Thread: TIMING 2.25 PETROL

Hi Sibbo,
8O Preemium Unleaded (lead Replacement) :roll: If you are running a standard 7:1 compression 2.25 or even the 8:1 compression export spec motor you are wasting your hard earnt $s they will both run happily on std unleaded 91 octaine, Premium unleaded is 96 octaine

Ign settings as follows
Points .014--.016 th in (0.36--0.040)

8:1 Compression Ratio TDC using 90 octaine fuel

3deg ATDC 85 Octaine fuel

7:1 Compression Ratio 6deg BTDC 90 Octaine fuel

3deg BTDC 85 Octaine Fuel

I run my 21/4 ltre 2a at 6-8 before and use standard unleaded,

Spark Plugs 8:1 Champion UN12Y
7:1 Champion N8
Gap 0.029--032 (075--080mm)
Rocket [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

Rocket, many thanks for the reply, one more quick question how do i find out what ratio my engine is?. i have no idea.

thanks

sibbo [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

Hi Sibbo
If it is a standard aust built Ser 3 it will most probably be a 3 main bearing engine, if it is an exported completly built vehicle it could have a 5 bearing in it (5 Bearing engine has a horizintal long X casting in the lower section of the block ) these engines were usualy only in the late (79/82) stationwagons , [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img] You have a 95 percent chance of having a good old 3Main Bearing 7:1 comp 2.25 litre that will run forever if you are happy to travel at about 90/95 kph and give it regular oil changes

Regards Rocket [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

uncle ho

are you saying you use standard unleaded in your 2.25? i heard that u can harden the valves if u don't add lead substitute. Is the flashlube i am using unnecessary?? confused!

john

1. The 8:1 engine is identified by a square boss cast on top of the head between the rocker cover and the carburetter. If it has an 8 stamped on it, it is 8:1. If it is blank or has a 7, it is 7:1, unless the head has been planed without it being changed. Early 7:1 heads did not have the boss, and these heads cannot be safely raised to 8:1, as there is a risk of grinding into the waterways.

2. The 2.25 engine has cast iron valve seats, and although hardened seats are recommended for use with unleaded, it is worth noting that this engine was sold in Canada for a number of years when only unleaded was available, without any reports of problems. The consensus in the UK seems to be that fitting hardened seats is unnecessary unless you are doing sustained operation at close to full power, for example on freeways.

In any case I suggest doing what I do - run it on unleaded and watch for signs of valve clearances closing. I have been doing this since leaded petrol stopped being available, and have had no problems. I had the head off a couple of years ago, and there was no sign of valve seat recession or wear.

John

Originally Posted by Bisho

uncle ho

are you saying you use standard unleaded in your 2.25? i heard that u can harden the valves if u don't add lead substitute. Is the flashlube i am using unnecessary?? confused!

john

If you use unleaded (without any additive) you will eventually get valve seat recession (VSR) on the exhaust valves. This is an effect caused by lack of lubrication that is otherwise caused by lead.

HOWEVER - studies by fuel companies have shown that the average engine can do about 25000 miles (after ceasing to use leaded petrol) before serious VSR occurs - due to the lead memory effect.

Also, some fuel companies use different additives. Halph use valvemaster - an organo-phosphor compound, half use a manganese compound. If you have half a tank of each type of fuel in your tank, you will have the same protection as if you were running unleaded only (i.e. none).

To make your engine happy to run unleaded all day every day, all you need to do is get hardened exhaust valve seats fitted. But you can also just run unleaded, and get the seats fitted when needed down the track (may need new valves as well by then, but they are cheap).

EDIT - back when my IIA had a 2.25P and was a daily driver, I used to run it on unleaded. I had a SIII 8:1 compression head fitted. I did probably 40k miles on that motor, mostly on unleaded. When I pulled it down it needed 3 or 4 valves replaced ( I got hardened seats fitted at the same time). Back then the seats were only about $20 each, and valves were $15 each. No big deal.