Identification of heads & pistons?
Discussion
I have just stripped down my top end in search of a few more bhp.
I have a Typhoon cam that has done 25-30K and want to replace it with a higher output cam without sacrifying low end flexibility too much as well as having everything "gas flowed".
Are these heads "Big Valve Heads", I wouldn't have thought you could squeeze bigger valves in?
I was told by the previous owner that the pistons were 10.5-1, flat top pistons.
Are these flat top?
Depending on what pistons these are, they will restrict my cam choice.
Engine is a 4.6, cross bolted block.
As they say on ebay, "thanks for looking"
I have a Typhoon cam that has done 25-30K and want to replace it with a higher output cam without sacrifying low end flexibility too much as well as having everything "gas flowed".
Are these heads "Big Valve Heads", I wouldn't have thought you could squeeze bigger valves in?
I was told by the previous owner that the pistons were 10.5-1, flat top pistons.
Are these flat top?
Depending on what pistons these are, they will restrict my cam choice.
Engine is a 4.6, cross bolted block.
As they say on ebay, "thanks for looking"
Edited by haircutmike on Monday 27th December 22:51
Measure the valve diameters and post up by all means but they look like standard 4.6 heads to me and the chambers do not seem to display any signs of re-working. Any pics of the ports?
Cam choice probably will be constrained by the pistons insofar as there are no cut outs on yours, which are very necessary to accommodate the longer durations/higher lifts out there, although your comments about wanting to retain low speed manners might indicate against anything too hairy in any event. Have read of people managing to cut/enlarge valve pockets with the pistons in the motor but I wouldn't fancy it.
Can't say on the likely CR as this depends on so many variables including gasket thickness and chamber volumes.... only way to be sure is to burette it all up although there are known combinations of bits that give particular results and someone may be able to say whether the dish in the crown looks shallower than 'usual' (or is it that the crown is higher above the wrist pin?)
ETA might be worth posting a pic of the piston at TDC so it can be seen where it all sits in relation to the deck
Cam choice probably will be constrained by the pistons insofar as there are no cut outs on yours, which are very necessary to accommodate the longer durations/higher lifts out there, although your comments about wanting to retain low speed manners might indicate against anything too hairy in any event. Have read of people managing to cut/enlarge valve pockets with the pistons in the motor but I wouldn't fancy it.
Can't say on the likely CR as this depends on so many variables including gasket thickness and chamber volumes.... only way to be sure is to burette it all up although there are known combinations of bits that give particular results and someone may be able to say whether the dish in the crown looks shallower than 'usual' (or is it that the crown is higher above the wrist pin?)
ETA might be worth posting a pic of the piston at TDC so it can be seen where it all sits in relation to the deck
Edited by Pupp on Wednesday 22 December 07:34
t.... knew there was something I had to do today!! At a glance the bottom end looks standard LR, thought TVR always cut pistons when fitting BV heads + high lift cam..
The inlet valve de-shrouding looks more than std LR heads I think? On TVR big valves just below the collet groove on the valve stem are markings REC 460 (461) which are faint but clean + magnifying glass makes them reasonably clear.
It's not the original engine in your car anyway is it? Sounds like the owner that converted it was sold a pup or was very confused that std pistons (no valve reliefs = 'flat top'
) were somehow better... The racy cams you may be considering will be very dependent on the CR, Dr Rob is quite likely to be able to give you the best advice on what cam + basic mods needed from your starting point.
TBH looking at it, you may be better flogging it complete and buying one that has the better balanced crank/rods/pistons(cut) and good heads.. It costs rather a lot of money to do all the engineering that Dom did on the real BV engines, if you have that in mind.
The inlet valve de-shrouding looks more than std LR heads I think? On TVR big valves just below the collet groove on the valve stem are markings REC 460 (461) which are faint but clean + magnifying glass makes them reasonably clear.
It's not the original engine in your car anyway is it? Sounds like the owner that converted it was sold a pup or was very confused that std pistons (no valve reliefs = 'flat top'
) were somehow better... The racy cams you may be considering will be very dependent on the CR, Dr Rob is quite likely to be able to give you the best advice on what cam + basic mods needed from your starting point.TBH looking at it, you may be better flogging it complete and buying one that has the better balanced crank/rods/pistons(cut) and good heads.. It costs rather a lot of money to do all the engineering that Dom did on the real BV engines, if you have that in mind.
Thanks Spend, I need to do a bit of investigating.
Funny thing is, engine only makes about 275 bhp but is quick on the track.
When we did Coombe some months ago, it was quicker then a standard 5.0 and exactly the same speed down the main straight as Wadsapple's 5.2 JE griff, (although the griff had bags more torque then my 305 and really pulled out of the bends!).
Funny thing is, engine only makes about 275 bhp but is quick on the track.
When we did Coombe some months ago, it was quicker then a standard 5.0 and exactly the same speed down the main straight as Wadsapple's 5.2 JE griff, (although the griff had bags more torque then my 305 and really pulled out of the bends!).
Hi Peter !
Thought this maybe useful.....
http://www.rimmerbros.co.uk/content--name-Rover-V8...
Just robbed it from TVRCC.
Looks like you are getting quite involved with that engine !
Roy.
Thought this maybe useful.....
http://www.rimmerbros.co.uk/content--name-Rover-V8...
Just robbed it from TVRCC.
Looks like you are getting quite involved with that engine !
Roy.
Edited by roysum on Wednesday 22 December 23:09
Are you sure it's not 56D----1A ?
if so you will find it on page 12
http://www.rimmerbros.co.uk/Images/PDFs/Discovery2...
But then it's listed as a 4.Oltr
if so you will find it on page 12
http://www.rimmerbros.co.uk/Images/PDFs/Discovery2...
But then it's listed as a 4.Oltr
Edited by roysum on Thursday 23 December 00:07
Its a bitsa built up....
Heads maybe your cars original heads with filler in the 4 outer bolt holes, from whatever TVR it was, but those valve guides don't look very TVR'ish to me TBH.
Block sounds like a 4.0 with a std 4.6 crank+rods+pistons chucked in - nothing to do with TVR at all. They may have used 4.0 pistons to raise the compression a little bit ~ the previous owners 'flat top' comment?
Heads maybe your cars original heads with filler in the 4 outer bolt holes, from whatever TVR it was, but those valve guides don't look very TVR'ish to me TBH.
Block sounds like a 4.0 with a std 4.6 crank+rods+pistons chucked in - nothing to do with TVR at all. They may have used 4.0 pistons to raise the compression a little bit ~ the previous owners 'flat top' comment?
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