An engine build... Kinda' GT40 related

Kirby Schrader

They're mostly silver
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Was talking to Mike Trusty and he reckoned some of y'all might be interested in an engine build that a friend and I did for the Pantera race car. I intend to rebuild my GT40 427 Windsor similar to this (especially the valve train) but with less compression for the street. I've never been really happy with the GT40 motor since I've had it...

Ron, if this is the wrong place for this, slap my hand and point me to where it should go...

The Webers were donated/loaned to me by Mike, but I'll keep the EFI that I have now on my GT40.

My friend has run this kind of engine in his race car for years and it is damned near bullet proof. His big problem now is, yes, you guessed it... the ZF.

We are both running in a vintage class, so aluminum heads are a big no-no.

Pantera

FWIW,
Kirby
 

Kirby Schrader

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Might mention why everyone was so against putting Webers on a big HP motor like this.
Ahhhh.... Yes, everyone, including my friend Tom, thought I was a nut case/glutton for punishment/idiot for running Webers.

In fact, the machine shop guy said if they were such good stuff, everyone would be running them!

Well, they work just fine, thank you very much! it took me some time to get them right, but I'm getting right at an AFR of 12.6 at full throttle down the straight at TWs.

I know I'll get asked, but I did not dyno the motor. Tom had already dyno'd his and mine has just slightly more stroke and less bore. Both motors are 353ci. His dyno'd at just over 700HP. I had mine rev limited at 8000, but I was hitting the limiter at the end of the straight in 4th, so we bumped it up to 8200.
Tom is running 8800 with his.
They both sound nice, but I think mine sounds better with the Webers.
:thumbsup:

Thanks for the complement! It was quite an experience to build something like this, have it start on the first crank and then run like it does.

FWIW,
Kirby
 
Three questions: rod length?, Block height-9.2" or 9.5" and the three holes in attached pic on LH pan rail?

I see stroke is 3.300" and 353 cu in suggests ~4.130" bore.

Interesting, Ive been looking & thinking about those numbers from a clients engine I work with, it was / is just shy of 900hp on the 4 barrel.
 

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Kirby Schrader

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Three questions: rod length?, Block height-9.2" or 9.5" and the three holes in attached pic on LH pan rail?

I see stroke is 3.300" and 353 cu in suggests ~4.130" bore.

Interesting, Ive been looking & thinking about those numbers from a clients engine I work with, it was / is just shy of 900hp on the 4 barrel.
Rod length... Darn, I don't remember. I'll have to look.
Block height was supposed to be 9.2", but it was closer to 9.15".
354", actually. 4.133" bore.
I/we don't have a clue what those three holes are for... We asked ourselves the same thing when we were putting it together. I'm not using them for anything.
This block is apparently discontinued. Roush said I got one of the last ones.

I'll look up the rod length tonight, Jac, and get back to you.

Kirby
 

Ian Anderson

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Hi
Question here from a novice

You say 4V heads but those do not look to have 4 valves per cylinder

what does the 4V represent?

Great build by the way - how does the ZF do coping with the power?

Ian
 

Kirby Schrader

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Hi
You say 4V heads but those do not look to have 4 valves per cylinder
what does the 4V represent?
Great build by the way - how does the ZF do coping with the power?

Ian
4V was Ford's way of saying they were '4 bbl heads' (as opposed to 2V, for example). It's the description for the larger port and valve combination. There were 4V quench style and 4V open style head chambered heads.
The quench heads 'or closed chamber are better for performance.
They have a big '4' cast in the corner near the exhaust port.

So far, the ZF has been fine. I'm not doing drag race starts and I hope being 'nicer' to it. My friend, on the other hand, has so far broken 4th gear, twisted off an output shaft and then, most recently, an input shaft.

FWIW,
Kirby
 
Hi
Question here from a novice

You say 4V heads but those do not look to have 4 valves per cylinder

what does the 4V represent?

Great build by the way - how does the ZF do coping with the power?

Ian
Here you go Ian, look at difference between the port sizes of the windsor offerings vs the 4v Cleveland

Top some 210cc volume inlet runners on some ali heads, some standard iron gt40p heads below and the Cleveland at the bottom



 

Randy V

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Re: Three holes..

I suspect that they are for indexing pins for a crankshaft scraper. The tolerances needed for effectiveness are too tight to use the oil pan bolts alone. Well, that's my somwhat educated guess..

Love the cam bearings..

It always seemed odd to me that Ford had abandoned the Cleveland head. It had to be an emissions issue of some sort. Still, the Windsor head design was one of the most efficient in all of Detroit's offerings. Far more efficient than the SBC head as far as I'm concerned..

