[plum-crazy]

Hi.
Is my first post in your forum.
I built a 440 0.030 bored in a 1970 challenger. The specs are :
10.34 trw pistons (L2295-F30), stock 906 heads, edelbrock performer rpm intake with edelbrock 750 manual, 233º-240º @ 0.50 compcams cam with 0.474-0.474 lift, hooker headers 1 7/8, 2400 stall converter b&m, high volume water, fuel and oil pumps, electric fan, 727 transmission race kit, new radiator.
Pushrod length 9.290" (old and stock) I think original of mopar performance size is 9.310", old and stock rockers, and new too hard springs from compcams for the stock and old valves.

When engine is cold runs well but when is hot we have a very strong pinging noise, we must put the advance in 0 degrees and maximum without vacuum up to 23-24 degrees to avoid pinging noise.
Car on dyno test is 290 hp, and we can't use full throtle because enging goes down.
Cam advance is on 0, no advanced and no retarded, is possible that heads get a lot of temperature and it makes pinging?
I checked lift valves but I only can check about 0.400 lift more less on each one instead of 0.474 of this cam. Is this cause hard springs? Maybe short pushrods? Lifters are hydraulic ( from cam and springs kit).
Now the engine is disassembled again to find the problem but we can't find the real one. We thing the previous questions I asked you will be the answer, maybe not. I'm in a trouble, here is hard to find good professionals to upgrade engines.
Pictures are engine finished out of car, into the car and now, disassembled.
Sorry for my english and I hope to get help from you.
Best regards and thanks again.

[dave-r]

It sounds very much like you have too much compression for the fuel you are using.

Check very carefully what the actual compression ratio is. Don't just go by the numbers quoted for those pistons. What grade fuel are you using?

Checking the cylinder pressure might be a good idea.
The cylinder pressure is a result of 5 things, the static compression ratio, cylinder head material (iron or aluminum), the closing point of the intake lobe, the altitude of operation of the engine and the final displacement of the engine.
When using 93 octane gasoline aim for 160-170 psi cylinder pressure with a camshaft like this.

Engine temp and fuel mixture also effect 'pinging'.

You cannot measure the valve lift at the valve with no oil pressure. The lifter does not lift so much? You have to use weak testing valve springs or measure the cam lobe directly and multiply by 1.5 to get valve lift.

However the valve springs you use MUST MATCH the cam you have. So if they are too strong for your cam change them. They will not cause this problem you have right now though.

Also you must use correct length pushrods. Tell me if you have adjustable or non-adjustable rockers and I will tell you how to check.

[plum-crazy]

First of all, thank you very much for your quick response.
Here in spain we use a 97 octane fuel.
Certainly I checked valve lift wiht engine out and no oil pressure but lifters charged, maybe is not the correct process.
We checked valve damage (only the exhaust ones) we thing due to high temp and now we have a little leak and guides damage too, we check at first and was all good but it damaged only in 800 miles. You can check the graphic.
anyway I ordered to summit racing a new set of edelbrock performer rpm heads with 88cc chambers (like 906), complete, I mean with valves, springs , retainers, etc..., new pushrod set with 9.310 length, and before assembly we check again cam and lifters but we saw them ok, car only has 800 miles with this engine and we maked the brake time running 30 minutes at 2500 rpm first time we turned on the engine.
With this changes we want to : Vanish temperature of heads, get the correct pushrod length because we do not have adjustable rockers, use fuel without plumb, and use the correct jets of carburetor to get the correct air/fuel ratio and why not, get more HP from the engine ( I believe that this heads have more flow than the original ones).
We will use cooler spark plugs this time.
If you need anything more to know, please let me know and thanks a lot again.
alfred.

[dave-r]

Here in spain we use a 97 octane fuel.

That is good enough for a 10:1 compression engine without a doubt.

Certainly I checked valve lift wiht engine out and no oil pressure but lifters charged, maybe is not the correct process.

No you will always get some leak-down in the lifter. Check out the Crane Cams website for technical details on how best to do this.

I ordered to summit racing a new set of edelbrock performer rpm heads with 88cc chambers (like 906), complete,

Because of the better cooling of these heads effective pressure will drop in the cylinder to a level near a 9.5:1 compression iron head engine. So that should work perfect.

If I was you I would use adjustable roller tip rockers. 1.6:1 ratio should give you more lift.

