I have tear the engine apart and will rebuild it. One cylinder wall has been damage, so we bore it .060.
I'm a rookie on this part, so it would be nice to have your support.

467 cui with:
Holley 850DP
Singel plane manifolder
Rectangular iron heads 325IP / 118CC open chamber
2" headers, dual 3" pipes and flowmaster mufflers
Manual 4-speed with 3.55

I wan't fair bottom end / ~500HP on top / Reliable HP Street use.

Which C/R and pistons? I have found:
Forged Speed Pro with C/R 9.7
Keith Black Silv-O-Lite with C/R 9.1 or 10.3
(all @ 118cc)

What kind of cam, Hydralic or Hydralic-roller? The roller costs $700 more here in Sweden. Quite expensive for my budget...

And finally, which duration and lift?

Thanks, Lasse.

 

Lasse:
This is just my opinion. I would shoot for 10-10.5:1 compression ratio, I'm currently running somewhere in between 10.5-11:1. Out of your two cam choices I would go with a hydraulic roller if money is not a problem. With a hydraulic roller you should easily hit 500HP.

 

Lasse, My new 467 motor has Merlin heads, with 310cc intake runners and 119cc chambers. My cam is a Crane powermax 296-2 and my pistons are Keith Black hypereutetic, compression is about 9.5-1. I love the combo and my engine guy said go with the 9.5-1 comp so I don't have to use racing gas!! I am burning Mobil 93 octane and it works great. According to the Desktop dyno its making about 500hp+ at 5500 rpms, I love the exhaust sound, when you stand behind the car it just about knocks you over!! I personally think the compression should be about 9.5 to 10 -1, IMO. Good luck, Tom

 

am running JE pistons, 10.2 c.r. , comp cams 288AR solid lifter roller, runs fine on 93 octane

 

Lasse: I love your front rims! Are the rear the same style? Where did you get them? Did you need adapters?

 

Lasse, has your engine ever been decked? Without knowing the deck height and head gasket thickness, you really can't figure out the compression ratio. To make the type of horsepower you're looking for, you can probably stay under 10:1 without a problem. If you try to go higher, much more precise measurements will be necessary to ensure that the engine doesn't detonate. Compression ratio quotes are nothing more than an educated guess until you actually measure all the parts involved. For instance, my new JE/SRP "10.25:1" pistons measured out at less than 9.7:1 once they were installed with my heads. If I took the manufacturer's word, this combo would have been around 10.3. They assume a "0" block deck height, and most don't have that.

You can make 500 hp from your 467 with a regular flat tappet hydraulic. Personally, I like solid flat tappets for weekend toys. You'll get performance very similar to the hydraulic roller for much less money. The trade-off is that you have to adjust the valves manually (I'm wierd, I like that :))

-Joe


[Modified by Flareside, 8:49 AM 6/11/2002]

 

Don't forget that your cam can bleed off some compression also depending on overlap.

 

Just my 2 cents with ALUM heads up to 10 to 1, on 93 gas.....as noted some cams can bleed off cylinder pressure...........in my case 427, alum heads, 110 CC , TRW 2300 F pistons, my compressoion is 9.5 , will go with short duration high lift cam...a Tourque monster as also have 3.08 rear gears :crazy:

 

I can see how changing the intake centerline would effect compression, since you're changing the point that the intake valve closes, but not overlap. If you kept the same intake centerline, but moved the LSA (and therefore changed overlap), the running compression would stay the same since the point that the intake valve closes hasn't moved.

 

The greater the overlap the more time the two valves are open at the same time and less comp is built/created. Comp cams had some great info on their web site about cam design. I am no expert but that was one of the things I picked up from their info.

 

Bence - I have thought of that route. But, don't I have to go for a long duration cam then, >290-300, to bleed compression? And see the bottom end (2000rpm) go away?

467 Ratman - Sounds pretty. How does the engine work on lower rpm:s and idle (< 3000 rpm)?
My previous cam was a Crane Roller with 252/262@.050 and 290/300 adv.dur. .680/.708 lift. But that one was to nasty for my taste, backfiring when cold, no vacuum and nothing below 3500 rpm. (~11.2 C/R)

GDaina - I have looked for JE pistons, but I can't find any between 9-11 C/R with my 118cc heads. Strange :confused:

Kevin - Yes the rear are same style, but wider... :yesnod: Press my sig and checkout 'My own Vette' for more info.

Flareside - Do they assume zero deck height?! The seller said that the engine was'nt decked, but I can't find the blocknumber either :confused:
How can I measure the deck height, without buying new piston.

