|
Title: Grey Distributor Unleaded Specs. Post by: Rod on June 13, 2006, 12:08:48 AM Hi all,
Has anyone got any grey motor distributor specs for running on unleaded fuel (ie: regraphing). I am hoping to get this done in the not to distant future and would like these before getting it done just in case the regrapher hasn't got them. Cheers Rod Title: Re: Grey Distributor Unleaded Specs. Post by: Dr_Terry on June 13, 2006, 06:29:09 AM Hi Rod.
The octane rating of fuel has gone 'full circle'. By that I mean that the RON (research octane number) of normal unleaded is around the same as 'standard' petrol of the fifties. Super petrol wasn't pushed by the oil companies until there were cars on the market that needed it, a bit like 98 octane today. Engines required compression ratios of up to 9.5 to take advantage of Super's higher octane, but Grey motors (& others) of the fifties) had compression ratios of 6.5 to 7.5 & are perfectly suited to 91 RON unleaded fuel. The only upgrade necessary for long term operation on unleaded fuel is hardened valve seats. Get the dissy checked out on a distributorgraph, by all means, it probably needs a bit of a service anyway. But you will find the existing advance curve will be OK. Dr Terry. Title: Re: Grey Distributor Unleaded Specs. Post by: HARKO on June 13, 2006, 06:43:52 AM While we're on the topic Id like to add that I know of a few cars that have been running on unleaded for years without hardened seats with no problems whatsoever .
Terry or anyone in the know can you please correct me if this isnt true .. An educated guess here but I'd believe that if you do run the standard head it will only result in the valve seats burning out which will then need replacing with hardened items in the futre And I'd also believe on a standard engine there'd be little chance of that happening under average driving condition's ,I could see it happening in an engine that is being revved hard alot allowing the valves to realy heat up . Title: Re: Grey Distributor Unleaded Specs. Post by: TorqueFC on June 13, 2006, 06:59:13 AM dont know if this helps at all, but we purchased a 308 about a year or so ago and the guy said 'i have been running it on unleaded, runs fine....' once we pulled the motor down we found that the valves were about 1/8" below the combustion chamber :O id say this is the result of not fitting hardened seats prior to running unleaded.... :-/
Title: Re: Grey Distributor Unleaded Specs. Post by: collecta on June 13, 2006, 09:38:17 AM Im with you Harko on this one,
Ive been running both my greys on a diet of straight unleaded, the black FE as long as 2.5 years with no noticeable problems. As a qualified mechanic if it was a problem i would expect the seats to wear causing my engine to miss as the valve clearance would close causing the valves to be kept open on overlap, this has not been the case and they are just about due for a tappet adjustment as they are starting to get a bit noisy,when hot. As Harko stated if the seats/valves do wear, then i will replace the seats/valves not before. Im also suprised that a 308 with 1/8" wear in the seats would run very well at idle. cheers Scott ps I also run my 350 without additives. Title: Re: Grey Distributor Unleaded Specs. Post by: TorqueFC on June 13, 2006, 11:02:14 AM we went by his word we never heard the motor run....
we had the fb for 6 years straight on unleaded without any additives and it seemed to run fine, although was starting to lose a bit of power about 5 years into us owning it, this could have been a number of things tho... Rod, the guy who does your dizzy will know what to do to it, if not, theres a bloke in nunawading vic who specialises in em...cheers... :-/ EDIT: come to think of it, that 308 ran on lpg! this would most likely explain it... :o |