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BlownCoronas 1971 Toyota Corona

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  • 5 months later...
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Continuing through my checklist to get it cert ready, scored a half day on Friday so spend the afternoon at work fixing everything (or so i thought)

first problem was that the handbrake cable went straight through the driveshaft hoop. so i made the spreader bar that the cable loops around and goes off to the two wheels slightly wider. and reshaped the driveshaft hoop a little. this also stopped the exhaust hitting the hoop. bonus. 

i also replaced a bunch of exhaust gaskets and its sealed up good now. but compared to the crown it sounds like shit, so that will require attention futher down the line, i might even put a massive muffler on and shut it up, letting the supercharger noise be the main sound. 


with all that done i was please and in the frame of mind that that car should be able to be booked in for cert, im not sure on the brakes. the datsun 1200 master cylinder has made the pedal feel not solid like a race car now. its a bit spongy which i expected. but it still doesnt stop very well. now im not sure if it really doesn't stop very well. or it doesn't stop very well compared to the recently sold Audi S4 i was dailying, which i fitted 325mm brakes to, and would probably throw you through the windshield. so i think ill send it for cert and if the cert man isnt happy ill figure out something then


anyway i gave the wheels a rotate, and noticed the front brakes were dragging, im 99% sure the new master cylinder, although sold to me as a disk/drum unit probably has the drum brake one way valve things in both front and rear, so ill have to remove that and re bleed the brakes.


no pictures cause i got into too much of a roll... 





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The suspected residual valve that shouldn't be there. 

This valve helps hold positive pressure on drum brake slave cylinders. But is not required for disk brakes and causes slight pressure to stay on. 

Have removed and even though they need bleeding, can tell its fixed the issue


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  • 2 weeks later...

Well i spoke too soon. im currently trying to bleed up the brakes, which in itself is going horribly. 

but the problem with the wheels binding up with pressure from the brake system not releasing when you let off the pedal is still there. 


Does anyone have any ideas why this would be happening? its a brand new master cyl, and when i crack the brake lines the wheels immediately go back to rolling very freely, takes a pump or two and they are back to dragging, but not locked on like the brakes were pressed. 


im really sick of working on this car, all i want to do is drive it and these endless boring jobs with non stop problems is really hammering my motivation. couple with only getting about an hour a week to do anything on it. 

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im pretty sure it does. its all custom made so could be fucked up. but when wound right in to give as much clearance you have to press the pedal nearly to the floor before you feel anything engage in the cylinder. 

theres a possibility that its still not enough clearance though. im just not sure how to tell for sure without pulling the rod out, shortening it, and possibly finding out that its now too short and im back at square one. 

its several hours work to get the master in and out. 


edit - also discussion should go in this thread but you probably knew that already


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MUCH more success today! 

shortened up the brake pushrod and made some changes to how its retained. to further shorten up its length inside the master cylinder. bled all four wheels and it just seemed to go right today. 

pedal felt great. just how id hoped it would with the particular valving id choosen. the car doesn't have a booster due to space issues. but i didn't want a rock hard pedal like a race car. 

the valving i chose gave more mechanical advantage over the slave cylinders at the "cost" of longer and a bit spongier pedal throw. which is also exactly what i wanted. the car brakes just as good if not better than the original boosted brakes with incredible control over the brake pressure. you can lock the rear brakes up with moderate pressure, which isnt actually a good thing, however the fuel tank is dead empty and i limped back to the garage ending up on 19psi of fuel pressure, so itll probably stop doing that with a bit of weight, otherwise a simple 2 port bias valve will sort it right out! it feels like the fronts would lock up if you really stood on it harder than you probably ever would which is about right. 

very very happy as this has been one extremely long headache and im over the moon to have it finally working how i wanted it. 


Image result for heavy braking

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  • 2 weeks later...
  • 3 weeks later...

2 days untill cert. 

Took it into work today to give it a good cleaning and degrease the engine. 

Blown head gasket, its pumping its coolant out the overflow tank. 

Rang Ian and cancelled the cert, he was really good about it, even at such late notice, I think he knew it was a genuine blindside and not me being slack. 


So gutted, so very gutted. This will now mean plans I had for the future to rebuild the engine and add intercooler ect will now need to be brought forward. Which takes time I don't have. 

Hopeing to atleast use the anger to pull the motor out this weekend. 

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still angry

got stuck in

engine is ready to pull once i get my crane back


fuck this car. 

atleast the new engine will actually make power/not surprised this has happend this engine came out of a paddock 

what initially started as a suspicion the gasket had failed, due to some weird pressurization going on in the radiator, was then confirmed today when it started hemorrhaging out the overflow tank, and on closer inspection there now looks to be water in the oil, so i expect a full blown gasket failure it what i will find. 


aleast i know this car like the back of my hand and can get the engine out super quick, but thats the cheap part.....

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  • 1 month later...

finally got around to cleaning some things for a measure up and a parts order. 

the engine is all stock sizing wise. however when i cleaned the oil from the bores i discovered they really wernt that flash. 

cyl 1 & 2 are pretty okay, some staining which would come out with a hone.

but cyl 3 & 4 have some fairly deep corrosion when the pistons/rings sat, from when this engine was sitting in a field for years. 


Cyl 1

Seems i didnt photograph Cyl 2, looks much like 1


Cyl 3 (the worst)


Cyl 4


quite gutted, always seems like nothing ever goes smoothly on this car, theres always something. perhaps this post should be in the depression thread cause not very much has gone well in the past wee while.


i haven't got the gear at home to measure how deep the corrosion is. but can borrow it from work. its looking like my options now are to try and find a new second hand good block, or if its not too deep, bore it 1mm over and use the 89.5mm forged pistons that are available. this will add over $1500 to the bill and probably 6 months of saving up if not more.

im surprised to find this since it ran awesome, and the compression was great, even when i suspected an issue and checked it very recently. 

please give educated opinions here. including options for perhaps yet another engine swap, although that will most likely cost more and i can personally think of any an engine id rather see in the car.

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  • 3 months later...
  • 2 weeks later...

Struggling to find a way to keep the compression low, this block has been decked a fair amount. 

Building a nice N/A motor is an option but I'd really like to keep the supercharger. 

Any ideas? A really thick mls gasket is close to 500 bucks before shipping... 

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  • 1 year later...

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