WillieB's 1275 Engine Rebuild

[BruceK]

I wonder if the belt helps cut down some noise?

[MiniDave]

I'll know later next week, when I fire it up in the engine stand, but I don't remember there being a lot of noise coming from the chain drives.....

[BruceK]

Yeah, not less you put a stethoscope to it. 

[cstudep]

So all in all is the belt drive timing setup any easier to get going than the standard setup? Do you suppose it is worth the extra cost? it sure does look nice.

I would imagine there is enough noise in the rest of the valvetrain that just a timing chain to belt change wouldn't be super noticeable but you never know.

[MiniDave]

This is the easiest adjustable timing setup I've worked with, setting the std timing is as simple as aligning the dots on the respective gears. Otherwise you're using offset keys which requires putting the chain on and off several times to get the timing set. Other adjustables I've used are similar to this one but this one is easy to move and has reference marks on it.

WillieB says his research shows the belts are only good for 20-30K - not that most people drive their classics that far in the time they own them....most are lucky to do 1000 a year so I doubt that's really an issue. Replacing the belt would require removing the radiator, and doing it in the car would not be fun.

As for price, I think WillieB got an exceptional deal on this kit.....most of the vernier adjustable timing chain kits cost way more than this and don't include the aluminum housing and such.

Next up I'll install the other three pistons and button up the bottom end then set it on the transmission for the rest of the build. I still have a few things to do to the trans to get ready for the engine.....new axle and shift shaft seals, as well as install the oil pickup tube.

[94touring]

I have one of those adjustable vernier double chains ones with lightened something or other. Don't remember how much it cost. 

[MiniDave]

About $150 IIRC....they range all over tho. spares has them for about $125.....no idea about how theirs works but it looks like you have to remove and install pins to lock it down. Others use a series of screws like this one does.

[94touring]

Inno has the stock double chain.  Even with a cam and 1410cc's it idles better and quieter than me!  It's like a sewing machine. 

[MiniDave]

The pistons are about 10 thou proud of the deck height, and I wasn't able to borrow my friends CC'ing kit, so I'm just going to buy one for myself. I want to calculate the compression ratio of this set up so I know where we're at. It won't be a problem if it's higher than the 10.3 I normally prefer, but it affects how far you can go with the timing among other things.

It also won't be a problem with the pistons hitting the head as the head gasket is much thicker than 10 thou.....

[94touring]

Dave's going to get final specs on piston/head volume, but we ran numbers for what it most likely has, including gasket volume and ring land, and he's at 11:1 compression as is.  Going to need to bump the volume up about 2.5cc's per cylinder to get it down to 10:3.   

[Willie_B]

Could the CR be dropped with a thicker head gasket?

https://www.cometic.com/applications/automotive/austin/mini-comper/1969

[94touring]

Yes you could.   They list compressed thickness too.  I'm out at dinner but will run some numbers when I get back to the hotel.

[MiniDave]

Could the CR be dropped with a thicker head gasket?

https://www.cometic.com/applications/automotive/austin/mini-comper/1969

wow, I had no idea there were so many of these sizes available! Are these stateside or England only?

Edit: Looks like there are plenty of places out west of here

Edit 2: it says they're made to order, 5-6 weeks out

[94touring]

You need this one.  It will take you down to 10:15:1. 

BMC 1275 A-Series .060" MLS Cylinder Head Gasket, 73mm Bore

Me either Dave!  Great for my turbo conversion!

[MPlayle]

The Cometic website's "Contact" page lists an Ohio address as the company address along with US phone numbers.

Their "Locate a Dealer" shows a shop in Lenexa, Kansas:
Star Performance
14320 W. 99th Street
Lenexa, Ks 66215
Phone: 913-647-4644

Edit: For near(ish) to Dan:
Engine And Performance Warehouse Inc.
4230-b Charter Avenue
Oklahoma City, Ok 73108

[MiniDave]

Yeah, but 5-6 weeks out.....

[MPlayle]

Can't hurt to call the shop in Lenexa on Monday to verify?  Who knows, you may get lucky and they have one in stock?

[94touring]

Maybe they can make a 0.55 one.  The .51 gives 10:4 compression.  That's an option too.  Personally I'd just do the 10:15 and feel good running premium fuel at a normal timing setting.

[MiniDave]

I will call, but while they may be a Cometic dealer they deal in American muscle cars, not funny little British imports.....I know them.

Those are the compressed values, I wonder what they are before compression? The std gasket I have now is 55 thou uncompressed.

[94touring]

I will call, but while they may be a Cometic dealer they deal in American muscle cars, not funny little British imports.....I know them.

Those are the compressed values, I wonder what they are before compression? The std gasket I have now is 55 thou uncompressed.

You've got that 3.4cc compressed gasket.  Even the 4cc one wouldn't be enough that spares sells.  Nice to know there are options, even if it does take 5 weeks!

[Willie_B]

I left a message for an overseas vendor that listed as available in 10-14 days to see how real that was.

[94touring]

Dave if you get a moment check to see what needle he has in the hif44 that Brads running.  It should be pretty close to what I run, without the shaving I required, but I also have port work and probably bigger valves so that should equal out the modified needle work.  Really need to get a wideband on it when it's all said and done to make sure it's in a good safe tune.  Didn't check to see if you had the CSI there with you, but once it's hooked up, remove the cap, turn the ignition on and count the blinks on the CSI.  With a tiny screw driver select it to blink 7 times.  This will be pretty close to an Aldon Yellow that's set to 10 degrees at idle.  With a timing gun verify static timing at 10 degrees at an idle up to 1k rpms before the curve will begin to increase.  Usually it bounces a little that low so I like to verify higher up.  You could check 3k which should be a little shy of 26 degrees. You should see 30 degrees at 5k and 32 degrees at 6k.  I just set the idle screw to the rpm and dial in the timing gun to match, easy peasy.  Not sure how high Brad revs it on a spirited drive.  If you/he want something more conservative (10:5 engine compression zone on pump fuel) I'd set it to blinking light number 3.  This will show about 24.5 degrees at 3k, somewhere around 27.5 degrees at 5k and 30 degrees at 6k.  If his redline is say 5k-5500 you could probably go with blinking light 10, which would give you about 24 degrees at 3k and about 31 degrees at 5k, but full in is 34 degrees at 6k if revving that high which is still safe just on the end of it, and you'd want to make sure your air fuel is in the 12's up there at WOT and be more at that 10:15 compression on pump fuel.  My motor didn't produce any more power beyond about 32 degrees on the dyno.  Avoid curves 13-16. 

Worth noting if you modify the idle static it modifies the whole curve.  Subtracting or adding from the base of 10 degrees moves the whole curve the same amount.  Maybe it idles better at 12 degrees so going with curve 3 makes more sense, or it diesels on shutdown and likes 8 degrees so curve 10 is best, ect...

[MiniDave]

I'll be using my HIF44 carb, I don't remember which needle I wound up with, I think it's either a BDL or BDK....

I always set the timing to 8* on a new engine and suggest to keep it there the first 500 miles or so.

He does have a CSI so I appreciate the input on which curve to use, my plan was to start with a modest curve, so probably the three. I'll be interested to see what curve it's on now.

I don't currently have a wideband hooked up, but it doesn't matter anyway since there's no load  on the engine in the test stand....he would need one in the car to set up the carb. I don't have his carb here so he'll have to do that part of the setup.

[94touring]

Right yep, it's for him to think about when he's got it in the car and before he goes out and stomps on it.  4.gif

[Willie_B]

I have a BDL needle in the carb now.