compression ratio

[Meep-Meep]

A nice flat dome like that shouldn't give any problems at all.

 

[67 B-body]

Wow I like that style dome piston. A nice flat type dome. I would think that works very good. What brand piston is that 67 B body ? Ron

They are sold under the Speed Pro Power Forged name now... They added the anti-scuff coating to the old Forged Aluminum TRW pistons, and they might be lighter too than their predecessor.
They can be purchased in a complete set that is weight matched,,, but I still had some more weight taken off the lightest one of the bunch and the rest made to match..

 

[Doright]

OK well I still don't get it ?

I have a original 69 440 out of a Chrysler whatever? any way it has 50K miles on it and ran good when I pulled the heads 906's which I stuck in the corner under a shelf in the shop and had a set of 452's rebuilt with new valves and springs for a Big flat tappet from Comp Cam I wanted the Hardened Valve seats of the 452's with out springing for all the machine work on the 906's the 452's fit the bill and are comparable to the 906 in most arguments.

Original idea was to just do a valve job and add a good Cam and enjoy with a stock bottom end knowing not to spin it to hard, I think my Static compression may be ok but with the cam I ordered may be way to big? XE295HL 295 307 251 257 .564 .564 110°

Actually I know its too dang big I bought it when I was going to build a nice engine with new everythings but Money isnt what it used to be so now what do I do?

Originally I wanted to build an E85 engine and do all the upgrades for it SS fuel lines new Tank whole deal I still may as Its the only true way not to worry about Detonation problems.

 

[67 B-body]

OK well I still don't get it ?

I have a original 69 440 out of a Chrysler whatever? any way it has 50K miles on it and ran good when I pulled the heads 906's which I stuck in the corner under a shelf in the shop and had a set of 452's rebuilt with new valves and springs for a Big flat tappet from Comp Cam I wanted the Hardened Valve seats of the 452's with out springing for all the machine work on the 906's the 452's fit the bill and are comparable to the 906 in most arguments.

Original idea was to just do a valve job and add a good Cam and enjoy with a stock bottom end knowing not to spin it to hard, I think my Static compression may be ok but with the cam I ordered may be way to big? XE295HL 295 307 251 257 .564 .564 110°

Actually I know its too dang big I bought it when I was going to build a nice engine with new everythings but Money isnt what it used to be so now what do I do?

Originally I wanted to build an E85 engine and do all the upgrades for it SS fuel lines new Tank whole deal I still may as Its the only true way not to worry about Detonation problems.

Ok,,, What exactly do you not "get"?
Is their something one of us can help you understand? Feel free to ask,,,, one of us is bound to know.... If not you'll at least get to see a bunch of opinions and maybe a few contests of wit...

 

[RustyRatRod]

These are the KB400s.

 

[Garys1969RR]

Hey Doright, With a long duration cam like you have, it needs more C/R. I am running 12 to 1 on a 451 with a 509 cam. Has 242* duration at .050 lift. What is your current C/R? Give us the piston to deck clearance, (or compression height so we can determine deck clearance), head gasket thickness, head cc, dome volume, bore and stroke. Then after determining C/R we can recommend a cam. Does it run different with the 452 heads and big cam? Compared to the 906 heads and a smaller cam? Let us know.

 

[wedgie]

View attachment 87233View attachment 87234

I decided to install the Eddy produced MP452 heads as cast. The math works out to be 8.82:1 static. Should lose some ponies but be able to run almost any available gas. I'm going to try keeping the Racer Brown ssh-25 cam for the time being. After I get a few miles on it, I may change. Just finished today. The silicone at the corners of the intake gasket has to set up overnight, so I'll be starting it in the AM. Hoping that I have accomplished my goal of a "stock" look to the non-Mopar enthusiest.

 

[Doright]

Hey Doright, With a long duration cam like you have, it needs more C/R. I am running 12 to 1 on a 451 with a 509 cam. Has 242* duration at .050 lift. What is your current C/R? Give us the piston to deck clearance, (or compression height so we can determine deck clearance), head gasket thickness, head cc, dome volume, bore and stroke. Then after determining C/R we can recommend a cam. Does it run different with the 452 heads and big cam? Compared to the 906 heads and a smaller cam? Let us know.

Its just a low milage stock 69-70 440 with a steel crank Its got like a .010-.015 of a ridge in the cyl walls I have gone back and forth on boreing it and doing forged pistons and Eagle rods but If I go that far I know I will get Alum. Heads & go roller rather than flat tappet.

