Technical Flathead Porting: Soup to Nuts . . . Pictures, Details and Opinions

Looks good!

More details on engine specs and port work, please
Michael

 

Hi
Motor 35/16 x 41/8 Scat crank Scat rods Ross piston high dome (dome height .687" radius 2.291") Isky 400jr cam Isky double valve springs thanks to this tread will modify custom guides to reduce use of shims. Valves 1.72 inlet 1.5 exhaust.Flat Attack heads as cast to be machined to suit pistons, 4 turbos, custom manifolds efi, coil per cylinder Autronic SM4 controller. I have cast a one piece crank girdle also that I am now in the process of fitting.
Porting wise I did a lot of the gross metal removal using a router with a long burr working through an angled plate that kept the burr at the correct angle to the port I have only done the intakes so far on an unusable block. Spent the last several weekends working on the girdle kind of scary to think about the time investment in one of these blocks especially if you break through on the last port.
Grant

 

Hey great stuff! What did you cast your girdle out of? If it is aluminum, are the cap sections also aluminum? Did you happen to cast multiple ones - might want to "acquire" one for a special project. This reminds me of the 417 Donovan! Keep us posted - I like what you're up to.

 

What he said....lookin good !

Rat

 

I was going through some old pics and took these before I sent my engine out and figured I would post them since we brought up the domed pistons, I took a pic next to an old Jahns just to get an idea of the difference, the rod is from Crower. These are the ones I'm using with the Navarro heads.

 

DANG! Sweet stuff.

 

"Spent the last several weekends working on the girdle kind of scary to think about the time investment in one of these blocks especially if you break through on the last port."

Never fear, silver solder will work wonders.

 

By the way, I don't mean to pour cold water on your project but SCAT cranks
are made of nodular iron and are very short lived when either a big load of nitro or a lot of boost is applied. They seem to be as long lived as a Merc crank in street applications.
About 3 years ago I sold 2 SCAT rough castings to 2 different prominent vintage drag racers. They finished them with extra large radius's. They both ran 100% nitro.
Neither engine made it a 100 feet from the starting line on the first run... Poof, 4 piece cranks.
I have gone to Moldex cranks myself.

 

That is a very cool looking engine and I'm sure you've done your homework but,I have to agree that Scat products leave a lot to be desired. There's a reason they're lighter than an equivalent crank of another brand. It's called density.
There used to be some dirt car guys around here that ran 'em and threw away 3 to 5 cranks a season.
Cat stuff on the other hand seems to be fairly decent stuff.

 

Hey Pete . . . I've heard the same things on the SCAT cranks - I'm headed toward Moldex for a special build I'm working on this winter. Was wondering what you think of the Merc crank versus the SCAT - any thoughts on comparable strength for Nitro or blown applications? I'll probably be running a Don King girdle, steel caps on all three and potentially a stud girdle/support between the caps. Thanks - always trust your opinion!

PS: The Potvin 3/8 you recently made for me - worked GREAT in Chris Daniel's engine . . . just love that cam!

 

I'm interested to here the thought on SCAT vs. Merc crank as well. Also general thoughts of these in a naturally aspirated plain gas engine. I started working on the flathead for my bellytank and can't decide which way I want to go for 4 1/8" stroke. I will be using at least billet caps, possibly a Don King girdle as well.

A few other questions, I would like to go with 1.7 intake valves, what are you guys using? With the stock style lifters instead of the adjustables are you reusing originals or is there a source for new ones that are decent?

Great thread by the way, this showed up just as I was making metal dust on doing the rough porting of my block. Very informative.

 

Over the last 5 years I have installed 3 SCAT cranks in street engines.
They were 1/2 inch strokers... as always I had to remove several pounds from the throw sides to balance them without any heavy metal ( Mallory).
They perform well and stand up well in street applications..It is too bad the rough castings
aren't fatter so more stroke could be obtained...4.4 is all I have been able to get.

As far as valves go for a street engine, almost any size will work good...1.7 is good.
The limiting factor here is when they get too big they touch each other.
Many years ago we did flow tests on valves and ports and after about .500 lift with a 1.7 dia. valve the flow does not increase even if you take the valve completely out of the port.

With lifters, the stock steel ones work very well...Refaced ones work fine..Be sure the top end is faced also..Many have become cupped over time.
New ones show up ocassionally but even these should be magged as the weld between the top and the face is sometimes not completely fused.

 

Hey Pete: What are your thoughts on the strength of a Merc crank for blown and fuel applications? I'm leaning toward a Moldex for a special high-output project - though I was wondering what you thought the practical strength limits of a 4 1/8 Merc is . . . assuming steel main caps, Doug King girdle, etc.. Also, if you've ran a Moldex before - did you use a standard flathead snout and flywheel flange . . . or go SBC?

