Can you help a Vixen owner with crossflow questions
Discussion
Hi Guys,
I'm a PHer on the TVR Classic forum and own a '72 TVR Vixen with a crossflow engine. I'm looking to spend some money on the engine but would appreciate some help from those in the know.
I purchased car 6 months ago in need of getting into a roadworthy and usable state. All now done. However, I now need to make a decision about whether to get the engine set up properly on a RR or whether to run as is whilst I sort out a replacement crossflow.
Basically the engine starts and drives OK, just a bit flat peformance wise. Feels like it's probably pushing out 90-100 bhp. Compressions are 168, 168, 163, 170 and it doesn't burn any oil nor make any worrying noises.
I understand that the engine has been over-bored to 1760cc running an A2 cam, Burton stage 3 head, duplex timing gear, lightweight steel flywheel, steel crank pulley, twin webers (40's). It's a 711 block that was taken from an ex-rally Escort Mexico big wing. It appears to have been decked (running copper head gasket). It has a 2000e gearbox (4 spd).
This work was carried out back in 1988 by a previous owner of the car and I think was a pretty standard setup at the time. I'm working on the basis that it wouldn't have been converted for unleaded.
My questions are :
1) should I spend £250 - £300 getting this set up properly as is, or is the money better spent starting again with a more recent performance setup ie Kent 234/44, unleaded head etc.
2) as it's already at 1760, when it next needs a rebore it that possible or is the block maxed out and therefore will be scrap?
3) should I keep the short engine as is but change the cam and get the head converted to unleaded before the RR?
I'd appreciate any thoughts and ideas.
Thanks in advance..... Moto
I'm a PHer on the TVR Classic forum and own a '72 TVR Vixen with a crossflow engine. I'm looking to spend some money on the engine but would appreciate some help from those in the know.
I purchased car 6 months ago in need of getting into a roadworthy and usable state. All now done. However, I now need to make a decision about whether to get the engine set up properly on a RR or whether to run as is whilst I sort out a replacement crossflow.
Basically the engine starts and drives OK, just a bit flat peformance wise. Feels like it's probably pushing out 90-100 bhp. Compressions are 168, 168, 163, 170 and it doesn't burn any oil nor make any worrying noises.
I understand that the engine has been over-bored to 1760cc running an A2 cam, Burton stage 3 head, duplex timing gear, lightweight steel flywheel, steel crank pulley, twin webers (40's). It's a 711 block that was taken from an ex-rally Escort Mexico big wing. It appears to have been decked (running copper head gasket). It has a 2000e gearbox (4 spd).
This work was carried out back in 1988 by a previous owner of the car and I think was a pretty standard setup at the time. I'm working on the basis that it wouldn't have been converted for unleaded.
My questions are :
1) should I spend £250 - £300 getting this set up properly as is, or is the money better spent starting again with a more recent performance setup ie Kent 234/44, unleaded head etc.
2) as it's already at 1760, when it next needs a rebore it that possible or is the block maxed out and therefore will be scrap?
3) should I keep the short engine as is but change the cam and get the head converted to unleaded before the RR?
I'd appreciate any thoughts and ideas.
Thanks in advance..... Moto
If the engine work is that old, I'd get an engine builder to look at it. Call it preventative maintenance.
I'd have to find out more about A2 cams but for a 1760 your output is very low.
The engine in my Seven is not directly comparable. It is an AX block (these were those cast in South Africa and are stronger than the 711s) and is only +90thou but with a Kent 234 the recently refreshed engine makes about 150+BHP (I'm not after a number, I want reliability and great road driving). I chose to have the refresh as the car had covered some 93,000+ miles and the engine had last had a refresh at about 55,000 - and that was a lesser exercise.
Just have a rebuild/refresh does not mean you have to have any more bored out and I think few builders would go beyong 1760 anyway.
Happy to answer more questions.
I'd have to find out more about A2 cams but for a 1760 your output is very low.
The engine in my Seven is not directly comparable. It is an AX block (these were those cast in South Africa and are stronger than the 711s) and is only +90thou but with a Kent 234 the recently refreshed engine makes about 150+BHP (I'm not after a number, I want reliability and great road driving). I chose to have the refresh as the car had covered some 93,000+ miles and the engine had last had a refresh at about 55,000 - and that was a lesser exercise.
Just have a rebuild/refresh does not mean you have to have any more bored out and I think few builders would go beyong 1760 anyway.
Happy to answer more questions.
Power does seem down a bit might be worth a chat with a knowledgeable chap like Scholar top x flow people, tell them compressions spec. I bet they'll be able to tell you if it needs a rebuild/reringing/ head doing/best you can expect with that cam etc....
http://www.scholarengines.co.uk/contact.html
http://www.scholarengines.co.uk/contact.html
Thanks guys, I just spoke with Alan at Scholar. It's a shame they're not local to me as he was a good guy. Any engineering work I do, I'll certainly use them to do it.
In brief, he said not to worry about it being 1760 as they can re-sleeve or will do a straight swap for another block if I prefer. Said no problem with the thin walls concern or with the current spec. & compressions. Recommended that it's worth spending the money on a RR as is. If it does need any work doing it'll show up straight away on the RR (before the bill gets big), then it's worth doing the unleaded conv. and fitting a Kent 234 if I want.
Seems a sensible approach to me.
Moto
In brief, he said not to worry about it being 1760 as they can re-sleeve or will do a straight swap for another block if I prefer. Said no problem with the thin walls concern or with the current spec. & compressions. Recommended that it's worth spending the money on a RR as is. If it does need any work doing it'll show up straight away on the RR (before the bill gets big), then it's worth doing the unleaded conv. and fitting a Kent 234 if I want.
Seems a sensible approach to me.
Moto
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