thanks charlie

Terry,

The vacuum retard you have is only going to provide retard under light load which is the opposite of what you want. You need to limit the mechanical advance to 15 degrees total. Again, I would run a locked distributor and set the timing to 15 degrees so you have no question as to your timing. If this were a street/strip car and you ran around under light load more I would then use more mechanical advance and use pneumatic or electronic boost retard, but I don't think you need it.

I would also put O2 sensors in cylinders #1 and 6 and see how they compare to the other cylinders. Chances are very good you have the center cylinders richer than end cylinders.

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Joshua

thanks joshua, i will try a lock dist, how much timing do you use and at what boost?. i found that my 60ft times slowed with the more timing i have taken out.

B & M used to sell an advance / retard dashpot to go with their blowers for chevy engines. I don't know if they still do, but it may be another adaptable option if the ford part cannot be found.
Electronic is really the best way to go and easier to adjust. Summit is now selling private labeled mallory ignitions. The system complete with a map sensor is under $300.00. I have had good luck with the mallory versions, and they are much less expensive than MSD. This would allow you to use a normal vacuum advance and still get all the retard you need.

I would expect you should be able to run 18 degrees advance no problem with only 5 psi boost, but your fuel distribution will have to be correct. If you were not under boost for nearly your entire run I would run more timing advance and use boost retard.

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Joshua

The head studs will help. But the truth is, the gasket being able to blow out is probably saving you your engine. Its like a safty factor. I agree that they are probablly going lean on 1 & 6 and that is causing det which is really what is blowing the gasket.


You should look to the big nitrous guys and learn how they read there plugs. It will anwser your question on how much timing & fuel you have in each cylinder. If you have any det at all it will show on the plugs, and you have to do a plug reading a certain way to get good results with your readings. The problem is it take a lot of time & work to get the readings as needed. But it does tell the true story.


The way you have your vac retard setup, I am sure you where running the full 25* when you was going down the track. Like was suggested, just run it locked out, this will be the most consistant & accurate way for getting a good tune.


As far as the tune, you may have to run a colder plug on 1 & 6. I often wander if these two cylinders run hotter than the others and that is part of why they have problems. Another trick would be to run different valve lash settings on those two cylinders to try help them out.

Jess

thanks jess, those are good points, this dist only saw one pass at the track and it will be it`s last,as for the other recurved dist that i have been running from the start ,it has been set as low as 20degs total with the same result. so the plan for now is new gasket and 7/16in studs, that are order to be here next wednesday,the 2/600cfms are going ,to be replaced with the 750cfm mech that i ran on the smaller blower, dist will be fix at 15degs to start,as for jetting i will have to make sure it over rich untill i get a pass at the track.for octane i`m stuck with av gas and will have to hope that timing and carb selection were the biggest problem.i never hurt any plugs with the 600holleys(9y champions)but i will put cold plugs in #1&#6. i could try play with different lash setting, but i need just one full pass under full power without hurting anything just so i can get some sort of direction.thanks for the help (keep it coming)

Just a little note here Terry, on a spray car over rich will cause just as many problems as an over lean condition. Over rich kills piston top ring lands and can push head gaskets out. Boost is boost.

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Official Cookie and Mater Tormentor.

so if i have to be careful not to over jet,what is a good starting point. if i go with a single 750 mech holley should i jet 4or8 size above factory jets to be safe on the rich side.it`s been sometime sense i ran this carb but if memory serves me i think i ran 80s to 86s with power valve pluged on the smaller blower??

Starting piont is hard to say for me, I have never ran draw-thru blower setup. I dont think you will get to the piont of too rich at your power level. Although it is very possible to do that, and even if its not hurting piston ring/top it is still washing the oil off the cylinder wall causing it to wear more.

I think I would just go with what I have known to work, but take it slow & check closely. Like dont pull the RPM up all the way at first until you run some checks. Pull the timing back as far as it will go and still run & pull good. If it will work at 10 or 12*, start there. Then work your way up slow & check at every ajustment. And get the timing right, before making any fuel ajustment (unless the fuel is just way off).


I know it takes alot to really tune like this. When I start with a new combo I will go through as many as 12 sets of plugs just getting the fuel & timing right. Because the only way to get a true reading, is to put a new plug in, push the car up to the starting line, make a pass, at cut the engine off at the end of the pull & then pull/tow the car around & check the plugs. If you let it idle much it will mess up the readings. If I am way off on the tune up, I will just use two new plugs, do the same thing with my pass, tow the car around, read the two plugs and make my ajustments. Then when I get what I think is getting close. I will put a whole new set in & make the pass, get my readings. At this piont you can get a very good idea on which cylinders are rich & lean. Then you can do ajustment to effect each cylinder one at a time with a new plug in it for each ajusment & reading. It is a lot, and it takes time, and money. But it is the only real way to tune a forced induction or NOS car. It is just to easy to melt them if you dont.


There was some very good info on reading plugs I had linked to. But I have not been able to find it lately. I will look for it & some others to get some pics that show what to look for. You really have to cut the plug apart, and have a lighted magnifying class or jewlers eye piece to read them. But I will see what I can find for info & post it back.



Jess

thanks jess

Here is one good page that has alot of info. Also go to the bottom of the page & there a lot of links, every one of them has good info. And when you go to one link & start reading you will find other links within them.


One of the links also goes to a website that even sales a DVD of tuning info. I do not have this DVD myself but others have told me it is alot of good info.



You will find that there is some debatable subjects retaining to Heat, and Timing marks. Some do it this way, some do it that way. What I have found, is that Heat & Timing are the same thing in there own right. Between cross referancing with the Detination readings on the insulator to find the balance between the heat range of the plug & the timing of the engine. Basically, more timing causes heat. So changing heat range of the plug will change timing needed, and may be nessessary to to change the heat range to find the max ( or the amount it performs best at)amount of timing the engine can use.


So if you was to put a colder plug in, then it could need more timing to reach the proper heat reading. If the engine reasponded with more power then good. If it ran into detination, then timing would have to be taking out, but then if the plug does not reach the proper heat it would have to go back up in heat range. Balancing these two is a big part of the tuning, and at the same time when tuning for this it will effect the fuel, even without and changes to fuel. SO its a three way balancing act that has to be juggled to find the right combo.


When you read through the info notice how clean & white some of the plugs are, that even some of them are considered rich. It is a fine line to ride to reach tuning at this level. But it is what is needed to have a motor that lasts & performs.


I really believe this DVD that is offered would be a good thing for most that are starting to learn to tune. I do plan to buy it myself because of the Dyno & carb info that is on it. At around $20.00 its a pretty cheap buy. There may be info on how to change the timing on each cylinder by itself, even with a distributor. This may be easy by changes to the dizzy cap, but I am wandering if they may have some really slick ways of effecting it.



Jess

Jess
Your link didnt come through.
Thanks
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

yes i second that i see no link

LOL, I sliped there didnt I . I didnt even try to post the link I forgot by the time I got through typing all that....


Anyway here we go.
http://www.dragstuff.com/techarticles/h ... plugs.html


Jess