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Tech anyone????

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Punch this!!!
 

I’ve gained a lot of experience and knowledge over the last 18 mths during the rebuild of my engine…..from both working with guys who know their stuff and through trial and error.

 

I was lucky to have some people around me who knew the tricks...and it prevented me making a huge number of mistakes...and from using some very poorly prepared parts.  

 

Listed below are pointers and tips….which budding engine builders can refer to….and hopefully avoid some of the dramas I’ve had.

 

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AIR  FUEL AND TUNING 
 
 
When the air density increases, you will need to richen the air-fuel mixture to compensate. When the air density decreases, you will need lean-out the air-fuel mixture to compensate.

Use the following as a guide to correcting your setting when the weather changes:

Air temperature: When the air temperature increases, the air density becomes lower. This will make the air-fuel mixture richer. You must lean the mixture to compensate for the lower air density. When the barometric pressure decreases, the opposite effect occurs.

Humidity: When the percentage of humidity in the air increases, the engine draws in a lower percentage of oxygen during each revolution because the water molecules (humidity) take the place of oxygen molecules in a given volume of air. High humidity will make the air-fuel mixture richer, so you should lean the mixture.

Altitude: In general, the higher the altitude the lower the air density. When driving at racetracks that are at high altitude, you should lean the mixture and increase the engine's compression ratio to compensate for the lower air density.

This is a guide to help you understand the effects of air and how weather can change tuning. Allthough this is an important and true factor. Theres no big need to focus on whats going on if its confusing to you , this is for the more advanced user so use this if it helps. Otherwise the printable chart above is the best for referencing how to tune your motor.

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March 08 update
 
If you decide to use a cold air induction system and  or block off your heat riser, be prepared to do some serious fattening up of the carb, particularly in the idle / power transition jetting. The MUCH colder A/F mixture demands a richer mixture.  
 
 
Sep 07  Update
 
As noted in my Rat Patrol update, I suffered the unusual occurrence of a melted dissy cap centrepost in my last trip to Calder Raceway.
 
I've since been told this can be attributed to a loose plug lead or a dead plug. Soooooo......check your leads b4 you race!! 
 
Fitting headers to a Small Block??? - Note the cast boss half way down the block on the right side - and you'll also note that the primaries from # 4 and 6 cylinder ports rest against this casting boss.
 
Problem? The casting boss wont allow the header tubes to sit close enough to the block - the result is the  header flange wont bolt flush to the head ports......
 
Result? - A damn annoying header leak from the base of siamese flange
 
The fix? Pull out the grinder and take the casting off before fitting the headers!!
 
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Machinists – My view is ALWAYS check a machinists work..never assume its right.  The quality of machining work from the three contracted machinists I used was BELOW standard.

 

  • The crank went back twice, due to taper in the journals
  • The block was not decked accurately,
  • Valve seats were cut sloppily effecting installed heights on the heads.
  • The anti leak groove on the tail piece of the crank was linished off but some GM idiot who didn’t know what he was doing, causing a rear main seal leak (Check anti-leak bearing under parts)

 Parts –

 

 Never assume they are correct!

  •  James found the wrong rings in two different packets sold to him by a local machine shop. 
  • I got sold a MP “HV” fuel pump that turned out to be std pump with the wrong p/no. 
  • Then, the replacement HV Holley pump had a defective check needle that caused chronic “loading up” of fuel and caused the bores to score slightly. 
  • ALWAYS check your lifters!! – Check the crown on the lifter face and that they rotate in the bore! – James had to blue print my lifter bores as some were patently too tight. 
  • Do not use the Mellings oil pump drive gear…it has a weakness at the base of the shaft…….use the Mopar Performance one if you need a HD item. 
  • Always check your re-manufactured carb. After fixing the fuel pump problem, I still couldn’t work out why the carb was flooding at 7 psi – Reason? – A needle was in the wrong way in the needle and seat..! 
  • Intake – Never assume a used intake will seal correctly. Get it faced to the correct angle. Its not just about bolt holes lining up, its about a full face seal as well. 
  • B&M flex plates do NOT use the std Factory converter bolts, they are one size too small….use either BW35 or HD ” converter bolts, and of course if your converter is factory, you will have to tap the converter lugs to the correct thread. 
  • The MP windage tray is a lousy fit…be prepared to do some minor panel work. 
  • The MP anti leak bearing is a beauty!! It saved me when we discovered the damage dione to the crank by the machinist...so far not a drop of oil on the tarmac!