[Christer]

We checked valve damage (only the exhaust ones) we thing due to high temp and now we have a little leak and guides damage too, we check at first and was all good but it damaged only in 800 miles. You can check the graphic.

That compression test doesn´t look good at all. From what I have heard, the compression should vary less than 1.5 bars between the different cylinders. On your engine, the compression varies 5 bars! I guess that all of the cylinders should have a cylinder pressure of 11 bars or something like that, if everything is as it should be.

I get the impression that you suspect that some of the valves are leaking. If I was you, I would also check if any of the piston rings have been damaged due to the pinging. Btw: Are any of the cam lobes worn?

[72 Challenger (Hans)]

That compression test doesn't look good to me too, way to much difference between those cylinders. I don't know exactly how many bar you need to have but I do know that one cylinder can not be almost twice as high as any other.

Also, I'm not an BB expert, it looks to me that these pistons gives you more then 10.5:1 Looks like they even stick out the cylinder a little bit. What do you think about that Dave? Don't know how to convert these BAR# to PSI or real CR, but if it really is to much of compression you could check for Cometic gaskets. These can be bought in any thickness you want. Also, if it was the pinging, eddy heads will solve a part of the problem too. Aluminium vs Iron heads can withstand more CR.

By the way, never thought of knowing a Chally in Spain?? Driven through spain once with a old Furd and they were all looking like what on earth is that... lol

[dave-r]

You just reminded me Hans. As I was falling asleep last night a thought in my head wondered just how close those pistons were coming to the head?

Anything less than 30 thou between the top of the piston and any part of the head (quench chamber) and the pistons would be hitting the head.

[dave-r]

Oh and about Spain. Never been. But I did have a girlfriend from there once while she was a student over here. I always promised to turn up in a Mopar one day. Don't think her husband would be very happy about it now though.

What was the place called? Soria I think? Where they filmed Doctor Zhivago apparantly.

[Christer]

You just reminded me Hans. As I was falling asleep last night a thought in my head wondered just how close those pistons were coming to the head?

Anything less than 30 thou between the top of the piston and any part of the head (quench chamber) and the pistons would be hitting the head.

You will find the piston spec if you follow this link:
http://store.summitracing.com/default.a ... u&N=301942
(Search for: TRW-L2295F30 )
I don´t know if it helps or not.....

[Christer]

I think that the #906 heads have 80 cc chambers (I can´t find the exact figure right now.). That means that the CR should be more than 10.34:1. I guess that 11:1 is closer to the truth.

[bryan]

14.7 psi =1 bar

[plum-crazy]

Thanks to everybody.
I try to tell about all you say to me.
Original 906 heads are 88cc.
We checked clearance pistons to head and no problem with it.
Yes my pistons are TRW-L2295 L30, with 10.34:1 CR with 88cc heads.
New alu heads are on the way to spain, edelbrock performer rpm #60189#, I ordered new pushrods, new camshaft (edelbrock 7194 cam kit with 238º-246º and .280-.295 lift) and new crane aluminium roller rockers, but only 1.5 ratio, I don't want to make a mistake with clearance piston to chamber, because pistons are domed. Check the picture.
I hope more flow, less temperarure on the heads and more power, lower specific cylinder compression, is possible that idle will be more lopey, never mind I like it but maybe I will loose vacuum on the brakes, actually my cam is 233-240º and .474 lift. (is nostalgia camshaft from comp cams #21-670-4#). What do you think about it?
Now I'm trying to know about head gaskets, I've see that head gasket have less water holes than block and heads It is normal? Is a fel-pro.
Check the pictures please.
Can you see on the top between 1-2 and 3-4 piston holes there are two oval water holes and no holes in the gasket. And on the bottom, there are three holes between 1-2-3-4 with only a little lines now obstructed.
Maybe I need to make new holes on the new head gasket? Can I loose cooling pressure? Is possible on the new heads instructions tell something about head gasket installation?
Maybe my stock 906 heads get too high temp due to this head gasket and then make pinging?
I know that I'm making a lot of questions to you but is hard to find here in spain somebody who know about mopar performance.
Sorry and thanks again.

Ah. I'm from Alella, near to Barcelona , it is about 300 miles from Soria.

[dave-r]

You will have very little vacuum at idle.

What do I think of the cam?

