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 Post subject: head porting
PostPosted: Wed Aug 25, 2004 7:06 pm 
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TBI Slant 6
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ok i am thinking of getting my heads ported abd was told the best type would be a veloicity port job and am wondering what the diffrence is i'm planning on just a port job with no polish done to it and am wondering if i could use valves from any other engines like a 318 or 3.0, 3.9, 2.2, or 2.5have been told the slant is undersized in the valve department

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 Post subject:
PostPosted: Wed Aug 25, 2004 10:18 pm 
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Location: Sonoma, Calif.
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For a mild SL6 engine just clean-up the ports and knock the sharp lip off the underside of the valve seat.
There was a thread below about the SI oversize valves, they are a "drop-in" and would be a good choice.
DD


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 Post subject:
PostPosted: Thu Aug 26, 2004 5:15 am 
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doc, will you have some pix of one porting job? Thanks anyway...

what you say is very clear but I'd love to actually see some...

take care

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 Post subject:
PostPosted: Thu Aug 26, 2004 9:32 am 
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Location: Sonoma, Calif.
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Opening-up the "port pocket" area just under the valve seat is the place where you will get the most gain for the least amount of work. There is a sharp edge where the valve seat machining stops and the "as cast" port walls start, this sharp edge needs to be removed.

If you plan to use oversize valves, "rough-in" the new valve seat location first and then grind-out any extra metal to the inside of the new seat. Grind straight down from the inner seat edge, do not cut metal underneath the seat, that metal will be needed for later valve seat grinding and helps heat transfer.
DD
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http://www.dutra.org/pictures/engine/pa ... ction1.jpg


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 Post subject: More porting advice
PostPosted: Thu Aug 26, 2004 10:36 am 
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Location: Pittsburgh, PA
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Feel around on the short side for casting bumps and spikes. Seems like there is plenty of material to allow for blending there. It's a little tough to see and get at with the grinder, but a common spot to find casting imperfections on the heads I've seen. Removing the valve boss, or as much as possible has been suggested, but it's in the hardest place to reach.

It's a pretty labor intensive job porting a head with just hand tools. I can see why a milling machine would work a good bit faster.

Be sure to wear eye protection. I'm not the only one who's been to the hospital to have filings removed. :wink: (that's me trying to blink a metal filing out)

All my porting work so far has been muted by the fact that my rings are shot. I can hardly wait to get a cam and a decent block with this head on it. :twisted:

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 Post subject:
PostPosted: Thu Aug 26, 2004 4:09 pm 
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Thanks for the pix. To Doc: I've been wandering tthru your images section on your website. I found lots of answers w/o asking (that's cool :D ) but I may need to bother you with this 2 (or 3) q's

1) where did you got the roller rocker arm. I NEED one... I may not be able to sleep till I get one of these babies

2) I've seen that you use threaded rods and washers/nuts on some head installation... may I ask why? is easier to get the head on working alone? there are any benefits from that setup?

3) did you custom filled the aluminium block as I'm guessin?

4) does steel gasket need retorque somewhere along the road? mine has 4kmiles plus on it... (this q obviously is for anybody that's willing to help)

thanx

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 Post subject:
PostPosted: Thu Aug 26, 2004 5:16 pm 
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doc you killed that head
my uncle told me about velocity porting a little and told me to ask i'm just wondering what the difference is from a normal port job i'm going to be sending it in for the porting and to be plained

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 Post subject:
PostPosted: Thu Aug 26, 2004 7:37 pm 
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Location: Sonoma, Calif.
Car Model: Many Darts and a Dacuda
"Velocity porting" leaves the port pretty close to it's current size and just cleans-out imperfections and works on the port's shape. Sometimes metal is added into the port to speed-up the movement of the air/fuel mixture thru a low velocity section of the port. Good velocity helps low rpm performance and helps keep the fuel suspended in the mixture.

"Race" porting opens-up the port size or cross section area to allow more mixture to flow through. This improves the high RPM ability of the engine but kills some of the low speed performance.

For argentina-slantsixer:
-As for roller rocker arms, the Cox Boys sell them.
-Head studs allow for higher torque and better head gasket clamping force.
-I have done a lot of interesting things to Alm. Block Slants, closing the top deck is one example.
-You should check the torque on a steel shim gasket after the first 1000 miles or so, after that, it is set for "life". These really don't compress much after their first heat cycle.
DD


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 Post subject:
PostPosted: Thu Aug 26, 2004 10:11 pm 
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Thanks Doc

As far as Cox bros are concerned I got in touch with'em to get a roller timing gear set, so I figure I can add some roller rockers in my order.

I gotta say that you've done a lot of interesting work not only on alm blocks... I really admire your work and think that's very inspiring.

About my head gasket... I think that I'm loosing compression... :cry: so if after 1k mi is "cooked" for good I may have to replace that... that would be a nice time for installing studs instead of bolts. I'm not sure yet about this, but I'm getting poor idle till 4~5 min after dead cold startup or 2 min after letting it rest for like 2~4 hs. I have to choke it at about 1300 rpm those first mins or I get stalling and erratic idle speed or sputtering when steppin on it from 1200~1500 rpm in 3rd gear. Anyway I'd like to port one spare head and do "all at once"... so I may wait. My current head is what I believed to be mildly ported but I just removed too little on the seats and smoothed out the valvle boss... let's say just surface clean compared to what I've saw. I think that a good porting job would make my long duration increased lift cam, free flow headers and recurved distributor shine to their best.

By the way, those li'l critters and animals are just great. (The yard weld art)

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Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.


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 Post subject:
PostPosted: Fri Aug 27, 2004 10:28 pm 
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so in other words i would probably get a velocity port job done to my slant since i'm planning on doing a little towwing with it from time to time

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