Flow numbers 492 heads

[Jerry G.]

Re: Flow numbers 492 heads

I lost the cam data along with the program, but I'm sure I have it in an e-mail. IIRC the cam was basically okay. In fact, most similar cams won't be much different. It's head flow, not the cam (within the range of typical racing cams of a given type) that make power.

So, assuming you dyno the engine, how about installing both a 30-30 retarded four degrees, and your existing cam. The 30-30 can use less valve spring than an aggressive solid roller. Then you can make the call as to whether the modest loss in performance with the 30-30 offsets all the valvetrain problems.

The 142 springs at 110 pounds on the seat would only be at about 270 pounds at .450" lift, which is what you get assuming a max rocker ratio of 1.44:1. That will sure reduce valvetrain loading.

To win, you have to finish!!!

I don't have a fax... can you scan and attach it to an email?

Duke

Duke...you have mail Jerry

[Clem Z.]

Re: Flow numbers 492 heads

http://www.freepatentsonline.com/5860398.pdf shows a flat tappet rev kit

[Tim S.]

Re: Flow numbers 492 heads

Duke / Jerry,

Do you feel the port work you came up with is fairly repeatable? I am plannig to jump into my 65 L76 for a 327 LT-1 project in the coming months. I must say, for stock (ported) castings, those strike me as some impressive flow numbers.

I have considered some "cheater heads" (epoxy) but I am a little sceptical of the 327 being able to make good power given the stock intake and exhaust manifolds. I have some other questions, but I will start a different thread.

Tim

[Duke W.]

Re: Flow numbers 492 heads

I don't recommend "full porting" for road engines. Review the Special 300 HP engine article in the Fall Corvette Restorer. The point it to improve the port flow coefficients, not make the ports bigger.

On a carbureted engine, larger ports can reduce port velocity, which can reduce low end torque and throttle response due to poor fuel vaporiation. They may be okay on FI engines because fuel distribution/atomization/vaporization is better than carbuerted engines.

Full porting is best for racing engines where the primary objective is peak average power in the upper third of the rev range.

See said article for representative flow numbers of SB pocket ported/port matched/chamber overhang relieved heads with both valve sets. This is what you want for a road engine.

Duke

[Jerry G.]

Re: Flow numbers 492 heads

http://www.freepatentsonline.com/5860398.pdf shows a flat tappet rev kit

WOW very elegent. Did you make these?

[Clem Z.]

Re: Flow numbers 492 heads

WOW very elegent. Did you make these?

not me i found them in a patent search for the rev kit for flat tappet cams. the NASCAR flat tappet rev kit used standard flat tappets with a ball bearing/spring combo that allowed to tappet to rotate. i got one of the GM NASCAR engineer looking into this for me.