Compression & Ignition Question

My point about how I drive the car is that I don't put it into a position where it will be prone to detonation. You sound like you are a cautious guy. If you are not and want to do donuts in the local parking lot on 90 days with the car temp at 230 then trouble will follow no matter how you build it. I've driven my car 1000's of miles with no problem I'm just being very about it. If I had aluminum heads I'd have less to think about.

Things you have going for you:

My car weighs 4000+ lbs. without me. Your car is more than likely less.

I drive in mostly close to sea level areas. What is the altitude where you'll be driving the most? I'm pretty sure yours on average will be higher than mine. A higher altitude allows for higher compression. I've had my cars into the Rocky Mountains and they barely idle up there because of the low cylinder pressure up there.

You have aluminum heads. That is worth at least 1/2 point of compression as far as octane is concerned. In fact when you run aluminum heads it is recommended to raise your compression ratio to make up for the better heat dissipation of the aluminum which actually lowers power output compared to comparable steel heads. In effect if you run identical heads of steel and aluminum the steel will make more power than the aluminum because of this. The aluminums only make more power in this case because of the newer chamber and better flow. The newer chamber will probably help ward off detonation also.

Tight quench is good in just about any engine but when running the typical piston in the 455 with only the outer ring, and not a flattop type piston, the actual quench area is very small. Only about half of what it would normally would be. So it seems to me its effect on detonation would only be 1/2 of what it could be.

Remember that DCR is not the do-all, end-all because sooner or later as RPM increases the cylinder pressure increases because of better scavenging of the longer duration cam. That's what a bigger cam does. It shifts the power band to a higher rpm.

I also like to use 0 overlap at .050" as the point when the rumpity idle starts to become noticeable. Not that it is much at that point but it is when you can hear it more clearly. I have a cam in now with 8 OL and that is almost too much for me. I like the speak softly and sneak up on them idea. That being said I do like that 230/240/116(TA 288-96H) cam for your situation. With 3 of overlap at .050" it will only have a slightly "worse" idle than the 212. If you get it ground on a 118 LC then it would have -1 OL and have a very slightly "better" idle than the 212. That should allow you to sleep at night. The C118 cam has way too much spread between intake and exhaust for your setup.

 

Let’s look at the effects of changing Cam Timing versus SCR to achieve a DCR of 8:1.

For your engine the SCR needs to change from 10.5 to 9.8 to get an 8.0 DCR
The Thermal Efficiency drops by 1.8% for an overall drop in power by 1.8%.
You still need to measure the actual dish volume in the piston.

Leaving the SCR at 10.5 you would have to retard the intake valve closing from 60.5 degrees ABDC for the TA 212 to 70 degrees ABDC using a different cam.
At very low rpm that is an 8.4% drop in Volumetric Efficiency and corresponding torque.

Of course as the engine rpm increases the VE increases and the torque will increase.
The difference will be the peak torque will move from around 3500 rpm for the TA 212 to over 4000 rpm with the bigger cam.

If you look at the Car Craft article, The TA 413 cam is represents a 10% drop in VE at low rpm from the TA 212 and if you look at the torque at 2100 rpm the TA 212 is 441 and the TA 413 is 401 ft lbs. 10%

So if you adjust the DCR to 8 by decreasing the SCR to 9.8 you only lose 1.8% power over all and you get to keep the TA 212. You will notice in the Car Craft article that good torque was produced even with an 8.77 SCR.

If you adjust the DCR to 8 by changing the intake valve closing from 60.5 to 70 degrees ABDC, you lose 8.4% at low rpm but will gain additional horsepower as the torque peak is shifted higher in rpm.

You would want to do this by using a longer duration profile and an increase in lobe separation to keep the overlap at 0 or less for a smooth idle.
Again using the TA 288-96H ground on a 118 center, the overlap is -1 and with the cam set at a 4 degrees advance the DCR is 7.4.
Horsepower would be closer to 500.

Now here's the fun part. With the TA 288-96H on a 118 center, you could 0 deck the piston for a 11:1 SCR and have a 7.75 DCR.
Your engine would be real close to The "Sneaky 500 hp" motor by Jim Weise which has a good idle, big hp and low fuel consumption.
If you had a transmission with a lock up converter, you could cruise at low rpm with great fuel mileage and have a high stall converter for acceleration.

Paul

 

:gp:
Wow thanks for this two very helpfull answer Mike and Paul. Mike, now i guess you thats possible to drive with the TA212 without troubles. But your suggetion with the TA288-96 is actualy the perfect cam for my setup!:TU:

Paul and Mike

Please don't understand me wrong, im not a man who wants a lot of hp to compare another things....... Fact is i have bought expansive heads and forged pistons, a new block (i made all required oil mods). There is a good basic to create a engine with 450hp-500hp . If i want 400-450hp thend are the parts "to good" for the mild engine and i have waste a lot of money..:spank:.

I have a stock TH400 and a 12 Bolt GM rear end with 2.93. I dont know how high is the stall converter, what u recommend?. If i need a bigger one for this cam, i will buy a bigger but not a 3000rpm. Is the TH400 to weak i will buy a proper TH700R2/4 <--- 2 has a shorter 1. gear right?

When i use the modified TA288-96H cam on zero deck, are notched pistons required?

Thanks

Robert

 

With a mild cam I would not bother changing the torque converter unless you are drag racing the car... Then I would go with a 2500 stall roughly.

BTW, the 7004R is a 4 speed auto overdrive trans... The main advantage these have over the 3 speeds is that they cut the rpms down on the highway... The downside is that the 700 is not a good swap for a 455 car because it does not fit easily and is weak compared to the th400. Same goes for the 2004R except it is an easier swap into a Buick.

