L88 ( clone) timing
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 753
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L88 ( clone) timing
Hi,
preparing myself to the arrival of my L88 ( look at pics in my album) need advises about high octanes gas and timing
let's assume that my L88 motor has 12:1 CR ( PO sayed very high CR and used premium gas+octane booster but doesn't know how many octanes actually: about 100 I think)
how many octane gas should be actually used at which timing?
the premium gas in Italy is 98 oct and I can boost it to 100 for quite cheap.But gas is expensive in Italy...so I'm ready to retard the timing and adapt the engine to 98 oct only to enable me to use the car more often ( 2-3 times per week , short rides , usually about 20miles)
the distributor on my L88 is not anymore the OEM point style but a MSD ( L88 cam , intake , holley850, headers....)
thanks for the advises
preparing myself to the arrival of my L88 ( look at pics in my album) need advises about high octanes gas and timing
let's assume that my L88 motor has 12:1 CR ( PO sayed very high CR and used premium gas+octane booster but doesn't know how many octanes actually: about 100 I think)
how many octane gas should be actually used at which timing?
the premium gas in Italy is 98 oct and I can boost it to 100 for quite cheap.But gas is expensive in Italy...so I'm ready to retard the timing and adapt the engine to 98 oct only to enable me to use the car more often ( 2-3 times per week , short rides , usually about 20miles)
the distributor on my L88 is not anymore the OEM point style but a MSD ( L88 cam , intake , holley850, headers....)
thanks for the advises
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
I use an MSD in my BB LS-7. Basically it's a 454 version of your L-88. I'm running 40* TOTAL timing with no problems on 110 octane gas. Runs great. I don't remember which stop bushing I used or which springs, but I think it was the light springs and the red bushing. Set it for the total and let the initial fall where it may.
Drifting
Joined: Sep 2006
Posts: 1,259
Likes: 2
From: MS
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
You will need race fuel. A typical bottle of octane booster will raise your octane rating one point. That is from 93 to 93.1 Not 93 to 94
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 753
Likes: 0
I'm a little worried...
in Italy we have regular gas ( 94 oct) and premium ( 98 oct) . I was sure that octanes was an international standard...why the italian 98 is actually 94 in the US? different way of measure?
The racing fuel is unbelievable expensive...
If so , there's no way out : I have to retard the timing or reduce CR with a suitable head gasket... please advise me about
in Italy we have regular gas ( 94 oct) and premium ( 98 oct) . I was sure that octanes was an international standard...why the italian 98 is actually 94 in the US? different way of measure?
The racing fuel is unbelievable expensive...
If so , there's no way out : I have to retard the timing or reduce CR with a suitable head gasket... please advise me about
Drifting
Joined: Sep 2006
Posts: 1,259
Likes: 2
From: MS
You can google around for more info but my understanding is that the Europe standard is the Research Octane Number (RON) which is a more simple unloaded test. Another rating is the Motor Octane Number (MON) and this uses an engine that is operated under load to check for detonation and gives a more accurate indication of the fuel's resistance to detonation, which is really all the term octane means. The US uses the standard of RON + MON / 2 so they take the average of the RON and MON to get our number, so the exact same fuel in Europe would be rated much higher even though it is the same.
The L88 fuel warning decal said that it required 103 RON or 95 MON. This works out to 99 octane in the US but still 103 octane in Europe and just don't think you can boost your 98 pump gas to 103. This assumes the L88 is still 12 or 12.5 to 1. You really have to find out what the compression is and how it is built. Don't think any amount of head gasket will reduce compression enough to matter if it still around 12 to 1.
The L88 fuel warning decal said that it required 103 RON or 95 MON. This works out to 99 octane in the US but still 103 octane in Europe and just don't think you can boost your 98 pump gas to 103. This assumes the L88 is still 12 or 12.5 to 1. You really have to find out what the compression is and how it is built. Don't think any amount of head gasket will reduce compression enough to matter if it still around 12 to 1.
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 753
Likes: 0
You can google around for more info but my understanding is that the Europe standard is the Research Octane Number (RON) which is a more simple unloaded test. Another rating is the Motor Octane Number (MON) and this uses an engine that is operated under load to check for detonation and gives a more accurate indication of the fuel's resistance to detonation, which is really all the term octane means. The US uses the standard of RON + MON / 2 so they take the average of the RON and MON to get our number, so the exact same fuel in Europe would be rated much higher even though it is the same.
The L88 fuel warning decal said that it required 103 RON or 95 MON. This works out to 99 octane in the US but still 103 octane in Europe and just don't think you can boost your 98 pump gas to 103. This assumes the L88 is still 12 or 12.5 to 1. You really have to find out what the compression is and how it is built. Don't think any amount of head gasket will reduce compression enough to matter if it still around 12 to 1.
The L88 fuel warning decal said that it required 103 RON or 95 MON. This works out to 99 octane in the US but still 103 octane in Europe and just don't think you can boost your 98 pump gas to 103. This assumes the L88 is still 12 or 12.5 to 1. You really have to find out what the compression is and how it is built. Don't think any amount of head gasket will reduce compression enough to matter if it still around 12 to 1.
yes I have to measure the actual CR when the car will be here. But you know, before this, I want to ride the car first ( I can't wait...) . so I need to have the right fuel in my hands soon. I would like to ask you about a certain US made additive. can I post the link or is it a kind of advertising?
