Head work

[Sabz5150]

I've gotten my hands on an A20A3 head that I'm currently doing a self P&P job on. It's going rather well, albeit slow (aint gonna rush this one). I was wondering if anyone else has done this job themselves and has any tips on what should be done. Are there any trouble spots that I should pay particular attention to? Any places I should NOT do work on?

Lemme know, the head awaits.

[racerx]

although I have never done this myself, my friends have given me their advice, and i will give you theirs:

Take your time. Looks like you got that one down.
Think about and draw out what you plan to do BEFORE you do it.
Don't over port any part. That's why you draw it out first.

I know this isn't specific to the accord head, but it's just general head p&p advice i have heard.

[Sean]

sabz email me. ive got a few tips.

[riced_roach]

You may pick up some tips from

http://www.theoldone.com/

Unless you have a flow bench and some theory under your belt your just porting strictly based on speculation. Port/remove material in the wrong areas you will just slow down port velocity and create air/fuel separation. Port the correct areas you will gain. Fluff and buff is what I'd do since you may be wasting your time doing it yourself. This is where you gain power and by having no experience you are basing everything on gut feel rather than effective porting. In otherwords get an experience head porter familiar with honda heads to do the work otherwise you may make the car even slower due to oversized ports that do nothing but create flat spots rather than real hp.

[night]

i know from B work that the short radius is a huge part. the bowl should be pretty much left alone. fancy valves grinds are a waste. and leave the port size itself alone.

although the only for sure to apply to an old A head is the short radius

[Sabz5150]

The only thing I'm looking to do is to smooth out the ports. Remove all the casting flash and roughness and smooth out the curves. Nothing extremely major.

Unfortunately the head I got had a busted valve guide, so back to the boneyard it went. I'm gonna read more, get the right tools and then start the work.

[riced_roach]

i know from B work that the short radius is a huge part. the bowl should be pretty much left alone. fancy valves grinds are a waste. and leave the port size itself alone.

although the only for sure to apply to an old A head is the short radius

"fancy valve grinds are a waste" That is absolutely inaccurate. Radius cuts or a very good 3 angle or 5 angle will increase CFM flow. Also back cutting the valve will increase flow. Talk to any reputable head porter and they will tell you what I've mentioned.

[Accordtheory]

Finally someone on here references theoldone.com... everyone should read the softhead 99 article at least

[rjudgey]

i agree keep ports same size just match and flow smooth, then concentrate on flowing out the machined edges in the valve throat area, also valve grinds and valve back cuts essential for good flow but best off all is radiused seats a basic 3 angke but the 60 degree angle is rounded off either by a very steady hand and a rotary grind stone or with special valve cutting equipment, but something no ones mentioned is flowing the chamber remove all machining edges around valves, unshround them to the gasket, also make sure chamber roof is flush with valve seats, yes you'll go he's dumb you'll loose cr ratio etc. etc. but the gain from doing this is far greater than loosing a bit of cr ratio, in fact i also take out chamber walls to the bore walls this lowers cr giving more low end torque, but also allows bigger boost or converts head to a better hemi design which enables more ignition advance without detonation problems, and if running n/a you can allways take 1mm off the head and block surface even 1.5mm and that will bring the cr ratio backup or custom valves without dished heads will also increase cr ratio, but a vernier cam gear or modding existing cam gear will need to be done as -3mm will retard timing quite a bit.
thats what i would do and i;ve modded a18 head, et head, et1 head, and working on a20 at the mo, also have done bmw head and lotus elan head which uses a isuzu dohc 16 valve engine similar to a20 inlet port shape, but also don't forget doing flow job on inlet manifold and exhaust will help too.

[ET2]

Here's some of Richard's handy work

[Sean]

ok now ive gotta post some pics of my head dammit.

[Justin86]

Yea I have an extra head that I have been wanting to P&P, but since I lack a flow bench and the experience I'm affraid to mess it up.

[rjudgey]

don't forget the pics are a prelude head from 1.8 ports are tiny compared to a20 which a huge in comparison but in my pic i've opened them up to improve flow. a20 heads are fine stock unless you plan on boosting 300bhp+!

[Justin86]

well yea cause I turbo is forcing in more air so you would see a bigger need for a good P&P but running NA and have a P&P head is also a good mod.