340 on pump gas

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racingjoe67

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ok all of you racing guys i need some help making a couple decisions. The goals are simple 400 plus horsepower pump gas street strip car. We have 340 0ver 30 with 10 to 1 j.e. slugs stock forged rods and cast crank that i was told not to worry about. this motor has 360 heads 188 160 valves 480 480 comp cam edelbrock ld 340 intake. electronic ignition 727 and I have 456 gears for the back. I want opinions on cam selection im leaning towards a good hydraulic and I have the 273 adjustable rockers and push rods, heads (I want the eddis) , and carb size. I want my 67 cuda coupe to run 7.50/11.50. don't be afraid don't hold back I need your input.
 
Ported heads bigger valves, and solid cam to start with and look at something other than comp for a cam.
 
I think with what you have you are looking at a mid to high 12 second car. You need heads that breath, a bigger solid cam, and an intake to match the combo.
 
I have run a 10-1 iron headed 360 on pp gas before. You will be fine with the current short block combo and iron head. I would use 2.02 valve and port the head.
Otherwise, that cam and the parts you have are good for 400HP.

A cam to match the gears is another story. I would start looking at cams in the 250@.050 area with as much lift as the ported head can handle.

A single plane intake, 750 or better Holley and this Comp Cam; http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=633&sb=2

The LD-340 is restrictive to running mid 11's. While possible, make the move to a M1 single plane or a RPM at a min.
It is possible to trade out right for the M1 with the LD-340.
 
krazykuda said:
10:1 compression on pump gas????
Click to expand...

YES!!!!!!!

A larger than normal camshaft should be used with the best pump gas you can get. Careful distributor timing must be employed.
 
Solid cam! Why go with a hydraulic if you have the 273 rockers? Especially with 4.56 gears. Solid cam all the way.

I have a 340 with the MP .557 cam, single plane intake and 4.30:1 gears. Best car EVER on the street. Highway, not so much.

And yeah, might want to look into getting some head porting done.
 
I have a 1970 340 with T/A heads with the "bumps removed" from the ports. TRW pistons with some machine work to get to 9.25 compression - objective was pump gas operation. Bigger cam was custom ordered by Gene Pearson of performance automotive in Forest lake MN, who assembled the engine for me on this conversion. dyno tested at 396 HP at 6200 RPM, losing a few HP per 100 RPM after that, shut it off at 6500, for what it is worth.
 
rmchrgr said:
Solid cam! Why go with a hydraulic if you have the 273 rockers? Especially with 4.56 gears. Solid cam all the way.

I have a 340 with the MP .557 cam, single plane intake and 4.30:1 gears. Best car EVER on the street. Highway, not so much.

And yeah, might want to look into getting some head porting done.
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This is what I would do with 1.6 rockers and fully ported heads. Edelbrocks or W2's would be my head choice. It's actually in the parts gathering stages now.
 
If you can go to a solid cam, I'd make the switch. Something in the 240's at .050 and .520-.550ish lift. Even if you don't switch, run a hyd cam in that range and you'll have enough to hit your target

Intake, run what you have. The LD340 is a good intake and it's not worth getting rid of it for an RPM or Air Gap intake. Use the LD and a 1" open/tapered spacer, it's more than capable and will move more than enough air. Top it with a Holley 750DP.

ET is about chassis and converter efficiency. Get the car to 60 foot an the rest will fall into place. Poor 60's mean you need to make up that lost time through excess MPH for your ET. 7.50 1/8 is around an 11.80-90 1/4 mile time.

Put the best converter you can afford in it! It's the single most overlooked item and unfortunately, IMO, the most important piece of the puzzle.
 
The 528 Mopar cam would be a good choice.
 
crackedback said:
If you can go to a solid cam, I'd make the switch. Something in the 240's at .050 and .520-.550ish lift. Even if you don't switch, run a hyd cam in that range and you'll have enough to hit your target

Intake, run what you have. The LD340 is a good intake and it's not worth getting rid of it for an RPM or Air Gap intake. Use the LD and a 1" open/tapered spacer, it's more than capable and will move more than enough air. Top it with a Holley 750DP.

ET is about chassis and converter efficiency. Get the car to 60 foot an the rest will fall into place. Poor 60's mean you need to make up that lost time through excess MPH for your ET. 7.50 1/8 is around an 11.80-90 1/4 mile time.

Put the best converter you can afford in it! It's the single most overlooked item and unfortunately, IMO, the most important piece of the puzzle.
Click to expand...
Yeah, thats why I had a custom converter built. 750 dollars shipped to my door!:burnout:
 
crackedback said:
If you can go to a solid cam, I'd make the switch. Something in the 240's at .050 and .520-.550ish lift. Even if you don't switch, run a hyd cam in that range and you'll have enough to hit your target

Intake, run what you have. The LD340 is a good intake and it's not worth getting rid of it for an RPM or Air Gap intake. Use the LD and a 1" open/tapered spacer, it's more than capable and will move more than enough air. Top it with a Holley 750DP.

