340 BREAK IN

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CFD244

CFD244

"I LOST MY ID IN A FLOOD"
FABO Gold Member
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Hi Folks

Well, I finally broke in my fresh 1971 340 build after 4 months. This engine is going into my Cruiser 1971 340 Demon this spring (hopefully).

Here's the rundown on the build........

.040 Cast Silvolite pistons .018 out of the hole. Piston clearance .00075

Hastings moly rings
Compression rings .017 gap
Oil rings .037 gap

OEM Re conditioned 340 rods with ARP bolts. .0017 clearance

OEM steel crank .002 main clearance, .003 end play.

Melling HV oil pump with hardened shaft.


Cast "O" heads with 2.02 valves and 70 cc Chambers. Comp 942 springs with installed height 1.7 inches.
OEM hydraulic 340 rocker gear with .035 preload and .040 shaft shims. Comp Hydraulic Lifters.

OEM 340 HP Manifolds

Comp XE 262 Camshaft, .0025 endplay.

OEM Cast intake with 6139 Thermoquad (stock).

MP adjustable distributor (Mallory)
Champion RN 12Y plugs

Hi flow water pump with Robert Shaw 180* stat.


This combo started and ran like a champ on the run stand. 20 minutes at 2000RPM using Comp Cams break in oil and a WIX oil filter. Then 20 more minutes varying the RPM from 1500 to 2500 RPM. Timing at 34* during the entire break in. Shut her down, drained the oil and changed the filter. Re filled with Lucas Hot Rod oil 10w30. Let it cool, then fired it up for another 15 minutes varying the RPM as well. Shut her down, let it cool off during lunch....and then a compression test.

Observations...............

#1 Holy crap, not a single leak anywhere!
#2 Hot idling oil pressure is 60 lbs.
#3 Compression is 180 lbs across the board.
#4 16 inches of vacuum (rock steady needle) idling at 850 rpm with 20* idle advance.
#5 20 inches of vacuum at 2000 rpm with 34* advance.
#6 The break in oil looked really good after being drained. A couple of barely distinguishable silver streaks in the oil when scrutinized. LOL....No chunks!

For a Comp Cam's flat tappet break in, I feel that it went well. Time will tell. Here are a couple of pictures.........

Thanks for looking:)

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I just broke in a very similar engine. How long are you supposed to leave the breakin oil for?
 
Sounds like you got it, buddy! Any chance we can get a video to hear it?
 
4spdragtop said:
Congrats Troy! I am not surprised at how well you and the engine did.
Awesome stuff, now where's video?
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Sorry, no video......Stressed to the max. Didn't want one more thing on my mind.

30 years in emergency services, I haven't felt this nervous in a looong time.
 
JDMopar said:
Sounds like it went well. How about some more pics of the run stand when you get a chance!

:thumbsup:
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Will do. It doubles as a "from underneath" install stand, and breaks down for storage. Pics of the run stand...........

The post with the control panel gets removed from the base, and a post with a transmission support fits there.
The side supports through the K bolt holes get removed, and the "T" under the K gets a post with 2 pins that fit the 2 holes in the center of the K. This allows you to drop the car, and put in the bolts.

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I’m a believer too when it comes to test running new engines. My test stand is fugly for one time use. I found a leaky frost plug which would be tough to fix in the car.
 
1MeanA said:
I’m a believer too when it comes to test running new engines. My test stand is fugly for one time use. I found a leaky frost plug which would be tough to fix in the car.
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Definitely the place to find any problems first. I did a pressure test on my cooling system before I even turned the key. If A/F was finding it's way into the crankcase.......I wanted to know before it ran. All was good.
 
CFD244 said:
Will do. It doubles as a "from underneath" install stand, and breaks down for storage. Pics of the run stand...........

The post with the control panel gets removed from the base, and a post with a transmission support fits there.
The side supports through the K bolt holes get removed, and the "T" under the K gets a post with 2 pins that fit the 2 holes in the center of the K. This allows you to drop the car, and put in the bolts.

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Click to expand...

Sure like the way you setup/built your engine run stand, very nice.


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@CFD244 Thanks for posting the extra pics of your run stand. I've had a design to build one for myself rolling around in my head for a while and yours is about an exact match for what I've been wanting. A test run stand saves work if an OOPS arises!

:thumbsup:
 
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