Fevre - Yes I know. But how much Dynamic C/R is normal without racing gas? I get from 7.3 to 7.5 in Engine analyser on the HR ones and 7 to 7.3 from HydrFlatT (with 9.5 - 10.0 Static C/R). Are that figures OK? I've heard that I should be over 8 !?

Straydog - Yes, I dream of oval alum heads with more torque, but the price is $2200 in Sweden. :rolleyes:

 

Lasse

Please note the disclaimer:

Now my ignorance shows. :bb I am not sure what normal is but I am sure more experienced members can answer that question.

 

I'm sorry! I aimed it for the pro's. :blueangel:

for example: my engine with static 9.9 C/R and Crane 139731 (HR , 288/296 dur and .587/.610 , 112 LSA).
Get 7.45 in dynamic C/R from Engine Analyzer.





[Modified by Lasse, 10:46 PM 6/11/2002]

 

Interesting chart. Two things stand out me:

1. Vol Eff is incredibly high without FI, 97% . I have heard 90% is extremly good.

2. The actual cfm max at 847 but doesn't get over 700 until after 5000 rpm's. You have a 454+ ci motor which makes me think most 350 couldn't pull 750 cfm's.

BTW What numbers are you using to calculate the dymanic c/r?

:cool: reference, all things considered.

 

1. Yes, I also think so. I hope I can trust the figures. I have done the input... :rolleyes:

2. Ditto.

The dynamic C/R comes on the printout from the Engine Analyzer application.

Oh no, my wife say's it time to go to sleep. I write more tomorrow. :seeya

 

Believe me, I'm no expert either :) I've read Comp's catalog tech pages from front to back and I'm still learning. I'm just trying to understand what I read here on the forum and then apply it to what I know about engines. Since overlap happens at the top of the exhaust stroke, it could never change compression which happens on the following stroke. As overlap occurs, the piston continues down with the intake valve open. Once the piston passes the bottom and starts back up, the intake valve closes so that compression can start. Moving the intake centerline and/or increasing the intake duration will make the valve close later and reduce dynamic compression. Changing the LSA and overlap will not *if* you don't move the intake lobe. Oh well, maybe a cam guru will set us straight!

 

Sorry, but I don't know of any way to measure the deck height without a piston :( You buy the pistons, measure the deck height, then have the block, heads, and gasket matched to make the compression you want.

SRP is the "affordable street piston" division of piston maker JE. They are the same company. Maybe Gdaina has their pistons? I'm sure they have the piston you're looking for. Check here for part numbers: http://www.flatlanderracing.com

TRW will also have a piston for your application.

 

That is correct, I have the SRP pistons, made by JE. and their matching rings. Only combo that was available: 4.47" bore, 4.25" stroke and 6.3XX" rod

 

Flareside.... You're getting GOOD at this stuff!! Been doing your homework I see!!

As you start juggling cams to get dynamic compression where it won't detonate, you can get into all kinds of problems. All these things have to work together.

What often happens is you use a larger cam that has a later intake closing or spread LSA or increase duration or whatever method you use to bleed cylinder pressure, and it works great at low speed. The bad part happens at higher rpm when you really start pounding on it and that big cam gets into it's happy territory and all of a sudden those cylinders start getting filled very well. The higher rpm allows the engine to "outrun the leak" so to speak just as intended and cylinder pressure goes very high. Then you get detonation that is often undetected because the driver can't hear it as he's banging gears at 7000 rpm!

I'd use the SRP's. They are great pistons, reasonably priced and can run relatively tight wall clearance. I'm using .0045 on the 540 and they are dead quiet even when cold. Plus they are much lighter than the common TRW's. I'd steer away from the hypereutectics for your application.

If the engine is already apart, you can use a BHJ gauge to measure deck height. The machine shop should have one. Otherwise, you can get a rough idea if the engine is together. Bring it to TDC and measure current deck height. If no decking has occured it will range between .017-.022 or so below the deck typically.

You want to end up with a TOTAL of .035-.040 between the piston and the head including gasket. Very important to making pump gas power. So if they end up at .020 just use a steel shim .018-.020 head gasket for a total of .038-.040. If it's at .000 or so use a .038 compostion gasket to get it right. No more than .040 total though!

You can easily build a 10.5-11.0 compression iron headed big block that can run on 93 octane under full power. If you can get better gas it's even better.
If you want to stay safe considering differing gas qualities, build it as a 10.0 motor.

Gdaina's setup is a good one. The Comp 288 street roller is great. Use the .623/.623 244*/244* at 110 LSA version.

Otherwise I know of a couple of Crane solid flat tappets that work fantastic.


Jim

 

This guys got it! I knew it only 'bleed' off at low rpm's and the 'bleeding' reduces as rpm's increase hence the detonation problem at higher rpm's. Good to have guys like 427Hotrod around to help us less experienced fellers.