Engine tight
Thread Starter
Instructor
Joined: Feb 2022
Posts: 203
Likes: 10
Engine tight
Put my 406 together. Put rods and pistons in turned over at 33lbs.now I put oil pump on cam in front timing chain and damper on.now it takes almost three times as much to turn. Is this normal or is there something wrong.
Race Director
Joined: Feb 2007
Posts: 15,417
Likes: 8,867
From: northern california
C2 of Year Finalist (track prepared) 2019
My instinct is that something is wrong. I have two data points. Make of them what you will:
1. The tightest engine I've ever assembled required about 40 ft-lbs torque at the crank to turn it over. This is with pistons, crank, and stock valve train installed.
2. The TRACO 377 in my bride's Grand Sport required only 22 ft-lbs. This engine was a full roller motor, no sliding valve train surfaces
1. The tightest engine I've ever assembled required about 40 ft-lbs torque at the crank to turn it over. This is with pistons, crank, and stock valve train installed.
2. The TRACO 377 in my bride's Grand Sport required only 22 ft-lbs. This engine was a full roller motor, no sliding valve train surfaces
Intermediate
Joined: Feb 2023
Posts: 44
Likes: 16
From: Tennessee
Just crank rods and pistons are 33lbs? way too tight, what are the bearing clearances at?
need more specifics on engine clearances, I have done vids on the difference just .001 will make on a crank main.
piston to wall clearance? type of piston used?
were the rods installed correctly they have a camphor on one side that goes towards crank fillet
lot goes into assembly.
need more specifics on engine clearances, I have done vids on the difference just .001 will make on a crank main.
piston to wall clearance? type of piston used?
were the rods installed correctly they have a camphor on one side that goes towards crank fillet
lot goes into assembly.
Last edited by Bgblock427; Mar 14, 2023 at 05:41 PM.
Racer
Joined: Jan 2012
Posts: 372
Likes: 59
From: Central Valley Cali
Just crank rods and pistons are 33lbs? way too tight, what are the bearing clearances at?
need more specifics on engine clearances, I have done vids on the difference just .001 will make on a crank main.
piston to wall clearance? type of piston used?
were the rods installed correctly they have a camphor on one side that goes towards crank fillet
lot goes into assembly.
need more specifics on engine clearances, I have done vids on the difference just .001 will make on a crank main.
piston to wall clearance? type of piston used?
were the rods installed correctly they have a camphor on one side that goes towards crank fillet
lot goes into assembly.
I always use a black sharpy with notes all over my motors with plenty of pictures so I can go back and double check stuff.
Drifting
Joined: Jan 2001
Posts: 1,358
Likes: 26
From: Florida
Tight
Last edited by andy60; Mar 14, 2023 at 07:26 PM.
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Race Director
Joined: Feb 2007
Posts: 15,417
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From: northern california
C2 of Year Finalist (track prepared) 2019
I assume you mean 33 ft-lbs? (Let's use correct terminology.) That by itself is really high.
Is there any chance you got some of the main bearing caps out of place? Or even some rod bearing caps?
Team Owner
Joined: Apr 2008
Posts: 31,730
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From: Middle TN by way of KY, OH, VA, IL, CA, FL, NY, SC, HI
What were the measured main bearing clearances, crank end play readings, and measured piston ring end gaps during assembly?
Did the bare cam spin smoothly when initially installed? How tight was the cam chain?
What is the cam lift and spring pressure at full lift?
Did the bare cam spin smoothly when initially installed? How tight was the cam chain?
What is the cam lift and spring pressure at full lift?
Race Director
Joined: Jan 2003
Posts: 17,658
Likes: 3,665
From: Central Arkansas
I’m no engine builder and defer to the others on the 33 ft-lbs but setting that aside for the moment it sounds like something went horribly wrong when you installed the balancer and the fuel pump if you engine turn over torque shot up to the vicinity of 100 ft-lbs, I would remove those items one at a time and see if the turnover torque decreases to figure out which one is the culprit. You definitely need to figure that out. Then check the overall assembly for clearances.