ET is about chassis and converter efficiency. Get the car to 60 foot an the rest will fall into place. Poor 60's mean you need to make up that lost time through excess MPH for your ET. 7.50 1/8 is around an 11.80-90 1/4 mile time.

Put the best converter you can afford in it! It's the single most overlooked item and unfortunately, IMO, the most important piece of the puzzle.
Click to expand...
Yep,don,t cheap out on a convertor.I run an 8 inch Coan 4500 matched to my cam,gears,tire size$$$I,m running 6.71@102mph in the 1/8th 60fts 1.44 10.5-1 410ci on pump gas.
 
you need better heads, w-2 or edelbrock and them worked with a mid size solid and a good convertor 3500 or better, with a air gap or victor intake, and that will do it my combo 340 bored 30 srp, 540 549 solid hughes fully worked edies , victor 340, 1.6 rr, 4200 stall 410 gear 750 aed, low mid 7,s and mid 11's all day it a full weight street car, dynoed 386 at the wheels, hope this helps:D
 
345man2 said:
you need better heads, w-2 or edelbrock and them worked with a mid size solid and a good convertor 3500 or better, with a air gap or victor intake, and that will do it my combo 340 bored 30 srp, 540 549 solid hughes fully worked edies , victor 340, 1.6 rr, 4200 stall 410 gear 750 aed, low mid 7,s and mid 11's all day it a full weight street car, dynoed 386 at the wheels, hope this helps:D
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And a really good working suspension which you obviously have:D.
 
I agree with the aftermarket heads I have a 67 cuda with 340 mp .557 solid cam j heads and some bowl port work. best et has been 11.7's pretty much your combo and the car works great. I could write a page here on whats been done. Should have done w-2 or edelbrock heads was my only mistake!!! I would go with the M-1 intake edelbrock heads, .555-.590 solid cam, 850 carb or go E-85. Make sure you get the large tube headers they make a tenth - tenth/half over 1 5/8 that wrap around steering when you start making steam! Everyone is right on don't cheap out on the convert. Match to your combo but from my exp. go 3-400 higher than what they recomend they seem to be a bit to tight for me everytime.
 
got the cal trac setup with 26 11.50 et streets it works pretty good:D
 
I run a '69 Dart that weighs 3033lbs with me in it. I have a .040" over 340 with the .557 DC cam in it; the compression is 10.8:1 and I run 93 octane pump gas, the heads are the Eddys with a little portwork done to them. The intake is an Edelbrock Torquer II with a Holley 830CFM carb. The rockers are 1.5s. The headers are 1 5/8" primaries into 3" collectors. I run a 904 with a PTC 5200 8" converter. The rear is a 4.10 with Hoosier 26"x9" slicks. The Dart consistently runs in the 7.30s in the 1/8 and 11.40s in the 1/4. The best times are 7.129 in the 1/8th and 11.359 in the 1/4.
 
my 70 duster had a 340 with bme piston dome tops and would run on pump with the timing set about 30/32 and on 110 with it at 36 at the track..car went 7.40 in the 1/8th mike and carry the wheels out then unload them best 60' was 1.67 on qtp and slicks...cam was a comp 282xs solid 520/540 lift with crane rollers,ported j heads and a x-cal intake and 950 carb,15/8 headers into 3" flowmaster 727 with 5600 8" turboaction verta...all steel with 2 seats 83/4 with 4.57 gears..have the heads for slae in the parts section at a deal..lol i think the car had more in it but i sold the short block and got big block parts for a full out race motor...:D
 
racingjoe67 said:
ok all of you racing guys i need some help making a couple decisions. The goals are simple 400 plus horsepower pump gas street strip car. We have 340 0ver 30 with 10 to 1 j.e. slugs stock forged rods and cast crank that i was told not to worry about. this motor has 360 heads 188 160 valves 480 480 comp cam edelbrock ld 340 intake. electronic ignition 727 and I have 456 gears for the back. I want opinions on cam selection im leaning towards a good hydraulic and I have the 273 adjustable rockers and push rods, heads (I want the eddis) , and carb size. I want my 67 cuda coupe to run 7.50/11.50. don't be afraid don't hold back I need your input.
Click to expand...

Your goals are easily attainable. 400HP will run mid 11s all day. Your cam is a little weak, would consider the .508 hyd, or equivelant solid. The problem is the "street" part, depending on what you can live with. My car with 380HP and 3150 weight runs 7.35 @ 91 in 1/8, 11.60 @ 114 in 1/4. That's with 4600 stall 8 inch converter. Same package with a 2900 stall only ran 12.30 @ 108 in 1/4. The converter and chassis setup are key to get where you want to go.
 
8" 4500 converter will do more for you than anything, assuming you got a stock/near stock converter now
 
:Dnew numbers, was at a show last week and there was a dyno there so i thought what the heck its fun and addictive i might as well, so no tuning or nothing made 391 at the wheels on 93 pump gas
 
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