Thanks as usual!

Dale

 

Bradley told me one time that about 12 runs was all he could get from a Merc crank.
These were welded strokers.

I installed a customer's Moldex crank in his engine once. It had the standard Ford snout and rear flange.

I usually use aluminum SBC flywheels on my engines because they are much cheaper than flathead ones. I use the Chev starter.(gear drive) They are easy to redrilll and most come drilled for several clutch options.

 

"What did you cast your girdle out of? If it is aluminum, are the cap sections also aluminum? Did you happen to cast multiple ones"
Hi
Girdle is SG iron. At the rear I have attached an aluminium piece to hold seal and allow drain back from seal area I have attached some clearer photos. Still have the pattern it would cost a bit in freight as it weighs a ton. I didn't like the idea of aluminum on the basis of differential expansion although I have seen similar girdles made out of aluminium. Thanks for feedback on Scat cranks.I spoke to the people at Scat around horsepower numbers they were happy at HP plus 300 they rate other 9000 series cast cranks at around 7000rpm 600hp with a 5 bearing crank thats why I am going to the trouble of making up girdle couldn't afford the $2500 $3000 for a billet. Scat rate 9000 at 105000psi tensile 6% elongation which I didn't think was too bad and the engines not for a race car just going in a 34 Ford 3 window hotrod.

 

Hi
Maybe others may be interested in this for port thickness testing or bore wall thickness checking. Its a modified digital outside caliper used in woodworking
got mine from Rockler Woodworking Tools. $25
Grant

 

Great Thread!

 

Just discovered this Thread..... Fantastic, just what I need to know for my current build.... BTT for all to see.

 

Just checking this out again, great stuff. Bump for all the Flathead guys who haven't seen it.

 

Hi Dale!

Any uppdates?

Got my Crower roller home, still misses the lifters!
Have done alot of porting, and will call it good for now, stage 1.
I would like to keep anought materiall in the ports to take alot of boost,
made pullys to go as high as 38% overdrive!!??
It will be intersting to see how much HP it will make!?

Br
Kjell

 

Hey Kyell, can you send me the statistics (timing tag) on your roller -- are you waiting for them to make the roller lifters? I was chatting with them just last week - seems they are going to be making them again, so hopefully you have an order "in line" with Kerry. I've been workng on a few other projects at the moment -- SBF 306 road-race motor, more work on the 392 and getting ready to work on a big Flathead Cadillac block (bunch of stuff including port work, valve work, etc). I've been collecting a bunch of stuff for a new flathead build -- can't let the cat out of the bag as of yet, but it will be fun!

 

Damn Dale, how did I miss this thread over the last couple years, lots of good stuff here to ponder on a Sunday morning for my next flat motor!

 

I like Cadillac flatheads!

..and it's a felony not to let a cat out of the bag in Colorado! Animal rights and such....

 

Hi Dale.

I will make a scan of the cam tag and send it to you.
I have the cam and the tag at the other workshop. I will go there this week.
I hope the lifters will arrive soon, Crower informed me that the bodys were done,
just had to mount the rollers, then heat treat them. I talked to them aprox. weeks ago, said they would bee done in aprox weeks.

See that you have been busy with other prodjects, but it would have been intersting to see more on your killer Ford Flathead!?

I have spent the time doing all the small stuff, maily polishing all the details on the engine, and the FED. Just some small fabrications left before painting the body! I love the new Moldex, was almost xmas when i got it.

Do you have any idea of hove much HP we can expect?

Br
Kjell

 

See up above . . .

 

For now, the Flathead is like this:

1988 French Flathead
Ported an reworked aprox like your first in this tread+some of my own ideas.
New home made HQ. mains with girdle (Baron style)
Moldex crank, 4 1/8 stroke.
Scat rods, with Buick journals.
Kustom Ross pistons, reinforced for more load/pressure. Coated.
Total Seal gapless rings.
Manley Hi flow ss. valves. 1.625 inn. 1.5 ex. Will be undercut.
Isky 185G springs, with Titanium retainers.
Turned down stock valve guides
And the Crower roller
Reworked Offy .400 heads
Home made blower inntake, from a Offy quad.
A GMC 4-71 blower, pullys for 7% / 18% / 25% / 38% overdrive
Hilborn 2 port fuel injection. for Methanol.
4 th exhaused port out of the inntake.
Vertex Magneto to fire this thing up!?

Manually shifted C4 with transbrake.

4.10 rear end ratio.

Have the Hurst 10" slicks now, but will order a set of M&H 12.00x16".

Br
Kjell

 

Great thread much to be learned here

 

bump for a great thread

 

Oldie but a goodie.......any pics of the exhaust ports done

 

Have anybody cut 8BA block? Are water passages in same locations and thicknes is same? Well, I think they are, just asking...