I would leave the th400 alone if it works well...

You should check the valve to piston clearance on any engine, ONLY then will you know if valve notches are required. Have you measured the piston in the hole depth or deck height yet?

 

I would suggest running the new engine without changing anything else.
Then you can figure out what converter stall you really need to match the engine power.

There are several options for converter and transmission changes that will allow you to stay with the stronger type TH400.

You can use a switch pitch converter that lets you switch between a low and a high stall speed.

Precision Industries makes a lock up converter for the TH400. I haven't
talked to them but I'm sure it requires modifications to the transmission.

The 4L80E transmission has a lock up converter and an overdrive.
TCI makes an adapter plate for Chevy transmissions to Buick engine.
The 4L80E can be modified for manual shift control.
There are lighter aftermarket lockup converters to reduce the rotating inertia.

There is always the 5 or 6 speed overdrive manual transmission if you don't mind a clutch.


Tim at TA said they usually don't have to notch pistons at .500 lift, but Sean is correct that valve clearence check is standard procedure. There should be 0.100 clearence and more is better just in case you want to move the cam timing.

Paul

 

I will stay by the TH400 and after a troubles i will replace it with a 4L80E or a 4L60e from performabuild.

So back to the topic.

The TA288-96H seems to be just the right of that. When i order this cam, than are few modification required ( longer duration, increase lobe seperation) . What should i say exactly to get 100% that cam that you mean Paul.

Thanks

Robert

 

You want a TA288-96H with a 118 lobe center.

Paul

 

*Update*

Now i have ordered from TA the 288-96h camshaft with a 118 Lobe center. They mean it will takes a week or more time...

Next i tried to measure out the cc's of the Speedpro L2353 piston. That was a bit difficult, because to get the water in the dish and the air out of the dish without loosing water. I filled 25ml of water in it and there was few mini air bulbs under the plastic deck. I wealth a volume of 25cc maybe little bit more..

With these numbers i have a SCR 10.88:1 with zero deck. After assembling the engine i will soon as possible do a dyno run. Im very curius about the numbers... Paul what you mean should i take choose another stall converter after a dyno run? to see first the power band?

Thanks alot to all People who helped me!

I will be back in few weeks, with the strongest 455 in switzerland ( i hope it):beers2:

Robert

 

Yes wait for the dyno run.

Are you doing the engine assembly?

Paul

 

I have completly disassembly the engine. But all the difficult thing was made by the machine shop. They have a good know how, but they dont know the buick oil mods etc. Thats the reason, why im in the process.
Paul is there something to consider extra?

Robert

 

Since there is extra deck machining to get zero deck piston height
you may have to machine some material off the intake manifold to
get the head ports to align with the intake manifold runners.

An adjustable push rod should be used to check all 16 positions to
determine what push rod length is needed.

Paul

 

*update*

- Now i have the new TA288-96H cam with a 118 lobe center angle.
- Block is bored to the next over 0.30". honing next week

To do:

Find the best sparkplugs with wires for my engine? Any recommends? Paul, Mike?
Next week will the crank get balanced (Crank,Balancer,timinggear ,Flywheel,pistons,rod and bearings)

Paul how i should install the cam ? 4* advance or standart?

Thanks a lot

Robert

 

4* advanced

 

Robert

As Scott said, 4* advanced.

Did you get a cam card with the camshaft?

Right after the cam is installed, please put the
lifters in for cylinder #1 and check the cam lobe
timing for intake and exhaust.
Record the .050 and the .006 lobe lift degree wheel readings
Also verify the lobe center by checking .050 readings down
from the top of the lobes.
I'm anxious to see what the actual grind is compared to the specs.

I don't have any recommendations for plug wires.
Hoping someone else will comment on this

Paul

 

*Update*

Now have all rods and pistons the same weight +/- 1g.
Today i took the all required parts to another engine shop for the balancing.
My block will be till friday honed and the cranks + stuff are balanced. Then i put the crank in and check the clearance to deck, valve etc. Target is zero decked, i guess thats the right way.

LS1 powered camaro will bring the parts fast and save to the shop :3gears:

 

*Update*

- Block bored and hohned 0.030"
- Crankshaft, Flexplate and balancer with pulleys fine balanced (internally)
- Meassure how deep are the piston in the hole 0.035" (after clean mill)

Hi all and just a little *update*

Jobs this week:

- Target CR are 10.8 -11:1
- Final deckheight should be 0.005", so mill down the deck 0.030"

Next steps:

-Put the engine together and check the the valve clearance

Everyone recommends me a sparkplug? any expierence with the E3? from the motorcraft testengine?

Thanks

Robert

 

Any Updates?

 

Nope... im waiting still for the call from the maschineshop.
My uncle knows the owner from the shop. So i can do most of the work self (Disassemblied, oilmods, prepare for milling balancing..) So i can save much money and i can learn more about a BBB! And i love the work with it!

Only change is: Bought a TA Timing Cover witch the lager oilfeed holes and ready for the double roller chain.

Thanks paul nice of you to ask!

Regards

Robert

 

Robert

I also replied to bring this thread back to the front
hoping someone would answer your question about
what spark plugs they recommend using.

Paul

 

*Update*

Block has now zero deck. Today i put the cam and crank in to check valve clearance. I press some modeling clay on the piston and it shows a clearance of 0.078". I hope the cam is installed at +4* Advanced. I take a pictrure from the timing gear. Can everyone acknowledge that?
The piston is in this position on zero deck.

Than another question, has my carburator (750cfm rebuilded by cliff) for my old 400 engine to small jets insert? When yes wich size is the right?

regards

Robert

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