The Aftermarket Cylinder Head Thread!!

[jon93PGT]

Yeah, we had that... Thanks though!

[Pintoracer]

ZE intake HLAs are 31mm, and the DE HLAs are 30mm....

Hey Jon,
I measured my HLAs today. I left the measurements at the shop but the difference between the intakes & exhaust was .118 inches. According to the shop owner the conversion from inches to mm is done by multiplying inches times 25.4

.118 X 25.4 = 2.9972 which could be rounded off to 3mm. Where did you come up with 1mm?

[elder GT]

There was a thread in the tech forum about a week ago saying the intake hla on a ze is 33mm. There was even a link to a parts listing showing this size....
The mystery continues.

[jon93PGT]

Hmmm, I don't know.... I never actually measured my HLAs.... I will bring them to work with me tomorrow night and measure them and post.......... I heard 31mm and just sort of assumed it to be true...

I'll verify tomorrow.

[jmmdm2]

i got suckered into buying some ze heads cheap, but had no hla's and could never get ahold of him.....so anyways for hla's my only source is millenia (int & ext) hla's from the dealer or??????

I had the same sort of issue... I received a few of the intake HLA's with my cheap set of ZE heads. I have a friend that had a parts set of ZE heads lying around with all the intake HLA's so I used those for my heads.

I do have a some leftover ZE HLA's hanging around here and with this sort of issue becoming more common... it's possible I am not the only one with some odd ZE intake HLA's lying around. I'm sure anyone reading this thread with some spares would be willing to contrbute to a full set for you.

I'll take a look around to see how many I have left and make sure they are in decent condition. They should be cleaned before installation (as in taken apart and cleaned).

I know this is going to raise a few eyebrows in concern... I don't like the idea of using parts such as HLA's that are not the same original HLA from one specific spot in the head.

I've been through the search for HLA's and after Mazda quoted me 54 each for Millenia HLA's, I kinda accepted the use of the used parts from where ever I could get them. I thought of the solid lifters from the 626 that were less money but then of course the cams become an issue.

Next... I see everyone is considering a spring that is the diameter of a DE spring on the ZE intake side. I'm assuming that the springs inner diameter is the contributing factor for safe usage on the ZE HLA. What I mean to say is... nothing is flopping around in there right? It has been done before with success several times I hope.

My ZE heads are at the shop now with a 3 angle valve job, back cut, bead blasted and I'll be introducing the Colt SS cams to the shop soon. I'll post some pics when I run down there to check the progress. This particular shop seemed to think a port and polish was not necessary and in the case of the ZE heads I believe that's true.

I would like to get more thoughts on polishing the combustion chambers though... might as well get it done while the heads are there if there's a valid reason for it. In addition, I've heard discussion of measuring each chamber make sure all are exact. I've seen this on the TV show "RIDES" and the heads were off a Lamborghini. Necessary for the KL?

Very informative thread guys! Nice to see these every so often.

[Pintoracer]

The owner of a local shop that does racing heads says there is very little to be gained with porting our 2.5 ltr. heads.

[jon93PGT]

Hey guys.. More great replies...

jmmdm2- As for your post.. I have a few comments.. As for used HLAs, no worries. After a good cleaning, they should be fine! And they don't even need to go back in the original bores, although it won't hurt to keep them organized.. Mine weren't.. As for using the DE spring on the ZE intake, its fine.. The spring seat in the head is a hair larger, and the HLA is bigger, but I was assured by both my machine shop and also Alistair at Interprep that this would NOT be a problem. As for your machine work, I'd look again at where you're spending your money. If you plan to boost, I would not recommend the 3 angle valve job. The extra heat will wear that seat out quicker, even though initial seat may be a hair tighter.. It will not last as long. Also, the stock valves already incorporate a back cut, so again, is it necessary? My machine shop did nothing more than grind the valves smooth and clean... They did a standard valve job and that was it... Spend how you like, but from my research, you'll be sort of wasting money...

As for port work on the heads, there is always the rule that "every little bit helps" but I cannot justify $1200 for a couple horsepower... Heck, even 10 hp... Not worth it in my book. The price of ZE heads over DE heads is about all that is worth it for the increase in port size.

As for what you saw on Rides. I saw that too.. What they are doing is measuring the volume of the combustion chamber incredibly accurately, and then making slight adjustments to the head as needed to ensure that ALL cylinders are exactly the same... This is for the guy with more money than brains, especially on a KL.. I can see doing it on a 3000 HP top fuel drag car, but for our application it is simply a waste of money. I do not know the cost of it, but its really not necessary..


Ken- I have my HLAs with me... I will be taking measurements tonight and posting them soon!

[jon93PGT]

Alright Guys........ Here are the HLA dimensions as requested... This should help those of you that want to cross over and look into solid lifters...

KL03 HLA size (same for intake and exhaust)
Overall Diameter- 1.180" or 29.97mm (this is the 30mm HLA)
Diameter at Oil Relief- 1.119" or 28.42mm
Oil Relief Depth- 0.030" or 0.77mm
Overall Height- 0.948" or 24.08mm

KLZE HLA size (intake, exhaust is the same as KL03 sizes above)
Overall Diameter- 1.298" or 32.96mm (this is the 33mm HLA)
Diameter at Oil Relief- 1.235" or 31.37mm
Oil Relief Depth- 0.031" or 0.80mm
Overall Height- 1.021" or 25.93mm




Take it for what its worth!

[Pintoracer]

Wow! For the overall diameter Jon & I came up with precisely the same measurements down to the thousandths of an inch. That's amazing considering there can be production tolerances in the parts & calibration differences in the measuring tools.

[jon93PGT]

Wow! For the overall diameter Jon & I came up with precisely the same measurements down to the thousandths of an inch. That's amazing considering there can be production tolerances in the parts & calibration differences in the measuring tools.

Yes, and even more so... I just grabbed one of the 12... I didn't bother measuring them all and averaging...

[jmmdm2]

I appreciate the comments, I'm relieved to hear another opinion about the use of HLA's from different cylinder heads.

How many people here have used the same head bolts in their rebuild? I want to know for certain now if I need to buy new head bolts rather than have that issue hold up the installation.

[Fastest95PGT]

How many people here have used the same head bolts in their rebuild? I want to know for certain now if I need to buy new head bolts rather than have that issue hold up the installation.

In the factory service manual there are size tolerances which the head bolts (and cam bearing caps and a couple others) should not exceed. I plan on re-using my head bolts if they are within spec.. I'm sure I've heard others re-use them also without trouble.

[rurockn]

I re-used my head bolts.

Also would like to comment that the millenia engine I owned had solid lifters, I am not sure of the specifics but I was also under the notion that 98+ 2.5L engines ALL had solid lifters due to warranty complaints of HLA ticking.

[jon93PGT]

Thanks for your replies guys... As for reusing head bolts, that is not a problem, as long as they are within spec, as was already said. Just make sure to double and triple check measurements..

[Pintoracer]

Too bad I didn't know about the head bolt spec a week ago. I just put my heads back on with new bolts.