My engine is still running a little hot at idle and am wondering if richening the idle jets of the Edelbrock 500 slightly, would lower the temperature?
Kevin.
Effect of idle jets on running temperature.
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CastleMGBV8
- Top Dog
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- Location: Sidcup, Kent, UK
I doubt it Kev!
Its the old MGB V8 lack of under bonnet air flow thing mate.
Have you removed the rubber seal at the rear of the bonnet near the scuttle? It does allow warm air to creep out a bit better. But you can then get engine bay smells in the cabin if its a bit of a stinker.
Its the old MGB V8 lack of under bonnet air flow thing mate.
Have you removed the rubber seal at the rear of the bonnet near the scuttle? It does allow warm air to creep out a bit better. But you can then get engine bay smells in the cabin if its a bit of a stinker.
Perry Stephenson
MGB GT + Rover V8
9.62 @ 137.37mph
Now looking for 8 seconds with a SBC engine
http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw
https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw
MGB GT + Rover V8
9.62 @ 137.37mph
Now looking for 8 seconds with a SBC engine
http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw
https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw
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CastleMGBV8
- Top Dog
- Posts: 2334
- Joined: Sat Aug 18, 2007 5:09 pm
- Location: Sidcup, Kent, UK
Perry,
I have the RV8 exhausts manifolds so the engine bay vents well through the inner wings.
As mixture can effect how hot the combustion is I thought it might make a difference.
The old 3.5 engine always stayed within the correct temperature range but the new 4.35 engine is getting a little warmer than I would like at idle in traffic, 95c + it's fine once you get moving and drops back to the mid to high 80's
I havent changed the idle mixture since the engine change but the carb has been re-calibrated, from memory the screws are at approx 1 3/4 turns out as recommended.
Kevin.
I have the RV8 exhausts manifolds so the engine bay vents well through the inner wings.
As mixture can effect how hot the combustion is I thought it might make a difference.
The old 3.5 engine always stayed within the correct temperature range but the new 4.35 engine is getting a little warmer than I would like at idle in traffic, 95c + it's fine once you get moving and drops back to the mid to high 80's
I havent changed the idle mixture since the engine change but the carb has been re-calibrated, from memory the screws are at approx 1 3/4 turns out as recommended.
Kevin.
Hi Kevin,
You are quite correct in that a richer mixture won't burn as hot as a leaner one but at idle you are burning so little fuel that the cooling system should have a massive over capacity to keep the lump cool. A retarded ignition could make the lump run a little hotter, what is your timing figure at idle?
BTW I found that my stage III engine and my mates standard 3.5 both need the pilots out 2+1/4 turns out. The LC1 shows both running at 12.2:1, neither lump was happy when the mixture was set any leaner.
His lump pulled 18" at tickover (I think), mine pulls 15" of mercury.
Cheers,
Pete
You are quite correct in that a richer mixture won't burn as hot as a leaner one but at idle you are burning so little fuel that the cooling system should have a massive over capacity to keep the lump cool. A retarded ignition could make the lump run a little hotter, what is your timing figure at idle?
BTW I found that my stage III engine and my mates standard 3.5 both need the pilots out 2+1/4 turns out. The LC1 shows both running at 12.2:1, neither lump was happy when the mixture was set any leaner.
His lump pulled 18" at tickover (I think), mine pulls 15" of mercury.
Cheers,
Pete
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CastleMGBV8
- Top Dog
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- Joined: Sat Aug 18, 2007 5:09 pm
- Location: Sidcup, Kent, UK
Pete,
I'm pretty sure it is set at 10 deg. static so will be approx 34 deg. all in with the advance curve modified to your specs but with no reduction in max advance.
This was only a temporary measure as I was going to fit the Megasquirt to control ignition and all the EFI kit i've collected.
As I've got the engine running so well on the carb not sure I can be bothered to fit it all and have the hassle of getting it right. knowing me the car will be off the road again for most of the summer!
Was thinking of fitting the Megasquirt and just using it for the ignition and then it can be set up very accurately with a specific advance curve and max advance of say 32 deg + a bit for cruise and idle.
I'm going to get the car out tomorrow to do a pre MOT shakedown and may try richening the idle slightly to see if it makes any difference, could be that the increased overlap of the cam is also having an effect but only guessing.
Kevin.
I'm pretty sure it is set at 10 deg. static so will be approx 34 deg. all in with the advance curve modified to your specs but with no reduction in max advance.
This was only a temporary measure as I was going to fit the Megasquirt to control ignition and all the EFI kit i've collected.
As I've got the engine running so well on the carb not sure I can be bothered to fit it all and have the hassle of getting it right. knowing me the car will be off the road again for most of the summer!
Was thinking of fitting the Megasquirt and just using it for the ignition and then it can be set up very accurately with a specific advance curve and max advance of say 32 deg + a bit for cruise and idle.
I'm going to get the car out tomorrow to do a pre MOT shakedown and may try richening the idle slightly to see if it makes any difference, could be that the increased overlap of the cam is also having an effect but only guessing.
Kevin.
CastleMGBV8 wrote:Pete,
I'm pretty sure it is set at 10 deg. static so will be approx 34 deg. all in with the advance curve modified to your specs but with no reduction in max advance.
This was only a temporary measure as I was going to fit the Megasquirt to control ignition and all the EFI kit i've collected.
As I've got the engine running so well on the carb not sure I can be bothered to fit it all and have the hassle of getting it right. knowing me the car will be off the road again for most of the summer!
Was thinking of fitting the Megasquirt and just using it for the ignition and then it can be set up very accurately with a specific advance curve and max advance of say 32 deg + a bit for cruise and idle.
I'm going to get the car out tomorrow to do a pre MOT shakedown and may try richening the idle slightly to see if it makes any difference, could be that the increased overlap of the cam is also having an effect but only guessing.
Kevin.
Hi Kevin,
You could push the static up to 12-13, you could gain a few BHP up to the point where all the advance is in, after that it won't make any difference. The only problem would be that you would have to restrict the total advance using a sleeve. I bet your tickover goes up if you increase the static which would indicate the engine likes what you are doing!
My 4.6 runs 34 all in even though the general opinion seems to be that 28 is the figure for a 4.6. Mine defo pulls harder from 4K upwards with the higher advance figure.
Let us know what you do and how it goes!
Pete
