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maximum allowable runout for an 1147 cc engine

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gt350mk Marc Kay
Aurora, CO, USA   USA
Thank you for your response,

I just did a quick measurement as I have a but of restlessness. I put the 2.6 anvil with the .12 spacer on it the bore gauge making a total of 2.712 inches. I zeroed out the gauge. The gauge moved to the right between 12 - 14 or .0012 - .0014. I subtracted 2.7200-.0012 and .0014 which is 2.7188 and 2.7186. The super quick reading was at the top of the bore or approx 3/4 - one inch down. Keep in mind the bore gauge is room temp and the engine is approximately 40 Fahrenheit, in dim light while my dog did his thing and me looking at many projects.
What do you all think
Thank you,
Marc

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gt350mk Marc Kay
Aurora, CO, USA   USA
Hello

The replacement standard pistons fit fine in the bores upside down without rings. I am thinking I could get this thing going with some special rings at most, hopefully with the standard rings that came with it. Fingers crossed.

I do have those neat looking standard pistons with the extra oil control ring above the king pin. We're those supposed to be for worn cylinders? Or were those a performance option? I thought they were to prevent piston slap and to keep more oil around the piston given it has split skirts. Don't really know. Not much on the web at all.

The car came with some neat parts:
Original no rust Stahl header tapped for exhaust temp probes. Awesome 1 of 3 off cylinder head meant to prove, that all things held equal, the 1147 cc engine is better than the other two, fully ported, polished, cc'd, note to get high lift roller rocker arms. You all can see why I want to get her running.

I have never driven a Spitfire. Would a Spitfire with 85 rwhp be fast? What sort of fast?

Thank you,
Marc Kay

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
Honestly, if you are intending to get the most out of that engine (85hp) I would not be using split skirt pistons of any sort. Plus more rings does not help or make things better.

85hp you will be winding that mill pretty high, not the sort of think you want to do (or could do) with an engine that has NOT been carefully built.

Just my opinion.

A Spitfire with 85hp would be a blast to drive, but not FAST by any standard! That might sound odd, but it is the character of the car and it's basicness that wins us over. It FEELS fast.

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gt350mk Marc Kay
Aurora, CO, USA   USA
Thanks for the response,

Are our cars grossly under powered? Would a scooter take it to town? The closest I've come to driving a Spitfire was in high school which was a Datsun 210 with 45 HP. It wasn't fast by any means and thank god there was a mandatory 55 mph limit.

I was thinking the Spitfire might give a straight six Mustang a run for its money. Seriously how fast or slow are these cars?

Thank you,
Marc

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1506905 by gt350mk Thank you for your response,

I just did a quick measurement as I have a but of restlessness. I put the 2.6 anvil with the .12 spacer on it the bore gauge making a total of 2.712 inches. I zeroed out the gauge. The gauge moved to the right between 12 - 14 or .0012 - .0014. I subtracted 2.7200-.0012 and .0014 which is 2.7188 and 2.7186. The super quick reading was at the top of the bore or approx 3/4 - one inch down. Keep in mind the bore gauge is room temp and the engine is approximately 40 Fahrenheit, in dim light while my dog did his thing and me looking at many projects.
What do you all think
Thank you,
Marc

You are failing to understand the limitations and proper usage of your dial bore gage.
If it's similar to the Peacock unit I have, it resolves to 0.0001", and can measure a range of about 0.10".
The anvils are sized in 0.20" increments from 2.00" to 4.00", and the spacers are 0.100" and 0.050".
The anvils and spacers are NOT precision pieces. Once installed they are stable and will not move.
But they are intended to set and match the limited gage plunger travel range to whatever bore size you are working with.
Each time that you remove and install the anvils and spacers, you must calibrate again, using a precision ring or micrometer.
By zeroing the gage, you have only referenced the internal plunger stop, which corresponds to some unknown distance that is roughly 2.72".
The gage will accurately display the differences in bore size, but without calibration, not the absolute bore size.

I recommend some research on how to properly use your instrument.
It's not hard, but you must understand the fundamentals.

Please realize that I'm not attacking you, just speaking plainly, I want you to be successful.



Edited 1 time(s). Last edit at 2018-01-11 08:50 AM by clshore.

