Anyone have any flow data for casting 186 heads, 64 cc and 1.94 and 1.50

Stock 186 with 1.94/1.5" valves

Lift" - Int. / Exh.

0.050 - 25.4 / 24.8
0.100 - 54.0 / 42.0
0.150 - 76.4 / 59.5
0.200 - 103.0 / 73.0
0.250 - 125.3 / 89.8
0.300 - 150.0 / 104.3
0.350 - 168.2 / 112.0
0.400 - 177.9 / 118.7
0.450 - 177.9 / 121.2
0.500 - 178.8 / 122.2

Notice how the flow does not get much better after 0.400" lift. This is due mostly to valve shrouding.

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www.grapeaperacing.com (http://www.grapeaperacing.com)

Thanks for the help. I can see now just how bad my heads really are.

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the 186 heads are very good factory peices, with some pocket porting they can almost out do the famous turbo heads(they actually do below .400 lift). 186 heads are very good for the street,the motor will be very responsive and torquey.with about 7-10 hours of your time you can add about 20 h.p. to those heads and extend the rpm range 500-1000 rpm more.pocket porting is easy if you have patience and a steady hand.

sldhd is right, a simple pocket porting can easily add 20 hp. You can get a kit from Standard Abrasives through Summit or Jegs that wil give you what you'll need to do a set of heads. They also give you an instuction sheet to guide you through a basic pocket porting. Do that with a 3 angle valve job and 20 hp or so is cheap.

If you want more than that, the cost start going up. Those heads can actually make some good power, but a flow bench is a must if you really want to rework the ports. With the aftermarket today, it usually not worth the cost or trouble.

I have some bench data around somewhere on 186's that had minor port work done with a 3 angle valve job, but I can't find them. When I do I'll post the #'s and the specific mods that were done.

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www.grapeaperacing.com (http://www.grapeaperacing.com)

Thanks all for the help. Its been a long time putting a motor together. In high school it was just a big cam, 4bbl and headers. I'm now realizing how important heads are.

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I agree with the other posters who posted...
I dug up old data sheets I made many moons ago ( yellowed paper)... and the stock 186 casting has flow numbers vertually the same as posted..
Here is a simple rule of thumb that is easy to remember... 1.94 flows 194....@ .5" ....
If you were to keep the 1.94 valve..and do some bowl work and open short side radius and some porting and ect..the head will at best flow about 194 CFM @ .5" ..
When the 2.02 is put in and chamber de-shrouded you can get the flow up to about 210 CFM at best...
The 186 castings are cool because they have the assecory holes...BUT they don't like to be cut for bigger springs without striking water...this is for the outside springs..some guys use a shim then a larger valve on the outsides to "sneak by"....
Still the 186 casting is better than the 461 chambers for many reasons...
I have a set of clean 186 castings sitting around doing nothing..when I decide to sell them I will put them in the FOR SALE section...
CHEERS
Chris

if you deside to pocket port ONLY open area under valves 85% of the diameter of the valve. they say you can go up to 90% but after that you lose flow. so if you stay at 85-87% and mess up a little you still have a margine there. only go down an inch and taper the port.norrow the guide bosses. have valves back cut,faces of exhaust valve radioused and intake valves face cut back. this will help the low end a little have the faces modified. you'll need a dail caliper ,grinding stones,carbide cutter(if you want to make the job go faster.).dont polish the ports(hurts gas milage and does nothing for power). you can polish the chamber(helps reflect heat to keep detonation down). this is very simple and can be very fun in the end seeing the improvement and saying(being manly and all)I DID THAT!. good luck!