Author Topic: 1275 A+ Engine Build  (Read 45573 times)

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #25 on: February 07, 2016, 04:05:29 PM »
So today I took the block back up to school to measure the bores for wear and taper - they were pretty close to the end of tolerance, but I decided to see if a light hone would clean them up and still be in tolerance.

All of the bores had wear at the top of the ring travel that would not clean up - the ring ridge wasn't bad but it was there....and of course the last cylinder I tried turned out to be the worst - it has rust pits in it bad enough that they may not clean up with an overbore. It almost looks like that cylinder sat a bottom dead center and water was trapped either just below the rings or at them.

So, a couple of options -

1- bore and sleeve all cylinders back to stock - that way I can reuse the original pistons.

2- see if the cylinder will clean up at one of the standard overbores, that will require new pistons.

Either way, it's off to the machine shop.......the customer wants oversized exhaust valves too, so the head will go too as well as the crank to check for wear and taper.
« Last Edit: February 07, 2016, 04:07:12 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #26 on: February 07, 2016, 10:00:34 PM »
Pulled the valves out of the head and took a look at things......guides are a little loose, so if we're going to attempt to put bigger valves in we'll need new guides too. The seals were still pliable and not a lot of carbon build up on the backs of the valves, but there was some nasty rust in a couple of the ports......I cleaned up one of the intake valves to check them out - they look fine to re-use.

It will pretty much need everything to make it first rate, but hey - in for  penny.....right?
« Last Edit: February 07, 2016, 10:23:04 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: 1275 A+ Engine Build
« Reply #27 on: February 07, 2016, 10:04:30 PM »
That's interesting rust build up.

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #28 on: February 07, 2016, 10:28:56 PM »
Seats weren't damaged tho, so it will clean up OK.
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline jeff10049

Re: 1275 A+ Engine Build
« Reply #29 on: February 07, 2016, 11:59:41 PM »
Does that block already have liners? some 1275's did kinda looks like it in the pictures but that might just be the head gasket sealing ring area i'm seeing.


Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #30 on: February 08, 2016, 12:07:06 AM »
No, it's the shadow left from the head gasket....
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline MPlayle

Re: 1275 A+ Engine Build
« Reply #31 on: February 08, 2016, 09:21:40 AM »
You might try the "molasses and water" soak method that the user "Hunter2" on Mini Mania used recently to clean up a cylinder head.

Here is one of the threads discussing it.

http://www.minimania.com/msgThread/118924/1/1/Molasses___old_Proportioning_Valve


Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #32 on: February 08, 2016, 12:39:01 PM »
I am familiar with using molasses for removing rust, it's stinks tho!   ;D 

I took everything down to the machine shop today, in a few days we'll have some options figured out, then the customer can decide just how wild or mild he wants to go.
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #33 on: February 10, 2016, 07:02:08 PM »
Block will have to be bored, but he thinks it will clean up between 20 and 40 over.....


Cleaned up a few parts today.....

« Last Edit: February 10, 2016, 07:06:15 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: 1275 A+ Engine Build
« Reply #34 on: February 10, 2016, 07:09:28 PM »
I messaged Mike at minisport about heads.  He's getting back to me about the porting on their various stages.  So far I'm at a loss of additional information to make decisions regarding valves.  A stock 940 head had the 33mm inlets and 29.4mm exhaust but the metro and turbos had 35.5 x 29.4.  Then some S's even had 30.5 on the exhaust, however are prone to crack due to lack of metal between valves.  I have 3 options right now.  35.5x29.4, 37x29.4 or 35.5x30.5.  Anyone have any expert advice? 
« Last Edit: February 10, 2016, 07:12:15 PM by 94touring »

Offline 94touring

Re: 1275 A+ Engine Build
« Reply #35 on: February 10, 2016, 07:11:07 PM »
Wondering if you should send those for me to paint up while they're clean and off...

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #36 on: February 10, 2016, 07:26:09 PM »
I thought I'd just hit them with a good coat of self etching primer and let you paint them all together? Your call......

33 and 29.4 is what's in this head.
« Last Edit: February 10, 2016, 07:30:34 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: 1275 A+ Engine Build
« Reply #37 on: February 10, 2016, 07:40:24 PM »
That works too.  Just so long they aren't rusting while they sit.