Born Loser Avatar
Born Loser Silver Member Matthew Taylor
Land O Lake, FL, USA   USA
In reply to # 1506905 by gt350mk What do you all think

Honestly, and don't take this as harsh criticism (I dont intend for this to be mean), I think you are going to need to get solid measurements - dont "wing it" for a ballpark, and try to do any evaluation - its just too fine of a difference from "needing to be punched out" to "just clean it up with a fine hone".

As far as "how fast"? these cars are not drag cars, and they dont have an impressive top end. What makes them fun, they are one of the best cornering cars you will ever drive (if set up properly). They like the slow tight turns - A LOT. Think of the yellow signs with 15-35 on them. Thats what these cars do better than most - mine runs about double the sign + 5mph going in, and I give it some gas on the way out - thats what they are about. As far as off the line - the stock US set up is painfully slow. Thats 0-60 in about 16 seconds. I have done a BUNCH of things to my 1296, its a very hot streetable motor - in the HP range you are talking about (maybe a bit more) - and the fastest times I have ever clocked (using a pocket dyno) was 9.9 seconds (off a red light, driving on the street, and not wanting to destroy anything). For a Spit, that is REALLY fast. In fact, I can run down a stock TR6 with no problem. Your Mustang straight 6 will take a stock Spit. My "hot" build is a bit faster than the stock Mustang. That being said, most Honda Civics will eat my lunch off the line, by 2-3 seconds. Until we hit those turns. Even the rice rocket bikes get small in my mirror, until we straighten out again.



Matthew
1960 Triumph TR3a
1970 Triumph Spitfire MK 3
2012 Mini Cooper SS Convertible
2018 Jaguar F-Pace

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
In reply to # 1506909 by gt350mk Thanks for the response,

Are our cars grossly under powered? Would a scooter take it to town? The closest I've come to driving a Spitfire was in high school which was a Datsun 210 with 45 HP. It wasn't fast by any means and thank god there was a mandatory 55 mph limit.

I was thinking the Spitfire might give a straight six Mustang a run for its money. Seriously how fast or slow are these cars?

Thank you,
Marc

Depends on the model. It's mostly a transmission issue. The overdrive models handle the freeway fine. The standard four speed feels like it needs another gear at 45.

I've read rave reviews over 5 speed conversions. People describe it as a completely different driving experience which fits in with today's driving conditions including having the ability to cruise at 70+ indefinitely.

Look into swapping out the stock tranny if you want to see a difference.

Should mention the diff sucks too.

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gt350mk Marc Kay
Aurora, CO, USA   USA
I love the electric overpriced they offered on British cars, Normanville DeLaycock, of which the U.S counter part is the Gears Vendors Over/under-drive tail shaft add-on. The Gear Vendors parts is very expensive but can be used for most U.S popular manual and automatics!

The electric overdrive is something I've wanted to try forever. What did Lotus use? A ZF transmission and they all were 5 speed till the dreaded Elite 2s came out and I don't know much about the Lotus automatics, just something I've read to avoid. Speaking of Lotus...

Would a built, 85 HP Spitfire run with the Kent/Cosworth cars? My buddy drove a messaged over two plus two of which he said was faster than his messaged over 1967 Cougar with the 289 cid Ford. What about the Ford 1.6 litre cross flow Fords? I'm just trying to envision what it may be like. I have a mildly done 302 cid Mustang that is under the knife for the past five years with serious autobody as a learning project. I successfully replaced the left rear frame rail and torque box. Anyhow ad I remember that car felt dangerously fast with neck snapping shifts. I really worked over the suspension, which did wonders, but she wasn't really designed for slalom/corners. What do you all think? Do you guys run the Spitfire totally stripped of weight including windscreen? Has anyone ever driven the Morgan's with the motorcycle engine?

