that sounds good to me also, thanks

i am baffled, just back from track,lost compression on #1 CYL , I HAD 750CFM CARB JETTED #74 PRIME/WITH POWER VALVE, #82 secondary, dist locked at 15degs no advance, bolted head with new 7/16in ARP head bolts torque 85fts then rechecked when hot,back off lash to 0.028in on int/ex from 0.016int and 0.020ex, spent sometime at end of track tuning getting air / fuel meter to read 900mv which i though equals 12/1 air fuel ratio,checked plugs after full throttle shut down and timing marks were just at bend in ground of sparkplug/ base color was full circle around plug,i forgot to get magnafing glass to get a good look down in plug porcelain base,i though plug looked close enough for a full pass,i would have liked more black soot buildup on plug base,anyway i made a full pass, car left hard could hardly hook the tires 1.73 60ft car pulled hard through 2nd with 7.80 at 1/8 mile, the hole while down the track the air /fuel meter read over 900mv but in 3rd gear it done the same thing she started to lose power so i lifted as soon as i could feel the power going away.when i got back to pit check plugs all look good except #1 was wet ,when i done compression test all cyl had comp except #1. the track is going to try one more weekend so i have a stock steel head gasket with mopar spray adhesive it`s a shot in the dark but the fel/pro gaskets look like there pushed egg shaped before they blow, i checked the surfaces with strait edge and seemed fine be for assembly, all i know is this has me stummed???

just finished going through the engine again, head gasket blew out on #1 and pushed egg shaped on #4 all others good, so i was talking to local mopar parts dealer ,they had cans of sealer/adhesive they use on head gaskets, so i use it and a steel stock gasket i had here,then i put engine back together and add another 5lbs to arp bolts (90lbs),so the engine is fire up again, i kept timing at 15degs and kept 750cfm carb and change champion bbl rv9y to accel 262, now the jetting i stopped looking at plug color and the air fuel gauge and started jetting untill the engine was over rich, will i went from #74 prime+power valve& #82 secondaries to #86+power valve prime&#96sec jetting. i don`t know what it will be like at the track but the idle is stronger the exhaust gas from headers is cooler and header are not heating up as fast sitting idling in the garage. i hope that my idea of rich by reading the plugs at the track is way off because if some one told me to jet a 750 this much i think there crazy.the engine starts and idle perfect, i just hope i can make this extra weekend that the track is planning

It makes perfect sense to have to jet that high, with the bigger carb you have less signal getting to the boosters. This would dictate the need for bigger jets to get the same fuel ( kinda like you have to do with a tunnel ram setup).

The EGG shape you see on the gaskets, this is good indication that it is detination that is causing the blowning of the gasket.



The plug readings, you need to see the base of prorcilin (ah, thats not spelled right) and the eye peice really helps what you can see when looking for detination markings.


I think you need to shot for something like 11.5 :1 on fuel to start with. 12.5 is kinda starting to get to the zone of pushing things and the very piont that you will be able to run will depend on many things. As fuel is leaned out power should be made, then you cross the line & boom. Finding that line takes very small steps & time. And it is even harder with a carb instead of EFI.


I am also wandering if the carb tends to go a little leaner when you aproach higher RPM at the end of track, in this case you would have to be over rich to keep from going to lean at that piont. A problem like this would require a lot of work & time into the carb with the metering plate & other tuning to achive a A/F ratio that was consistant at every piont down the track.

As far as what A/F will be safe, many things come into play. What is safe on one engine may not be safe for yours in other words. I am afraid the /6 does not have the best combustion chamber and may need extra fuel to help it. Anothere thing I am guessing about , is that you dont know what tempature the air is after it is compressed. The hotter the air the more there is a chance of detination. And as you get farther down the track the air may be gaining in tempature.



