V8 'heads question

[chassis 33]

What is the difference between the carb and fuel injected RV8 cylinder heads, other than the notch in the inlet ports for the injector?

Is it possible to convert carb heads to EFi heads with a bit of patience and a small grinding bit?

Regards
Iain

[chassis 33]

Andy,
Fancy a drink at the Boat later in the week? Thursday perhaps?
Regards
Iain

[tallbloke]

chassis 33 said:

Is it possible to convert carb heads to EFi heads with a bit of patience and a small grinding bit?

[boosted ls1]

You can swop the heads over and check out the notch for the injectors. Also depending on the age of the carbed heads there may be chamber volume differences compared to the efi heads and really early heads had smaller valve sizes so injection heads would be bigger valved.

Boosted.

[tallbloke]

Paul B is selling some tricked up heads with big valves and fancy guides. Lots of dosh though. He told me he has £3k in them.

[chassis 33]

Lifted from the Rimmer Bros website

Carburettor Engines -
Early Engines (pre 1976) - Head diameter: 38mm.
1976 on - Head diameter: 40mm.
Efi Engines - 3.5, 3.9 & 4.2 litre - Head diameter: 40mm.
'Big Valve' - Head diameter: 41mm. With waisted stem.
Machining required to valve guide and seat.

Exhaust Valve;
Carburettor Engines -
Early Engines (pre 1976) - Head diameter: 33mm.
1976 on - Head diameter: 34mm.
Efi Engines - Head diameter: 34mm.

I'd be tinkering with SD1 stuff anyway so would be ok in terms of valve sizes, although EFi valves have different part numbers to the equivalent sized carb valves. Anyone know the difference?

Regards
Iain

[chassis 33]

Yeah, that would be useful, if nothing else to see how theyre ported!

If you cant make it up to The Boat I'll come for a blast down your direction.

Regards
Iain

[350matt]

the EFI valves are stainless to cope with unleaded, the carb valve are not

Matt

[tallbloke]

350matt said:

the EFI valves are stainless to cope with unleaded, the carb valve are not Matt

The same would be true of the valve seats I'd guess.

[mr-scott]

350matt said:

the EFI valves are stainless to cope with unleaded, the carb valve are not Matt

Most EFI engines had waisted valve stems - certainly SD1 Vitesse and 350i and post '94 rover V8's - carbed engines did not. To confirm the valve seat material was upgraded around the arrival of the SD1 in'76-'77 to cope with unleaded for the USA market and was standardised to the best of my knowledge

[chassis 33]

Hmmm, not so sure on some of that, have no facts to back me up, but only gut feeling.

The only mention on the Rimmers site of waisted stems is on the 41mm/35.5mm 'big valves'.

If the difference is the waisting, in real terms how much torque/power is gained? I would imagine it's only in the single figures due to a slight increase in volumetric efficiency?

Alls I'm wanting to do is to rebuild one of the spare carb SD1 V8's I have knocking about (as one does) into a high torque 3.5/3.9 engine giving only what Rover reckoned a SD1 EFi pumped out (ie 190bhp) but vastly improed torque characteristics. The difference in rebuild kit from Rimmers is £120 between 3.5 and 3.9 setups. I've got spare EFi manifolds, looms, ECU's etc.

Regards
Iain

[boosted ls1]

Don't forget the TR8's for the US market had to run on unleaded hence the hardened valve seats being standardised across the board. I saw a lot of research on this stuff when I was registrar in a car club. Also, the vitesse had the waisted stems and this was carried forward with the other efi heads iirc.

Some flow bench data from that period showed the none waisted valves making better low/mid range torque whereas the vitesse waisted valves were better up the rev range. I think the vitesse valve seats were recessed.

Boosted.