[tom s]

I have a friend with a 61 SD NASCAR alu 4 bbl intake.If you use the 60 timing cover you would have to plug the water donut in the intake.It is a 55-60 water pattern and is a slight hi rise like a RA IV.Let me know if you might be interested.Also the 991 2-4 intake will work on 60 heads.Tom

[25stevem]

Gavin here are stock flow numbers from this head.

I freshened up the valve job.

These numbers are @ 28” and was taken on a 4”” bore adapter.

First column is intake flow. Second exh flow.

.050”. 33.4. //22
.100”. 45.7. //47.4
.150”. 104.7. // 70.5
.200”. 133.2. // 94.8
.250”. 150.3. //108.4
.300”. 155. //119.2
.350”. 158.8. //127.4
.400”. 159.7. //131
.450”.//////////////-131.8
.500.///////////////- 133.

The overall exh to intake ratio up to .500” is 78%

This exh flow test was done on a end exh port.
Tomorrow I will flow test a center exh port, so these numbers will drop as they always do.

[25stevem]

Sorry, this is a 1963 head with the 1.88", 1.600" valves.

[gavin]

Thanks for the info. I’m pretty sure he will using an early tri power. I can make up radius entry plates to have a look at different flows in the intake manifold ports when on the head. Being a low rise design there may some in flow improvement in the manifold ports after finishing head porting.

[peters23]

Here is a summary of what I have accomplished to date with the 1960 heads.

I am using ARP 290-7201 rocker studs which do require significant modification. Butler does have some BBC style studs without the hex part but you need to helicoil for these and I am not sure how well helicoils work in partially supported holes. There are threads that will get picked up on the insides of the oil gallery to help support the studs. I ended up taking 0.100 off of the stud bosses to account for the hex head area.

From what I can tell the (Howards Cams 90007) SBC rockers match the Pontiac in terms of fulcrum length on the valve side (and so must be the same on the pushrod side, but height could differ), from pattern testing, with rocker set at stock height above the stud boss.

I got all of the stud holes drilled and tapped, using custom (11 degree) angle plates on my Rockwell mill. 20 degree plates were used to do the valve guide mods. I did have to consistently shim one head about 0.020 more than the other, which indicates a difference of 1/4 degree on the tilt of the studs and valves from factory tolerances (I did not attempt to fix).

The valve guides were cut down .075 to allow room for the tops of the 530 seals. That should handle lift of .455 without interference using stock style retainers and keepers. Plus .050 keepers can be used to raise the retainers for higher lifts, although from 25stevem tests it seems as you don't get much more flow over 0.400 lift, so probably best to stick with stock cam profiles.

[gavin]

Was looking at spotts straight stud kit with half”thread on bottom. Would these not work in with this head? I have a mill so can copy your method.. the other thought I had was using vortec long slot guided rockers so no need for guide plates if pushrod holes are worn. I wait with interest on your progress. Thanks for shearing.Gavin.

[gavin]

To be clear sbc rockers can be had in 7/16” but I have yet to find vortec rockers (in stock style) in 7/16”. I am hopping these can be used with the spotts studs.

[peters23]

gavin, not sure which Scotts (ebay fbpaul) stud you reference but this one looks to be the next best solution on these heads and might work without mods. You will need to use helicoils with these. If you are able to minimize any cutting down of the bosses there will be more meat for the helicoils. Its probably good idea to face off the bosses a bit.

https://www.ebay.com/itm/275061640877

I am not familiar with the Voretec engines but thought 7/16 studs were used on certain SBC engines, and are popular with racers, so there are some aftermarket products out there. Below is a roller tip product (Sportsman #57583520) I may end up using.

https://www.speedwaymotors.com/Small...tud,32740.html

Some tips on drilling/tapping, especially for the ARP studs...

I would recommend doing this on a milling machine. They do make these 2-hole alignment blocks that could potentially be used but will not be very precise.

Use a dowel pin to roughly locate the original hole, ideally use indicator to find true center and do all ops at that location.

Drill into the oil gallery to the bottom and maybe spot 1/16" or so into the bottom. You do not want to drill though.

Use a combination of a plug tab followed by a bottoming tap to get as many threads in as you can. It will feel a bit rough when tapping near the bottom of the gallery, that is normal, as you do not have full engagement.