I think your metal head gasket will hold up to more punishment. I stess you need to be carfull & take small steps, that head gasket blowing is saving your can & you are not mealting pistons because of it. If the head gasket can not blow when things get out of wack then that is what will happen. You are being pushed because of time & the ending of the year, dont let this push you into making a mistake that could be avoided if you had the time to figure this tuning out & see what the engine really needs & wants. Very easy to do, and sometimes its best to just let go & come back to fight another day as they say.


Like I said, the EGG shaped gaskets is telling you that there was detination, why & what is needed to correct it is the question. Jetting the carb up to be rich is probably a good step & having some leadway on the problem.


I dont know if you have a good camera, but I would be interested in seeing a picture of the burn pattarn on the top of the pistons & spark plugs if time & equipment allow.


Jess

thanks again jess, i never took any pitures never thought of it,i know i am rushing thing here but with only 8 race weekends and 3 of them got rained out this year so with this unplanned weekend i have to try, the car a noticable change to idle temp and tone just idling in the garage, i am tempted just going all the way and jetting it with #99 because it still start on idles great even with this much jet,i wish i had a piece of road close to home just to try a full blast but that impossible here,i do see improvement with some of the thing you suggested so thanks again

Terrylittlejohn, you are welcome & no thanks are needed.


I did a little checking, and a statment I made about O2 voltages used by the Buick guys was way wrong, so I edited the post and removed that.


Is this a Norrow Band O2 sensor you are using? If so the statment you made about .900mv = 12/1 A/F ratio could be way off. Believe it or not it is possible for .900mv to be 14/1 A/F. A lot depends on the tempature of the sensor if it is a Narrow Band instead of a WBO2 sensor.

Anyway, if it is a Narrow band sensor then trusting it is kinda hard to do. But here is a chart that shows what mv equals what A/F at differnet tempatures. I guess if the true temp of the sensor can be measured it may give a better idea of what it is reading. Looking at the chart tells me unless the temp is atleast 900* it will be hard to get any good readings from one.


http://www.innovatemotorsports.com/reso ... es/n32.jpg


You may have a WBO2 (wide band O2) & then this does not matter, but I thought I would meantion it just incase.


Jess

i am not sure , i will have to find out ,it`s a single wire bosch o2 sensor.

If it is a single wire, then it is just a narrow band O2 sensor. IN other words, cant be trusted without extremem care & knowing how it matches up to a WBO2. The only way to really do that is to put a WBO2 with it & run test to see what it reads compaired to the WBO2. Or maybe documenting what tempature it runs at in the exhaust and the chart I listed to will give a close guide.


Your not by chance going to be at Bristol Tenn this week end are you?



Jess

one off my dreams is to tow my car to one off the closes slantsix events but that won`t possible untill my youngest daughter finishs university,but i would love to see bristol.

just wanted to let everyone who followed this tread that the steel head gasket sprayed with mopar sealant/ adhesive, held up at this the last weekend of racing, only played with jetting left timing at 15degs and left the 750 holley on ,with plugs still showing rich and jetting down 6size front and rear she ran a best of 11.85et/111.56mph, needless to say i have a big grin ear to ear, now i have to plan the winter build, thanks to all for your ideas.

Good One Terry! Sounds like Team Newf is flying!

( I really admire your open mind and perseverance)

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Good work Terry!

You may want to invest in some solid copper head gaskets.
DD

Congrats Terry!!!!!!!!!!!!!!!!!!!!!!!

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Official Cookie and Mater Tormentor.

were can i get copper gaskets and is it best to o-ring the block or the head or can you just run copper like i did the steel with sealant spray. i have heard some here say the cox brothers make them but how do i contact them?

Cox Bros Inc.
1487 Weldon Ave.
Columbus, Oh. 43224
614-268-9920
CoxBros66@msn.com
It is best to call them, I have not had much luck with e-mails.

I have one of thier gaskets on my turbo motor, with "O"-rings and coated with Hylomar sealer. Their catalog states "O"-rings are required. They are available in a couple of different thickness

Corrected error in phone number on 10-16-07

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225