All Small Six 68 small log head porting

[chad]

"...see a lot of traffic and stop and go driving, therefore I am happy if I get as much low end torque as I can. As for the highway, I have a 2.79 gears in the rear end and cruising even in stock form now is sufficient for me. Or would you suggest..."
sometimes (all ways 4 me) the cheepest, easiest, quickest is golden - how bout tire diam change?
Ever use an on-line gear calculator? Plug in rpm, tires, rear gear, trani gear (drive line #s) and get different results? Better'na ride dwn a greased telephone pole...

 

[clochard68]

A little question regarding valve guides: how do you guys measure the wear of your valve guides?

I have new valves and put them in the old valve guides, opened the valves a little (~1/5 inch), then measured the distance the valve head can move with a dial gauge. How much of a distance is acceptable, and at what opnening height of the valve does it make sense to measure?
Or is there a better way to test it?

I don't have a tool to measure the inner diameter exactly at the moment. Would that be the best way to determine the wear?

 

[B RON CO]

Hi, just to see if the guide is really worn, you can insert the valve and put your finger tip over the top of the guide. As you pull the valve out, there should be enough suction created to snap the valve back when you let go. If the valve won't snap back the guide is worn. This is just a quick check and no substitute for an inside measurement on a quality engine rebuild. Good luck

 

[clochard68]

B RON CO, should I do this test with an oiled or dry valve stem?

 

[chad]

head machined for the newer guides or still the ol umbrella type?

 

[clochard68]

I purchased the positive valve stem seals in the photo since I'm going to install double valve springs.
But at first I want to check if the valve guide replacement is absolutely necessary. I don't have a trusted machine shop yet, so I want to (at least at first) test for myself if the valve guides need replacement. It is a small log head after all...

 

[B RON CO]

Hi, try the quick test with a little oil, but wipe it off with a rag so the stem is not bone dry. If the new valve is wobbling in the guide the guide is worn and you will burn oil. Good luck

 

[bubba22349]

You can measure the valve stems with a mich or calipers and the valve guides with a snap gauge. After you have done lots of heads you can actually feel the valve clearance in the guides by wiggling the valve, turned around 180 degrees in the guide makes it easier. If you have from .0008 to .0015 of clearance you should be ok i shoot for about .0010. X2 With excessive valve stem clearance you will pull oil into the combustion chambers. Good luck

 

[chad]

"...pull oil into the combustion chambers..."
smokey runnin~

 

[clochard68]

Thanks B RON CO, I did the "slightly oiled" test and it "plops" quite nice . When I find a reliable machine shop in my area I will def. talk to the machinist also if valve guide replacement is necessary.

One more general question about pulling oil into the chambers as bubba and chad mentioned: If I use positive valve stem seals as pictured above that sit very thight on the guides, wouldn't that hinder the oil getting pulled into the cylinders even with severe worn guides?

 

[gb500]

Mopar, ( Chrysler) in their factory repair manuals fir the 1960's/1970's small block v8 ie 318/360 (cast iron pushrod heads) give a wobble test figure of 0.017 " ( 17 thou) for the valve when at full lift as max wear of the guides ie 8.5 thou each way .
Can google it.
Note this equates to about 7 thou guide /valve wear.

Ive measured guide and valve wear myself with a micrometer for the valve stems. And a cheap $25 ebay adjustable ball guage ( and micrometer)for the guides.

 

[chad]

those guides R for heads machined first, not oe "umbrella". I'm, yet again ( so common, 's how I grow) confused~
8^ 0

 

[clochard68]

Hello chad, yes the guides are somewhat machined. I guess somebody wanted to install positive valve stem seals. I tried the Comp Cams Viton 0.530 and the Teflon P.C. Vlaves 0.500 on the machined guides, but both were just a little to large to fit properly. Thats why I purchased the blue full rubber Viton seals I posted above, the have an ID of 0.475 and sit snug over the guide.

One more thing I have to do is machine down the little step I have at the spring seat that was initially there because I had single springs installed. So I got the comp cams spring seat cutter which has an 0.630 ID. I measured that the inner spring of my dual valve spring set from clay smith cams has an 0.680 ID. So I am going to machine the spring seat down to a close flush surface that both the inner and outer spring sit on the same seat plane as shown in my drawing (arrows).

The inner spring is shorter than the outer spring, is that compensated by the retainer geometry?
I have two type of retainers:
1) from the falcon handbook the suggested OEM Ford E6TZ6A536-A retainer
2) clay smith cams retainer fro double springs

I guess the Ford retainer is only designed for single springs? I would like to use the Ford ones as they are lighter than the clay smith ones, but I am unsure if the geometry is adequate for the inner spring? What would the forum suggest?

 

[drag-200stang]

Use the springs that are recommended by the cam designer.

 

[chad]

2X^^^^

 

[clochard68]

Cam is still the stock cam.
I have 1.65 roller rockers, that's why I chose the double spring to prevent valve float.

I also have a set of single springs B6A-6513-A from national parts depot, but have not yet tested the seat and open pressure. Maybe these are a better alternative for the dual springs?

I will not rev the motor above 5000rpm, maybe the dual springs are too much. On the old fordsix.com tech articles dual springs are always recommended when using higher ratio rocker arms...

 

[pmuller9]

Cam is still the stock cam.
I have 1.65 roller rockers, that's why I chose the double spring to prevent valve float.

do not use more spring than needed for sake of valvetrain longevity.
If you are staying with the stock cam use a single spring.

What is the height under the retainer to the spring seat on the head?
I'm assuming the first step under the retainer and the step on the head is just under 1.00" in diameter?

 

[clochard68]

pmuller9 you are right, the installed height of the spring is around 1.67" and the diameter of the first seat step is 0.968".

In the falcon handbook they have a chart where they measured spring pressures at open 1.22" and closed 1.59":
78 up stock 200 springs: 150 lb open (1.22")
54 lb closed (1.59")
73-75 302 V8 springs: 200 lb open (1.22") --> recommended springs by the falcon handbook for better valve control
80 lb closed (1.59")

For the double springs I calculated from the values that I could find online that they should be around:
200-205 lb open (1.22")
75-80 lb closed (1.59")

My installed height is higher than 1.59", so the closed pressure should be even lower.
Anyhow I will try to get both my spring types tested tomorrow if possible to see what the real numbers are.
I get the idea that most of you think the double springs are not a good idea, even with 1.65 rockers?

PS: measurements in the pictures are in mm

 

[pmuller9]

It looks like the installed height is close to 1.7"
If that is the case use the Comp 903 spring which will give you 80 lbs closed @ 1.7" and 190 lbs open @ 1.319" or .381" valve lift.

 

[clochard68]

pmuller9 thanks for the suggestion of the comp springs! I couldn’t find a machine shop I my town who has a valve spring tester, but one shop said they can try to measure it with a bench drill and a scale. I will visit this shop tomorrow and will post the result for the dual springs afterwards.

I hope that the installed height pressure is below 100 psi. Otherwise I will machine the valve seat down a bit. Maybe I sound stubborn but I really want to install the double springs if possible because of their harmonic advantages. I will post an update on the measured spring pressures as soon as I get the numbers…