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Sweet engine you have.
But when you have almost 12:1 doesn't that mean very high octane gas?
My L46 11:1 run on Shell 99 octane and still I can hear "knocking"
(99 octane in Europe is 93-94 octane in USA I think)
Thx,
John
First off with aluminum heads that have an efficient combustion chambers in them with that tight quench I have (.034"), it makes the engine less sensitive to detonation and it requires less overall ignition timing, 32 to 34 degrees total.
I had a very good cooling system with a 160 degree thermostat. I tuned the carb with a digital AFR gauge and a vacuum gauge. I still run a vacuum advance. It is adjustable for vacuum and I made a simple limiter to adjust how many degrees I allow it to come in. It ran great on good 93 octane out of a dedicated hose.
First off with aluminum heads that have an efficient combustion chambers in them with that tight quench I have (.034"), it makes the engine less sensitive to detonation and it requires less overall ignition timing, 32 to 34 degrees total.
I had a very good cooling system with a 160 degree thermostat. I tuned the carb with a digital AFR gauge and a vacuum gauge. I still run a vacuum advance. It is adjustable for vacuum and I made a simple limiter to adjust how many degrees I allow it to come in. It ran great on good 93 octane out of a dedicated hose.
Sorry for all my questions, but:
1. Is high ignition = more early detonation ?
1a. If yes, then I will try to lock my MSD 8571 @8
2. Are you also telling me, that if I lower my engine temperature, that will help with my early detonation?
2 a. If yes, then I will buy a new thermostat.
Is there anything else that can help me wit my early detonation?
Michael just call me again regarding his engine.
He is happy with the power he has, the engine has more power, than he use for daily driving.
But he think his cam is too rough, he would like to have a street cam, and maybe with EFI within a year or so.
He is ok about loosing power by downsizing the cam.
We know that the heads are too small, and should have been bigger, but the budget is not for that right now. We know that AFR 220+ would be better.
What would be a good cam for him?
Would it be a good idea to go for 4/7 swap?
He already has a torque monster, I would put the money for a new cam into a new set of heads when he can afford it, if the engine is running good then leave it the way it is until he can afford new heads.
I don't think a cam change is going to make much difference if you lose HP you will lose TQ they go hand in hand.
What he needs is properly matched components and the heads are way too small. If he gets bigger heads both the TQ and HP will go up across the board and still be nice to drive in traffic.
Sorry probably not what you wanted to hear but a new cam is a crapshoot he could end up with something he doesn't like
He already has a torque monster, I would put the money for a new cam into a new set of heads when he can afford it, if the engine is running good then leave it the way it is until he can afford new heads.
I don't think a cam change is going to make much difference if you lose HP you will lose TQ they go hand in hand.
What he needs is properly matched components and the heads are way too small. If he gets bigger heads both the TQ and HP will go up across the board and still be nice to drive in traffic.
Sorry probably not what you wanted to hear but a new cam is a crapshoot he could end up with something he doesn't like
Michael just called me again. The first time we talked today, I told him he needs bigger heads, I told him my guess is AFR 220 or a bit more.
All this made Michael think and call me again, so now the plan is:
New heads and the cam will be OK and the Carb is OK as long as it is tuned correctly. I would just slap on the new heads in 220cc range and you are looking at a killer engine with the HP and Tq Both going up across the board and it will be easy to drive on the street.
I run a solid roller cam 248/254 dur. with AFR 227 heads and you would not know how much power it has as the street manners are perfect. Until you hit the happy pedal then you know.
Big heads, big cam, I don't see any lack of mid range TQ or HP in the engine I built and have been driving around for a few years now, I don't understand the small heads / small cam or big heads / small cam ideology
Big heads, big cam, I don't see any lack of mid range TQ or HP in the engine I built and have been driving around for a few years now, I don't understand the small heads / small cam or big heads / small cam ideology
If the heads flow more air quicker, you don't need to hold the valve open as long.
The LS type engines have small duration cams and make big power, but they also make even more power with bigger cams but not as big as the Gen 1 small block 23deg head engines like. A big small block will tame a 240-250 dur. cam.
The LS type engines have small duration cams and make big power, but they also make even more power with bigger cams but not as big as the Gen 1 small block 23deg head engines like. A big small block will tame a 240-250 dur. cam.
You only want to hold the valve open as long as you half to to fill the given cyllinder displacement to a given rpm range. Lifting it or holding open longer achieves nothing but a peaky powerband and less power.
I have pulled away camshaft duration and lift in many builds to come away with more power for the customer.
One thing I thinking about, the engine was made by Ohio Crank (but specified by a dane !!)
When I look at OC home page, and find there 434 short block, then I says:
434 Small Block Chevy Short Block
•Motown block (requires small base circle cam)
•Ohio Crankshaft 4-inch crank
•JE Pistons
•6-inch H-beam rods
•Total seal rings
•Federal Mogul race bearings
•Billet caps add $300
If he order one of the above cams, then I assume he will have problems right???
One thing I thinking about, the engine was made by Ohio Crank (but specified by a dane !!)
When I look at OC home page, and find there 434 short block, then I says:
434 Small Block Chevy Short Block
•Motown block (requires small base circle cam)
•Ohio Crankshaft 4-inch crank
•JE Pistons
•6-inch H-beam rods
•Total seal rings
•Federal Mogul race bearings
•Billet caps add $300
If he order one of the above cams, then I assume he will have problems right???
You only want to hold the valve open as long as you half to to fill the given cyllinder displacement to a given rpm range. Lifting it or holding open longer achieves nothing but a peaky powerband and less power.
I have pulled away camshaft duration and lift in many builds to come away with more power for the customer.
I guess you missed the post of my chassis dyno ? 325ft/lbs @ 2000RPM and over 400ft/lbs from 3000-6000 Rpm and still over 300ft/lbs @ 7000RPM.
If you " pulled away camshaft duration and lift in many builds to come away with more power " then what you did was match components correctly which is of course what you want to do in any build.
What you are saying is with this particular engine he will make more power Tq. and HP across the board with a cam smaller than what he has in there now or any cam bigger than he has now ?
I will stick to what I know works and with AFR heads in the 220cc range he will make more power with a cam in the 240-250+ deg range over a cam in the 220-230 degree range and still be able to tool around town at 2000RPM. I would never even think of putting a small cam in that engine. A difference of opinions here that's all.
03-24-2014, 02:22 PM
