.
Just focus on having it be a good running car. Everything else will come later.
I see Fishy has a good handle on things. Welcome aboard.
MoparDreamin
Well-Known Member
To add to the not enough info sentiment: what type of dyno and what conditions. Depending on these factors, 265rwhp may be nothing to sneeze at.
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