Check out the engine spec of my car http://challenger.mpoli.fi/forum/viewto ... =6144#6144

You can see from this that for the same duration you can have a faster rate of lift and more lift. This means that the valve is open wider for longer and will make more power. Stock heads flow their max at about 0.450" lift. Ported stock heads can flow well (depending on how well and how big they are ported) up to about 0.6002 lift.

The Edelbrock heads you have flow very well as they come and will respond well to lifts up to 0.550" I think? But to drive on teh street you need to keep your duration down to around 240 degrees.

The cylinder head gasket is OK I think. I will check later because I have a spare one in my garage.

[plum-crazy]

I do not know if is possible to use 1.6 rollers because my piston is domed, anyway now I ordered 1.5 crane rollers to use on the new alu heads but my really big question is about head gasket work now because I think that my pinging problem was caused by the high temperature of stock heads.
I asked this to edelbrock but I'm already waiting for his answer.
I saw your car and your specs, It's a grat work on it. I like the front bumper coloured like car and rear hoosier. I want to use a pair, I thought that correct size for me is 28x10 - 15, I not have relocation on the rear, now i put 275-60/15 in a minilite wheels.
My new cam is 238-246º is not good for the street use?
I saw your rear end, mine is only 3.23 sure grip, maybe large to run, but now i only want to try with new parts to eliminate pinging noise I then I will begin to make others.
Thanks for all, is good for me tell about this car and this type of engines to anybody more because here in spain is hard to find anybody who have enough experience.
Alfred.

[dave-r]

238 degrees on the intake is OK for the street but don't expect much above 3 or 4-inches of vacuum at idle. You will need to pick the correct springs for the rods in the top of the carb otherwise the carb will run very rich at idle.

You sound as if you really know what you are doing with this engine and challenger. You must be the #1 expert in Spain.

[plum-crazy]

+Thanks again Dave.
Where are you from? I saw your car in Santa Pod?
I like to go to see the races there someday.
We organize an american cars meeting here in Spain, is called American Cars Platja d'Aro (is in costa brava).
If you want you can check www.amccc.org is our web. Is only in spanish but you can see our meetings and some cars.
Maybe you will visit spain any time? We always make this meeting on june.

Thanks. Alfred.

[dave-r]

One day I might just make that big road trip around a few parts of mainland Europe that I have always wanted to do. There are some parts of Spain that look very attractive to me. Perhaps it is not possible in the Challenger but I should try it in something.

I live in the North East of England. In a town called Newcastle Upon Tyne. It is about 380km to Santa Pod Raceway from my house but our Mopar event we have at SPR is the biggest in Europe so it is worth the long drive.
We get cars from Germany, France, Belgium, Netherlands, Sweden, Norway etc. But I do not ever remember seeing any one from Spain. Maybe one day you will correct this?

[plum-crazy]

When is mopar meeting in Santa Pod? During the meeting will race your challenger on quarter mile?
Let me know the way to arrive, probably next time I will try to go.

One ask again of my engine.
Do you think this distance from the piston to the end of block is correct?
What do you think about these pistons?

[dave-r]

They look like good pistons. That big raised "D" shape on them needs to be exactly 40thou distance from the quench area in the combustion chamber and it should be just smaller diameter than the quench area around the edges.

Our big Mopar Nats is always the last weekend of July. See the "Events" section of this board. http://challenger.mpoli.fi/forum/viewtopic.php?t=5531

and YES we race each other all weekend long on the track. Even the very rare cars.

[plum-crazy]

Sorry, Dave. Could you clear me this?

"That big raised "D" shape on them needs to be exactly 40thou distance from the quench area in the combustion chamber and it should be just smaller diameter than the quench area around the edges. "

Is possible that you explain it to me again with other words to understand you want to say?

Now the deck clearance from piston to block surface is 0.053", but dome is 0.140 height, then dome is raised 0.087 from the block to head. (minus below head gasket head 0.039)
I read that correct deck clearance for performance engine is about 0.030", isn't it?
Now I ordered new head gasket with new alu heads, (fel-pro FPP-1009 on summitracing website) is compressed thickness 0.039 and is good for alu heads.

Thanks. Alfred.

PD : I hope that I do not be too insistent but I am concerned to resolve it well.

