Blowed my headgaskets again!

[InHock]

I am running julios alky system and am using methonal. Bought system last year about this time and installed it in december 09. I am running 60lbs of fuel pressure and it builds up to 65 to 68 under boost.

 

[bmackinnon]

I am running 60lbs of fuel pressure and it builds up to 65 to 68 under boost.

Speechless.....

 

[InHock]

Speechless,why? Is that to much or not enough? Damn, I am still learning these cars and lets face it they are not the easiest sobs to learn!!!

 

[Thumper]

Lets clearify the fuel pressure, are you saying 60lbs at idle????? should be in the 38 - 43 area with vac line off at idle. Do you have any knock at all? You might want to do a volume test on your fuel pump, pressure does not tell the whole story.

Thanks
Bill

 

[bmackinnon]

I'm speechless because I am simply amazed that you would be attempting to run 25 psi boost, without any apparent clue as to the basic operation of the fuel system for these cars.... I would have thought that with 260-something posts, you would at least have some sort of basic understanding... I'm not going to go thru all the trouble of typing a 4 paragraph explanation, which I've typed 500 times in response to other people, so I have just copied, and will paste below, what I said last time someone was having a fuel issue:

These cars use a fp regulator that is referenced to boost pressure. The fp MUST rise in a 1:1 ratio with boost. If not, the car will go lean, start to detonate severely, and blow the head gaskets... or worse! The ecm will pull timing when it senses the detonation (called knock retard or KR, causing the car to drastically lose power), but will be unable to compensate enough to save itself. Owning a shop, you surely have access to fp gage. You need to hook it to the front of the fuel rail, via an extension hose that will allow you to temporarily tape the gage to the windshield so you can see it while driving. I BET MY ARSE that what you will see as you start pouring on the throttle, will be the fp start to rise, and then as the boost builds the fp will begin to fall off a cliff... this will prove that the fuel pump is dead/dying. This is the VERY FIRST THING you should do before running the car hard again... I can't stress this enough!!! If you continue to run the car hard 'with no balls but a small gallop' , it WILL blow up.

Nobody, and I mean NOBODY runs the stock chip/fp reg. anymore, and I can't remember exactly what the 'base' (vac hose removed from the regulator) fuel press. should be, but for this discussion, let's assume it's 30 psi. SO.... fuel pressure for any given boost pressure MUST be 'base' + boost = fp. So at 12 psi boost, fp = 30 + 12 = 42 psi. This number will obviously vary depending on what the base and boost pressures are. THIS MUST BE VERIFIED TO BE OCCURING IMMEDIATELY!!!

Here's a link to another explanation at gnttype.org.... you need to read it...

Fuel System Check Up

And for the record, we typically run about 43-45 psi 'base' fuel pressure... NOT 60 psi.... nor the 30 psi mentioned above (that was for a stock fpr, and just as an example)....

Not trying to be an ass, and sorry if I sound like one, but sheesh!

 

[bmackinnon]

Lets clearify the fuel pressure, are you saying 60lbs at idle????? should be in the 38 - 43 area with vac line off at idle. Do you have any knock at all? You might want to do a volume test on your fuel pump, pressure does not tell the whole story.

Thanks
Bill

Yes, pressure tells the whole story... if the volume is insufficient, the pressure won't build... simple as that...

 

[GullsGN]

Speechless,why? Is that to much or not enough? Damn, I am still learning these cars and lets face it they are not the easiest sobs to learn!!!

My God!!! How is that motor even togeather. Sounds like it is going to be a door stop! Well, to start with, fp should rise 1 pound for every pound of boost. That means that 25 lbs of boost should result in 85 lbs of fuel pressure. Holy crap, Batman!! KAPOW. You should be starting with 43 lbs of fuel pressure with the vac line off. Turn the boost down to 15 and get it running right from there, or not, and be one hell of a supporter to our vendors. Do some serious studying before you try playing at those levels.

 

[bmackinnon]

I am running 60lbs of fuel pressure and it builds up to 65 to 68 under boost.

