T/A heads

[PRH]

i have a couple of sets of TA heads here.
This first set are just going on a mild street motor.

They had a fresh valve job, guides, resurfacing.
The surface job looked kinda like a very coarse mill bastard file.
Seats were done with stones(nothing wrong with that), but they could have dressed the stones a bit more often.
You can hardly even make out the angles.
If you look at the exhaust seats closely, you can see the width of the 45 seat varies quite a bit.

The guides were knurled on the intake, and the exhaust had 1/2” iron grooved replacements.
I’m not really fond of either of those, so I put liners in the intakes and swapped out the exhaust for 1/2” bronze.
They weren’t really here for any “performance enhancements”, but the intake bowl diameters varied quite a bit, and there was a slight step in the exhaust bowl after I installed the hardened exhaust seats.
I didn’t do any work at all to the runners....... just the most basic of a bowl blend.

Here is how they flowed as rec’d:
Lift———in/ex
.100—- 60/44
.200—-120/88
.300—-174/113
.400—-204/126
.450—-207/128
.500—-206/131
.550—-204/132
.600—-206/133

 

[PRH]

So, install new guides, and hardened exhaust seats.
Machine and finish grind seats(valve job), and mildly blend bowls....... along with a mild tweak of the short turn to help keep the flow from backing up over .450-.500 lift.
These are being paired with a .470-ish lift hyd cam...... and exhaust manifolds.

Lift———in/ex
.100—- 69/46
.200—-132/94
.300—-189/129
.400—-211/149
.450—-211/155
.500—-213/159
.550—-213/162
.600—-213/164

 

[replicaracer43]

Nice!

 

[abdywgn]

those pictures make me want to break out the die grinder and carbide bits. thanks for taking the time to test and share.

 

[PRH]

I’ll be working on another set fairly soon.
There’s probably a story behind those.
They’re also “done”, other than assy, but one is fairly ported, and the other has barely some bowl work done to it.
So, I’ll be working at trying to make them into more of a “pair”.

 

[yellow rose]

I thought you gave up grinding on iron!! Sometimes you gotta do what you gotta do.

 

[PRH]

It’s def not my favorite.

I don’t mind little jobs like this.

They’re pretty painless.

 

[512Stroker]

So, install new guides, and hardened exhaust seats.
Machine and finish grind seats(valve job), and mildly blend bowls....... along with a mild tweak of the short turn to help keep the flow from backing up over .450-.500 lift.
These are being paired with a .470-ish lift hyd cam...... and exhaust manifolds.

Lift———in/ex
.100—- 69/46
.200—-132/94
.300—-189/129
.400—-211/149
.450—-211/155
.500—-213/159
.550—-213/162
.600—-213/164

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Flow numbers look nice for no port work
Is the T/A head made by Indy?
Still in production?
Thanks for posting

 

[PRH]

Those are factory T/A-AAR 915 heads(going in a real T/A).

It’s not zero port work...... it’s a basic/mild bowl blend.

 

[512Stroker]

Those are factory T/A-AAR 915 heads(going in a real T/A).

It’s not zero port work...... it’s a basic/mild bowl blend.

I try to learn something everyday.
Job over for today.

 

[Hot Metal]

I managed to get a pair of T/A heads back in my day for the 340, thought they were better, spent a lot of time trying to get W2 rockers to work cos I never got the rockers with them, which I almost succeeded in doing, but motor kept spitting pushrods at over 6k rpm. Wish I would've known then that they were nothing special and the stock 2.02 heads I had were as good or better, mine didn't look anything as good as those with no bowl work just a lap in of the valves. No wonder I only made 368fwhp with them on a 10:1 340 with a .590" sft cam, race hdrs strip dominator and an 850DP.

 

[Cudafever]

Would be interesting to see what you tweaked on the st
Thanks for sharing!

 

[4spdragtop]

Thanks for sharing. I usually try and take a peek whenever there is some bowl/port work being done so I can learn/absorb.

 

[RustyRatRod]

You do some nice lookin work.

 

[famous bob]

You do some nice lookin work.

looks to me like a lot to be desired , ''not bad mouthing '', but you`d be surprised how something that u can hang ur fingernail on ''will and does'' affect flow !!
I`d smooth it up with no ridges !

 

[PRH]

Well, they’re all assembled and ready to go...... so nothing else is getting done.
I actually like having a little edge at the bottom of the valve job on the intake side. It helps re-atomize any fuel that’s sliding down the walls.
My leaving the edge there is intentional.

Originally, they weren’t going to get any blending at all...... so they’re better than they were.

As for the short turn....... basically i just put a nice radius where the floor transitions into the bowl.
I just got rid of the “cliff”.

Not every build warrants(or can take advantage of) a high effort porting job.