[dave-r]

I mean that the dome (shaped like the letter "D") has to be 40 thou from the quench area of the head (also shaped like "D"). If i understand your last reply correctly then I think that is what you have anyway.

[plum-crazy]

FINAL Decision :

I tryed, finally my combo is :

As you know until there, complete edelbrock heads 88cc open chamber, new pushrods, new crane 1.5 rollers, and new 238-246º with .480-.495 lift.
Now I choose 9.5:1 ross forged flat top pistons with 2.065 comp distance, and finally deck clearance is only 0.017" without head gasket and 0.056" with this.

What do you think about it?

I wish for 400hp and good torque, anyway some day I will use 1.6 roller if is it better for more torque and HP but I must begin anyway.

[dave-r]

Arrgh!

No No!

Keep the 10.4:1 pistons to use with the edelbrock heads! Because of the cooling effect actual chamber pressure will be lower giving a pressure the same as 9.5:1 pistons with an iron head.

You always need about 1 point higher compression when you swap to aluminium heads.

9.5:1 with iron heads = same combustion pressure as 10.5:1 with ally heads.

[plum-crazy]

Are you sure?
I still can use old pistons, because engine is disassembled. I only want to eliminate pinging and but I do not want to loose horse power.
Think that now you are "my mechanic" I do not want build again the engine and have problemas again.

And about deck distance clearance?

A option : Actual pistons lower comp. distance 2.029",0.053" deck clearance+head gasket 0.039" = 0.092" total deck clearance, 10.34:1 compression, 0.140" dome.

B option : New pistons higher comp. distance 2.065",0.017" d.c.+head gasket 0.039"= 0.056" total d.c., 9.5:1 comp. flat top

What is the real importance of deck distance?

You believe that first option is best?
How many HP could I loose with second option?
Maybe could I use 95 octane fuel with lower comp. pistons?
Any more think to know? Tomorrow I begin to build it again.


Yes , I know, a lot of askings But really you are the best information i have too much time ago.

Thanks ++++

[dave-r]

Heat = pressure. Less heat = less pressure.

Alloy heads cool the combustion because heat transfer to the water jacket is greater. So the combustion pressure is lower.

Pressure = torque. Less pressure = less torque = less power.

You need more compression with an alloy head to make the same power.

Reading this may help;
http://www.hughesengines.com/general/te ... d_tech.asp

My opinion is the higher compression pistons you have will work with open chamber alloy heads if you use greater than 95 octane fuel.

The lower compression pistons you have will work with any fuel you use but power will be down a little.

[plum-crazy]

Ok Dave I will do it as you say.
I cancelled pistons with lower compression, I will use actual pistons.
Final engine :
10.34:1 pistons 0.030 over.
238-246º .480-.495 lift
88 cc open chamber aluminium heads complete with springs
edelbrock performer rpm intake
edelbrock 750 cfm carb
crane roller rockers 1.5:1
1 7/8 headers 3"
2.5 " exhaust
2400 rpm stall holeshot converter
mopar performance distributior with orange box and accel supercoil
milodon high volume water pump
milodon high volume oil pump
carter high volume mechanical fuel pump
electric fan
727 auto trans with race kit
sure grip 3.23 rear end


I try to build it to our meeting on 4th june in Costa Brava

I think is something like this engine
http://carcraft.com/techarticles/116_0111_mopar/

I do not believe that this engine deliver 535 ponies, what do you think about

What HP will deliver my engine when we will finish it?

[dave-r]

I figure it at about 450hp @ 5500rpm and 470lbs @ 4500rpm.

Your rear axle gear is way off. You need a 4.10:1 gear in the rear to take advantage of the torque at such a high rpm (due to the long duration). I would get rid of the 3.23:1 for sure. It is the stock ratio that matched the rpm of the stock cam. Even a 3.55 or a 3.91 would be better but the 4.10 would be perfect.

[dave-r]

Also I think you may not have enough stall in the converter. I think you will need around 3000rpm stall.

[plum-crazy]

yes, I suppose that, I like gear vendors system to use a 4.10 rear end, I saw it on your car specs.
Probably I must change the converter but now I prefer to try with new parts and then decide it.
Probably next step will be transmission and engine oil cooler with the new style. Depends on money, I still want to paint the car.
Tomorrow we begin to built the engine, today we checked parts.I will tell you more things about it.

[dave-r]

Don't you just LOVE those Edelbrock heads?