I suppose that an excessive retard of the advance would not be a solution...since the engine would behave really bad
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Racer
Joined: Apr 2006
Posts: 477
Likes: 43
From: Millbrae California
a engine with a big cam like a L88 needs a lot of initial timing then you set the total to what the engine can take without pinging.
to determime what initial timing to use, one of the best guidelines for determining initial timing can be found in the Barry Grant catalog or Web site (in the Demon carburetor selection guide). The guideline recommends 10-12 degrees of initial timing when the camshaft duration is less than 220 degrees @ .050˝ of lift; 14-16 degrees with less than 240 deg @ .050˝; And, 18-20 degrees with less than 260 degrees @ .050˝.
I would try 18 to 20 degrees initial timing and maybe 32 to 34 total advance (black bushing with blue springs?) and then see how it runs.
I hope this helps Henry @ olescarb
to determime what initial timing to use, one of the best guidelines for determining initial timing can be found in the Barry Grant catalog or Web site (in the Demon carburetor selection guide). The guideline recommends 10-12 degrees of initial timing when the camshaft duration is less than 220 degrees @ .050˝ of lift; 14-16 degrees with less than 240 deg @ .050˝; And, 18-20 degrees with less than 260 degrees @ .050˝.
I would try 18 to 20 degrees initial timing and maybe 32 to 34 total advance (black bushing with blue springs?) and then see how it runs.
I hope this helps Henry @ olescarb
Burning Brakes
Joined: Jan 2005
Posts: 847
Likes: 1
From: spring branch texas
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 753
Likes: 0
Olescarb.
thanks!so once fixed the initial timing for good idle, I have to set a "quiet" slope of centrifugal+vacuum to avoid pinging at mid-throttle...
wfo76.
I meant this additive ( in Italy costs nearly 2and1/2 times than in the USA, but the final price of the gas with it would be less in respect to a pure racing gas)
http://www.klotzlube.com/storeProdDetails.asp?pi=34
thanks to you all for the valuable advises!
thanks!so once fixed the initial timing for good idle, I have to set a "quiet" slope of centrifugal+vacuum to avoid pinging at mid-throttle...
wfo76.
I meant this additive ( in Italy costs nearly 2and1/2 times than in the USA, but the final price of the gas with it would be less in respect to a pure racing gas)
http://www.klotzlube.com/storeProdDetails.asp?pi=34
thanks to you all for the valuable advises!
Racer
Joined: Apr 2006
Posts: 477
Likes: 43
From: Millbrae California
Elle88 FYI, we are having to limit the advance from the vacuum advance (to 10 degrees) to avoid ping problems at part throttle just in case you experiance a ping at part throttle problem. Reformulated unleaded gas burns faster at part throttle - low load driving conditions than the leaded gasoline that most vacuum advance units were designed to work with.
Henry @ olescarb
Henry @ olescarb
Burning Brakes
Joined: Oct 2006
Posts: 1,044
Likes: 0
From: Henrico VA
I'm sure you know your stuff, but I had an incident where the Seven Eleven sold me the wrong gas and the car didn't want to run anymore. When I finally walked to another gas station, I bought SLP Octane Booster and the car did eventually run again (I left out a lot), so it must have done more than more point that time. Also, elle88, I enjoyed the double meaning of that name.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
You dont need a vacuum advance with a L88, they never came with one that was operational. Purely centrifugal. Total it 37-40 with GOOD gas, 100+. As long as it`s driven easy lessor octane will work unless you hammer it. A reasonable substitute is aviation gas. I have put over 28,000 miles on a true L88 before it was necessary to rebuild it. And by the way a satisfactory idle is 850-900. Don't expect too much in the mileage category, 7-10 and determined by your aggressiveness...
Advanced
Joined: Nov 2003
Posts: 51
Likes: 0
Hi,
I live in Denmark and have an L88 T-Top from 69.
I am using 98 octane gas, mixed with 25% toluene (toluene is 114 octane).
I bought a barrel of toluene (200L), paid 14 DKK per liter = 2,7 $ per liter, which make the home mixed gas much cheaper than racing gas (30 DKK liter).
I have installed a detonation sensor, and have no pinging.
I can retard the ignition using a simple dial, in case I only have access to 98 octane and no toluene.
--
An alternative solution is to inject distilled water and/or alcohol.
I have not tried octane booster, as I believe that most will not increase the octane by more than a fraction for an entire tank of gas.
I live in Denmark and have an L88 T-Top from 69.
I am using 98 octane gas, mixed with 25% toluene (toluene is 114 octane).
I bought a barrel of toluene (200L), paid 14 DKK per liter = 2,7 $ per liter, which make the home mixed gas much cheaper than racing gas (30 DKK liter).
I have installed a detonation sensor, and have no pinging.
I can retard the ignition using a simple dial, in case I only have access to 98 octane and no toluene.
