23 replies to this topic

[dansalter]

wow, cheers chris i will pop up, thanks alot.

i'll ring you tomorrow about the block anyway.

might see you there too shorty.

As an example, I built a 1991 Cooper engine with a hif44 carb. and a head with 35.6 mm inlet valves. I just smoothed out the head, took a small amount off the valve guide bosses, cleaned up the short-side radius, removed the steps around the valve seats, tidied up the inlet tract surface finish with a flap wheel and skimmed 28 thou off to improve the C.R. The inlet manifold was similarly smoothed out, the engine was bored to 1330 and a new MG Metro cam was fitted with standard rockers. With an Aldon 'Yellow' dizzy, and RC40 rear box and a Maniflow Cherry-Bomb' centre silencer box it gave 84 bhp at the flywheel at 6000 rpm. It had good mid-range torque as well.

thanks for that, thats pretty much what i'm building, will hopefully pull well. that amount of power is more than enough for me.

Danny.

[Brams96]

Sorry to dispell all the negatives about using a Dremel but these pics show what I achieved with just that. I did however use a carbide tip on a standard drill to smooth inside the port and open it up a bit at the manifold. I bought 1 short and 1 with a 100mm shaft to get right in there. You dont need to apply that much pressure just be patient and let the head do the work.

Attached Files

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•  P_P2.jpg   118.06K   84 downloads

[mini7boy]

Sorry to dispell all the negatives about using a Dremel but these pics show what I achieved with just that. I did however use a carbide tip on a standard drill to smooth inside the port and open it up a bit at the manifold. I bought 1 short and 1 with a 100mm shaft to get right in there. You dont need to apply that much pressure just be patient and let the head do the work.

Brams96, you really didn't dispel the criticisms of using a Dremel for head porting. By your own admission, you had to resort to a drill motor to do the serious metal removal. Given enough patience and time, I guess one could port a head with sandpaper alone, but most of us value our time more than that. If it was even possible to do the heavy hogging with a Dremel, it would have either taken a long time or destroyed the Dremel. I have both a Dremel and a nice Makita electric grinder and I cannot take seriously your recommendation to use a Dremel.

For someone like AC Dodd, who ports head for a living, productivity is also important because time is money. A professional has no time to sit and watch while a Dremel nibbles away, slowly, at the metal that needs removing. He also doesn't need the aggro of a Dremel meltdown after hours when a replacement is locked behind shop doors or days away if shipping is required.

In his guide to DIY porting(link provided in my earlier posting), AC Dodd said the following about the use of a Dremel: "You can use a Dremel but it will be slow and useless with the carbide burrs. It will also kill the thing in no time as they are not designed for hacking up heads."

[Mr Joshua]

Brams,

But you missed a trick in not unshrouding the valve seats which are the major choke points of the head.

[Brams96]

Points taken guys
I was only suggesting a Dremel with a suitable grinding stone/polishing head is good for around the valve seat/spark plug area as you dont want to take 'chunks' of metal out just clean it up. Also for a pro yes I agree 'patience' isn't going to get the job done in time but the original post was asking about DIY P&P so he may have more time on his hands. As for the valve guides, yes , I haven't done around those yet as I need to get a machine shop to remove them before i finish the job properly, it is on my looong list of things to do.
Cheers

[bmcecosse]

Hardly anything useful has been done to that head! The Main Thing is to remove the valve guide bosses and open out the valve throats - they haven't even been touched - and a Dremel will not do that! It's only possible use is for the final light polish - and opinion is that's not really necessary anyway!

Edited by bmcecosse, 04 September 2009 - 08:09 PM.

[Turbo Phil]

Agreed ! The chambers need to be cut back around the valves to deshroud them, simply polishing the chamber will achieve nothing. Here's a head I did for a customer, 36-31 valves properly deshrouded.

[Cooperman]

"That's the way to do it", Phil. A very nice job indeed.

[bmcecosse]

Very very nice job! And certainly not done with a Dremel I bet!! And looking at Phil's avatar picture - you can see how the throats should be done too!

Edited by bmcecosse, 05 September 2009 - 04:05 PM.