Advice On Mild Head Porting Needed

[baldy]

Hi, I will be removing the heads on my car in the next month or two and fittig new valve seals and head gaskets does anyone have any experience in mild porting of a cylinder heads, prefferably a 16v head. ,as i would like to try to inprove the flow. They will be skimmed before refitting!!! tips on how to, pictures of your heads would be helpfull. here below is what ive been looking at so far Lee

[Conkers]

Probably not worth trying it yourself, you'll ust get dirty and it will not make much difference unless you know what you are doing.
More important, check the valve guide clearances and plan/budget to change the guides, also have the valve seats cut with mira (or similar) 3 angled tooling, make sure you get the combustion chambers volumed and equalised, these can be wayyyyy off on multi-head engines, and are rarely that good on single head engines either!

If you want the heads ported, then I would be happy to help you out. Either with detailed advice, or by doing it for you.

Finally, don't get too consumed by percentage losses, graphs and other theoretical mumbo-jumbo... R&D and years of experience is probably enough at this level of ambition. ;-)

Cheers,
Mike.

Racing Green Motorsports

[baldy]

Mike, I realise that i will not get as good results as some one with a flow bench and other equipment, I trained as a mechanical engineer during my apprenticeship and am quite hands on. I've done turning, milling, grinding and welding etc in the past.

My head has a water leak from the gasket thats why the heads are coming off, as standard the engine should have 137bhp with the carbs it has 148bhp and charactor its not a race car just a great cheap raw entertaining car for the weekend to have fun with. When I last removed the exhaust manifold I could see the exhaust valves and noticed a build up of crud on the exhaust valves, the engine has never been apart so a decoke shoud'nt do any harm.

Regarding the porting I was thinking of blending the bowl area slightly. the combustion chambers volumed and equalised using a home made device and measuring jug. Regarding the valves, do you think polishing the exhaust valves and lapping the valves would surfice as its not down on power? Your opinion on the latter and any other helpful suggestions would be welcomed.

Cheers Lee

[Conkers]

Sounds like you'll be ok, just smoothing things out and cleaning it up will be a good start.
I would spend the money on changing the guides and getting the seats cut with three angled tooling, these two things alone will give more improvement than any light DIY porting.
Don't go silly with the porting, just give yourself 5-10 minutes on each port with polishing cloth or 30 grit stone, and for the DIY-er NO rotary files. That way you'll clean it up without doing any irreversible damage!
Best to remove the valve guides first, clean it up and then have new guides fitted, seats cut, valves ground, vaccuum tested. Vacuum testing is better than lapping, lapping is old school (not necessarily a bad thing) but even with a the fine lapping paste creating a fine grey line and marking blue, you can leave particles of lapping paste in he seat, which will hammer the seat and widen it during initial running.. Then skim, volume and equalise the heads and you'll never have to remove them again.

Good luck and dont hesitate to ask me if you need any more advice.

Mike.

[baldy]

Hi, after finally getting my heads removed my water leak was quite easy to diagnose the near side cylinder head face is badly corroded and was allowing water in to the cylinders!! luckily no damage has occured to the bores and the head isnt worped.
So i decided to do some mild port work and smooth things out, easier said than done! but armed with an electric drill and a few various carbide burrs, and various grit emery and scothbrite, its turned out pretty good.
But let me warn you it is time consuming!!. after cleaning every thing i have decided to get new valve guides and get a three angle valve job done, plus a clean up skim on the face.
This will not be cheap but should complement the work ive carried out and hopefully in return i may get a few more horses

[Ross Parker]

good stuff mate,don't have the confidence to have a go myself so letting a local company port polish and gas flow my heads.they will also reprofile the original cams for me.expensive mind.anybody know how much that will gain in hp?the cams can only be reprofiled to a fast road rally state but i am sticking with the stock cams because im told they are pritty strong.

[alfaholic75]

Ross do you mind if i ask what they are charging for each thing? ie, profiling the cam, and the head work individually? I assume they are building the cams back up before profiling them?

I guess i should point out that if people are using cams from a cat car change them as the profile is wrong. they have been watered down to help with the emissions and produce less power!! only on the inlet side mind.

[Ross Parker]

280 per pair of cams and 500 for both heads.i have non cat engine so they should be fine.can you get them done cheaper?i would have thought they would build them up but i didnt ask.you probably know or haved heard of the company,its Maynards ltd in Stroud.

[sprintracer]

I have noticed that piper cams now list a fast road cam for the 16v. They are marked 'Repro' which I assume means they are regrinds. They are 260 durations and cost £320 plus VAT(15%!) Might be a cheaper option than your local shop. I would ask them if they know what specifications their regrinds will be (duration, lift etc). It does say that BHP increase is 8bhp. This is what all the comapnies I spoke to said, so i decided to get some made from blanks. Its just over twice the price but hopefully will give twice the power increase when timed.

8 bhp should not be ignored though it is nearly a 6% increase and would be a usable profile for the road.

[alfaholic75]

Wow thats expensive!!! I got my pair of heads done for 300quid!! I cant remember what the cams cost but i think it worked out about 250 for all 4! Piper cams and a set of verniers i bet would show a strong 15 bhp!!!! just slightly expensive. I would guess they are slightly longer duration!

