The V8 Owners Forum -

Probably more beneficial to concentrate on sorting the throat area of the intakes than spend to much time querying port matching pro's and con's IMO

I probably broke all the rules when I ported the heads that are on Daddy Cool right now. I opened up the manifold face as far as I could but then again I spent a lot of time on the throat and pocket area, I carefully calculated guide lengths to minimise protrusion in the bore, net result is worth at least 1/4 second on 1/4 mile ET. Then again this engine has two throttle positions, idle and WOT (WFO for those like me ) Also it is supercharged and that covers a lot of off idle woes. In terms of peak power I stand by my theories but I very much doubt they would be streetable in this form. Oh yeah valve sizes are still stock so there may be a little more to come, not a fan of replacing seats for a racing motor.

Alan

Hi Al
And you are also doing one thing I was trying to ignor. . . you are using methanol and a blower and about 3 to 4 times the weight of charge in the inlet tract and particulally a higher weight of charge flowing into those ports. As blown V8 has discovered the inertia in the port of the mixture (OH I did not want to get into this one) can change all sorts of things, flow mode, aparent boost pressure etc and the way the port operates.
I actually suspect that in your case Al opening up the ports this way is very benificial, that is why I said in 95% of cases don't do it, however you have found one of the 5% that it does help. I think that inertia of the heavier mixture is tending to carry the charge away from the manifold part of the tract and further into the port away from the manifold and holding it there while the valve is closed delaying the charge returning back up the port reducing the reflected pulse and holding a compressed slug of charge behind the valve ready for the valve to open. The added flow here is probably genune but only for a relativly short part of the rev range the extensive bowel work here will also be helping this giving more volume for charge to be held behind the valve. As you say those heads would be a dog on the road but Daddy cool is not a road engine and it is not running normally aspirated on petrol.
As I keep trying to say here head porting is a very complex subject just measuring the flow on air does not by any means tell the whole story. What works well for one engine will not necesserily work for another and weight of charge has as big an influance on what is going, boost is another!
I still think that Blown V8 is seeing a charge distribution effect and maybe a small gain, but I think it is all due to there being a blower upstream making the port operate differently.
Best regards
Mike

SimpleSimon wrote:Probably more beneficial to concentrate on sorting the throat area of the intakes than spend to much time querying port matching pro's and con's IMO

95% of the time most definatly yes.
Best regards
Mike

Totally agree Mike, the weight of the charge is exactly what I had in mind with these heads and increasing port volume seemed a good way to go. Totally agree on a street head I would go a completely different route to getting the best out of the massive amount of work properly porting heads can take. For sure I don't want to do another set like this in a rush

Best wishes

Alan

kiwicar wrote: As for best tool, a die grinder is ideal, a drill with a flexable extension drive is pretty good, a drill with a long shaft bur is good but a bit clumsey, never used a dremmel for this as I think it would burn it out, it would also be dead slow. I use a drill and a long shank bur for the stuff I have done on the chevy, then verious flap wheels cylingrical sanding thingys and hand tools.
Best rgards
Mike

Thanks Mike, did you use various heads on the long shank burrs? I want to clean up my heads around the valve stems and also work on the throats as has been suggested on here so what burr ends did you use?

Thanks

Hi
the long shank bur I have is about 1" long on the cutting part, 3/8 to 1/2" diameter with the end in the shape of a ball, the shank sticks out about 2 3/4" from the chuck so total reach about 3" before the chuck gets seriously in the way. I have 3 other similar sized burs on short shanks, 1 cone shaped, 1 cylindrical with a squared off end and one cylindrical with a ball end like the long one but on a 1" shaft. As I said earlier I do not port heads as such, I just match things up to each other and do general tidying up of heads.
Best regards
Mike

You can do it all with one of these - The diamond cut type is not ideal for alloy as it clogs but use some WD 40 and it will keep it clear

http://www.ebay.co.uk/itm/ATI-Garryson- ... 565afc27a1

Or the 1/2" from the same seller or get one of each of the 1/4 3/8 and 1/2 which will set you up nicely to do all aspects of the port in a simple cheap die grinder without needing a long reach type. But for finishing the port you would need a long reach and cartridge rolls / flap wheels

I used a similar shape but cut for aluminium. For finishing I used emery cloth rolls, cut to length and wrapped around a rod with a slot, worked perfectly, left intakes at around 80 grit and went to 300 grit on the exhausts.

Alan

Hi
mine is very like that one for shank and head size, pretty sure from the same manufacturer, mine is as described above, though I think I shall add one of those to the collection. Mine are all fine on ally, I dip them in slick-shift I have found it excellent as a cutting oil for ally.
Best regards
Mike

kiwicar wrote:Hi
Mine are all fine on ally, I dip them in slick-shift I have found it excellent as a cutting oil for ally.
Mike

Parafin works really well on ally.

Many thanks again guys, i'll look into the options when I get home tonight. I don't have a die grinder but intend on using a drill so might have to get the long shank versions. I don't intend to do any 'porting' as such, but like Mike I want to clean them up and open up the throats to match the valve openings as per piccies previous.

Die grinders run in the region of 30,000 rpm - I think you find a drill will be far too slow.

If you run those burrs to slow in a drill for example they tend to chatter and dig in much better suited to the die grinder like Eliot says burrs dipped in Paraffin/Diesel etc IMO

SimpleSimon wrote:If you run those burrs to slow in a drill for example they tend to chatter and dig in much better suited to the die grinder like Eliot says burrs dipped in Paraffin/Diesel etc IMO

They sure do, that is one reason they are clumsey, still useable but clumsey.
By the way don't get the swarf in your socks. . that really sucks!
Best regards
Mike