If using helicoils you need to use special helicoil taps, not sure if these come in bottoming style. You can grind down the tip of the tap to get further down.

[25stevem]

Hi gang!
I just got done flow testing a stock center exh port in this head.

I used clay to close off the crossover and dimensioned and shaped it to match a end port as best as I could.

Note that this port had a bit less casting crap in it then my first test on then end exh port.
As such and to my surprise allowed it to flow better .

The first column here are the numbers from the end exh port, the second column is the center port.

.050”. 22/////23.3
.100”. 47.4/////50
.150”. 70.5/////74
.200”. 94.8/////95.4
.250”. 108.4/////113.2
.300”. 119.2/////125.2
..350”. 127.4////130.3
.400”. 131/////133.7
.450”. 131.8/////134.4
.500”. 133.3

I will be moving on to a light bowl porting job on a intake port tomorrow.

[25stevem]

Boy!
I never realized that you just can’t use a 65 and later intake on these 64 and earlier heads.

[25stevem]

I had some time this morning to do some work on the center exh port so here are the details and flow results.
The first thing I did was to polish out the whole port of rust scale and casting nubs but for the rear of the bowl where I had closed off the exh cross over with clay.

As you can see from the photos the wall finish is still far from a 100% normal finish polish job.

The out side wall of the runner pinches in gradually on the roof as it approaches the flange .

This dimension/ width is 1.110” on the floor and tapers down to only 1.00” wide on the roof.
This is a pretty good restriction!

I ground this taper out and blended it in on back in to the runner opposite the head bolt boss as can be seen in a photo here.

I next attacked the head bolt boss itself.
Stock width here is 1.300”, and I ground it wider by .045”.
Next at the boss I reworked the taper from the boss on down to the roof .
The stock height here is .917”, I cut back this taper to .970” which is all you can do while leaving enough meat there to hold up.

What would be best is to weld enough on top on the outside of the head to allow the head near full removal of that taper!
Due to the way air enters the valve bowl at high lift this is a very active side of the port!

Next I did work on the short turn in the valve bowl.
On the intake valve side of the short turn I ground that side into much more of a D shape .

All grinding work that I did was then polished out and a long strip of belt type 80 grit was run thru the port and out the valve bowl as used to clean up and smooth out the other wise hard to reach short turn area.

Here are the flow results from what amounted to about 35 minutes of work.

The first column is the stock flow, the second is with the 35 minutes of work, and the 3rd column is the amount of flow gain over stock.

.050”. 23.3/////24.3::::::1
.100”. 50/////////49.7::::::-.3
.150”. 74.///////76.1:::::::2.1
.200”. 95.4/////97.8::::2.4
.250”. 113.2//////121.8::::8.6
.300”. 125.2/////138.2::::13
.350”. 130.3/////147::::::16.7
.400”. 133.7/////154:::::20.3
.450”. 134.4/////158::::::23.6
.500”. 134.4/////160::::::25.6
.550”. 134.4//////161:::::::26.6

[gavin]

That’s quite a significant flow increase particularly still using the small valves. I will be closely watching and following your lead.I can’t start on my heads just yet as I have a couple of other engines to work on first. It is a shame about later manifolds not being usable as it does cut your options. Thank you for posting.

[gavin]

Yes they are the ones I was looking at. I will investigate the helicoils. I will not be starting just yet so I will have time to see what you work out. Thanks for the info.

[25stevem]

Hi all!
I had some time this afternoon to do some work on a intake port.

On this one I did a light runner clean up and a light bowl port and blend in job.

Here’s the report.

The first column are the reworked numbers @28” and the second is the flow gain .

.050”. 40.7/////7.3
.100”. 74.8/////4.7
.150”. 112.7/////7.8
.200”. 144.7/////11.9
.250”. 160/////9.7
.300”. 173////18
.350. 175.8/////17

[gavin]

Quite nice gains for minor work. Thanks.

[Ducks Goat]

Originally Posted by tom s

I have a friend with a 61 SD NASCAR alu 4 bbl intake.If you use the 60 timing cover you would have to plug the water donut in the intake.It is a 55-60 water pattern and is a slight hi rise like a RA IV.Let me know if you might be interested.Also the 991 2-4 intake will work on 60 heads.Tom

Tom do you have any idea what your friend may what for the 4bbl intake? Thanks.

