Shaved 4age head issue's.

[too_quick]

Hey Hey,

I bought a ae82 the other month or so, Anyway it had a blown head gasket when i got it.

It had been off before once in its life so i was told so it would have been machined back then, I then took it to Beaudesert engine reconditioners to be fixed, So thats 2 machines so far. They fucked me around and did a shit job so i took it to UMR and they machined it for the third time.

So how much meat do they take off when machining a head under blown head gasket circumstances ?

Any way i can measure how much has been taken off all up and what comp ratio i will end up with ?





Des

[roadsailing]

you cna CC the combustion chambers, that would tell you how much has been taken off and tell you the geometric compression ratio.

you could also compare it to a standard head and measure the height difference, then compensate with a thicker head gasket.

i have a spare engine, so i;d just wham it on, fill up with the highest octane fuel you can find and off you go, then again i'd rather run timing than high comp.

ask the last person who machined it?

[too_quick]

Thanks for your reply.

I will see what UMR say tomorrow. Would i need to compensate the cam timing because the gears are closer to the crank ?

[roadsailing]

Would i need to compensate the cam timing because the gears are closer to the crank ?

i wouldnt bother, i worked out the difference a head skim would make to cam timing a while ago and it wasnt much.

if you have adjustable cam wheels and are bored i'd consider it, but more to cope with the increased compression than anything

[oldcorollas]

what diameter are the cam wheels?

(thickness of head removed) divided by (circumference of cam wheels) multiplied by 360 = cam angle they are now out by.
given crank moves twice as fast as cam, multiply by 2 to get crank degrees.

say they are 10cm round??
and head shaved by 3mm??

(0.3 / (Pi x 10)) x 360 x 2 = 6.9 degrees....

basically, each mm of head shaving moves the cams by about 2.3 cam degrees..... is that enough to worry? if anything it will shift the power lower(?) in rev range by retarding cams..

[Mr Revhead]

so.....
in using that you could work out how many degrees are in one tooth of ya cam pulley and get the head planned to that amount instead of just a skim that may throw them out by a bit.
provided of course that doesnt screw ya compression too much.

[Ben Wilson]

My motor (which I still haven't started), has a bit more taken off the head than that.

If you have a look at the lugs under the inlet ports you'll get an idea of how much we took off:



(The chamber mods are to try to bring the compression down a little and I decided to have a go at this)

When I bolted it on, I had to trim the metal timing cover in order to make it fit, but the cams lined up perfectly.

[Mitchee]

Nice to see you post on Toymods aswell, too_quick.

As I said on the AE82 Forums, I still think adjustable cam gears are a good idea, just to get the timing spot-on. Also, an SAFC might be a good idea, seeing as the compression will most likely be higher than normal, depending on the headgasket you use...

[too_quick]

Well today i measured the bore and stroke and got 83mm bore and 77mm stroke and a mate did some calculations and came up with 1666.47cc's. Also he estimates the CR to be around 10.5:1.

Head is on and torqued down.

ARP heads studs look pretty.

[pornstr20v]

hows the car go now

[fixeruperer]

i dont know about the cuts out of the chamber, i would have thought that any edge is going to be hotter and could cuase it to ping .
and your gonna direct all that pressure to the side of ya head gasket.

[too_quick]

hows the car go now

Got it running today, Kicked over on the 2nd kick as the fuel system was dry.

Runs great, No smoke and idles smooth as. Haven't given it any stick yet, Will wait a little while longer before i take it to red line.