Yeah 33 is just too small on the fast road cam.  I just can't find any data or power curves for the uprated options.  Aside from the 92hp Keith Calver made with a 35.5x29.4 940 head with I'm assuming some mild porting.  But will 37 yield more..or risk cracking...or push the power band too high?

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #38 on: February 10, 2016, 08:51:05 PM »
Since this head has already been cut for the hardened seats, I don't know how successful you'd be at putting 35s or 37s in this head.......



If you look in this pic you can see how they had to cut into the intake seat in order to put in the exhaust. I'm thinking the only way you could go to 35's or 37's is without cutting the head to put in the hardened seats.

No question bigger valves makes for more flow= more HP..... as long as you have the right porting and manifolds. The cam will work better from more flow too, but in general you want bigger intakes for more flow, the exhaust is less important since it's under pressure rather than vacuum.

I think bigger valves don't change the power band that much for the same given cam, but it is a dance - you have to make al the parts work together. The best thing you can do is follow the lead of the guys who have already done it......
« Last Edit: February 10, 2016, 08:55:36 PM by MiniDave »
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: 1275 A+ Engine Build
« Reply #39 on: February 11, 2016, 08:07:18 AM »
Stage 3 it is...

Dan,
Here's the official answer:

1275 -          stage 2 -     modified chamber shape, ports are modified according to valve type and sizes
                   stage 3 -     different chamber shape for better swirl, squish, and scavenging - inlet ports are modified according to valve sizes, exhaust ports are tunnelled to improve exhaust gas evacuation and to increase the surface area of the port  to assist in heat dissipation into the cooling system .

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #40 on: February 12, 2016, 12:06:40 PM »
OK, so plans have been made - the machinist is confident the bores will clean up at 40 over, so we'll get that sized pistons.

 The crank micc'd out perfect, so all it needed was a micro polish to get rid of the surface rust and it looks great - and will take standard sized bearings.

More as it happens!
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #41 on: February 13, 2016, 12:14:15 PM »
Cleaned the old head up today, it came out nice! Now I'll take it up to school and do a good three angle valve job on it, and grind the valves and it will be ready to assemble.

1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: 1275 A+ Engine Build
« Reply #42 on: February 13, 2016, 01:47:06 PM »
Nice.  I'm curious to see how the new head compares. 

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #43 on: February 13, 2016, 03:03:59 PM »
The biggest, most noticeable difference will be the exhaust ports.
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #44 on: February 16, 2016, 07:11:07 PM »
Got the gearbox cleaned up today, still haven't had a chance to figure out the final drive ratio - there was a vinyl tag on the diff case but all the printing was long gone. All I have to do it lock it in 4th gear and count the number of turns on the input shaft vs 1 turn on the pot joint. I'll get to it, I promise.....

Here are the before and after shots of the gearbox. Folks, if you tear down an engine, don't leave it exposed for 7 or 8 years, at least wrap it in a plastic bag or something!   ;D  ;D  ;D  ;D



1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: 1275 A+ Engine Build
« Reply #45 on: February 16, 2016, 07:26:21 PM »
But it's more fun if it's dirty!

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #46 on: February 16, 2016, 07:42:32 PM »
No.........it's not....... ::)   ;D

That was about 2 hours of solid work, and I may put it back in the tank and give it some more before I'm done with it. BTW, you are getting a trans gasket set, right? Might as well replace all the easy ones at least......
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline 94touring

Re: 1275 A+ Engine Build
« Reply #47 on: February 16, 2016, 07:45:53 PM »
Yeah I'll get you a full gasket set too. 

You can see why I'm happy having my own shop.  I can manage the cleanliness!

Offline MiniDave

Re: 1275 A+ Engine Build
« Reply #48 on: February 16, 2016, 07:59:39 PM »
Me too!
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Online John Gervais

  • A Really Swell Guy
  • 1380cc
  • *****
  • Posts: 878
  • Total likes: 26
  • Karma: 0
    • Copenhagen, Denmark
Re: 1275 A+ Engine Build
« Reply #49 on: February 16, 2016, 09:47:16 PM »
Dan, I've sent you an E-mail -
- Pave the Bay -