[25stevem]

Sorry that it’s been so long that I reported back on my continuing porting results on these 345 heads.

Here’s the current flow numbers and the flow increases over stock.
I am at the point now with the near 40 cfm increase out of these 389 heads that it does not pay to put more effort into porting them without stepping up to a 1.66” valve size.

When I post back again this will part of the next rework.

Note that as of now this center exh port is flowing 10 cfm more at .300” lift then what the stock exh port was flowing up at .450” lift.

The only difference between these flow numbers and my last posted batch was a further rework of the short turn.

As you can see in the photos the short turn all the way around to near the crown of the short turn was made into more of a D shape from the pinched in C shape that was there on that stock intake valve side of the exh valve bowl.

Note that I still have not gasket matched the exh port yet which is usually the first thing that naive folks with a grinder in hand go for!

First column, flow at 28”
Second column, flow gain over stock.

.050”. 27/////+3.7 cfm
.100”. 51.3//////+1.3 cfm
.150”. 76.9//////+2.9 cfm
.200”. 101.3//////+5.9 cfm
.250”. 125.5//////+12.3 cfm
.300”. 144//////+18.8 cfm
.350”. 157.5////+27.3 cfm
.400”. 163.4//////+29.7 cfm
.450”. 166.4//////+32 cfm
.500”. 169.4/////:+35 cfm
.550”. 171.3//////+36.9 cfm

[25stevem]

Ok I am back with more, but I changed my mind.

Instead of continuing with more exh port work I figured I would change over to the intake side since I had the exh port flowing within 4 cfm of a stock intake port.

From the photo you can see that I trimmed and boat tailed the valve guide a good amount.

Also I increase the throat size from its stock 1.420” ( 75.5% of 1.88” ) up to 1.470.

I also kicked over the common wall by .015” and I rolled over the lip of the short turn enough to blend it back into the floor.

I light blend was done in the valve bowl, but as you can see everything is still ruff cut.

I also recut the valve seat to a OD of 1.870”
I put in more 60 degree bottom cut to decrease the width of the seat down to .065”.

First column = flow @ 28”
Second column = flow gain over stock.

.050”. 46.6/////13.2
.100”. 78/////7.8
.150”. 115.7/////11
.200”. 136.8/////3.6
.250”. 159.4////9.4
.300”. 175.5////20.5
.350”. 182////23.2
.400”. 183.2////23.5
.450”. 184////24.3

[25stevem]

I got more porting time in on the intake in these heads last evening so here are the results and some photos.

This intake port is now flowing more at .350” lift then it was at .450” in the last test.
.050”. 46.6////47.2//+.6

.100”. 78////78.3//+.3///72.2

.150”. 115.7////115.8//-.1//108.8

.200”. 136.8////137.9//+1.1//134.6

.250”. 159.4////162.2//+2.8

.300”. 175.5////181//+5.5//175.6

.350”. 182////189.5//+7.5//190

.400”. ////////////////////////////199


Once again it’s all still ruff cut work.
I increased the throat size from 1.456” to 1.550” as seen in the photo.
The upper bowl area and the transition to the window area will allow a 1.60” template to go in there as can be seen in one photo.
The common wall has been cut back a bit more and the valve guide narrowed down more also.

Note the new short turn arc which still needs to be layed back more to put it into the needed arc.

The first column is flow from where I left off with the last post.
The second is the flow from this rework.
The third is the amount of flow gain.
The fourth column is the stock flow from the intake port in a #15 casting with its stock 1.960” valve.

[25stevem]

Hi all!
I have a report on the latest work I have done to these 389 # 345 castings .
This will show why it pays to have a Mule head to work on!
With the 1.88” valve and the throat size I am at now ( 85%) it just does not pay to go any larger.

I am at the point where reaching for more higher lift flow is making for some pretty good flow losses at lower lifts.
My next move will be to step up the the later 1.920” valve size.

Here are the stock flow numbers in the first column, and my current numbers in the second column.

.050”. 33.4/////33

.100”. 70.2/////67

.150”. 104.8/////101.9

.200”. 133.2////133.8

.250”. 150.3/////160.6

.300”. 155/////179.6

.350”. 158.7/////184.3

.400”. 159.7/////190.8

.450”//////////////////191.4