J400 GED Chimaera Chassis refurb
Discussion
I've just had a chat with V8 Developments and the 11.5mm is valve lift not cam lift. Apologies to all for my error previously.
Having said that, with a ratio of 1.6 valve to cam, 11.5mm valve lift equates to 7.2mm at the lobe. So, on the one hand the cam isn't as worn across the lot as I first thought, but it is still worn by approximately 2.5mm on several of the lobes and therefore requires replacement.
Having spoken to V8 Developments, I will be going for a V8 Developments Stealth Cam as the replacement.
Having said that, with a ratio of 1.6 valve to cam, 11.5mm valve lift equates to 7.2mm at the lobe. So, on the one hand the cam isn't as worn across the lot as I first thought, but it is still worn by approximately 2.5mm on several of the lobes and therefore requires replacement.
Having spoken to V8 Developments, I will be going for a V8 Developments Stealth Cam as the replacement.
J400GED said:
I won't be doing the cam change myself, I may send the engine 5 miles away to RPI in Horsford. I will shop around first before making a decision.
I will only ask them to fit and time the new cam for me, the rest I can do myself.
How hard can it be? There are plenty of tutorial vids on youtube that will give you a good idea.I will only ask them to fit and time the new cam for me, the rest I can do myself.
This weekend's update:
On Friday I had a look over the chassis now that it's back from blasting. It's not as bad as I had first thought. There was one bodged repair to the LH front outrigger diagonal, where it had obviously been repaired with the body still on.
Then there were the inners of the front corners of the outriggers and the rear portions of the outriggers, as well as a section of the RH upper tube under the manifold.
Finally, the lower left rear bolt had sheared and I broke an easy-out whilst trying to remove it, so that rear plate will be replaced.
After that I started to strip the engine down ready for the replacement camshaft, only to be thwarted by the two pick up bolts that fix into the timing cover. This means the sump has to come off to access said bolts, so I need an engine stand and I will be borrowing that next weekend.
I have been pleasantly surprised by the cleanliness of the internals of the engine.
And all I did today was clean the engine block and the gearbox and replace the tail seal and the clutch release bearing.
On Friday I had a look over the chassis now that it's back from blasting. It's not as bad as I had first thought. There was one bodged repair to the LH front outrigger diagonal, where it had obviously been repaired with the body still on.
Then there were the inners of the front corners of the outriggers and the rear portions of the outriggers, as well as a section of the RH upper tube under the manifold.
Finally, the lower left rear bolt had sheared and I broke an easy-out whilst trying to remove it, so that rear plate will be replaced.
After that I started to strip the engine down ready for the replacement camshaft, only to be thwarted by the two pick up bolts that fix into the timing cover. This means the sump has to come off to access said bolts, so I need an engine stand and I will be borrowing that next weekend.
I have been pleasantly surprised by the cleanliness of the internals of the engine.
And all I did today was clean the engine block and the gearbox and replace the tail seal and the clutch release bearing.
Update from last weekend - 17-18 April:
Activities last weekend consisted of cleaning down the engine - especially the rocker covers
and then replacing the camshaft and timing it up:
I also replaced the front cam bearing and the timing gear.
The old cam was an original TVR cam and the replacement cam is a Piper V8BP270.
The chassis repairs have been completed and tomorrow I am going to view the chassis prior to it going for paint.
Activities last weekend consisted of cleaning down the engine - especially the rocker covers
and then replacing the camshaft and timing it up:
I also replaced the front cam bearing and the timing gear.
The old cam was an original TVR cam and the replacement cam is a Piper V8BP270.
The chassis repairs have been completed and tomorrow I am going to view the chassis prior to it going for paint.
Chuffmeister said:
Great work! Can you do a complete guide for refitting and timing the cam?
Chuffy, stripping out the cam and installing the new one is a simple process: remove the intake manifold and gasket, rocker assemblies - if you are re-using pushrods, note their position and orientation when you remove them - and timing cover and then remove the timing gear, cam and followers - always fit new followers with a new cam. As for timing the cam, there are many websites that will give you a far better write up than I could. Top tip for timing the cam is: if you have the gearbox removed, remove the clutch as well and turn over the engine via the flywheel - that way you don't disturb any timing disc and the likes that you may have on the front of the crank. Because of the procedure for timing the cam, you only need to look at the timing disc once you have determined your reference points on the cam lift - I am deliberately not giving specific timing advice here as it may be mis-interpreted.
You could always try this link: http://www.v8developments.co.uk/technical/camshaft...
Cheers Ged. It is just the timing I don't get. I've watched a few vids on YouTube, but it isn't what they're doing, it is why they are doing it in that particular way. I guess it is one of those things, that once you've seen done in the flesh and asked a couple of questions all will become clear.
Chuffmeister said:
Cheers Ged. It is just the timing I don't get. I've watched a few vids on YouTube, but it isn't what they're doing, it is why they are doing it in that particular way. I guess it is one of those things, that once you've seen done in the flesh and asked a couple of questions all will become clear.
Basically, you want to find out where the Maximum Open Position (MOP) of No1 Cylinder inlet valve occurs in relation to Top Dead Centre (TDC) of the stroke for No.1 cylinder, it is relative to this reference point (TDC No.1 cylinder) where the ignition is also timed. To do that accurately for the cam timing you need to measure a given amount of reduction of valve lift either side of MOP and split the difference to pinpoint it.
The confusion that most people have is the fact that the cam rotates at half crank speed and get mixed up because the angle change on the crank is twice that on the cam, that's all.
HTH
Ged
Edited by J400GED on Friday 24th April 11:10
Pics of the naked repaired chassis below:
All the joints on the tubes are sleeved joints by the way.
So, next step is to be hot zinc sprayed and then 2 part painted - in white - ready for the rebuild (the chassis that is, not me!!
).
The chassis should be back with me in a fortnight.
That gives me 2 weeks to re-assemble the engine and gearbox ready for the chassis' return.
All the joints on the tubes are sleeved joints by the way.
So, next step is to be hot zinc sprayed and then 2 part painted - in white - ready for the rebuild (the chassis that is, not me!!
).The chassis should be back with me in a fortnight.
That gives me 2 weeks to re-assemble the engine and gearbox ready for the chassis' return.
Edited by J400GED on Friday 24th April 11:21
Gassing Station | Chimaera | Top of Page | What's New | My Stuff