#7 Lean, Solution to re-route rear vacuum source
Run a 4 corner crossover, make sure that your coolant system is completely air free, and you will have less issues with #7. I also believe that a product such as NPG can help the situation. It is my personal opinion that hot spots are being created in the combustion chamber due to steam pockets. This results in detonation and leads to holes in pistons. I have no scientific proof, just my theory.
Andrew
Andrew
I have this exact problem as well as alot of other guys and none of us have found a solution. Ive replaced the fuel pump/filter/regulator, plugs/wires, 02's, removed my catch can (which I thought was the problem as well since I found a crack in the catch can but alas..) If you ever figure this out Id sure like to know what it was.
Teching In
Joined: Sep 2006
Posts: 23
Likes: 0
I just lost my 383 due to failure in #7 pot . Forged internals , 10.8:1 , 18 psi boost . Did not hear any detonation prior to the event but have a huge hole in the back outer sleve of #7 . Tune was safe at 11.4:1 Afr & timing was low at 7* . Agree that it may be due to heat as there was no knock heard or detected . Am now going to build a 402 cast engine to push some real boost .
Still has me wondering why most failures are in this pot !
Troy
Still has me wondering why most failures are in this pot !
Troy
Teching In
Joined: Sep 2006
Posts: 23
Likes: 0
It was running on 98 octain unleaded fuel with 25% Toluene mix which gives a total of around 103-104 octain levels . Had been running like this for 3 - 4 months with no issues . I'm pushing more to the fact that alloy block with thin sleves as it had been bored , this was a N/A engine that I built some 4 yrs ago which had a pin loosen in a lifter & caused some damage . It was decided to doctor the engine & use it as a test engine for boost prior to building a suitable cast engine to achieve 1000 rwhp . Obviously our fuel differs from what you guys have . In N/A form running 11.8:1 CR my engine ran fine on 98 fuel running as much as 28* timing & producing mid 400 rwhp on Dyno Dynamics chassis dyno .
It's all part of real world R&D !!
It's all part of real world R&D !!
UPDATE
I located the source of my issue, I ended up pulling my motor and completely rebuilding or re-freshening re-using all the hard parts and found my problem to be my #1 fuel injector (60 lb Mototron) was not firing fuel at full capacity and it was leaning this cylinder periodically or intermittently. I had an issue once before that likely did this injector in but not sure if it was the intake port collapsing from the ported thin walls combined with the boost or if the injector failed and that caused the port to come apart, regardless this was my issue and now it runs like a bat out of hell with a new motor and new injector. Life is good except for now my RAM HD clutch is letting out too far at the top and is partially disengaging at higher RPMs in higher gears 3rd, 4th, etc.. I'm about to pull out the clutch linkage rod and modify it to make my clutch master cylinder adjustable and hopefully this will fix my problem, in essence there is a bit too much pressure on my pressure plate with the clutch pedal all the way the upright position, I can drive down the road in high gear and blip the clutch pedal a half inch or so and it will fully disengage and spin up. Any other ideas to try to fix this? What about bleeding the slave cylinder line will that help at all?
I located the source of my issue, I ended up pulling my motor and completely rebuilding or re-freshening re-using all the hard parts and found my problem to be my #1 fuel injector (60 lb Mototron) was not firing fuel at full capacity and it was leaning this cylinder periodically or intermittently. I had an issue once before that likely did this injector in but not sure if it was the intake port collapsing from the ported thin walls combined with the boost or if the injector failed and that caused the port to come apart, regardless this was my issue and now it runs like a bat out of hell with a new motor and new injector. Life is good except for now my RAM HD clutch is letting out too far at the top and is partially disengaging at higher RPMs in higher gears 3rd, 4th, etc.. I'm about to pull out the clutch linkage rod and modify it to make my clutch master cylinder adjustable and hopefully this will fix my problem, in essence there is a bit too much pressure on my pressure plate with the clutch pedal all the way the upright position, I can drive down the road in high gear and blip the clutch pedal a half inch or so and it will fully disengage and spin up. Any other ideas to try to fix this? What about bleeding the slave cylinder line will that help at all?
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