GT40s.com
MK-I  MK-II  MK-III  MK-IV  GULF  MIRAGE  J-CAR  LOLA
GT40s.com
Home Forum Gallery Support GT40s.com  
Register FAQ Advertisers Search Today's Posts Mark Forums Read

Go Back   GT40s.com > >

Notices

GT40 Tech - Engines/Induction/Exhaust Motors and engine related - right here!

Reply
 
Thread Tools Display Modes
Old 16th January 2018, 07:38 PM   #1
wealdenengineer
10 tenths
United Kingdom
 
Join Date: Oct 2001
Location: East Sussex, UK
Posts: 1,932
No 2 main failures

So tell me about these failures !
wealdenengineer is offline   Reply With Quote
Old 16th January 2018, 07:58 PM   #2
Big-Foot's Avatar
Big-Foot
Administrator
United States
 
Join Date: Jan 2007
Location: Kenyon, MN
GT40: Gulf Cart
Posts: 6,801
Re: No 2 main failures

You mean the ones that preceed the Ford 302’s block being split in two when pushed hard and north of 400hp?
__________________
Regards - Randy
-- Youth and talent are no match for old age and treachery!
GT40 RCR40 #45 G50-331-Weber IDAs ((Sold))
My build site:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Big-Foot is offline   Reply With Quote
Old 16th January 2018, 08:00 PM   #3
wealdenengineer
10 tenths
United Kingdom
 
Join Date: Oct 2001
Location: East Sussex, UK
Posts: 1,932
Re: No 2 main failures

Yep, seem to be more common these days , even at lower HP
wealdenengineer is offline   Reply With Quote
Old 16th January 2018, 08:03 PM   #4
wealdenengineer
10 tenths
United Kingdom
 
Join Date: Oct 2001
Location: East Sussex, UK
Posts: 1,932
Re: No 2 main failures

Got one in the shop today!
wealdenengineer is offline   Reply With Quote
Old 16th January 2018, 09:03 PM   #5
MikeP's Avatar
MikeP
Gold Supporter
United Kingdom
 
Join Date: Dec 2005
Location: Oldham
GT40: GTD
Posts: 1,477
Re: No 2 main failures

Internal or external balance?

Cheers
Mike
MikeP is offline   Reply With Quote
Old 17th January 2018, 12:40 AM   #6
jac mac's Avatar
jac mac
I Have No Life
New Zealand
 
Join Date: Dec 2005
Location: Gore, NZ
Posts: 4,373
Re: No 2 main failures

Being a bit frugal with info Frank.. Brg failure or block web or both. Then how many RPM, 50/28/ 0 or other balance factors, wet sump or dry, steel or iron crank, block year, balancer& flywheel clutch size/weight, who balanced it, bob-weight used, type of Bob Weight...................................
__________________
AMGT Rep Steel Mono x Plans, FE328 T44R.
[email protected]
jac mac is offline   Reply With Quote
Old 17th January 2018, 06:09 AM   #7
wealdenengineer
10 tenths
United Kingdom
 
Join Date: Oct 2001
Location: East Sussex, UK
Posts: 1,932
Re: No 2 main failures

I like to entice worldwide comments before getting into individual details. How many others have had similar failures, more common on race engines using standard or semi standard two bolt mains ? This one is a two bolt main, steel crank and 10.5 to 1 compression on pop up pistons machined back. Appears to be only a cap failure, but I wouldn't trust the webs so I think its scrap. Will go for a Dart SHP with 4 bolt caps if the owner will afford it.
wealdenengineer is offline   Reply With Quote
Old 17th January 2018, 09:10 AM   #8
MikeP's Avatar
MikeP
Gold Supporter
United Kingdom
 
Join Date: Dec 2005
Location: Oldham
GT40: GTD
Posts: 1,477
Re: No 2 main failures

Hi Frank.

Hard to comment properly without the full story of what the spec is and how hard it has been used in terms of revs etc. External balance cranks still give the mains a severe beating at high revs because even though the engine is balanced overall the crank is not and this can knock out main bearings etc. This repeated severe vibration can also fatigue the caps and block.
I would not want to re use that block. The Dart will be plenty strong but I would still go the (accurately done) neutral balance route as it is a far better solution from a basic engineering viewpoint.
Time for someone to dig out the credit card!