I figure the 12-15 cfm gains in the .200-.300 lift range, along with the modest gains at full lift....... with an increase in port volume that might amount to 2-3cc’s should work just fine in this application.

 

[Wyrmrider]

so basic bowl work includes the short turn?
I did a basic bowl blend as part o a valve job-
I do not consider it porting
agree wit you on the lip-great point
goes along with not polishing
wonder how those would wor with 30 degree seat on the intake
shows why cam does not need half inch lift
just a rolled over nose as application dependent duration increases
cheers

 

[PRH]

I work on a fair amount of stuff where any blending/porting/bowl work isn’t legal....... so I def don’t consider it as something that’s included as part of a “normal” head reconditioning.

On heads with fairly tall/steep short turns, if you don’t address the short turn to some degree as part of the bowl blending, you will often end up with less high lift flow than if you hadn’t done any porting.

If the bowl capacity exceeds the short turns capacity by enough, the air column starts skipping over the turn, and that effectively blocks off a portion of the bowl....... and the flow numbers start dropping as the lift increases.
On the stock port I tested, even the unblended bowl was overtaxing the stock short turn.

So, when I do the bowls...... I at least make some attempt at addressing the short turn to try and keep the flow backing up situation in check.

Sometimes there is still some minor flow regression though....... although it would be less than if the short turn hadn’t been tweaked.

One thing to keep in mind is, these stock heads can vary quite a bit in stock form.
I had a pair of factory 2.02 915’s off the same motor.......with only a fresh valve job, one flowed like 215....... the other only 196.
I’ve had some fairly low mile T/A heads here that still had the not-too-beat-up factory valves and valve job...... those were only 200cfm.

Also.....My experience has been that stock X heads typically outflow stock J heads.

 

[PRH]

For comparison...... some brand X stuff:

Last summer I did the same basic job to a set of 1969 Chevy 302 z-28 heads.
Those already had the exhaust seats installed, and whoever did them used a radius cutter for both intake and exhaust.

I recut both seats and blended the bowls, radiused the short turns, deburred the chambers adjacent to the valve seats.

As rec’d:
Lift———in/ex
.100—- 65/48
.200—-121/90
.300—-171/111
.400—-200/124
.450—-208/127
.500—-215/129
.550—-219/129
.600—-219/129

 

[PRH]

After reworking:

Lift———in/ex
.100—- 67/50
.200—-133/98
.300—-183/129
.400—-216/157
.450—-220/162
.500—-223/166
.550—-228/168
.600—-229/168

 

[gzig5]

I find it interesting that going from a smooth(ish) radius profile to a series of stepped flats on the valve seat improves the flow. Seems counter-intuitive to me, but I don't doubt the results you show.

 

[PRH]

Not using a radius for the intake seat isn’t about the flow.

It’s been pretty well established that the multi-angle intake seats make more power.

There could be exceptions to that, but without dyno testing every combo how would you know?
I take the approach that in most cases the multi-angle intake seat will be better...... so that’s what they get.

 

[PRH]

I’m starting in on the second set of T/A heads.
This is also a set of “finished” heads.
In fact, it appears they had already been assembled at one point....... as there were remnants of assy lube bunched up around the guides, down in the bowls.

A few odd things with these heads......
Someone painted pretty much the whole head with cast blast paint.
Inside, outside, the chambers, down in the ports....... everywhere.
I think they sat around and started to rust, and the paint was a quick way to hide it.

At some point, someone thought it would be a good idea to port these.
They got most of the way through the intake ports on one head...... then called it quits.
I’d say that whoever did the work on them last did some work in the bowls on both heads...... to blend the valve job into the bowls, along with a very slight touching of the SSR.
The first head(A) is the one that has only the bowl work, the second head(B) has had a fair amount of intake guide trimming, along with removing the pushrod bulge.

These heads have new guide liners installed already, and were supplied with new Milodon street series SS valves.

Head A-
Tested as rec’d, 4.00 bore, 28”:

Lift—— in/ex
.100— 62/45
.200—128/93
.300—186/128
.400—213/144
.450—213/150
.500—206/153
.550—210/157
.600—211/159

This head has basically the same type of job done to it as the previous heads in this thread....... valve job, minor bowl blend.

 

[Hyper_pak]

Can these numbers be compared to other head flow values? I know each bench varies, but were these done at a standard pressure? I have seen some slant six flow numbers and was wondering if it's apples to apples. Thanks for the data.

 

[PRH]

Head B-

Tested as rec’d, 4.00 bore, 28”:

Lift—— in/ex
.100— 62/46
.200—132/93
.300—194/129
.400—235/145
.450—243/150
.500—237/155
.550—233/157
.600—235/161