porting head

[Cakky]

Ok, how much averagely am I going to be looking at to get my head mildly ported, the mechanics got it off at the moment changing the foocked headgasket so I thought... while its off lol.

Also bluetop cams, yes you can change the redtop cams for these, but it is a straight ( and safe ) swap? Do i need the bluetop valves or shims or anything like that?

Thanks
Matt

[Jebus]

Dont bother porting, just clean up the ports with some 400 grit to get rid of the casting marks.

Its worth doing blue top cams, nothing else needs to be changed, you can check your clearances if ya want, otherwise just slap them in and off ya go.

[crnkin]

if you do go for porting, for a nice cleanup, thing too major, i got quoted 480+gst.

For a simple cleanup was $360 plus gst

Bluetop cams mint, do it

[Ae92typeX]

...Also bluetop cams, yes you can change the redtop cams for these, but it is a straight ( and safe ) swap? Do i need the bluetop valves or shims or anything like that?
...

If going to an effort of rebuilding a head you will want to measure the clearances and get the correct sized shims...if you dont and just slap in you may loose any benefit of the bluetop cams and have a noisy head.

[AE85coupe]

if its a red-top t-vis, do not port it!

the ports are already huge, infact they are too big, you would actually be better to fill in the ports if you want to gain anything

just a tidy up of all the burrs/casting marks would help though

[crnkin]

oh didnt see the tvis part in his sig.

Polish those ports up for a gain, or buy a smallport head and save yourself like 400 bucks

[Ae92typeX]

I've read several articles/books which basically say polishing does not reap any benefits. Shaping, deburing and flowing yes, but polishing no.
Have not read any otherwise, but if anyone has any articles/books saying it does I'd be interested to read.

[Dell'Orto]

Polishing the intake ports can have a negative effect, as it can make the fuel pool up (Or so I've been told).
Im gonna try polishing the exhaust ports on one of my spare head to see if that makes a difference.

[Cakky]

ok sweet... so I think I won't bother going into porting much further...

the cams, sorry, but i'm not really that mechanically minded haha, what do you mean by clearances? if i put the bluetop cams in am I going to get any problems? or should I just buy them and give them to my mechanic and let him sort it out haha.

[Ae92typeX]

Re:cams
Get your mechanic to sort. but basically, your cam lobes push onto small round shims, which go on the buckets which push the valves. The clearance gap is the gap between the shim and the cam at a certian point of rotation
If you do a search, somewhere on here before the correct gaps have been posted. I remember doing them. What your mechanic wants to do is ensure these gaps are correct. Too little and it may cause a burnt valve. Too much gap and you will loose some lift as well as create a more noisy engine.

Oh, and as far as buying them- your mechanic will want to assemble the engine/head with the old shims. measure what they are gap wise and then calculate what is needed. then you go buy them.

[Cakky]

ok, they're not particularly expensive though are they? I saw a complete bluetop head on trademe for $40...

anyone got any for sale? lol

[Ae92typeX]

depends how many you need. 16 would add up to a bit (more than a $40 head on trademe for sure), but you should get away with less- just a case of measuring the old ones when you take them out- some may be suitable for different valves.
Im sure he would, but this is when you label and draw which valve needs which shim.
Been ages since I last got quotes on shims, os flick Revhead an email.

[crnkin]

by porting, I consider it as making them bigger. By polishing, i think of it as cleaning up the cast marks.

Dont listen to half the stuff on here, go into a engine rebuilders and talk to them, like lynn rodgers or similar.

[Ae92typeX]

by porting, I consider it as making them bigger. By polishing, i think of it as cleaning up the cast marks.

Dont listen to half the stuff on here, go into a engine rebuilders and talk to them, like lynn rodgers or similar.

Ah, I assumed you meant polishing to a mirror finish...I guess its just peoples different definitions. Cleaning up cast marks is worth doing for sure.

& yeah, good point, it could be an idea to have a chat with any rebuilder. Its possible your mechanic would send the head off to one anyway if you are going to get all the shims etc done. Just cut out the middle man.

[crnkin]

exactly. your onto it