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alexg89

KA with sidedrafts

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The jut nuts have a very small head diameter, with a built in flange/washer. They use a 3/8 wrench (which is odd, since they are metric), whereas the original 8mm nuts use a 12mm wrench. That should give you an idea of how small they are.

 

I like using studs on a manifold. Two reasons, much easier to line everything up, and more importantly, you can get more torque on a stud without worry of pulling a thread of the aluminum head.

 

You can get the jet nuts here - https://www.pegasusautoracing.com/productselection.asp?Product=MJET&utm_source=google&utm_medium=cpc&utm_campaign=MJET&gclid=EAIaIQobChMIgI3R9tun4QIV7x-tBh1YSAwOEAQYASABEgLYS_D_BwE

 

You could also use metric 12 point nuts from ARP. They also have a small diameter. The coating on them is probably better too - https://www.summitracing.com/search/brand/arp/product-line/arp-12-point-nuts/thread-size/8mm-x-1-25?autoview=sku

Edited by Stoffregen Motorsports
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36 minutes ago, Stoffregen Motorsports said:

I like using studs on a manifold. Two reasons, much easier to line everything up, and more importantly, you can get more torque on a stud without worry of pulling a thread of the aluminum head.

 

 

good to know


Wish i knew the size id go ahead and order them up now lol i know i have to get new studs too .. shank on the old studs sticks out past the intake 

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4 minutes ago, Stoffregen Motorsports said:

I know the studs are 8 x 1.25 thread, but I don't know the length.

That works for me, at least i know what size nuts to order and i can get the studs locally 

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I buy stainless all thread from McMaster-Carr and cut studs to what ever length I want.

One stick will last the normal guy years.

Cut it with a hacksaw, spin it in a drill while holding it up against a belt sander, and you will have pretty ends.

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I've done this with grade 10.8 threaded rod for head studs to beat paying $150+ for the same thing from ARP. So far the total is about $35 including the nuts .

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Well, not quite...

ARP have a tensile strength of 195,000 psi.

Metric 10.9 fasteners are only 150,000 psi.

 

Metric 12.9 fasteners are 176,000 psi, and why the Japanese replace L-series main cap bolts with 12.9 shcs.

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The large smooth shank of a double ended stud helps make sure the studs seat properly into the head. A stud made out of allthread may not hold when taking things apart later.

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On 3/29/2019 at 5:49 PM, G-Duax said:

Well, not quite...

ARP have a tensile strength of 195,000 psi.

Metric 10.9 fasteners are only 150,000 psi.

 

Metric 12.9 fasteners are 176,000 psi, and why the Japanese replace L-series main cap bolts with 12.9 shcs.

 

I wonder what the head bolts are by Nissan.

I guess the take away is the higher the numbers the better. Well for 10.8 grade,10 bolts times M10X150 is about 1.21 sq in (give or take) so there's 182, 800 pounds available. That's the weight of 66 1/2  710 wagons piled 299 feet high pushing and holding the head on.

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Even with a tiny 75mm bore, and typical full throttle combustion chamber pressure of 1000 psi, you are looking at 70,000 lbs. of force per cylinder being retained by M10 bolts, that at their weakest point, are not 10mm dia.. but 8.5mm (root diameter of the thread).

Can't count all 10 bolts since the front 2 bolts don't hardly contribute anything to seal the next 3 cylinders.

So, with 150,000 psi steel, that gives you almost 53,000 lbs. holding force on a cylinder that can generate 70,000 psi of force.

 

The only thing that is keeping head gaskets sealed is maybe a little safety factor in where bolt manufactures come up with their tensile strength numbers, and what little surrounding bolts contribute to sealing a cylinder 4" away from them.

Add any pre-ignition pressure spikes, and you will have slight, momentary leakage.

 

I've seen high speed photography of high output engines at full throttle, spewing combustion gas past the head gaskets, that after tear down showed little sign of the gasket failing, but under race conditions, will.

 

What keeps head gaskets in normal, every day vehicles, is that under normal conditions, they are very seldom ever at full throttle. 

 

Guys playing with Japanese turbo engines are playing Russian roulette with head gaskets, some are going from 12mm bolts to 14mm studs, and swapping out head gaskets after a day at the track.

I laugh when I see people throw a cheap turbo kit on a stock engine, because I know what's coming, seen it so many times over the years.

 

Now, a stock L-series engine, with smallish carb, restrictive intake manifold, pissy little 8.5:1 compression ratio, and restrictive exhaust probably won't make 1000 psi in the cylinder, but when built for competition, with higher compression, good induction, and free flowing exhaust, it will.

 

Seems like I found somewhere the tensile strength of the stock bolts. Went searching for those numbers after seeing the builders in Japan using commercial 12.9 bolts for mains & head applications, and realized why they were doing it.

Did not find what the turbo-Z head bolt numbers are, but they are known to be stronger.

It's a shame that so much info on these older engines is lost to time, and who knows what tricks were developed on cars like the turbo Z that Paul Newman drove. I bet there were lots of secrets that never left that shop.