Oh one very cheap mod that works although i can't remember which way round it is but to run 4 exhuast or inlet cams. If you find which is the better cam and then buy another 2. I bought 6 cams for 30quid. The trouble is its banned in our regs so had to take them back out

[Ross Parker]

might buy the piper cams then.how do the verniers give you more power?

[sprintracer]

They allow you a greater degree of cam timing to achieve optimum settings for power.

[Conkers]

Looks like it turned out nice, not bad for a first time attempt....

What were the guides like? Are you changing them...?

And a good tip for voluming the chambers is to use a syringe rather than a jug, if you dont have a burette. A piece of perspex with a hole drilled in close to the edge of the chamber, seal it with a thin smear of grease, likewise to seal the valves... dont forget to blow the spark plugs dry if you mess up or need to recheck any of them. And try to be consequent with the method and amount of grease you use.... aim to get them within 0.2cc.

Mike.

ps... Bruce Forsyth voice... Didn't he do well! ;-)

[baldy]

Hi, the exhaust valve guides aren't in bad condition, but i will get them changed for piece of mind along with the inlet ones. The inlet guides are the worst and are slightly bell mouthed, but the valves themselves measure ok and are in spec. Where are you based and what would be the cost of the valve job?
Regarding the voluming of the chambers using a syringe, i guess this is done after the head is skimed? Does there need to be two holes in the perspex to allow the air out as the water enters?
Thanks lee

[RSFruitbat]

The cc's in the head are ideally done before and after. reason being the two heads may be different and you can match them up on the skim.
The five heads that I did measured from 28.8 to 29.1
If you look on the "how much power" thread I have given some numbers on what amount of skimming gave me what cc drop.
I use 2 holes close together as you say so air can get out.

rsfruitbat

[Conkers]

I volume with a burette, so use one hole and the air gets out of the same hole. Two holes increase your chances of error, but as long as you get a repeatable process then the error margin will not matter so much.
A good tip is to not volume with water, it's viscosity is a little low and annoying, use diesel or paraffin if you have it.... wash tank fluid works good also, if it's clean.... many wash tanks use diesel or paraffin anyway...

Rule of thumb for skimming heads is around 6-6½ thou (0.15-0.16mm) per cc. And certainly a good idea to measure before and after. Then you can carefully open up the smaller chambers to match the lagest one.
Aim for +/-0.2cc, but if you have plenty of time and a slighty tricky process/repeatability, then aim to get them exactly the same.
I am based in sweden, so you probably wont want to send the heads here for machining. but most reputable engine reconditioners will have three angled valve cutting available. Ask if they have a MIRA cutter or Serdi, they are similar and the only system I would trust.
If they start talking about neway and/or using three separate cutters, walk away.... you want a combined, all three angles in one hit cutting tool.
Make sure you have valves ground on the seat. Shows up and distortion or bent valves too.
Ask if they have a vacuum tester for checking the sealing. With new tight guides and no stem seals you will want around -700 to -800mb of negative pressure. Any less and the seats will need lapping with fine paste.
With the stem seals fitted it should be -950mb or a max sealing of -1000mb. Obviously this is all compered to zeroing the tester on a flat surface before starting. Zero = -1000mb (full seal.)

Use 1-1.5mm inlet and 1.5-2mm exhaust seat widths. And point out to them that they should set the valve seat edge on the OUTSIDE edge of the valve, not the middle or centre.. this increases your effective minimum valve seat diameter on the valve.
For example. 30mm valve with 1mm seat width in the head, gives an effective valve seat diameter of 28mm. If you run a 2mm seat width, this drops to 26mm. If they then machine the seat to land on the middle of the ground seat land of the valve itself, then you could easliy lose another 2-3mm of diameter.....

If you want me to do it I'll be happy to help.... but if you can find a good head guy close to you then it's better to keep it local!

Cheers,

Mike.

Welcome to Racing Green Motorsports

[Alfasixnut]

Hi
Just a quick note on the cam reprofiling - quite often for mild increases in power the companies only reprofile within the existing shape - ie they cut away in the base circle - (say 50 thou) so they can keep the same height on the "point" of the cam or take a bit off the point (20 thou) and give more duration.

[Spacenut]

Ah - I wondered how they got more lift from a reprofile - cutting the base circle means you can shim up the clearance underneath and then when the valve gets up on the cam its increased its lift by the depth of the shims . Thanks for the explanation Sixnut!

When I (eventually) get my Warrior engine built up I will need a pair of fast road cams, although I have a pair of 105s to be going on with...

Lauren

[baldy]

I've been looking for workshops in my area and came accross this company: Impulse Developments :: Cylinder Head Reconditioning :: Modified Cylinder head :: Gas Flow Heads
They seem to know there there stuff and after speaking to them on the phone i feel confident they will do a good job. has anybody had dealings with this company before?

[baldy]

Hi, I got my heads back yesterday, they checked the valves were ok. The heads were not cracked, but they had to grind out and weld around two of the water gallerys due to corrosion, before a .010thou reface. All the valves have been reground and the seats recut, the exhaust guides I was told were in very good condition. The inlet guides were reamed out and k-lite guide liners fitted for very reasonable 220 pounds.

[baldy]

Another picture

[Greg]

I would be slightly concerned about the lack of material in the corner of the galley at the bottom right in the pic. You are not going to have much of a mating face with the gasket to make a good seal - the opposite one(bottom left corner)is better when you compare them. You can see how they should look in the pic from your original post.