Old School 340 Build

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67autocross

67autocross

A new iron curtain drawn across the 49th parallel
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Last summer I spun a bearing in the 340 in my 69 Valiant and decided it was time to build a new 360 EFI magnum engine for that car.
My buddy Mike suggested we should take the dead 340 and give it a cheap rebuild using parts that I have laying around and install it in a cheap car and do some drag racing this summer so I figured why not.
I dropped off the following list of parts at Mikes a few months ago and he put it together:

1. 30 over 340 block which he sent out to get honed
2. steel 340 crank which Mike got cut and balanced
3. J heads with 2.02 valves , Mike did some porting and installed new seals
4. Victor single plane intake
5. Crane 691191 Solid lifter cam 480 in 500 ex lift used and used lifters
6. 7 Keith black Pistons
7. Stock oil pan and windage tray
8. Old chrome TTI step headers
9. 750 AED carb

We purchased the new Scat rods as the factory rods I had had a bunch of grinding done them over the years. Mike also used total seal gapless rings and a new oil pump and put it together with his usual great attention to detail, compression ended up at 9.6 to 1.

Today we hit the dyno with it.....any guesses to the HP output?
 
9.6 compression,head porting,solid cam and headers...how about 360 hp,380 torque?
was it dynoed without water pump, alternator, fan,fuel pump using open headers?
 
Last edited:
67autocross said:
Last summer I spun a bearing in the 340 in my 69 Valiant and decided it was time to build a new 360 EFI magnum engine for that car.
My buddy Mike suggested we should take the dead 340 and give it a cheap rebuild using parts that I have laying around and install it in a cheap car and do some drag racing this summer so I figured why not.
I dropped off the following list of parts at Mikes a few months ago and he put it together:

1. 30 over 340 block which he sent out to get honed
2. steel 340 crank which Mike got cut and balanced
3. J heads with 2.02 valves , Mike did some porting and installed new seals
4. Victor single plane intake
5. Crane 691191 Solid lifter cam 480 in 500 ex lift used and used lifters
6. 7 Keith black Pistons
7. Stock oil pan and windage tray
8. Old chrome TTI step headers
9. 750 AED carb

We purchased the new Scat rods as the factory rods I had had a bunch of grinding done them over the years. Mike also used total seal gapless rings and a new oil pump and put it together with his usual great attention to detail, compression ended up at 9.6 to 1.

Today we hit the dyno with it.....any guesses to the HP output?
Click to expand...
Around 390-400 hp ish @6500.
Had one similar build, same pistons but ran a .528 solid , x heads flowed 218- 221cfm int by .450 lift. 9.6 comp made 392hp
 
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If the porting was decent, around 435 hp at about 6400, and 415ish torque.
 
67autocross said:
Last summer I spun a bearing in the 340 in my 69 Valiant and decided it was time to build a new 360 EFI magnum engine for that car.
My buddy Mike suggested we should take the dead 340 and give it a cheap rebuild using parts that I have laying around and install it in a cheap car and do some drag racing this summer so I figured why not.
I dropped off the following list of parts at Mikes a few months ago and he put it together:

1. 30 over 340 block which he sent out to get honed
2. steel 340 crank which Mike got cut and balanced
3. J heads with 2.02 valves , Mike did some porting and installed new seals
4. Victor single plane intake
5. Crane 691191 Solid lifter cam 480 in 500 ex lift used and used lifters
6. 7 Keith black Pistons
7. Stock oil pan and windage tray
8. Old chrome TTI step headers
9. 750 AED carb

We purchased the new Scat rods as the factory rods I had had a bunch of grinding done them over the years. Mike also used total seal gapless rings and a new oil pump and put it together with his usual great attention to detail, compression ended up at 9.6 to 1.

Today we hit the dyno with it.....any guesses to the HP output?
Click to expand...

7 pistons? I'm gunna guess 115 horse, 100 pound feet of torque. Need 8 pistons for it to run well! lol jks

Hmmm my honest guess....

