The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by Flatdog, Mar 4, 2008.
I an posting some pics showing the difference side to side in late flathead .
(the basic valve angles dictating side differences would be as shown 1946-53, all the commonly used engines. Earlier engines are spread a bit more.)
I am going to try to explain some stuff .I doin't think difference in port shape means much after you port.Some of these pics are stock ports some are modified.If you study them you will see that stock ports need to be opened around valve guide.IMO. None of what your seeing it cutting edge stuff but it will help you very much to build a nice running flatmotor.This info is only part of the whole picture you must have all other parts of the motor working together.Hope this helps.
man you guys from jersey sure know how to blow up a motor !
great info , and great talking with again this afternoon .
I was trying to figgerout how to measure or otherwise describe those differences (see Thickstun offset discussion!)...now I can see the utter hopelessness of describing them even more clearly!
Thanks for the great pictures!
Has anybody ever come up with a good explanation of why Henry did that? There must have been a logical reason.
could you please explain your reasons? some feel that simply matching the bowls to get consistancy in the volumes and actually adding some to the floor of the runners to keep velocity up is a significant improvement
Thanks Flatdog, love those cut aways, shows it well
Who does some refer to? I think adding to port floor in what I am gonna call the belly area would be a benefit.I have also seen many porting jobs that have been opened up in that belly area which I think is wrong.
Flatdog, the tape picture for the short port is kinda fuzzy but the long dimension appears to be about 2.500 from the deck, what is the short dimension??
And thanks for the pics!
Short runner I got 2 inch. Thinking again you also have to take transfer area when fidgering port length.I wouldn't make a big deal about all of this .Think it wrong place to spend a lot of time .
Wow! That must have taken a whole bunch of band saw blades to cut those up!!
Those are the first ACTUAL cross section pictures I have ever seen, of the "air/fuel path" in a flat head.
It's interesting to see how the two cooling passages come close to the the runners.
With those pictures in hand; it will be easier to avoid grinding into them.
It's kinda like having an x-ray of them.
Shaping (tapering from top to runner) the tops of the valve guides - for good flow - would appear to be different from one side to the other. (left to right)
Most information I have, treats both sides the same
Any words of wisdom on how you have been doing them??
Thanks Flatdog just trying to verify the approxamate length difference.
Dig,Broke them apart with sledge hammer till I could lift and hold on chop saw.Yes lot of work and danger. Yes you need to see where water dwells to port. I treat both side the same.A couple of the pics are of good ports.But I think last job done with keyed guides is probbally better.
I need to do the same with a Chrysler flathead 6. Thanks for the cutting tips. Did you use a chisel at all to score the blocks before you used the sledge? That seems like a better plan than finding a 5 HP industrial bandsaw, two guys and a hoist.
N B R
Nope just whacked away .The voivces in my head told me where to hit.
A picture is worth a thousand words! Thanks for a lot of hard work!!
What would you recommend to fill the belly area, any block repair epoxy?
Does the porting in front of the guide and tapering the guide help in any way to smooth the flow on the backside of the guide and port? Looks like a virtual 90* dead end turn there, and that some sort of radius would make the transition cleaner. Maybe build up the back top on the guide, or radius it concave front to back? Would it stay in position? Or would it matter? Just thinking out loud.
What would you recommend to fill the belly area, any block repair epoxy? # 1 Yup. #2 If I told you to much more I have to wack you .Good thinking but hard to do...... But not impossible.
hmmmmm...so that's (#2) do-able? Ha, c'mon, spill the beans. Modify the guide or the wall or both? Leave the guide high on the back, slopeing to the front? Don't want to steal any "speed secrets"
Yes you do. Everyone does.
I think this answers a lot, actually.
One clarification request & one question - when you say "belly" I assume you're referring to the bottom (as shown in your pics) - yes?
Question - how did you key your guides?
Looks like you could do it right through the lifter valley - sort of like drilling holes for the punch on an adjustable lifter? Might take a pretty creative tap wrench but maybe you drill and tap to 10/32 allin one shot with the guide in place? All guess work here - just looking a running on at the mouth.
A crazy person with access to a machine shop with an affinity for small interesting jobs could even come up with custom guides. Pre-shaped to fill in the majority of the port belly? Fill in the rest with block repair epoxy.
Ernie/Kevin, you're right! I missed that one sentence on the earlier post. Doesn't say that it has to be a "square" key, does it? Maybe drill/mill a vertical hole with the guide in place, centered on the guide/wall mating surface and pin it from the top? The old 8d nail trick. Build up the back of the guide to make the radius.
Kevin's idea sounds easier from a machining standpoint; sort of a set screw into the valley side of the guide, right?
Kevin - you'd be drilling up if I'm following you...short, compact right-angle drill maybe?
Almost seems easier to drill straight down from the valve bowl. A true masochist would broach in a square key though!
There are clues in an early 1960's flathead racecar feature involving a famous old builder in HRM...
Sooooo, what issue might that be in? Mine only go back to '64.
Pay-pal, money order or Nigerian bank cheque?
A square key could fall out? I think.
I'd drill a round hole, split between the block and quide. ream for a press fit on a dowel or a spring roll pin. Used to call this operation a "Dutch Pin"
Maybe if enought of you guys speak up I can come up with some new ideas to try.
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