Cheers

gt350mk Marc Kay
Aurora, CO, USA   USA
No, please, criticize away. I have not done this in over a decade (I somehow got into Swiss Watches).
Right now I am just playing with the dial bore gauge to get a feel for it and get to a semblance of responsibility.
I see what you are saying though. I have not set up the dial bore gauge with a known value. I just added an anvil and spacer and subtracted what the gauge read, 2.7200 - 0.0012 = 2.7188 which is very close to the specification listed as 2.7280 of which the shop manual says no more than .0002 of which my quick reading would show the absolute maximum wear.
I also used it to see if there were any significant changes between the 4 cylinders of which the range was 0.0012 to 0.0014, but like I said originally it was a 15 minute excersize. One thing I'm not understanding is if I have zeroed out the gauge prior to testing, I don't see why it couldn't be used if I measured say three times and took the average of the three Throughout the cylinders. I mean this exercise is to show what the cylinder looks like and with enough readings I think one could build their selves an accurate picture if the cylinders either method ( Method A being taking a known accurate value and setting the bore gauge to that and zeroing it out which allows the end user to find straight up as the bore gauge needle swings to and out of maximum values; whereas Method B only allows the needle to go in one direction, that is zeroing out the gauge right after placing the correct amount of anvils and spacers, then take the reading where the gauge will only move to the right and then rests at zero, and as the bore gauge reaches its maximum, that is the reading to subtract from the total anvils and spacers on the bore gauge).
I'm not seeing a third way.
To your absolute credit one should not do this in a hurry and plan on a good six hours of readings so that at the end you could tell Hastings or another ring manufacturer what each cylinder looks like and (and allowing the possibility of an over bore or RE-sleeve). I think you also state that one should Mark every spot in the cylinder a reading is to be taken and associate that Mark for, say distance from the top of the cylinder do that there is repeatability from cylinder to cylinder.
Question: is it common to take readings top, middle, bottom, then with the crank, perpendicular to the crank and 135 degrees from parallel to the crank?
OR take readings 5 places from top of cylinder then every 45 degrees?
OR how granular must this be?

Thank you all!
Marc Kay

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Lizzard d id
san jose, CA, USA   USA
Take two readings per cylinder . Just below the ridge , 1/4 inch down from the ridge , one reading north / south , one reading east / west . Subtract one reading from the other .

6 hours ? You are not making a nuke .

"so that at the end you could tell Hastings or another ring manufacturer what each cylinder looks like"
They don't want to hear about it .

clshore Carter Shore
Beverly Hills, FL, USA   USA
There are some very slick instruments out there now.
Using a laser scanner system, can resolve the entire surface to accuracy of better than 0.0001",
recording each entire bore into a data file (typical file size is 150 GigaBytes)
The data file can be analyzed for any distortion that you may be interested in, and display a
3D graphic that shows all the variations in different colors.
Ideal for evaluating the distortion effects of torqueing down head, main bearings, and accessories,
plus evaluating the effectiveness of various honing and finishing operations.

Used by OEM and other deep pocketed users.

If you want one, bring the BIG wallet.

gt350mk Marc Kay
Aurora, CO, USA   USA
Thanks group,

Can one purchase rings for highly worn cylinders and if so explain how they work. Given what a few have said I don't think even the toughest would last... or maybe they last as long as a ring in a good bore.

Thank you all for your input. I definitely got the answers I was seeking.

Thank you,
Marc

mkivmarty Avatar
mkivmarty Marty Yanik
N.E.Ohio, USA   USA
In reply to # 1507194 by gt350mk Thanks group,

Can one purchase rings for highly worn cylinders and if so explain how they work.

Highly worn cylinders are typically glazed (shiny). If they are, no ring available will ever seat in them, and your engine will never run right. This sounds like a tear down, with at least a honing of the cylinders. You may be able to use .010 rings on the standard pistons, gapping as necessary.

Marty



Edited 1 time(s). Last edit at 2018-01-13 09:44 AM by mkivmarty.

Lizzard d id
san jose, CA, USA   USA
Have you or have you not done the test I requested ? If you have done the test , what are the results ?

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
In reply to # 1507194 by gt350mk Thanks group,

Can one purchase rings for highly worn cylinders and if so explain how they work. Given what a few have said I don't think even the toughest would last... or maybe they last as long as a ring in a good bore.

Thank you all for your input. I definitely got the answers I was seeking.

Thank you,
Marc

Geees Mark, Anything less than perfect is a compromise. OE manufactures and high end engine builders go to great lengths to get things as 'right' as possible. If there were Magic piston rings that did not care what the bores were like yet sealed well and lasted a long time, life would be a dream.

If you just wanted to get that engine back together and (kind of) running, that is one thing.

But if you have high expectations of that 1147 (which is IMO a great engine, but only produced 50-60 hp in stock configuration ) compromising will not get you there.

We have a saying up here "Are you going to fish, Or cut bait?

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