Race Engine Forum UK

A friend that owns an Alfa that I replaced a cylinder head on asked me to help with his Vectra track car. It has a red top ( C20XE ) in it, 45 DCOE and 304 cams. Arias pistons, mechanical followers. He doesn't have a lot of history and background on it. He basically bought the car, busted the bottom end and had it rebuild by several people on several attempts, never successful. The car was sitting in his driveway with the engine supposedly making loud ticking noises a few minutes after starting when I was asked to look at it.

I first looked over the obvious things like oil in the coolant, coolant in the oil, fluid levels, loose bolts, electrical connections, all that. I found that the cam belt was extremely loose. There were previous marks on the verniers that were inconclusive about where the TDC positions should be, but the owner told me that he used a certain set the last time, so I proceeded to do the belt up with those marks. The owner wanted to start the car since he was convinced it was okay now. The car started, but it was obvious that the valves were hitting the pistons (lightly) immediately. After being annoyed with myself about not checking interference manually before cranking, despite the owner, I now have a dilemma.

I don't have the timing data for these cams. It's obvious I'll need to set them up to the degree with the verniers. I don't know how much damage the valves have taken. I do not want to pop the head off if it's not required, but with so much unknowns, I am afraid it can be avoided. The last thing I want to do is rebuild the top end of his car in his driveway, so I'm looking for alternatives.

I'm inclined to do the following: Set the timing to either Piper or Schrick cams specs, depending on what I find when I map the cams. Just go for the closest one. They are really close when it comes to opening/closing degrees, it's the TDC lift that differs mostly. After that, check for interference manually. When that is okay, do a compression test. If I have a healthy and equal compression, start the car.

If I get that far, it will still leave a very uneasy feeling. This is an engine with double valve springs and it's supposed to red line at 9000 rpm. I have no experience with red tops at all, so I have no idea how easily the valves bend and how brittle they are. I don't even know if it still has stock valves or some brand over sized ones. I've seen someone try this with a stock 16V turbo Lampredi and fail catastrophically after about 60 minutes of run time. He didn't do a compression test and when he heard ticking noises, he didn't stop the engine, so it's not exactly the same.

The owner is trying to get the car running again on a budget and wants to take a lot of shortcuts. He is aware of the risks of taking them, but I'd rather avoid the risks if at all possible without running up a large expenses tab. I would like to hear if others have experience with this particular engine in this state of tune and what they would do. Even if you don't have experience with this engine, if you have any useful hints to give, please tell.

Check if the engine still has has the hydraulic lifters. if so then they often make lot of noise if the engine was not used for longer time so maybe it was not noise of valve hitting the piston.
If it has solid lifters then better take the head off.

It has the solid lifters. The noise right now is caused by valves hitting the pistons. I'm sure that if I time it right and the valves aren't (too much) bent they will clear again. The question is mainly how much risk I will be taking by not taking the head off to inspect the valves for damage.

After reading this post I would have to ask because I do not know what a "304" cam is. Is the cam and grind installed designed specifically for solid followers? The hydraulic lobe is different and if solids are put on a hydraulic cam they WILL be very noisy and eventually beat them selfs to death. Solid lobe profiles have clearance ramp that take up the valve lash at a slow rate before the net lobe lifting ramp comes in. Hydraulic lobes do not have clearance ramps and hammer the solids.

You may have this fixed by now but thought I would post it anyhow.

Robert

I haven't touched the engine since the first post I made here. The cams were made for solid lifters. I have too many unknowns in this engine to feel safe about just running it. The more I think about it, the more things that might be a problem come to mind. The bottom end was rebuilt, but I don't know what parts were used. It's supposed to have arias pistons, but who says they will fit the valves used? Are there still over sized valves in the head? Where are the old parts? I might need those to get measurements if the new parts don't match with the rest of the engine. I think I'll be pulling the head off, especially if I don't see parts that were left over and receipts with used parts on them.

Log on to Migweb. That is a dedicated Vauxhall site and you will find out just about all you need to know about these engines, or at least get pointed towards sites that can help if they can't.
Personally I've been more into my Vaux then Lancia/Fiat, but would recommend ditching the lot and putting in a SaaB turbo lump instead. Much more power and reliability for the pound so to speak !

stevemanby wrote:Log on to Migweb. That is a dedicated Vauxhall site and you will find out just about all you need to know about these engines, or at least get pointed towards sites that can help if they can't.
Personally I've been more into my Vaux then Lancia/Fiat, but would recommend ditching the lot and putting in a SaaB turbo lump instead. Much more power and reliability for the pound so to speak !

Thanks for the pointer. The owner first wants to get the car running and then decide if he is going to keep it or sell it. I don't think he's willing to do another project on this car, or probably any car.

Just thinking out loud:

I don't suppose there's a way you can manually find out the point of maximun valve lift and adjust accordingly.

i.e. Dial gauge mounted at x degrees on the head (whatever angle the valves would be), turn engine over by hand and find point at which max lift is and then subtract 180 deg to find the opposite position.

If the valves were definately hitting the pistons when running would you be able to crank it round by hand anyway?

Other ways of finding out if the valves are damaged:
- Borescope? (expensive to buy but maybe you could borrow one)
- Remove inlet and exhaust manifold** and create a vacuum/+ pressure. I'm sure I've seen Guy do this to check if valves are seating/sealing correctly. If one was even slightly bent I doubt it would seal.

Or take the head off. I can't believe that someone would rebuild a head and not check the valve to piston clearance - even with plasticine - before putting it all back together.

Chris

** Afternote: You would obviously need to turn the engine over the valves would be in the closed position

I was planning on timing it manually with dials on the tappets. Also, take the manifolds off, put some liquid in the ports and putting pressure on the chambers through the plug hole. If I see bubbles, it's leaking.

The thing is, the owner had a bunch of people work on different parts of the engine and then put the head on the engine himself, with help from someone that has never worked on high performance engines before. If it was all stock, I'm sure what he did should have worked, but obviously, some parts at least are high performance. Since I have no idea what parts were used (I suspect part of the engine has been done with stock material since the owner was skimping on rebuild costs) I am not so certain it will last very long if I just time the cams and start it up. The more I think of it, the more potentially disastrous unknowns are lurking in this engine, so I'm currently leaning towards taking at least the head off to check for bent valves, verify clearance and all that.

Oops - ofcourse. Dial on the tappets would be much easier.

Testing the valve seating with the head still fitted could give false readings - if the piston rings/other piston damage was would also present quick loss of pressure. You could also plug in a pressure tester when you apply pressure via the spark plug (monitor pressure drop over a certain period AND just to make sure you don't apply too much pressure)

Nobby wrote: Testing the valve seating with the head still fitted could give false readings - if the piston rings/other piston damage was would also present quick loss of pressure. You could also plug in a pressure tester when you apply pressure via the spark plug (monitor pressure drop over a certain period AND just to make sure you don't apply too much pressure)

I wasn't planning on measuring pressure in the chamber. Just see if bubbles would appear in the liquid in the ports.