Grinding a 2TG block to fit 3T crank

[jb_22]

Hi all,
I'm in the process of building up a 3TG hybrid motor - 88222 2TG with a 3T crank & pistons. Since I didn't have room I never kept the 3T block, so I have to grind some of the 2TG block to suit the longer throw of the 3T crank. This is where the conrod bolt & nut interfere with the 2T block:




My question is how much clearance is needed to make sure Mr. Steven Conrod never meets Mr. Ken Block? My trial fitment at the moment turns over freely. The amount of clearance is this much: with a thick film of 20W-50 on the area, the top of the conrod bolt just pulls on this film as the crank is rotated to near TDC. Don't know how much this is but it gives you a good idea of the fit. I know with the heat and immense forces of running the motor things stretch a little, so I'm a little dubious about the clearance, but at the same time I'd rather not have to disassemble everything, block up all galleries & holes, grind more & thoroughly wash the block to remove filings etc.. blah blah if I don't have to.

Pics of trial fitment:






In this one above you might be able to just see the film of oil grabbing the conrod bolt.





Happy New Year everybody! My resolution is to get this friggin' thing back on the road

Cheers, JB

[Celica RA45]

just grind enough away and leave enough room say 2mm around near rod bolt and back of bore where it gets close

[andrew_mx83]

Mr. Ken Block

i see what you did there.


i think 2-3mm is a good rule of thumb, with thermal expansion alone that would touch, without taking into account stretching/bending of the crank etc. there looks to be enough meat where you are working to play it safe rather than sorry, id say keep grinding (unless there is some particular reason to not take much out)

have you checked clearance to oil pump, pickup, aux shafts etc? im not a T motor man by any stretch but i have come across these issues when playing with different stroke M motors.

[vanman]

Hi jb

I see from shirley's thread that this motor is back together, did you take any photos of how much grinding was done, or how much clearance you decided on?

Cheers
Vanman

[jb_22]

Hey Darren, here is what it looked like finally:



Hard to say how much clearance is there. Visually it looks like ~2mm. In my logic that should be enough clearance as ~2mm of stretch would mean the pistons would be hitting the combustion chamber anyway. If the motor blows up then I guess there isn't enough clearance

[MorGo]

Remember to block those unused cam bearings (unless you want low oilpressure..)
(I don't see the original "stuffers" in place (if that really is original 2T-G block)

[jb_22]

It is an original 2TG block as it did have the plastic coated "stuffers" as you call them. They sorta resemble a front main seal without the seal bit on the inside. The engine reco mob put new bearings in for the aux shaft but could only source 2Tc ones & yes the unused ones are rotated to block the oil galleries.

Oh & Vanman after looking at the picture closely I think that is the grinding before my first trial fitment of the crank & pistons. It did turn over freely with that much taken off, but I wasn't happy with the clearance so I grinded more. That pic gives you an idea of the minimal grinding needed, but I don't have a pic of the final pre-assembly.

[vanman]

No worries, jess... Pics looked way too close for my liking anyway, will probably grind further myself. I have a stock 2T, 3T and 13T at my disposal, so will measure standard clearance as a guide. Hope yours works well though

Cheers
Vanman

[jb_22]

Why don't you just use the 3T or 13T block? The only advantage I can see with using the 2T block is you keep the standard engine no. but the 3T in a sillycar doesn't need engineering anyways

[J-M kujala]

i have keep minimum 1mm tolerance, it have been enough at my engines... sometimes that block is very thin at nearby cylinders, like 4mm grinding and you got hole to the coolant side.

never got problems...

[vanman]

Jess, using the original 2t block is less for rego/engineering, more for insurance and racq membership, had dramas with both when I had a 5k in my ke10. Want the 22 to 'look' as standard as possible when I get it together... Plus the 13t came from toyboyracer/gordon, so not really counting on that, just got it for internals before I found the 3t cheap for the same reason... Looking at a rebuild either way...

[jb_22]

The grinding isn't that hard with a die grinder & compressor with a rounded bur using silicon spray as lube. The larger diameter bur the better as I found out after buying a small one. Took me a good day of masking, grinding, cleaning, assembling, disassmbling, masking... you get the idea, lol..

I never had a problem with my 3T in the TA22 even registering it. All that was needed was for the ditsy clerk to take a flashlight to the carpark and cite the eng no. - no engineering... Now my celica is technically a "standard" 2T

What are you doing for the rebuild? I went the whole hog and got the crank grinded for OS bearings & block rebored. If new bearings, rings and a hone is all it needs a rebuild should be pretty cost effective

[vanman]

The 2t in the car at the moment belches black smoke all the time, so will need some work at some stage, maybe a quick rebuild will do for that one to get the car back on the road while I rebuild a better motor. Car has to remain auto for the missus as well, so standard 2T power won't cut it in the end. If dollars and parts converge on me at the right time I want to end up with a 2T bored and stroked to the maximum with some old school compression, cams and carbs, to get the best power I can without changing the standard engine. A 2TG head on it would be the icing on the cake, but not necessary. Looking at alternative 4 speed autos as well so I don't lose as much through the gearbox. All plans and pipe dreams for now though. Most of this is going to depend on whether I go full resto before putting it on the road, or patching it up and driving it as soon as I can. Getting more itchy to drive the thing all the time...

where did you get your machining done by the way?

[jb_22]

Your story sounds exactly the same thing as mine. The car needs bodywork & painting, but I just wanna put the engine in & drive it first Everything in stages I reckon, just depends how long you're willing to keep the thing off the road.. What carbs are you going to run? The good thing about 2TG heads is the valve lift is 10.3mm, I think 3T are ~8mm lift. A stock 2TG head would perform similar to a 2T with the same sidedrafts & mild cam I guess.

I got the machining done at a place in Cairns recommended to me from a friend with experience building motors. They were quick & pretty decently priced considering the location.. I guess you're looking somewhere around brissy?

[vanman]

My TA22's off the road at present, so would have to make it pass bare minimum RWC before I can drive it anyway. Machining of engine bits would definitely have to be in/around Brisbane as opposed to Cairns :-) will most likely be slapping the 13T in for rego and hoping it's good as it was made out to be. I would have thought valve lift would have been due to the cams in the motor - does the 2TG have larger liftcams that the 3T can't be ground to? Not sure of carbs yet, current plan is maybe a Weber hiding under the standard air filter.

still unsure of the body work issue though - whether I can stand driving it as a bodge-up job or not. kinda want to do this one properly...