440 motorhome build- 30 degree intake seat?

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mgoblue9798
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440 motorhome build- 30 degree intake seat?

Post by mgoblue9798 »

I am building a 440 mopar for my old Travco. I will be using the top end of a 413 industrial motor. Heads are a 90 cc closed chamber with small valves- 1.88 and 1.5. Motor will be all done at 4.5 k. Using Mike Jones's RV cam made for the 440 202 @50 and 450 lift. Would this combo benefit from a 30 degree intake seat and slightly larger intake valve? Thank you all in advance for your input.
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Re: 440 motorhome build- 30 degree intake seat?

Post by Geoff2 »

Yes, 30* intake seat would be good for this application. Unless you install new intake seat inserts, you will have to use a larger valve because you need to find metal for the 30* seat that isn't there now. D. Vizard has written about the 30* benefit, you can probably find online.
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Re: 440 motorhome build- 30 degree intake seat?

Post by mag2555 »

Hi!
What is the overall length of your stock valves?
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Re: 440 motorhome build- 30 degree intake seat?

Post by mag2555 »

Wow!
That motor with those heads are way way undervalved even just considering a 4” bore size, no less the stock 4.250” bore size!

The 30 degree change is a good up grade for your motor and it’s intended use, especially since with the Cam your running being done by 4500 rpm you will not have overlap reversion issues to be concerned about as responders to your post will likely have a wrong opinion about for your type of build!

If your current 1.88” intake valve had a 30 degree seat then at lifts up to about .150” ( maybe more depending on the valve job applied ) that valve size would flow as if it had the curtain area of 2.25” valve in that low lift range!

Can you post some pictures of those chambers with the valves out, as I am interested to see if those chambers are like the 516 head casting?

One thing that’s for sure is that since you will likely need new exh valves also I would have all the guides converted over from the restrictive 3/8” ( .372” ) valve stems down to
11/32” ( .342”) while your at it!

I have to look deeper into it later today, but if you convert to the smaller valve guides you might be able to run
a Pontiac 1.92” x 4.980” valve with its 30 degree seat for the intake, and a Pontiac 1.66” exh valve also, both with minimal rework other then cutting the seats.

A SBC 1.625” x 4.916” exh valve looks like it would work well also.
I will get out to the shop and check things out later for you!
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Re: 440 motorhome build- 30 degree intake seat?

Post by mag2555 »

Sorry, I see your stock bore is 4.320”, not 4.250”.
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Re: 440 motorhome build- 30 degree intake seat?

Post by ClassAct »

There is no reason to use a 30 degree seat. Ever. They look good on a flow bench and that’s about it. Since the argue anything and everything crowd will chime in and tell you how stupid I am, think this through. Chrysler wasn’t stupid. And they didn’t bother with a 30* seat. Do you think they just said oh well, we are all tooled up for 45’s so let’s send it? You can bet they looked into it and didn’t do it. It’s all about the shape. And a 30* seat has a horrible shape.
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Re: 440 motorhome build- 30 degree intake seat?

Post by rebelrouser »

I have never done a back to back test of 45 degree seat to a 30 degree seat, but just looking at OEM engineering on a lot of older gasoline and even modern diesel engine which make torque and HP in the lower rpm range, many had 30 degree seats. A Dodge Cummins engine for example has an RPM limit of around 3,000 rpm and it has 30 degree intake seats for example. Lots of older GM and AMC V-8's also had 30 degree valve seats. And I would think, some changes may need to be made in the port shape to make the change from 45 to 30 degree seats. I did go the other way on a couple AMC engines but we were mud racing and raising the rpm level of the engines, they both ran very well, much better than the way they did before, but I have no data except flow bench that it was of advantage. And a lot of other changes were made so it was not a valid test of just the seat angles. Those heads did lose flow in the lower lifts, but picked up a lot in the higher lifts.
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Re: 440 motorhome build- 30 degree intake seat?

Post by mag2555 »

There you are!
I was waiting for you once again to make your no merit comment disparaging 30 degree seats!
I and many others ( by means of iron heads no less ) have produced well over 650 hp while running 30 degree intake seats , so I hope you don’t mind that myself and others continue to do so when we care to and not listen to you!

Stop misguiding people when there just looking for a simple motorhome up grade build
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Re: 440 motorhome build- 30 degree intake seat?

Post by Kenny M »

I did a back to back same heads Hot off the Dyno, in the 80s on a Show Room Stock IMSA L69 305 engine. 45 then the 30
The results acted as if i retarded the camshaft. Lost a couple down low, gained a couple upstairs. The averages were the same.
This was with a .410 lift camshaft. What i did noticed was a white fog on the intake valve side of the cylinder wall, when i removed the heads after running the 30. The 30 is pulling the fuel more to the cylinder side than the center of the bore.
It may have not helped because of such a small bore size 3.735
I have always wanted to retry the test on a large bore engine.
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Re: 440 motorhome build- 30 degree intake seat?