Cheers
Mike
MikeP is offline   Reply With Quote
Old 17th January 2018, 01:28 PM   #9
camp upshur
Rookie
United States
 
Join Date: Mar 2011
Location: SoCal
Posts: 24
Re: No 2 main failures

In years past I had experienced two crankshaft failures:
-a 271hp 289 4v catastrophic forward journal breakage; and
-a 306hp 289 4v (SAI original) nascent cracking filet area detected during magnaflux.

Both engines (then) external balanced (accurately FWIW) 10:5 CR C7FE camshafts, headwork etc.

Although the usual episodic reasons are usually causitive for the drama, I believe the cumulative effect of the original firing order set both of these failures up. (no kidding)

Steve
camp upshur is offline   Reply With Quote
Old 17th January 2018, 02:38 PM   #10
Big-Foot's Avatar
Big-Foot
Administrator
United States
 
Join Date: Jan 2007
Location: Kenyon, MN
GT40: Gulf Cart
Posts: 6,801
Re: No 2 main failures

Ford’s Mexican blocks are reported to be stronger, but I have no hands on evidence that this is true.
We bought one of the first BOSS blocks that ford was offering back in 2008 or so. It was rough bored both in cylinders as well as main bearing saddles. Once we took care of that and decking the block to bring it to spec, we would have been better off buying a Dart block that was already finished save for honing of cylinders. I am not aware if Ford is prepping the Boss block to a higher spec or not -but worth asking I guess.
__________________
Regards - Randy
-- Youth and talent are no match for old age and treachery!
GT40 RCR40 #45 G50-331-Weber IDAs ((Sold))
My build site:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Big-Foot is offline   Reply With Quote
Old 17th January 2018, 06:26 PM   #11
Scott Calabro's Avatar
Scott Calabro
10 tenths
United States
 
Join Date: Oct 2006
Location: Southwick, Ma.
GT40: Tornado TS40
Posts: 1,723
Re: No 2 main failures

HorsepowerSales.net and Valley Girdle Pro

This is installed on the 289 that was in my first TS40. Some folks think they are a gimmick....it was inexpensive, so to me, NBD. I think this damage happens most with late model 5.0 blocks as they are very light. A combination of a “heavy”car that can really hook places the block under more twisting force than it can stand reliably. Like a drag car with a good suspension and slicks. My engine inertia dynoed @ 385 HP and the car ready to drive only weighed 2120 lbs, so excessive “block loading”🤪 was probably not a factor.
__________________
Tornado Sports Cars USA Rep.
Scott Calabro is offline   Reply With Quote
Old 31st March 2018, 09:27 AM   #12
MotorEddy's Avatar
MotorEddy
Rookie
United Kingdom
 
Join Date: Jul 2014
Location: Lancashire, UK
GT40: Southern GT #48
Posts: 35
Re: No 2 main failures

Quote:
Originally Posted by wealdenengineer View Post
So tell me about these failures !
What firing order was the engine running, 302 1-5-4-2-6-3-7-8 or 351 1-3-7-2-6-5-4-8? Some people say that the 1-5 firing close together stresses the first crank throw, but I guess so much depends on balance, compression ratio, revs and a thousand other factors.
MotorEddy is offline   Reply With Quote
Old 1st April 2018, 06:22 AM   #13
wealdenengineer
10 tenths
United Kingdom
 
Join Date: Oct 2001
Location: East Sussex, UK
Posts: 1,932
Re: No 2 main failures

Eddy, the engine has standard 1 - 5 - firing order. The block has now been repaired by installing new caps and line bored, now got to rebuild with new 40th pistons and a rebalance. ( Customer choice to stay with old block ) .
wealdenengineer is offline   Reply With Quote
Old 12th April 2018, 11:11 PM   #14
bill kearley
A Tenth
Canada
 
Join Date: Jan 2008
Location: Canada
GT40: CAV 193
Posts: 133
Re: No 2 main failures

For peace of mind check with the guy that did your line bore, find out how much, if any, they cut from No. 1 web. I'v seen it stretch without showing cracks. and if your in the mood go with a cam and 351 order
bill kearley is offline   Reply With Quote
Reply

Tags
failures, main


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -4. The time now is 06:19 PM.