What heads/headwork should I get?

[samcat]

Hi everyone.

Have been thinking about replacing the stock heads on my engine. As you can see its already had a fair bit of work done :)

Tell me what you think/reccomend for heads/headwork (valve sizes etc) and WHY. I like to know the reason for peoples choices/suggestions.

The car is driven every day, and needs to be able to potter along at low speed as well as blasting around like a nutter :silly:

-------------------- Engine spec --------------------

Stock 2-litre crank and rods. Crank balanced with 914 flywheel and clutch. Flywheel

lightened.
Rods balanced end to end and with each other.
Rods rebushed.
New Mahle 94mm barrels and pistons, pistons balanced in weight to each other.
Eurorace E-grind cam (280o Duration 435" Lift ) with hydraulic followers.
Bolt together rocker gear.
Stock oil pump.
Case machined by JMR along with the Porsche fan.
Stock T25 heads rebuilt with new guides valves.
BAS 911 fan fitting kit.
BAS oil filler tube.
BAS Carb linkage.
Mallory Unilite optical with Vaccum advance (10o Initial, 24o Max centrifugal, pair of grey springs, Vaccum NOT connected yet.).

911 bottom pulley.
GT Mouldings fanshroud.

LA Performance J tubes and merge, custom made full flow stainless silencer system after the

single triangular flange.

Weber 40 IDF's with 32mm chokes. - SOON TO BE DELLORTO DRLA 40's.

MSD 6AL ignition system, rev limiter set at 6000rpm.
MSD Blaster 2 coil (with MSD coil bracket).
MOROSO BLue Max ignition leads, tailor made to the exact correct lengths.

Gearbox is a 911/01 5 speed transmission From a 1970 911.

-----------------------------------------------------

Thoughts please :)

Cya,
Sam C

[WipEout]

My suggestion would be to have your heads ported and polished (better flow= more power) while you replace the valves with 42mmx36mm sizes. That'll make for (you guessed it) better intake and exhaust flow. And from what I understand, those valve sizes are perfect for a 2ltr T-4 daily driver. My engine is a 2056cc with those valve sizes. It sounded great on the initial start up, but I've yet to get past the break-in procedures and actualy drive it. I should be taking a run down the street this weekend, though, so I'll let you know what kind of power the powerplant makes...



DAVID MANN

[lightning bug]

I don't know much about T4 heads so I'll stay away from that part. I can tell you though to get a head with alot of meat on it. Especially around the intake ports. Also, try to find heads that are efficient in cooling. I see guys running CB comp eliminators on their street cars and they can't understand why their cars are running high CHT's. Those heads have like 3 cooling fins on them. You see what I'm getting at. The most expensive isn't always the most practical. Nothing against CB, I run CB 044's, the Comp Eliminators are for race applications. As far as head work goes, it all depends what you can spend. We all know that air flow is very important when trying to gain power. You can gain alot of power from headwork. In my opinion, get as much as you can afford to match your engine specs, unshroud the valves and MATCH PORT YOUR MANIFOLDS or else your head work really doesn't matter. Also, if you can, get your work done by someone with a flowbench. That way you know what kind of a difference you'll be making. Hope it helps.

[Oliver Knuf]

42/36 is a good size, that's also my opinion, but 41/34 will run as good with the E-cam, as the cam with hydr. lifters is more torquey and powerful up to 5000 rpm! Runned it x times with normal lifters and good p&p 1,8l heads. The tip above is also true, as you have to search for good cores, that should be not cracked and not too bended, as the heads get weaker over the time through the heat.

[SilverBullet]

On the topic of heads, I was wondering whether the dual valve springs are set in the same orientation or they counter each other? Any reason why?
Still on the learning curve! :)

[Oliver Knuf]

That's a point, where I need the help of Alex to get it understand correctly, the counterwise is something, that I don't know, sorry! :confused:

[samcat]

42/36 is where I was thinking of going with this. Paying for professionally put together heads from stateside tuning or someone like that.

3 angle valve job?
full port and polish
42/36 valves

Are there any other bits I should get done to the head at the same time?
What Valvetrain/rockers etc should be used (BEST)?

Cheers for the advice so far :D

Cya,
Sam C

[Oliver Knuf]

Hey, Stateside is ok, greet James from me, he's a fine pal! P&p the exhaust as big as you can get it, matchport both, intake and exhaust, an exhaust bracing is cool, but nothing that you have to do, but i would weld on the intake sealing surface to get a bigger seal on the head! Thin seals are fast away! Don't forget to resurface your valve cover side!

[stkmtr]

I have heard that the exhausts flow alot less that the intake ports-as Oliver hinted at. If your gonna send them all the way to the US I would be really careful. I have heard stories of heads being held hostage -taking over a year to be completed!! This was one of the most respected head shops here. You would probably be better off finding a shop that will work closely with you and build them to suit your needs-I would also make sure they have a flow bench to measure the % of int. vs. Ex flow. Gotta get it out b4 you put more in. I tried porting my own heads this last motor and I went toooo far. It's easy and expensive to get carried away. I deshouded the valves to much and messed up the barrel sealing surface! I was confident because I had done plenty of "Fluff & Buffs" to aftermarket heads. Making killer heads out of stockers is a whole different ballgame. What do you want to spend? By the time you ship them to the us and buy parts you are looking at alot of time you could have spent hitting some apexes-SS