Assembly / start up tips

 

Use someone who knows how to blueprint! -  It’s amazing how many little tricks there are which even the best books don’t talk about….

 

Rotating assemblyDon’t assume your bearing clearances are right, check them with plastigauge. James found one bearing shell that was one thou below spec.

 

Cam break in - Main tip here is DON’T use cam lube on the lifter bores…its too sticky.  Use running in oil to lube the lifter sides, and cam lube for the faces and cam lobes.

 

Electrical

 

To avoid a potential “false start”, make sure the ignition system is reliable and the ECU is earthed well…..the vibration from a 2500 rpm break in can shake the ECU loose, and the engine will stop – not  a happy scenario.

 

 When you've dropped the dissy in, check to make sure youve got spark at No 1 and not No 6, just turn the ig. on and rotate the dissy by hand back and forth past the trigger point on the reluctor, with no 1 lead disconnected but placed next to an earth...you shoud see it spark if its firing to the right lead. Cool 

 

TimingThe factory dissy holds WAY too much timing in the mechanical advance for a HiComp motor. Reducing the advance in a dissy is NOT a complicated process…so don’t pay through the nose for it. 10 mins with a Mig and a file, welding up the slots in the dissy weights, and a degree wheel is all that’s required. You local Val repairer should be able to do the job for under $100….and it’s some of the best insurance you can have against a blown engine.

 

Cooling system

 

Water leaks – Yeah I know...pretty obvious, but when filling the engine, try to avoid splashing water everywhere….it makes water leaks much easier to pick up BEFORE start up

 

Some timing cover and intake bolts go to the water jacket…so make sure you use Ultra Copper to seal those bolts.

 

Oiling system.

 

Oil pump - The early Mellings HV pump used counter sunk faceplate bolts.  Latest production runs use bolts that sit proud of the 0il pump body – The result, the bolt head  nearest the corner of the oil pan actually rubs on the inside corner of the pan, and it will split the pan eventually if left unattended.

 

The fix? – Peen out the corner of the sump to provide the bolthead with some clearance.

 

Change – Dump your break in oil when it’s HOT!…that way the residual cam lube etc drains far more easily.

 

Fittings – If you are running a remote system, fit your block fittings and hoses B4 you drop the engine in….it makes life a lot easier and its one less thing to have to wrench on under the car.

 

Lines – UNDER NO CIRCUMSTANCES let your oil lines come into contact with any sharp edges or moving parts (steering column, drag link etc).  The hot rubber lines wear quickly and then Kaboom!!

 

Fuel 

  • Don’t expect a std fuel pump to feed 400 HP under load, take it from me, it doesn’t! 
  • DEFINITELY fit a fuel pressure gauge…having one on my engine would have saved me 5 weeks of heartache. 
  • DON’T use old fuel for start up….it increases the risk of detonation if you get your timing squirrelly. 
  • Buy yourself a couple of cheap plastic filters….if your car has been sitting, you don’t want to waste good filters on the initial start up “flush”. 
  • Dual pumps? -  It used to be necessary because old electric pumps lasted about 15 hours!!,,,but its not recommended to run an electrical through a mechanical pump these days….it can cause the mechanical to cavitate. If running an electrical pump, you can leave the mechanical fitted as “insurance”…just route a small length of hose from the inlet to the outlet and leave a small amount of fuel in the pump. That way it’s there if the electrical dies on you….  

Exhaust

 

Std exhaust manifolds (360 or 318) will not work effectively on a warm SB.

 

Factory 360 mans. KILLED the HP output of my engine…..so include the price of some headers in your build costs.

 

Also, not a good idea to use 360 headers on a 318…the port face area is not large enough to support a decent seal around the Siamese ports ….a sure-fire place for a leak.

 

[Ed note: - I’m going to keep adding to this list as I come across things…I know that most of this stuff I wouldn’t have know except for the knowledge and expertise of the guys who helped me….so I hope this helps in turn.]

 

Mopar Mal