Cylinder head advice

[Jenko606]

I have a 172 cup I use for hillclimbs and sprints. The suspension and brakes are all sorted and it has a full cage fitted. The engine is standard apart from the inlet which has been matched. I am thinking of getting some head work done, by cnc or ald or similar. From my searches on here am I correct in thinking I would be better off using a 182 or 197 head? (with a remap) am I also right in thinking that generally the opinion is that there are no real gains to be had, unless you do cams and other mods at the same time.
Would I be better looking at something like the sm/rs2 intake for example?
Or my final option would be to leave the engine as is for now and go for a lsd either m factory or gripper.
Thank you for your thoughts and if I have missed any old posts regarding these questions please post a link.

 

[TheCAB]

Just in the process of stripping my lads 172 Cup which he used successfully for sprints / hillclimbs. Ran a ported /modified head with Supertech valves / dephaser delete Cams and also fitted with a gripper, which was fitted new and only used for one season so very little use, same for head so I have some bits for sale which may be of interest to you, whichever route you look to go down.

 

[Jenko606]

Cheers, do you have a for sale thread or could you pm some details of the bits you are selling.

 

[TheCAB]

ok will do, I only started stripping it yesterday so I will sort out a list of bits and post them up for sale.

 

[Big P Dog]

It's worth doing some research before getting any cylinder head work done. Like a few others on this forum, ALD (or A.L.D) worked on my head and it's had major problems. In the half season of racing I've now missed, I've been in touch with him to try and resolve it and been given no help.

 

[Adam G]

From what I've heard, I'd give ALD a miss too.

 

[levaz]

Not had any personal experience, but ALD seem to have had a drop in quality lately.

Back onto the original question, the head to go for would be the ph1 172 head *in theory*
Reason being, the ph1 172 head has larger exhaust ports from standard over a ph2 / 182 head.
But, if you're getting headwork done, then it's irrelevant as you should be getting everything polished and port matched to the inlet / exhaust manifolds anyway.

The 197 head requires a little extra modification to fit a 1*2, I don't know if there are extra benefits to be had from the inlet manifold / plenum setup on a 197, but, if you want to run an SM / RS2, then a 197 intake system is bin fodder anyway!

If it was me in your situation, I'd be on the hunt for a spare head, an RS2 / SM and cams, get it all matched and polished, then built up and ready to drop into the car in an afternoon and ready for mapping

 

[levaz]

In the half season of racing I've now missed, I've been in touch with him to try and resolve it and been given no help.

Over skimmed it?

 

[NorthloopCup]

Not had any personal experience, but ALD seem to have had a drop in quality lately.

Back onto the original question, the head to go for would be the ph1 172 head *in theory*
Reason being, the ph1 172 head has larger exhaust ports from standard over a ph2 / 182 head.
But, if you're getting headwork done, then it's irrelevant as you should be getting everything polished and port matched to the inlet / exhaust manifolds anyway.

The 197 head requires a little extra modification to fit a 1*2, I don't know if there are extra benefits to be had from the inlet manifold / plenum setup on a 197, but, if you want to run an SM / RS2, then a 197 intake system is bin fodder anyway!

If it was me in your situation, I'd be on the hunt for a spare head, an RS2 / SM and cams, get it all matched and polished, then built up and ready to drop into the car in an afternoon and ready for mapping

Bigger doesn't always mean better mate. The later 172/182 heads are actually a better starting point. Big exhaust ports actually slow gas speeds down. My engine made 230hp on what were essentially standard sized ports on my 197 head.

197 head on a 1*2 bottom end will lower the compression ratio so you'd need 197 pistons and you also can't run a sm/rs2 inlet on it as the ports are totally different.

 

[bloke]

it's irrelevant as you should be getting everything polished and port matched to the inlet / exhaust manifolds anyway.

thought a step was best from exhaust port out to the exhaust manifold?

 

[TheCAB]

The 172 head is reasonably ok as standard, a ported and flowed head will just work better. On its own as a stand alone mod you will probably not really notice the difference when driving, however, as part of an upgrade package coupled with other modifications then its about aggregate gains. Replacing the valves with Supertech valves is a plus from a reliability standpoint, uprating the valve springs can also help. As a stand alone mod, fitting a plated diff will definitely reduce your times as long as you alter you driving style through the corners (sounds obvious) to get the best out of it.

 

[Jenko606]

Cheers for the replies, it looks as if my thought process was there or there abouts. Unfortunately this evening I have just learnt that the compression on cylinder one is down and there is a higher percentage leakage there too. (cylinder 1 is about 130 and the rest are about 170 and the leakage was 30% and the rest are between 5 and 15). Not 100% sure what this means but got to look into different options.

 

[bloke]

crack in ringlands?

 

[Big P Dog]

Over skimmed it?

He skimmed a big chunk off the head and the engine failed shortly after it was built. There’s question marks over whether he’d cleaned the oilways and whether he’d changed the valve guides which he’d charged me for separately. When I asked if the valve guides had actually been changed, he couldn’t tell me and just said he’d subcontracted the work because he was busy. I asked for a refund for the replacement valve guides and he refused.

 

[levaz]

@Big P Dog i'd heard reports from others where it'd been overskimmed and an oversized idler pulley was needed to take up the excess slack created in the belt!

 

[Big P Dog]

I'm sure someone will correct me if I'm wrong but I thought the guidelines were that these heads shouldn't be skimmed. In any case I think heads are normally skimmed by around 8 thousandth but mine was missing around 40 thousandth. I also had issues with the timing belt but I've used a thicker head gasket - I want to keep the compression ratio as close to stock as possible. If you know anyone else who's stuck with an overskimmed head, Agra in Dundee ordered two custom thickness head gaskets for me and I've only used one. They've got the other in stock and it's 71 thousandth thick so would take put a head which has been skimmed by around 1mm (which seems to be the norm for ALD back to standard.

 

[shiftspark]

I have a 172 cup I use for hillclimbs and sprints. The suspension and brakes are all sorted and it has a full cage fitted. The engine is standard apart from the inlet which has been matched. I am thinking of getting some head work done, by cnc or ald or similar. From my searches on here am I correct in thinking I would be better off using a 182 or 197 head? (with a remap) am I also right in thinking that generally the opinion is that there are no real gains to be had, unless you do cams and other mods at the same time.
Would I be better looking at something like the sm/rs2 intake for example?
Or my final option would be to leave the engine as is for now and go for a lsd either m factory or gripper.
Thank you for your thoughts and if I have missed any old posts regarding these questions please post a link.

I would go with the gripper diff straight away and leave the engine mods until later. Also would not bother with a quaiffe as the plate type diffs are far superior esp with a lower FD.

 

[Westyfield2]

+1 on not going to ALD.

They're not advertised on their website, but Pure Motorsport do CNC cylinder heads and are highly rated.