2.4 head porting pics

[RallyBob]

I ported this head many years ago, it is someday destined for a 2.5 litre turbo CIH engine. I removed it from storage in order to machine it for roller lifters, and took a few pics for my records. These things flow REAL nice with big valves and some porting!

[neuropel]

Thanks for posting that Bob!

Is the port job for this head something a typical speed shop could do (i.e. are there tricks here that a non-Opel shop would have trouble with or potentially ruin a head)? Is this head set up for the 1.94" intake/1.60" exhaust valves?

Anyone else out there looking to use the roller rockers on a 2.4 head that can chime in?

Todd K.

[opelwasp]

bob how much of the valve guide can be removed before it will adversely affect a ported head used on the street?

[RallyBob]

Originally Posted by opelwasp bob how much of the valve guide can be removed before it will adversely affect a ported head used on the street?

It depends on the head type (2.2 and 2.4 heads have shorter guides due to their raised ports), the valve spring rates, the camshaft profile, the guide material and the oiling. Without knowing these factors it's hard to estimate.

[RallyBob]

Originally Posted by neuropel Is the port job for this head something a typical speed shop could do (i.e. are there tricks here that a non-Opel shop would have trouble with or potentially ruin a head)? Is this head set up for the 1.94" intake/1.60" exhaust valves?

I'd say any competent speed shop/machinist could do this work, but they have to overcome their 'this is how we do it on a Chevy' attitudes. It just doesn't work that way for Opels. This head has the 1.94"/1.60" valves, yes. In terms of ruining the head, there are areas in a 2.4 head that you must be careful with, particularly near the head-bolt holes passing between the intake ports (thin casting here), and especially #1 exhaust port should not be 'reshaped' to match the rest of the exhaust ports. Intake spring seats should not be milled to match the exhaust seats (I've seen people try though), or you'll weaken them or break through altogether.

So to answer your question, a non-Opel shop could ruin an Opel head in many different ways if they were misinformed or just not careful.

Bob

[opelwasp]

sorry i was not clear bob. i am currently porting a 1.9 head with 2.0 int/exh valves in it. i would like to effectivly grind off the the whole shebang. but i dont want to remove too much of the guide if it will adversly affect reliability or increase posable component failure. and if done, what is the worst that could happen on a street engine?

[RallyBob]

Originally Posted by opelwasp sorry i was not clear bob. i am currently porting a 1.9 head with 2.0 int/exh valves in it. i would like to effectivly grind off the the whole shebang. but i dont want to remove too much of the guide if it will adversly affect reliability or increase posable component failure. and if done, what is the worst that could happen on a street engine?

Okay, on a 1.9 head I wouldn't grind the intake guide completely away. It seems to do better with a small bump 'in the way'. For the intake port, try to make the guide area look like a GT hood bubble, with the round side facing the port opening, and the tapered side facing the valve opening. In fact, basically 180 degrees off from what I've done to the 2.4 exhaust port in the pics I posted.

The exhaust of a 1.9 is VERY efficient, it can outflow the 2.4 head with ease, so my suggestion is to basically knock 1/8" off the top of the guide and just blend it in. Don't get crazy. If you improve the exhaust flow too much, the EGT's get higher, and the ports/guides/valves will run hot. So in this case you need as much guide as possible for heat transfer.

You didn't mention your cam profile or spring rates, but aggressive cams and/or high tension springs will put a ton of side-loading on the valves, and will wear the guides accordingly. So a shorter guide will wear even faster if you have these modifications. Based on this, yes, racing Opel heads wear guides pretty fast. Shortened guides, big cams, stiff springs....probably need guides replaced every 2-3 years (about every 500-750 miles!). But if you don't go crazy and leave the guides basically there (streamlined), with a street cam and modest springs you should get 50-60k out of a set of guides in a performance engine with hard use.

Synthetic oil helps a lot BTW, high heat really kills mineral based oils, and self-metering viton seals really kick ass too.

Bob

[opelwasp]

bob, i have limited info on the cam. all i got from the grinder before he went out of business was 252 dur and .420 lift. on a hyd grind. the springs are stock. also when i am grinding the guide "hump" i dont have a burr small enought to fit in between the hump and the wall. how far can i cut into that wall on the intake sides? i havent really done much on the exhaust side and i dont plan to.

[tekenaar]

Originally Posted by RallyBob I ported this head many years ago, it is someday destined for a 2.5 litre turbo CIH engine. I removed it from storage in order to machine it for roller lifters, and took a few pics for my records. These things flow REAL nice with big valves and some porting!

Nice work, Bob! You da MAN!!