Thread: blown slantsix

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just an update, it`s been a hard two years trying to sort out this comb(0.080 over bore /318 valves ported head/.556lift/ 256@0.050 degs cam and 750cfm mech holley/4-71 blower/slantsix) i started a thread awhile ago about using 2 650cfms on this comb,it seem that it wasn`t the problem behind my head gasket failures, after talking the problem through this site and the slantsix site i couldn`t get a handle on why i kept blowing the head gasket on #1&#6.it seemed to be lean on top end because it only happen in third gear on top end of the track. i pulled the 2/650 and replaced them with 2/600 cfms that were boost referenced,thinking that if my problem was caused by being over carbed the vac seconderies would only give me what i needed and not lean the motor out due to lack of flow, no luck, so then i tried just a single 750cfm that i ran on this comb with a smaller 4-53 blower,ever though the smaller blower developed 5lbs of boost just like the 4-71 that i am trying now it never hurt head gaskets,well it still blew the gasket but only on #1cyl, so out of disperation i had an old steel shim head gasket that i spraied with gasket adhersive/sealer and put 90ftlbs on the head stud(+5lbs just for insurance)and at the last weekend of racing the engine stayed together,starting with a super rich mix i ran a 12.49et/106mph by the end of tha day the car reached a 11.85et/111.65mph, finially got into the 11`set so now i have to wait untill next season to try the 2/650`s or the 2/600`s because the car did 60ft & 1/8mile better with the 2 carbs than with one.i just want to thank everyone who gave me some imput as where to look to get me into the 11`set with my car,thank again terry.

congrats on the inproving e.t. i admire a person that will dedicate to a dare to be different build. i would never have the patience to mess with something that long. and ya i think we all want to see a picture of this great acheivment, great work!

thats cool would of like to see it run

thanks pat, it was sure fun to be able to tune and feel the car getting faster, i never had any video, if i find some i will try to post a link.

Terry,
I know some of this might be an "apples to oranges" comparision but here's something we found that might help you out next season. I've always set the "total timing" advance at 32-34 BTDC and on our VW motor it likes it to come in early (all in by 2000 RPM, a drag motor). This last year we started playing with NOS as our power adder. At that time we installed an MSD retard box on to our exsisting 6AL system. We use a 3 to 4 degree retard chip when the NOS is engaged. And we have backed down the total timing to 30 degrees max.

What we found is the reduction in timing advance produced very little loss in low end power (our 60 ft times did not change since we leave at 6700), but a big jump in top end MPH even on runs without using the N.O.S.

How much total timing are you running, at how much boost? Do you have a way to retard the timing as the boost increases? I'm not "blower savy" guy but I do know that you can't run much static compression compared to a normally asperated motor.

Just wondering if this might be connected to you blown head gasket problem?

yes i did play with timing, i have no vac just mech advance, with the fel-pro composite gasket, as i tried more fuel i kept taking timing out but the gasket still failed, then with the steel gasket i locked the dist at 15degs no mech adv but i never had any time to do some fine tuning with timing,so the plan is to run the steel gasket or go to copper, the only trouble with copper the local machine shops can`t 0-ring the block,some racer say you can run a copper gasket with just sealer/adhersive and no o-rings if boost is low, under 10lbs, i am only getting 5-7lbs,as for ignition i have chy gold box with accel race coil and msd rev limiter, hopefully i can try and the timing will have the same result for me.

why cant you oring the block? if you did this and cut the receiver grove in the head you will blow the rods out the bottom before you move the head gasket did you call cometic

pat i called auto machine shops in this area and none of them have the tools to o-ring blocks and to buy the tool from isky is $500can. i need the smaller tool for 3.48in bore, the local industial machine shop said they can do it on a milling machine and it $70hrs (6hrs just for the block) i never asked about the head i didn`t know about needing a reciever groove.so i need to do some more testing with what worked this summer, if it doesn`t hold up long and starts blowing gaskets again i will have to try to get it o-ringed some way.

Originally Posted by terrylittlejohn

pat i called auto machine shops in this area and none of them have the tools to o-ring blocks and to buy the tool from isky is $500can. i need the smaller tool for 3.48in bore, the local industial machine shop said they can do it on a milling machine and it $70hrs (6hrs just for the block) i never asked about the head i didn`t know about needing a reciever groove.so i need to do some more testing with what worked this summer, if it doesn`t hold up long and starts blowing gaskets again i will have to try to get it o-ringed some way.

well i can o ring the block have the cutting setup for my rottler machine i think somone must do it not to far from you i would talk to nitro warrior . i think for your use i would do the head to lock in the head gasket if the deck and head bolt has a weak pattern .i do not know what size your head bolts are your running studs ?

yes pat i have 7/16in ARP studs,even spaced 4 bolts around each cylinder, which isn`t a good pattern for sealing under boost. have you ever heard of any body running a copper gasket with sealer and no o-rings? i was talking to SCE GASKETS they make a titan (brand name) copper gasket that can be used with no o-rings but there sce copper gasket must use o-rings and that is the only one they make for a slantsix. i can get the block o-ringed locally but the cost is as much as buying the tool to do it my self. i don`t know much about the process involved in o-ringing the block or the head and if you have to do both,also the wire size and the groove size, can you help with that so i can get a better price when i tell the machinist exactly what i need.thanks

you cut a grove around the deck abit smaller wire to hold it like 039 wire then when thats done you can blue the head deck side lay it on with the o ring installed this will make a print out were to cut the groove in the head needs to be abit bigger then the goove cut for the o ring in the deck there is other ways to do the head but this should work the best this for how hi the wire needs to be that has some to do with the how thick of a head gasket you use 500 just to cut the orings for the deck? to bad you do not live in mich you could drop if off and i could do it for you

yes that would be nice, maybe i could get in some more racing to,most of the big budget racer here send there engines to armstrong`s in NOVA SCOTIA, they do alot of engines for the maritimes and newengland states both drag and circle track.the local auto machine shops are just nonracing rebuilds.

well goodson tools and supplies sells the o ring cutter for many boring bars the rottler is a better bar to cut o rings with i think so if someone up there has one then you can buy the tool have them use it when done keep it or resell it on e bay or ship the block empty to me or a other shop and have it oring

pat do you know there price for the tool? rottler is the name of the boring machine that it well fit and is it possible to do the head with the same attachment?

Originally Posted by terrylittlejohn

pat do you know there price for the tool? rottler is the name of the boring machine that it well fit and is it possible to do the head with the same attachment?

look online rottler is the name of the boring bar but there is other makers you need to find what your machine shop has for a boring bar they all hold the tool differently as here is were to look www.goodson.com