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1500 piston question.

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gassman57 Avatar
gassman57 Richard Driscoll
Bolivar, Ohio, USA   USA
In the workshop manual it reefers to the bore sizes as F and G grades. What does this mean ? Sorry if it's a question previously asked I could not find in the forum.

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Speedracer Avatar
Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
The factory most of the time had more than one piston for a given bore spec, so as lame as it sounds for a car factory, yes bores differed enough for them to have slightly oversize, or undersized standard piston. This is why we never follow the factory's lead on anything, this, and factory sleeves, and many other idiotic things that cause this company to go out of business.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
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jmac Avatar
jmac Silver Member Jere McSparran
Greenup, IL, USA   USA
1978 MG Midget "Therapy"
1978 MG Midget "(SOLD)"
X2 what Hap said. Sad really.



JMac
JMAC Engine Shop
http://www.jmacengineshop.com

gassman57 Avatar
gassman57 Richard Driscoll
Bolivar, Ohio, USA   USA
Hap and JMac
so what do I go by when measuring the pistons and bore....F or G. Or somewhere between. How do you guys typically confront this situation?

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Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 3494902 by gassman57 Hap and JMac
so what do I go by when measuring the pistons and bore....F or G. Or somewhere between. How do you guys typically confront this situation?

First off we are talking about +/- .0005" -.001", I just bore the blocks, then I am in control from that point on. Confirm it is standard then over bore is my advice. In 30 years I seen 3 standard blocks that the bores were usable after measuring them. I spend zero time trying to save standard blocks, because most of the time it is compromise I am not willing to take. One of the biggest downsides to saving standard bore and pistons is ring land wear, in the rare cases where I did stay standard, I still bought new standard pistons.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - Alloy wheels for British Sport Cars,and others
76lucas Avatar
76lucas Gold Member Josh L
Floyd, VA, USA   USA
1978 MG Midget 1500
1979 MG Midget 1500 "Parts Car"
Makes you wonder what BL was using for measuring tools, a wooden ruler and a plastic school compass? Have to agree sloppy work like that is what killed these cars.



If you never try to do it You will never be able to do it

gassman57 Avatar
gassman57 Richard Driscoll
Bolivar, Ohio, USA   USA
Thanks Hap. It hhad been some time but I finally have startedon my project. Per usual the big "C" stepped in the way. God willing I will be able to drive my car some day.

Speedracer Avatar
Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 3496429 by gassman57 Thanks Hap. It hhad been some time but I finally have startedon my project. Per usual the big "C" stepped in the way. God willing I will be able to drive my car some day.

Good luck Richard, I've have fought that battle before, 6 years of remission now, thank God, and I wish the same for you brother. thumbs up
If I can help in any way, and I don't mean just car stuff, just shout.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - Alloy wheels for British Sport Cars,and others
gassman57 Avatar
gassman57 Richard Driscoll
Bolivar, Ohio, USA   USA
Thanks Hap! You have been very helpful in answering all my quedtions; just wish your shop was within driving distance, I would have you do it all.

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