Grey motor blocks

[colt]

Had an interesting one over the weekend.

A mate who races an FJ cracked his block horizontally below the welsh plug line behind the starter motor. Bear in mind that this motor is highly modified & regularly sees 7000 rpm. It still runs ok, the water jacket is filled with "concrete" up to the welsh plugs, so his water loss was minimal at first, but got worse with each race as the crack lengthened. Because he hasn't yet finished his 2nd motor he is going to try to stop the crack and fill it. We'll see how it goes.


I was curious if anyone had heard of this happening.

Colin.

[RET]

It sure as hell doesn't sound... sustainable 

But I'll be fascinated to hear what happens next.

cheers
RET

[kelnic]

if the crack is only on the external wall of the block and the crack is not entering the whelsh plug holes  this can be easily fixed.if you remove the starter motor you may be able to do this in the car.when i was in the engine reconditioning field we could repaire most cracks by drilling a hole at the start of the crack then tap a taper thread and using irontight sealer screw in a "A plug" untill the plug snaps off in the block.then you fit another "A plug" so it overlaps the first  "A plug" .when you have done the entire lenght of the crack then you get rounded punch and pean around the plugs to help seal and leaks then pressurise the cooling system to check for leaks.any engine reconditioning shop should be able to do this and be a premanate fix
cheers scott

[CraigA]

I've seen and heard of this on red motors but never a grey. Must be shoving some decent compression through that thing to go along with the 7000rpm. Big effort for a grey.

Grout filling is one of the methods used to try to protect against this happening but with reds some have drilled the blocks so that the main bolts go right through to the head area.

Couldn't he just replace the grey with a mildly worked red? Same power output and much more reliable. 

Woops, that comment will cost me.

[weddo]

CraigA !!!!!!!!!

Colt will tell you...... a grey is a grey is a grey is a grey....... not  a bloody red!
and besides its an FJ and must have a grey to race

regards
Weddo

[CraigA]

LOL.

I love greys too. Promise.

[colt]

Craig, Weddo is right, you can't race a red in Historics in an FJ. He pulled the motor out last night. As was said above, he is going to drill at each end of the crack, not sure of the plugs, I'll see it tomorrow.

FWIW, it's a 31/4 bore, lots of compression, home made roller rockers, 2 webers with one barrel blocked off on home made manifold.

Goes like stink.

[EffCee]

Colin,

When I used to play around with greys many years ago, I cracked a block that had been overebored because the block flexed. We had it on the dyno and it cracked through the welshplug to the block like your mates has done, We were actually able to measure the flex in the block on the dyno, least of all the more strain that we put the engine under the more the water ran out of it.

I didn't try to repair it, as I was on a limited budget it was time for a new block and redevelope it, this way I was able to save all the bits without catastrophic failure.


As RET said keep us posted.

Keith

[Rod]

This happened to me about 5 or 6 years ago. It was a standard block. However the crack was behind the generator and it was a vertical crack. Coolant seeped slightly. Did another block up and that solved that problem.

[colt]

Well, Murphy has struck. He has the motor out & on it's stand. As Kelnic suggested, that is exactly what he was doing when we turned up. The crack is just above the line where the block flares out towards the sump. About 8 inches long. The short story: he has drilled into the bottom of no. 6 cylinder. Not once, but twice! Being below the concrete (it mustn't have been installed? correctly, there was an air gap) technically the holes aren't subjected to full coolant pressure, which is 7lb anyway, he is going to try to seal the holes.

 Replace the block you say? So did I. This block unfortunately, (I am not too technically minded, so please no questions that I cannot answer) the crank tunnel has been moved up into the block, for a start. This I do know, there is plenty about this thing that I don't know. The time & effort involved IS worth it.

He is trying to have it ready for the Oran Park day/night meeting this weekend. We'll see how he goes.

Colin.

[Glenn 'Stinky' Stankevicius]

Goes like stink.

Can't be too fast then, I've put on a few kilos and not as nimble as what I used to be 

[colt]

HHMM. Maybe some some foot in mouth going on here. My apologies for that. I need to re-check.

Colin.

[colt]

Stinky, I said STINK!

[colt]

Regarding my comment about moving the crank up into the block, it has been moved up, but purely as a result of line boring and the movement was very minimal.

I misunderstood his comments.

I haven't heard yet about the success or otherwise of the crack repairs.

Colin.

[GOA350]

Hi Colt,
         Has this engine been dynoed? I would be most interested to know what performance mods he has done for it to go faster than your run of the mill grey motor. I know i went to alot of trouble with my grey motor to blueprint the engine before assembly so that i can get the most out of it without putting big dollar parts in that wont change the performance a great deal in relation to the price of the parts. I hope this makes sense. Are you building a period style race car yourself? I would like to bounce some ideas off you and get your response. I know i have put the cart before the horse a bit by building a Chev powered FE before building a grey powered FC. But you know how the saying goes, what new is old and whats old is new again. I do have a genuine interest in grey power these days (as the hair colour changes with my interests) and are very lucky to have a father, who yoused to muck around with them alot in the 60's, to tell me what they would do to them in the early days.
                                         Cheers Scott

[colt]

The engine went back in yesterday, he is running at Oran Park this weekend. No leaks as yet, but racing is different.

Scott, this engine has a lot of scratch built stuff in it. That is why he is trying to save the block, he can,t just swap everything into another block. He has to build another block to suit his internals. They don't run the cars on the dyno, with a 3 speed gearbox they go for torque, not power. I'll ask him if he is happy for me to post a spec list. There are basically no secrets, but I will have to clear it with him first.

Colin.

[Damo58]

Thers some stuff at work we use which is called liquid weld it is awsome stuff , There was an old guy come in  that was worried because his grey had a big crack in it the boss cleaned the area up with a die grinder poured the liquid weld in let it set for 24 hours and away the old guy went we havent seen him since and that was six months ago and he drives it every day it also works on cracked manifolds as well really good stuff you can get it through Bursons or Wurth 

                                                Cheers Damo58

[FC427]

And there is always Devcon  has the same expansion rate as cast they use it when making a 12 port head out of a 9 port head it is fantastic stuff can be drilled taped machined would seal that crack up .......FC427.......

[colt]

Yep, Devcon is the stuff he mentioned. Would I be right in saying that he put this over his repair? He said he repaired his drill throughs with some liquid metal stuff that sets hard. 

[FC427]

Sounds right .....it's awesome stuff they even make an Aluminium one ......FC427......