 

[RustyRatRod]

Just remember, the ridge is not what to go by when regarding cylinder wear. You essentially would divide the ridge amount in half. So, if it has .010-.015" ridge, that equates to roughly half that in cylinder to piston clearance, so it may not be too bad. As long as the ring end gaps are within spec, it should be ok.

 

[Meep-Meep]

Doright, that is a low compression 440 (judging by the dish in the piston) and the cam you have selected is not a good match in my opinion. If you want to just go down the road for now I'd get a much smaller cam, slap it together and drive it while collecting parts for the killer motor. Or just build it the way you want now if funds permit.

 

[Garys1969RR]

Doright, that is a low compression 440 (judging by the dish in the piston) and the cam you have selected is not a good match in my opinion. If you want to just go down the road for now I'd get a much smaller cam, slap it together and drive it while collecting parts for the killer motor. Or just build it the way you want now if funds permit.

I agree, those pistons are not 1969 type. They look just like the ones came out of my 1977 440. They sit .100" or more below deck. And with the dish, your C/R is probably less than 8 to 1.

 

[wedgie]

I decided to install the Eddy produced MP452 heads as cast. The math works out to be 8.82:1 static. Should lose some ponies but be able to run almost any available gas. I'm going to try keeping the Racer Brown ssh-25 cam for the time being. After I get a few miles on it, I may change. Just finished today. The silicone at the corners of the intake gasket has to set up overnight, so I'll be starting it in the AM. Hoping that I have accomplished my goal of a "stock" look to the non-Mopar enthusiest.

Test drove it this AM. No more rattle whatsoever. Dynamic compression ratio appears to be 7.31 with my 140# hot cranking pressure. I'm guessing 89 octane is all I'll ever need. Now I'll play with the distributor as it will probably like a faster advance now.

 

[Doright]

What I really don't get is how these new Crotch rocket bikes are all running like 12-1 static compression and they don't detonate????
Lots to be said about controlling all aspects of Fuel and ignition instantaneously with a computer.

 

[Meep-Meep]

What I really don't get is how these new Crotch rocket bikes are all running like 12-1 static compression and they don't detonate????
Lots to be said about controlling all aspects of Fuel and ignition instantaneously with a computer.

I'd say a very efficient chamber with multiple valves, precise mixture control and a lot of gears to help move the weight.

 

[Doright]

I agree, those pistons are not 1969 type. They look just like the ones came out of my 1977 440. They sit .100" or more below deck. And with the dish, your C/R is probably less than 8 to 1.

I dont know looks like an all original 70 block to me? I dont think this engine has ever been apart yet.
Going to tear it down next day or two need to scribe cylinder wall line into my cylinder heads so I can unshroud the Intake and exhaust valves in the combustion chambers of the heads. My home porting job on the heads is about done now I have more time into them than I would like But I think they will run ok.

I'm thinking truing up the big ends of the Rods and installing ARP rod bolts and Decking the block to increase compression and using a thinner head gasket and milling heads while keeping the current piston? what are your guys opinions?

I just don't have the funds currently for new Rods and Pistons just not in the budget. now if a Nice set of used ones fell into my lap? I HATE the idea of running 40+ year old stock rods!

 

[Kern Dog]

Congratulations on getting it back together!
Detonation sucks. You build a car to have some fun and sometimes you end up dealing with this problem. I have dealt with the same thing for years and have tried many things to stop it. Meep Meep mentioned to me several times that my problem boiled down to one absolte fact: I had too much compression ratio for the available gasoline. Two choices: Use higher octane fuel or lower the compression ratio.
I like what you did. You have a ratio now that may actually be tolerant of regular unleaded fuel with enough cubic inches to still be fun to drive.
What is a point of compression worth anyway?
If you have to drive easy to avoid detonation even with premium fuel, where is the fun in that? We build a big inch engine to go fast, not to limit ourselves to running at only 1/2 throttle. I think some of us see or read about a few people that were able to run over 12 to one on mid grade with no knocking but how common is that? I'd bet my full head of hair that these engines are tuned to the nth degree with all possible aspects of the engine fully optimized. By this I mean a perfect spark advance curve, a perfect fuel curve, evenly matched mixture distribution, cool air intake, etc. If you let your guard down on any one of these factors, you're knocking.
That sucks ***. My build is a 440 with the 4.15 crank. I have the Edelbrock heads which are similar to the aluminum 452s. I am tired of living on the edge or "beyond" it. I am to the point where I am willing to give up a point of compression to have vastly improved driveability. I hope that you have a blast with the car. Good luck!

 

[Doright]

Why not just run E85 its way over 100 octane mostly ethanol or methanol but who cares ?

stainless fuel lines and stainless fuel Tank build good carburetor for Alcohol and forget detonation........ No???