420 horse at 6200. 400 flat torque at 4500. It should wind with that cam and intake. Although crane says 83 is the IVC angle on that cam. That puts you down under 7:1 dynamic. I'd like to see that up a point or so.
 
yellow rose said:
Whatever it is, there is still 40-50 HP left in it. I'd bet all I have on that.
Click to expand...
Oh, there you go. Now he'll be embarrassed to tell us and we'll never find out. Without closure, my shrink stands to make a lot of money. I might have to build his engine combo and dyno it, just so I know.
 
B3RE said:
Oh, there you go. Now he'll be embarrassed to tell us and we'll never find out. Without closure, my shrink stands to make a lot of money. I might have to build his engine combo and dyno it, just so I know.
Click to expand...


I didn't to wait until after he posted the numbers and then say something. All the haters would have been hating me hard for that one.

I need closure too.

I looked at the cam. That's why I said what I said. I mean, you don't need a lobe that beats the edge of the lifter but that lobe is slooooooooooooooooooooooow. Slower than a 284 purple dong beater cam.
 
I am genuinely curious. To me the IVC on that cam really isn't going to help things. So I'm quite curious where it ends up.
 
fratzog lover said:
The man did say he was using leftovers...
Click to expand...


I got that it's a leftover deal and I'm good with it. But when the food has mold on it, you gotta throw that stuff out.

As an example, that cam is 17 degrees BIGGER advertised and 17 degrees SMALLER than the cam I run.

That lobe was slooooooooooooow when it was first developed. I think that, all by itself, is a giant power killer.
 
yellow rose said:
I got that it's a leftover deal and I'm good with it. But when the food has mold on it, you gotta throw that stuff out.

As an example, that cam is 17 degrees BIGGER advertised and 17 degrees SMALLER than the cam I run.

That lobe was slooooooooooooow when it was first developed. I think that, all by itself, is a giant power killer.
Click to expand...
I cheated...I had to look it up.

Brand:Crane Cams

Manufacturer's Part Number:691191

Part Type:Camshafts

Product Line:Crane Mechanical Flat Tappet Camshafts

Summit Racing Part Number:CRN-691191


UPC:021174013634

Cam Style:Mechanical flat tappet

Basic Operating RPM Range:3,000-6,500

Intake Duration at 050 inch Lift:238

Exhaust Duration at 050 inch Lift:248

Duration at 050 inch Lift:238 int./248 exh.

Advertised Intake Duration:300

Advertised Exhaust Duration:310

Advertised Duration:300 int./310 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.480 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.500 in.

Valve Lift with Factory Rocker Arm Ratio:0.480 int./0.500 exh.

Lobe Separation (degrees):114

Intake Valve Lash:0.022 in.

Exhaust Valve Lash:0.022 in.

Computer-Controlled Compatible:No

Grind Number:F-238/3200-2-14

Valve Springs Required:Yes
 
Horse Power was 451.9 @ 6500
Torque was 417.2 @ 4900
 
yellow rose said:
I didn't to wait until after he posted the numbers and then say something. All the haters would have been hating me hard for that one.

I need closure too.

I looked at the cam. That's why I said what I said. I mean, you don't need a lobe that beats the edge of the lifter but that lobe is slooooooooooooooooooooooow. Slower than a 284 purple dong beater cam.
Click to expand...
That's what gives it the rumpety sound. The lobe is so slow it actually stops for a while and then starts again. Gives it that blown alcohol sound.
That being said, if the heads were done right, I still think it will top 400 hp. I've had 340s and 360s with 20 degrees less @ .050", and a half point less compression do that.
 
67autocross said:
Horse Power was 451.9 @ 6500
Torque was 417.2 @ 4900
Click to expand...
I guess that makes me a winner. What did I win?
I'd say the heads were decent for them to carry the torque curve enough for peak hp at 6500.
 
On the Dyno

IMG_0699.JPG
 
67autocross said:
Horse Power was 451.9 @ 6500
Torque was 417.2 @ 4900
Click to expand...

I knew for sure it had over 400 to it. But didn't think it would make 452. When B3RE posted 435 I figured I'd post a hair under that, expecting it to land between us. The 6500 surprises me. Given the cam card lists max RPM at 6400 and valve float at 6800. I thought for sure it would be tipping over hard by 6500.

What's the full graph look like? I'm curious to see the start of the pull.
 
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