FWIW, if those numbers are accurate, it sounds like your fuel pump has $hit the bed... it should be able to go to 85 psi easy (60 base + 25 boost).... (should go to 100 pretty easy)

 

[InHock]

MY GOD,I get different info everytime I get on here and ask a question! When I was putting this motor together I was told to have fuel pressure at idle with the regulator at 55 to 65 lbs. So that is the way I set it up. I did have a fuel guage taped to my windshield the last time I drove the car and I was told fuel pressure should rise 1lb to every 1lb of boost. So at idle it was at 55 or 65[please excuse me because I really dont remember which one] and under boost it went up like I was told. So if someone is telling me one thing and someone is telling me something else what the hell am I supposed to do??

 

[dank GN]

Dam that alot of fuel pressure i was told that 42 line off is nominal add a pound or two if needed 60lbs of fuel pressure?? something wasn't right??

 

[scot w.]

After reading these posts the last thing I would be worried about is what kind of head gaskets to use!

I would be looking VERY close at your Bearings!



* 91 Octane & running 25psi of boost

* looked down at the temp guage and it was at 250 and I pulled off the road and raised the hood and felt of hoses and they did not feel all that hot. I was about 4 miles from home so I drove on in

* I have a 340 walbro

* I always have to re-dial my alky in to keep the knock sensor out of the red!!

* I am running 60lbs of fuel pressure and it builds up to 65 to 68 under boost.



Asking questions here BEFORE going WOT goes a LONG WAY and can save you a BUNCH of Money!!


Hope it's just a gasket issue.

SW,

 

[InHock]

Also, no one has ever told me about a vac.line to pull off when setting the fuel pressure. Which one?

 

[dank GN]

i didnt scroll down these guys got it covered

 

[dank GN]

Also, no one has ever told me about a vac.line to pull off when setting the fuel pressure. Which one?

the one going to the FPR

 

[InHock]

Thanks dank gn.I will pull that off when setting fuel pressure after I get it back together. I will pull the motor and it will be gone thru completly and checked and if any thing needs replaced it will be.

 

[bmackinnon]

the one going to the FPR

Yup, the one going to the top of the fp regulator.... just pull it off the top while setting (I also like to plug the line with a little plug while doing so I don't have a vac leak while setting). You will notice that when you plug the vac line back on the reg, the FP will DROP due to vacuum... same principle as rising under boost.... drops with increasing vacuum... thus the term 'base' or 'static' = at atmospheric pressure....:wink:

Also agree with the above poster... for god sakes, drop the boost down to 15-ish psi and verify everything is in order, then start SLOWLY sneaking up on boost, like 1 psi at a time... I find it unlikely you are going to make it to 25 psi without knock on 91 octane, without a LOT of alky... and even then..????

 

[Pronto]

I don't know how your car ran at 60lbs of pressure at idle. Fuel must be poring out the exhaust. Think you need not to listen to who ever told you to run that for fuel pressure.

 

[qwks6]

A relatively cheap addition may be a wideband o2 sensor and gauge, maybe a datalogger. Make sure you read instructions, post results, work your way up slowly. Good luck!

 

[Raymond Bunch]

InHock- It's a learning lesson, and I'm sure you have learned from it:smile: I did too a couple time over the years.
Also keep in mind, read, read, read.... These cars are like women, they need to be respected or you will pay dearly. No pun intended ladies Also, ask for more than one or two opinions too. When I got into my first GN about 10 years ago. The first thing I did was find out who knew these car inside out, had a good reputation and lived fairly close to me:wink:

On this note: The Felpro 9441PT are a good head gasket. My car on it first pass out ran 11.00 at 129. I drove this car everywhere, raced it and just had fun with it. On pump gas and Alky it made 579HP, on the first pull. So, don't give up on ALKY, it take time to tune it properly. After i sold the car due moving to a diffrent duty station (Marines). The car was dynoed again after a couple adjustments and mad 620HP....

Hang in there and ask questions, no matter how dumb, were a very small community and for the majority of us, it's our pleasere to help another brother/sister out. Good luck on the build, keep us in the loop.

Check, then double check everything again. - Ray

 

[bmackinnon]

InHock- It's a learning lesson, and I'm sure you have learned from it:smile:

Also keep in mind, read, read, read....

Hang in there and ask questions, no matter how dumb, were a very small community and for the majority of us, it's our pleasere to help another brother/sister out.

Check, then double check everything again. - Ray

AMEN!!! :wink: Well said....