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 An 89mm bore is only 9.6 sq in of area. 1,000 X 9.6 = 9,600 PSI per cylinder. No where near 70,000.

 

All the bolts will be contributing something to holding the head on. Take all the head bolts out except one in the back and try lifting the head off. Yeah, it won't move.

 

This isn't a 'race' engine.

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Hm, I wonder where that extra decimal point come from ?

Good catch.

 

You couldn't pull the head off, but I wouldn't give a dime for the head gasket holding....

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well to settle this lol i went and bout new studs at the hardware store .. i but 4 in and 2 bolts for the bottom side.. so we are all fine and dandy on that

 

as for the carbs, im waiting for my soft mounts to get here to eat up the space between them and the intake because the back of the bowl is coming in contact with the intake and it does not allow the mounting holes to line up 

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4 hours ago, G-Duax said:

Hm, I wonder where that extra decimal point come from ?

Good catch.

 

You couldn't pull the head off, but I wouldn't give a dime for the head gasket holding....

 

I'll tell you something. I've used more math here than any other time after school. I wish they had used compression ratios as an example of determining the volume of a cylinder using pi.

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So, i got my soft mounts/spacers for the carbs to sit on so they will clear the intake and i believe i will be good on clearance, hardware i bough is too short becuase i didnt think about the spacer and well i need more hardware. Yay

 

ive been doing some reading because now i will no longer have power steering being the water outlet is right were the power steering pump goes

Does anyone have any experience with electric power steering pumps.. been looking at these Volvo ones (4N51 3K514 DL) that are remote and ill probably scoop one from a junk yard here this weekend 

 

Just wondering if anyone has gone this route.. Im aware i need a larger alternator for the amp draw but a nissan quest alternator will remedy that problem 

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The Toyota MR-S  pump is a good choice4, as it's a stand-alone unit that all it needs is a speed sensor input to do digressive power.

That is, and slow speed it is at full power, but as the vehicle speeds up, it progressively drops power.

Don't use the MR2 pump, as it needs additional black boxes to be used.

 

MR-S_PS_pump-1.jpg

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23 minutes ago, G-Duax said:

The Toyota MR-S  pump is a good choice4, as it's a stand-alone unit that all it needs is a speed sensor input to do digressive power.

That is, and slow speed it is at full power, but as the vehicle speeds up, it progressively drops power.

Don't use the MR2 pump, as it needs additional black boxes to be used.

 

 

what if i dont have a speed sensor ? can i not just run it at 1 speed all the time?

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1 hour ago, G-Duax said:

The Toyota MR-S  pump is a good choice4, as it's a stand-alone unit that all it needs is a speed sensor input to do digressive power.

That is, and slow speed it is at full power, but as the vehicle speeds up, it progressively drops power.

Don't use the MR2 pump, as it needs additional black boxes to be used.

 

MR-S_PS_pump-1.jpg

Umm.... did you mean to say dont use the volvo pump?

 

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49 minutes ago, alexg89 said:

what if i dont have a speed sensor ? can i not just run it at 1 speed all the time?

Sounds like without the speed sensor you might get really quick steering at high speeds.... maybe more than you want.... 

Makes you wonder about the ones driven off the pulleys, If there output psi changes somehow.... 

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Well everything I was doing dosnt really matter now.. was bolting up the carbs and as soon as the bolt got snug the ear snapped off... guy I got the carbs from epoxyed it together and I never saw it ... pretty upset about it and have to find another carb

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It's a common mistake, so don't feel bad. Luckily, the carb can be welded. I worked on a customer's car last year that wasn't running right, and when I dug into it, I found this -

 

Trevor_510_Small_003_zps47z5lkpu.jpg

 

Trevor_510_Small_005_zpsduz8c8dt.jpg

 

After welding and some smoothing, it looked like this -

 

Trevor_510_Small_006_zpsecwqnz2c.jpg

 

Trevor_510_Small_008_zps3bs1tchn.jpg

 

Now, going forward, you know that with soft mounts, you only tighten up the nuts as much as is needed to squish the o-ring.

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33 minutes ago, Stoffregen Motorsports said:

It's a common mistake, so don't feel bad. Luckily, the carb can be welded. I worked on a customer's car last year that wasn't running right, and when I dug into it, I found this -

After welding and some smoothing, it looked like this -

 

Now, going forward, you know that with soft mounts, you only tighten up the nuts as much as is needed to squish the o-ring.

 

Unfotunetly i didnt even get it to that point of squishing the 0ring.. but being that the crack is through the Throttle stop screw and idle mixture screw its not goin to hurt it??

 

I feel like i t could be fixed but i feel as if these adjustments will be affected.. The few people i have talked to say it cant be welded either which really bums me out

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and i guess another question i have is if i find another one does it have to be made in the same place? ones i have are made in spain and i see some made in bologna and the tipo numbers are different.. 

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If it's broken through the mixture screw threads, then it would be more trouble to fix it than it's worth.

 

As long as the replacement is the same type, it should work fine. Doesn't matter where they are made. Webers aren't especially hard to find.

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