Post by In-Tech »

I appreciate all of the comments above as these are your results of trial and error and stupidness. If you gain low lift flow you have to change valve events to take advantage, you cannot just change one thing and expect EVERYTHING. Making 186 cfm at .300 with a 1.600 ex valve is not trivial but you will find you need a faster rocker and at least 12 degrees less exhaust duration @ .050" along with a quicker closing event. MASSIVE torque improvements can be had in the rpm range you wish for.

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Re: 440 motorhome build- 30 degree intake seat?

Post by mt-engines »

mag2555 wrote: Sun Jan 09, 2022 12:05 pm There you are!
I was waiting for you once again to make your no merit comment disparaging 30 degree seats!
I and many others ( by means of iron heads no less ) have produced well over 650 hp while running 30 degree intake seats , so I hope you don’t mind that myself and others continue to do so when we care to and not listen to you!

Stop misguiding people when there just looking for a simple motorhome up grade build
You would have made 700 with a 45 degree seat.
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Re: 440 motorhome build- 30 degree intake seat?

Post by BCjohnny »

I see absolutely no benefit with complicating things by changing seat angles

With what you're trying to achieve I'd get the heads worked over properly ...... pressure/crack test, guides, seals & surface ....... and go to a slightly larger inlet & exhaust valve such that you can achieve a good throat shape, blending the top and bottom cuts as needed

The only thing you'd need to consider is if the 413 heads have hardened exhausts (some versions were made into the late '70s IIRC) as, although I'm not a big fan of recommending fitting them for every build, on an RV I'd consider them pretty much essential

JMO
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Re: 440 motorhome build- 30 degree intake seat?

Post by mgoblue9798 »

I kinda suspected I might be opening a can of worms based on reading some previous posts on the issue. I am not a professional engine builder so I brought the question to those that do this for a living. I know David Vizard and Steve Dulcich have shown improved flow with the 30 seat, but does it translate into improved torque output on the road?

Idea behind this build is rock solid reliability under extreme conditions towing 6k or so behind a 10k RV in the mountains out west. Second goal is budget thus using the 440 shortblock and these heads I already have. Third is hopefully being able to use 87 octane gas for the most part.

The heads are purpose build for the 413-3 chrysler industrial motors. As is they are a closed 90 cc chamber head that will give me quench with the 440 I have with 6pack pistons at zero deck. They also have water running straight from the head to the giant water pump housing that bolts directly to them and the block. They flowed well enough on the factory 413 with its tiny 192 @.050 cam to make 480 torque at 2400 and 265 hp at 4200.

They also have sodium filled exhaust valves and hardened seat inserts from the factory. Exh valves, seats and guides are in excellent shape and will be reused. I am open to changing the intake and will have to do so if I use a 30 degree seat on the intake.


I'll go out to the shop and take some pics and measurements later this afternoon.





Wow!
That motor with those heads are way way undervalved even just considering a 4” bore size, no less the stock 4.250” bore size!

The 30 degree change is a good up grade for your motor and it’s intended use, especially since with the Cam your running being done by 4500 rpm you will not have overlap reversion issues to be concerned about as responders to your post will likely have a wrong opinion about for your type of build!

If your current 1.88” intake valve had a 30 degree seat then at lifts up to about .150” ( maybe more depending on the valve job applied ) that valve size would flow as if it had the curtain area of 2.25” valve in that low lift range!

Can you post some pictures of those chambers with the valves out, as I am interested to see if those chambers are like the 516 head casting?

One thing that’s for sure is that since you will likely need new exh valves also I would have all the guides converted over from the restrictive 3/8” ( .372” ) valve stems down to
11/32” ( .342”) while your at it!

I have to look deeper into it later today, but if you convert to the smaller valve guides you might be able to run
a Pontiac 1.92” x 4.980” valve with its 30 degree seat for the intake, and a Pontiac 1.66” exh valve also, both with minimal rework other then cutting the seats.

A SBC 1.625” x 4.916” exh valve looks like it would work well also.
I will get out to the shop and check things out later for you!
[/quote]
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Re: 440 motorhome build- 30 degree intake seat?

Post by modok »

30 seats can work well if the valve lift is very low.
Can also work well when the valve shrouding is too "open" but these heads i don't know if they qualify for that.

Why is it 30 or 45? The angle can be anything you want. 37 is a nice angle
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Re: 440 motorhome build- 30 degree intake seat?

Post by mgoblue9798 »

mag2555 wrote: Sun Jan 09, 2022 6:06 am Hi!
What is the overall length of your stock valves?
Stock valves are 5.668 in length.
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