--
An alternative solution is to inject distilled water and/or alcohol.
I have not tried octane booster, as I believe that most will not increase the octane by more than a fraction for an entire tank of gas.
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 753
Likes: 0
thanks everybody
here are a couple of videos made by the PO for me . car idling and car driven ( in quiet manner)
http://jimpascale.myphotoalbum.com/v...96&id=dscf8644
http://jimpascale.myphotoalbum.com/v...96&id=dscf8645
im these videos the motor is running with premium gas+some (cheap, I suppose) octane booster
Ironcross.
I supposed that no vacuum advance on L88 . sorry for my ignorance but i own a more usual 350 79 vette and sincerely little literature on the Net about BB and L88
Isorense. the Toluene seems a nice solution. did you get it at an oil company or chemical?chemical I suppose...
here are a couple of videos made by the PO for me . car idling and car driven ( in quiet manner)
http://jimpascale.myphotoalbum.com/v...96&id=dscf8644
http://jimpascale.myphotoalbum.com/v...96&id=dscf8645
im these videos the motor is running with premium gas+some (cheap, I suppose) octane booster
Ironcross.
I supposed that no vacuum advance on L88 . sorry for my ignorance but i own a more usual 350 79 vette and sincerely little literature on the Net about BB and L88
Isorense. the Toluene seems a nice solution. did you get it at an oil company or chemical?chemical I suppose...
Drifting
Joined: Oct 2005
Posts: 1,527
Likes: 148
From: East London/SW Essex UK
My very new 489 with mild (ish) cam and 10.5 c/r, 21 degrees static and 38 total does not 'ping' but will 'run-on' when ignition turned off. Engine builder says to only use Shell V Power (here in UK) I still had a tank of UK spec 4 star unleaded so added a container of Millers VSP lead subsitute which stopped the 'running-on'.
http://tetraboost.com/
Take a look at this - can't vouch for the claims from this UK company - and don't know if this is available in Europe.
My understanding is that this is classed as a 'highly dangerous' chemical and as such may be difficult to export.
I have spoken with this guy and he tells me that many members of the very small chain of specialist UK 4 star leaded fuel garages now source the additive from his company and mix their own gas. Some years ago I had a '71 Mustang 429 SCJ, this had a 11.2 c/r and when the old UK 5 star leaded fuel was withdrawn would not run well on the 4 star unleaded. I can remember using the USA sourced Tetra Ethly Lead additive and listening to the engine start to run and idle really smoothly and quiet once the treated fuel worked its way in to the carb.
Nasty stuff this - spill it on your exposed skin and die a slow death of lead poisoning!
http://tetraboost.com/
Take a look at this - can't vouch for the claims from this UK company - and don't know if this is available in Europe.
My understanding is that this is classed as a 'highly dangerous' chemical and as such may be difficult to export.
I have spoken with this guy and he tells me that many members of the very small chain of specialist UK 4 star leaded fuel garages now source the additive from his company and mix their own gas. Some years ago I had a '71 Mustang 429 SCJ, this had a 11.2 c/r and when the old UK 5 star leaded fuel was withdrawn would not run well on the 4 star unleaded. I can remember using the USA sourced Tetra Ethly Lead additive and listening to the engine start to run and idle really smoothly and quiet once the treated fuel worked its way in to the carb.
Nasty stuff this - spill it on your exposed skin and die a slow death of lead poisoning!
Pro
Joined: Nov 2004
Posts: 575
Likes: 0
From: Nice Lake Ontario
elle88, not meaning to dis your car but after listening to the vids it sure doesn't sound like a 12/1 comp car. Either you have some serious restricted mufflers or it's more like 10.5/1. I have never heard a true L-88 but been in the presence of true LS-7s back in the day with 12/1 comp & they absolutely POPed out the exhaust.
Are you sure what's in the engine?
Are you sure what's in the engine?
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 753
Likes: 0
elle88, not meaning to dis your car but after listening to the vids it sure doesn't sound like a 12/1 comp car. Either you have some serious restricted mufflers or it's more like 10.5/1. I have never heard a true L-88 but been in the presence of true LS-7s back in the day with 12/1 comp & they absolutely POPed out the exhaust.
Are you sure what's in the engine?
Are you sure what's in the engine?
FRAME OFF RESTORATION
original GM L-88 camshaft (P/N: 3928911)
Heads are cast iron hiperf. closed chamber (protoypes were cast iron closed chamber)
L88 valves, springs & rockers
L88 aluminum intake
solid lifters
Steel crank
MSD ignition
L-88 hood
Holley 850 double pumper
Muncie "rock crusher" M22 4 speed with Hayes clutch
Holley hiflow electric fuel pump
Of course I can't check what's inside the motor. But I suspect that the CR has been lowered to 11:1 or so. sincerely , I hope so!because it would be easier to me to use the car with a less expensive gas. And I will have anyway lots of HP and TQ...
Anyway I checked on youtube the idle sound of another L88 and was not so far from mine
more pics of the motor and car at
http://jimpascale.myphotoalbum.com/v...album96&page=2
thougths and advises are welcome
BTW I'll be happy if it's a 70-80% L88...that's enough for me