300 hp N/A carb 2.8 V6 engine

[34blazer]

Wow, that's terrible

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[veekuusi]

So the "old" is a previously set of ported heads, not stockers, correct?

Do you have a set of stockers flowed on the same bench for comparison?

That looks like quite a bit of difference...

The "old" is a 3400 head ported by myself. Not a stock one , but ported.
I do not have a stock 3400 head flowed for comparison, but it would be interesting to have one.

[Guest]

The "old" is a 3400 head ported by myself. Not a stock one , but ported.
I do not have a stock 3400 head flowed for comparison, but it would be interesting to have one.

Yeah, I was just wondering how each set compared to a stock set.

[SappySE107]

It probably didn't help flow to start with the worst gen 3 heads, but to have the strongest rocker arm, the notches for the roller rockers weren't desired. Has nothing to do with what you are pointing at. If you round that off, id love to know how it flows for you. I always show a loss. Same valves for both tests? The race valves flow the worst unfortunately, but they are the strongest.

[Guest]

So which heads were the base? If they were the worst heads, why would one start with them?

[SappySE107]

I would like to see the CFM. Exhaust reminds me of flowing with and without a tube. Unless the valve job itself is that bad, I don't even know. That side is about the same across the board between castings. Also, I don't know what you ported to for the gasket or how much you opened up the intake port. I wasn't porting for max flow, especially since you are carb. Perhaps that is also part of your comparison. Same clay molded opening? Intake side I could see being the valve and not opening it up but the exhaust is baffling.

non roller heads are the worst castings to start with for flow or consistency between ports. Spent a lot of time modifying the combustion chamber around the valves because those aren't angle cut until the 3400 heads. The rocker arms he is using are 7/16 and required drilling those out. They aren't very long on the thread into the head so I didn't want to start with a thread that is .200" below the pad where the guide plate is sitting on. Why use 7/16" thread and then compromise it with less than optimal depth? I didn't say that I left the heads like that, but it was a lot more work to make them look like the newer heads and then do our work on top of it. That was all done, but had I known this was a flow comparison and not something to hold up to 8k RPM, I would have used different heads, and I would have done stage 3 porting. Probably would have mentioned the 3500 valves too, though we don't know how they take that RPM and spring pressure.

[Guest]

So these were early 3100 heads? I don't see why you wouldn't start with 3400 heads, or at least large port 3100 heads. Machine the pedestals down to the needed height and since timeserts were being installed, the height of the stock thread is irrelevant anyway due to the original thread being drilled out...

A high RPM engine would be supported a higher flowing head better. Low RPM driveability might suffer, but with the desired use of this engine I don't think low RPM drievability is of any concern. If the "race" valves flow so poorly, why wouldn't a different set be sources with better shape to promote better flow? I highly doubt any serious racer would trade off flow for... I'm not sure what... strength? Weight? Maybe 30 years ago, but not today with the valves that are available and for reasonable prices, considering the application.

[veekuusi]

"Could you give me the price for a pair of “stage-3 3400 cylinder heads”.
With Manley race valves but with out springs and retainers.
And the most important thing, with 7/16” rocker arm bolt threads.
The thread has to be opened to bigger rocker studs, and helicoil threads has
to be done.
I have done the 7/16” threads my self here to earlier heads, it is not so easy.
Therefore I prefer to make first the 7/16” threads and after that if the work has been
succesfully, ported the heads.
Maybe a professional machine shop like you, has more experience with the threads."

That is the original email sent to Wot Tech ,10-24-2015.
And I expected to get best 3400 heads .
But now it seems that I have got a bad flowing set of 3100 heads.

[34blazer]

Well, if you paid for 3400 heads, I think you should get 3400 heads....

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[SappySE107]

11/1/15
Hi! I am interested in your stage 2/3 3400 cylinder heads. With Manley race valves, but with out springs and retainers.
And if possible, the rocker arm studs should be 7/16\" studs.
It means that the thread should be helicoiled to 7/16\" threads.
What would be the price for a such pair of cylinder heads?

I need also other parts, like piston rings, gaskets and bearings ....
but lets do business first with the heads.

You remember me , racing a Ford Capri with 60degree V6 engine here in Finland.

[SappySE107]

Well, if you paid for 3400 heads, I think you should get 3400 heads....

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Noted. Same thing in 2000, totally different before then.

[34blazer]

Noted. Same thing in 2000, totally different before then.

I don't understand your statement.

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[Guest]

Noted. Same thing in 2000, totally different before then.

I think you're saying that all heads are the same for the 3100 and 3400 after 2000, which is correct as far as I've seen, but it sounds like you started with early 3100 heads, since ALL gen3 heads were "roller" after 1996, even the small port heads. It was only 1992 to 1994 small port 3100 heads that were not roller rocker heads.

[SappySE107]

So these were early 3100 heads? I don't see why you wouldn't start with 3400 heads, or at least large port 3100 heads. Machine the pedestals down to the needed height and since timeserts were being installed, the height of the stock thread is irrelevant anyway due to the original thread being drilled out...

A high RPM engine would be supported a higher flowing head better. Low RPM driveability might suffer, but with the desired use of this engine I don't think low RPM drievability is of any concern. If the "race" valves flow so poorly, why wouldn't a different set be sources with better shape to promote better flow? I highly doubt any serious racer would trade off flow for... I'm not sure what... strength? Weight? Maybe 30 years ago, but not today with the valves that are available and for reasonable prices, considering the application.

Machine the pedestals down? Interesting idea for sure, but not practical. It is the length of the threads on the stud to be concerned with, and how far it goes into those threads in the head. The cost to design valves far outweighs what this market supports. They are for strength alone, considering the limits to stock haven't been found it may not be necessary.

[SappySE107]

92? Look, this is my last post. Email me if you need more information. 94-95 are non roller. He doesn't need the roller, so what is important? 94-99 3100 have a 1.72" intake. Otherwise no difference to the 3400 heads. Machine the seats to 1.76 and use 1.76 valve, and now its the same thing as a 3400 heads. Port it, even better. My point on the heads I started with was the effort to get them to where they would be as 3400 heads to start with, and that my job would have been easier in doing so. If I am going to be told that 3100 heads aren't going to be acceptable in place of a 3400 with work, im simply not going to listen to it. I don't have to answer to any one but my customers. If my customer want to throw me under the bus without question, so be it. Have fun posting on this forum about it.