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aquaholic72

  • Karma: +54/-0
Re: 750 vac secondary question
« Reply #25 on: August 07, 2015, 12:28:49 AM »
Wow..i didnt see the gasket pic

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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #26 on: August 07, 2015, 12:30:46 AM »
Block looks ok. Lots of carbon though. Cleaned up ok.
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aquaholic72

  • Karma: +54/-0
Re: 750 vac secondary question
« Reply #27 on: August 07, 2015, 12:33:26 AM »
77 frt 87 rr
good start.. better fat than lean but damn!!! Smoked that head gasket pretty quick

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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #28 on: August 07, 2015, 12:34:07 AM »
Hot!!!
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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #29 on: August 07, 2015, 12:35:07 AM »
I'll start with those jets.
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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #30 on: August 07, 2015, 12:35:56 AM »
Thanks for everyones thoughts, advice, and time. I'll keep u posted.
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aquaholic72

  • Karma: +54/-0
Re: 750 vac secondary question
« Reply #31 on: August 07, 2015, 12:36:00 AM »
Do u have a pic of a spark plug?  Maybe u have a water problem..

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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #32 on: August 07, 2015, 12:42:32 AM »
No. There was zero signs of water in cylinders, or oil
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aquaholic72

  • Karma: +54/-0
Re: 750 vac secondary question
« Reply #33 on: August 07, 2015, 12:50:24 AM »
Wow!! Id have the head checked just because.. did ur machine shop check the deck and surface the heads when they put it together? U have head bolts or studs? Clearly there was a problem.. not convinced it was a carb problem..

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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #34 on: August 07, 2015, 12:57:57 AM »
Block decked. Head resurfaced.
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Flusher

  • Karma: +84/-0
Re: 750 vac secondary question
« Reply #35 on: August 07, 2015, 08:40:55 AM »
Your head gaskets, acting like a fuse, saved your engine from detonating itself to death.

It would really help to see pictures of the sooting on your pistons and combustion chambers.  Reading the soot pattern can provide insight into what is actually happening inside the engine.

I'm thinking along the same lines as Aquaholic in that it is not entirely a carb lean condition.  You are building a lot of cylinder pressure at that RPM and your combination.

You need to spend some time creeping up on your final tune.  What you have now is not plug-n-play.

Sorry to put it bluntly.  I know what it is like to be on a tight budget and being excited for some seat time.  Throwing super wazoo carb tuning capabilities at it is cool and all,but you still need to be able to tune it or you are heading for a nuclear meltdown.
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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #36 on: August 07, 2015, 11:31:51 AM »
Someone duggested MLS head gaskets but now I'D be afraid of it holding it togeger and blowing a piston. Should I shim the gasket?

My understanding is I was way too lean and too much timing. I want to be closer to where I should be and not blow this thing up.
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Flusher

  • Karma: +84/-0
Re: 750 vac secondary question
« Reply #37 on: August 07, 2015, 02:27:13 PM »
Post up pictures of pistons, combustion chambers, and spark plugs.

Was the cam installed advanced?
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"I want to roll with my brother Joe" - Joe Bateman - January 29, 1950 ~ November 27, 2013

Flusher

  • Karma: +84/-0
Re: 750 vac secondary question
« Reply #38 on: August 07, 2015, 02:29:02 PM »
Someone duggested MLS head gaskets but now I'D be afraid of it holding it togeger and blowing a piston. Should I shim the gasket?

The block and heads need to have the correct surface finish or MLS gaskets will not seal.
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"I want to roll with my brother Joe" - Joe Bateman - January 29, 1950 ~ November 27, 2013

jimpen

  • Karma: +68/-0
Re: 750 vac secondary question
« Reply #39 on: August 07, 2015, 02:30:49 PM »

Someone duggested MLS head gaskets but now I'D be afraid of it holding it togeger and blowing a piston. Should I shim the gasket?

My understanding is I was way too lean and too much timing. I want to be closer to where I should be and not blow this thing up.
. Correct me if I'm wrong please. I see some big problems that needs the attention of some knowledgeable people to help you. If I remember right everyone said that it was a bad combo from the get go. At this point you need help not a guess. If your not sure about your timing or your lean condition find someone that is.  Sorry to put it this way but your builder that new everything needs to help out before it's too late. I hope the best and hate to see this happen to anyone good luck.


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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #40 on: August 07, 2015, 03:01:16 PM »
My builder says that this combo will work. Cam, pistons, heads, etc. He said bring down timing a little and richen up the carb. Thats it. He didnt agree with MLS gaskets. He seems very confident.

The cam was installed straight up.
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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #41 on: August 07, 2015, 03:03:25 PM »
He feels that 10.5:1 compression was going to be fine
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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #42 on: August 07, 2015, 03:08:31 PM »
Builder, old jet boat guy, and Ron Blanchard (carb guy) said the 750 vac sec could be made to work.
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Flusher

  • Karma: +84/-0
Re: 750 vac secondary question
« Reply #43 on: August 07, 2015, 03:20:50 PM »
Builder, old jet boat guy, and Ron Blanchard (carb guy) said the 750 vac sec could be made to work.

Indeed it can.  But I think it is not the root cause of your problem.  It may be lean, easily corrected.  I think too much timing, also easily corrected.  I think way too much cylinder pressure.
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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #44 on: August 07, 2015, 03:22:30 PM »
What u think about a head gasket shim? Or thicker head gasket?
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Flusher

  • Karma: +84/-0
Re: 750 vac secondary question
« Reply #45 on: August 07, 2015, 03:23:12 PM »
Is this at your house?  Offer still stands to come calc out your compression ratio.
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"I want to roll with my brother Joe" - Joe Bateman - January 29, 1950 ~ November 27, 2013

mobboss

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #46 on: August 07, 2015, 03:24:46 PM »
I am going to put my 2 cents in here well just cause. I think jimpen is right!! You should hand the boat to someone that knows what's going on!! No offense, but this time it cost you a head gasket next time it could be the the whole motor!! You have a issue that is not going to fix itself! New motors don't burn head caskets like that!!! 


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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #47 on: August 07, 2015, 03:35:55 PM »
Yes. It is at my house.
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el mojado

  • Karma: +15/-0
Re: 750 vac secondary question
« Reply #48 on: August 07, 2015, 03:40:05 PM »
As far as calculating my EXACT compression... i have not. This is what i understsnd needs to be done. Measure CC of heads. CC of piston head. How far down is piston in cylinder. gasket compressed thickness. Punch all those numbers into compression calculator.
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GT Jets

  • Karma: +192/-0
Re: 750 vac secondary question
« Reply #49 on: August 07, 2015, 03:46:19 PM »
When we build a new engine, the timing starts in the low 30's and typically fat as hell. It is not unheard of to start two steps fat and we run 2% Marvel oil in the gas.

From there we start playing with timing and then working on the fuel. Fuel is always last, then reevaluate the timing.

FYI

GT
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

 


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