Did the offset push-rod help much when porting? Seems most of the gains are in the pocket. No one really talks about the push-rod "pinch" when porting on the J heads.
Curious about AAR/TA Heads
- Thread starter Bodyperson
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I believe it depends on how much flow you are looking for and if you have enough motor to support that higher flow with your combination. Street motors need to flow only so much to operate low rpm and low speed operation as opposed to race motors that operate at wot in high rpm conditions.
Thank you for your response.
For you I shall rephrase my question. When porting a AAR/TA head for RACING did the offset push-rod help much when porting? Just a historic question for the people who have been there. Ya know, the guy that says "back in the day" LOL
PRH
Well-Known Member
It would make for an interesting dyno test.
Build something big enough, capable of making enough power to exploit any possible gains the pinch itself might offer.
Something like an 11-12:1 408/416, .600-ish lift cam, decent single plane intake, nice carb, 1-7/8” headers.
Take a set of TA heads and do a nice port job on them(260+), but don’t make the width at the pinch any bigger than what could be done safely without breaking through the pinch area of a non-TA J head.
Dyno test the motor.
Pull the heads, open the pinch area as much as is easily done without worry of breaking through with the TA configuration(no additional work...... only the pinch area)..... reinstall heads..... retest.
Build something big enough, capable of making enough power to exploit any possible gains the pinch itself might offer.
Something like an 11-12:1 408/416, .600-ish lift cam, decent single plane intake, nice carb, 1-7/8” headers.
Take a set of TA heads and do a nice port job on them(260+), but don’t make the width at the pinch any bigger than what could be done safely without breaking through the pinch area of a non-TA J head.
Dyno test the motor.
Pull the heads, open the pinch area as much as is easily done without worry of breaking through with the TA configuration(no additional work...... only the pinch area)..... reinstall heads..... retest.
PRH
Well-Known Member
Oh....... it wouldn’t surprise me one bit if that type of test was done “back in the day”.
There are plenty of people who like heavily porting OE iron a lot more than myself......... but for me, the biggest hurdle for big flow out of J heads is the SSR.
They go turbulent, then the numbers start backing up......and I haven’t found that more area at the pinch cures it.
So, I’d be interested in seeing if the added area at the pinch showed improvements on the dyno that I don’t see on the bench.
T/A heads
There are plenty of people who like heavily porting OE iron a lot more than myself......... but for me, the biggest hurdle for big flow out of J heads is the SSR.
They go turbulent, then the numbers start backing up......and I haven’t found that more area at the pinch cures it.
So, I’d be interested in seeing if the added area at the pinch showed improvements on the dyno that I don’t see on the bench.
T/A heads
Better off with after market aluminum heads or the indy cylinder heads iron ones, forget the name of them. If you must have mopar parts, w2 heads but then they require intake and headers to match. Best stock heads are 308’s. Swirl ports with closed chamber I believe. If you want to move the pushrods in any heads the hole can tubed (expensive). Alterating pushrod geometry is never a good thing, not that the mopar small block has real good geometry to begin with unless you have a 48 degree tappet bore angle R block to begin with.
You don't seem to understand or know the answer to my question. I'm not building anything here. Just CURIOUS.
I think most gains on most any head is in the bowl area. @MOPAROFFICIAL would be a good one to chime in. He's done a lot of work on stock type heads.
I agree. It seems the engineers went through a lot of work for nothing other than keeping their jobs by applying changes.
Wyrmrider
Well-Known Member
I agree with PHR
we had customers run the ta heads on road race and circle track
Would not use them today except for a restore job
if non ta heads you can sleeve the pushrod holes
but a lot of work for not much- unless rules require
we had customers run the ta heads on road race and circle track
Would not use them today except for a restore job
if non ta heads you can sleeve the pushrod holes
but a lot of work for not much- unless rules require
You'd have to install pretty large valves and open up the bowls a lot before the pinch of the pushrod becomes the limiting factor.
I'm guessing the T/A rules didn't allow moving pushrods so they had to cast them in.
Bob Mullen would move ports higher and wider by adding metal and moving pushrods to 340 heads for Pro stock and other high end racing which lead to the development of the W2.
I'm guessing the T/A rules didn't allow moving pushrods so they had to cast them in.
Bob Mullen would move ports higher and wider by adding metal and moving pushrods to 340 heads for Pro stock and other high end racing which lead to the development of the W2.
Hyper_pak
Old School Chrysler Fan
I think I understand your question, I don't know the answer. But here is a Glidden Arrow Pro Stock Head. Push rods have been moved.
Probably didnt even use a gasket between the ports.
IIRC ... Glidden ran W2s
pishta
I know I'm right....
What does tubing the pushrod hole do if your using the same rocker? do you use a narrow Cro-Mo pushrod or something? you barely got clearance in there for a 3/8, not sure I see a tubed pushrod holes worth?
yellow rose
Overnight Sensation
You beat me to it. lol
ok, yes back in the day it did but only with other modifications to the head or with slight improvement left stock. we are talking about a head that was on a car destined to be raced competitively.
Mopar LA Cylinder Head Comparison
Cylinder Heads Flow Data at 28" H2O
how do you know that is a Glidden Arrow pro stock head?
SSG_Karg
Enhanced member
Correction: that WAS a W2 head. That beast is a long ways past the way it was born.
gregcon
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The TA head was a minor 'tweak' that was sort of an 'easy to do' mod that might pick up a little HP after all the port work was done. It wasn't a 50HP, or better, deal.
I wouldn't pay a nickel more for a TA head unless I needed it for a resto. The minute I needed a better head than a stock 340....I'd be looking at W heads or aftermarket.
I wouldn't pay a nickel more for a TA head unless I needed it for a resto. The minute I needed a better head than a stock 340....I'd be looking at W heads or aftermarket.
Hyper_pak
Old School Chrysler Fan
A few pictures of Bob Glidden's Arrow motors have floated on the internet.
Opening the pinch doesn't make much difference unless you are making some real horsepower. We actually did a test like that on a pump gas 424ci/360 with the Indy/RHS LAX head. Calculations said the pushrod pinch would choke the engine @ 6,300 rpm............and it did make 620 HP there. Those heads have big pushrod holes so we plugged them and drilled smaller holes and opened the pinch. The engine jumped to 629 HP and held more power into the rpms. I've often wondered what would have happened if I had drilled the hole offset and used offset rockers to open the pinch even more.
Generally we've only opened the pinch to make it a bit easier to get to the more important areas in the port.
Generally we've only opened the pinch to make it a bit easier to get to the more important areas in the port.
PRH
Well-Known Member
Jim, 2 question’s......
1- did the wider pinch area show an improvement in flow on those heads?
2- 620hp vs 629hp peak to peak, but did the hp gap widen as the motor got higher into the powerband?
1- did the wider pinch area show an improvement in flow on those heads?
2- 620hp vs 629hp peak to peak, but did the hp gap widen as the motor got higher into the powerband?
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