By the way - this forum is just fine for this thread IMHO..
 
Could be index pins for a crank scraper, but only if the engine has been reverse rotation in a previous life, they are on the wrong side for a 'normal' clockwise rotation application.

Afterthought.. the three holes could be used for locating a 'pressure balance trough system' that pairs #front/rear and centre cavities for windage purposes in a shallow dry sump/pan
 
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Might mention why everyone was so against putting Webers on a big HP motor like this.
Properly set up Webers can equal or better a fi system for max HP at WOT only. Everywhere else in the rev range the mapable fi wins hands down so on a circuit that requires wot for most of the lap there will be nothing in it.

Bob
 

Mike Trusty

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Properly set up Webers can equal or better a fi system for max HP at WOT only. Everywhere else in the rev range the mapable fi wins hands down so on a circuit that requires wot for most of the lap there will be nothing in it.

Bob
You are correct assuming the "choke" size on the Weber is the same as on the compared throttle body.
These are obviously 48IDA and have 45mm chokes. About as big as you can make work. They are also about as small as you can hope to make power with this size motor.

If you compare these carbs with proper setup 50, 54, 58, 2.5", etc. throttle bodies the FI will win especially on larger motors than Kirby's.

I could make this motor idle at 600 rpm or 2,200 but not in between. Everything starts working together above 3,500. Definitely not a street motor.
 
You are correct assuming the "choke" size on the Weber is the same as on the compared throttle body.
These are obviously 48IDA and have 45mm chokes. About as big as you can make work. They are also about as small as you can hope to make power with this size motor.

If you compare these carbs with proper setup 50, 54, 58, 2.5", etc. throttle bodies the FI will win especially on larger motors than Kirby's.

I could make this motor idle at 600 rpm or 2,200 but not in between. Everything starts working together above 3,500. Definitely not a street motor.
Those that mess with 48`s have been known to chew the chokes out to the full 48mm which moves the goal post a bit, there are also guys that have bored out 48`s to 50mm so there are a few tricks about for getting past the 45mm choke.

Bob
 

Kirby Schrader

They're mostly silver
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Three questions: rod length?,
Jac,

According to the invoice, they are Dyer 6.285" LSBCQ rods.
There's also '4735A "D" (BE .905 wide) written below that.

So there ya' are... rod length. Sorry it took so long to get back with the info.

Regards,
Kirby
 
Is that a 'good' interesting?

Or a 'bad' interesting?
:worried:
Good.. I think. In relation to the compatibility of webers. A lot of noise is made about having to use smaller duration/wide lobe centres on cams for use with webers. if we look back a long way we had a few examples that seem to prove that theory wrong.

289 'Race' GT40- 2.87 stroke, 5.315 rod--- 1.85 to 1 rod ratio.
F5000 302 chev- 3.00"stroke, 5.700" rod-- 1.9 to 1 rod ratio

Find a few Weber equipped F5000 cars and they seem to drive around the pits etc quite well, no real issues , yet they are full on race engines & only 302 cu in.

Put the same carbs on a 'stroked' monster typical of many builds we see on this site and they seem to turn into a tuning nightmare... typical rod ratio on these things...6.200" rod with 4" stroke---1.55 to 1, or 5.400 rod with 3.400" stroke---1.58 to 1...

Concentrate on a getting a sensible cu in with bore increase and a longer rod ratio.
 
Good.. I think. In relation to the compatibility of webers. A lot of noise is made about having to use smaller duration/wide lobe centres on cams for use with webers. if we look back a long way we had a few examples that seem to prove that theory wrong.

289 'Race' GT40- 2.87 stroke, 5.315 rod--- 1.85 to 1 rod ratio.
F5000 302 chev- 3.00"stroke, 5.700" rod-- 1.9 to 1 rod ratio

Find a few Weber equipped F5000 cars and they seem to drive around the pits etc quite well, no real issues , yet they are full on race engines & only 302 cu in.

Put the same carbs on a 'stroked' monster typical of many builds we see on this site and they seem to turn into a tuning nightmare... typical rod ratio on these things...6.200" rod with 4" stroke---1.55 to 1, or 5.400 rod with 3.400" stroke---1.58 to 1...

Concentrate on a getting a sensible cu in with bore increase and a longer rod ratio.
Thats an interesting take on it Jac, the long rod motors gain a few degrees more dwell at tdc so they dont really need the added lobe separation. It seems Smokey Yunick was way ahead of his time :thumbsup:

Bob
 
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