can you use the aftermarket O/S valves (1.70" I, 1.44" E) mopar or otherwise in the later style peanut plug head with out needing to have new seats machined and put in? also has anyone used thease and if so are they any good?
http://cgi.ebay.com/ebaymotors/225-DODG ... 4450QQrdZ1


chris sutton

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1975 Plymouth Duster,225/6 2bbl. and duels, 904, 7 1/4
1986 Dodge Charger Shelby, 2.2 Turbo I, A525

Just get a new set of valves for a 300 CI <ford 6> They are about .010
longer stem length and have the proper size valve guides installed. you will have 1.88" intake and 1.56" exhaust

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Part of Tyrde-Browne Racing

The parts shown it that ebay auction will work in any SL6 head that currently has the stock valve size.

Anytime you increase valve size, the seats will need to be "remachined" to match the new valve. Doing the remachining work (regrinding) will usually cut below the factory's surface induction hardening treatment on the exhaust seats so it is best to use the special hard seat inserts on the exhaust valve seats.
DD

You need to be careful with exhaust valves that are over 1.500" My sons dart with a .030 overbore would not accept 1.540 valves without notching the top of the block. I thought the 300 - 6 intake valve was 1.780?? Anyway, others with more expertise will chime in.

Rick

i thought that the largest you could go on a stock bore and without needing notches was the 1.70,1.44? so the seats are not needed but highly recomended especially on the exhaust side?

chris sutton

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1975 Plymouth Duster,225/6 2bbl. and duels, 904, 7 1/4
1986 Dodge Charger Shelby, 2.2 Turbo I, A525

sick6 is running 1.88 and 1.5 with no notch, and I beleive .060 oversized pistons. take a look at the last few "aluminum head" threads

-dave

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what part of "illegal" is so confusing???

Years ago I mocked up a standard bore 225 block and head with 318 valves (1.78" and 1.5") and nothing hit. This doesn't mean they would flow well as the shrouding was probably pretty severe. The ported head I did used Ford 300 valves with the stock 1.78" intake, but I cut down the exhaust to 1.45" as the engine was only .030" overbore. With a .060" overbore 1.48" to 1.50" exhausts would have been fine. Bigger bore and relieved chambers are part of the key to making big valves work.

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Joshua

You really need to do a "mock-up" and get the head chambers well centered over the bores when the valve size starts getting really big.
The wide open production tolerances are why some users can make the same big valve combo. fit while other can't.

Truth is that the head ports and "shrouding" start becoming more of a restriction then the valve head size.
DD

I guarantee that you do not need an intake valve bigger than 1.70 to go fast.

Has sick6 ever had his motor running? Last I knew it had only been flowed on a bench.

I am very interested in seeing some hard performance numbers on that motor.

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Official Cookie and Mater Tormentor.

you and me both. I think he is moving right now and hasn't been here much

-dave

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what part of "illegal" is so confusing???

I used 1.72 intake 1.50 exhaust on the Valaint with a 60 overbore.

I radiussed the chambers and did my compression milling on the block to avoid shrouding and bore notching. I rollderover and checked for clearances before assembly (with no head gasket) There was a ton of clearance between v/vs and pistons.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

DD, you then recommend going to seat inserts with the 1.44 exhaust valve, weither its a stnandard cut or a 3 angle cut? GRT

Hard seats for the exhaust valves is a great improvement, doing this insures that you will not get valve recession. The hard seat inserts are not needed for the intake valves.

We have a special issue with the installation of hardened exhaust seats when using the oversize (1.44) valves.
The seats come in fractional OD sizes, 1 7/16 (1.437) and 1 1/2 (1.500) and we have had the 1.5 seats break into the water jacket and cause leakage problems.

It can be done but there are some "tricks" we use to keep from breaking into water.
When changing to OS valves, always try to raise the seats up into the combustion chamber. When regrinding seats onto the cast iron or when using the inserts, always keep them as high as possible, don't sink the seats into the head. The higher the valve is in the chamber, the better it will flow.
DD

My 1.5 seats sit up very high (I thot it was bad when I saw them) Keep in mind that this changes compression ratio. You will need to CC the chamber AFTER the valve work is done.(in my case I milled the block to get the CR I wanted after getting the head work done and the head CCd)

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I am only on here for a mintue so I will have to give you the short answer.

yes, it has been on an engine, just not mine. I actually copied a friend of mine (his name was brady stewart) specs for my head, however his head flows even better than mine for some reason. we have the same valves, milling, all of that but his still out flows me.

Unfortunalty I have since lost touch with him a couple years ago, and his phone and email no longer work. but I can give you a link to another person that has the bigger valves that both brady and I do:

http://www.225.ca/tech/s6rn04.htm

I beleive this may be where he first got the idea, and then guinea pigged a few heads to find out just how far it could go.

I can tell you that he had a hard time fine tuning it, but this was due to him experimenting with different carbs until he settled on a holley 600. after he found the magic combination it ran wonderful. the car was his only daily driver too.....

My head on the other hand will have to wait a bit untill I get this move finished and see what the finances will be after I get settled in.

I will let everyone know as soon as I can how it turns out.