Big Block Camshaft And Compression Help!!
 

Looking for a little Camshaft and Compression Help?

I have a super clean 1988 D100 Short Box that I just want to make into a cruiser. I want it to sound good, I’ll never race it, a Big Block a new paint job and I’m off to the car cruze.

The Engine I’m using is a 446 Stroker and it was originally built in 1989 and was in a 1982 Mirada. The Mirada is long gone but the Engine has been in a 1950 Ford PU and has low low miles on it. It did have the Mopar Performance P/N #P4120235 cam (.284/.284 - .484/.484) and it sounded great!! But was a little Doggie.

Behind the engine the Mirada had a GER Pro/Street Tranny with a 2200 Stall and an 8 ¾ Rear with 3:23 gears. Tranny and Read End will be going into the D100.

Engine has been disassembled and I’m in the process of refreshing it.

This is what I have going on now.

Engine: 446 Stroker - .030 bored 400 block – 440 Crank – Alum Childs & Albert Pistons running 10.5 Compresion
Running a stock 4 barrel intake manifold with a Thermo Quad.
906 Heads that have been Ported & Polished
Stock Center dump Manifolds with dual exhaust
Mallory Unilite distributor

I really don’t want to run the 2200 stall just want to use the stock convertor so I’m looking at Idle to 5500 RPM range.

I know Cam Tech has cam a long way since 1989 so I’m looking for some suggestion on a good street cam for the set up I have here.

Also I’d like to get the compression down to maybe 9 or 9.5 to run today gas, has anyone ever done this? Steel or Copper head shims and if so how thick.

Thanks
Air Bubba

284 cam needs a 2800 stall converter !!!! and a 3.55 min gear. It would be a dog like you say with the stock converter. Some of the HP mptors came with a 2200 stall from the factory. You could probably keep the 10.5 pistons IF you switched to aluminum heads.
You could possibly have a machine shop cut some off the top of the pistons ? Depends on quench area and how the motor was built

There are some conflicts in the build... Exhaust manifold on 906 heads with a stock 4 barrel intake and 46 additional cubes? Over cammed and choked. She needs to breath...

But you are going in the right direction now. You can go a couple ways with this.

Certainly consider knocking down the dome on the pistons and getting a quick re balance and be done. Or grab a low cost stock replacement piston. Depending on machining costs. Or a hyper piston to keep it light and dial the compression back some.

Or

You can also run the MP .020 steel shim with the bigger Fel Pro .051 - .054. Ive stacked before without issue. BUT the deck was set up for the shim.

For the stock converter and use in a truck go no bigger than XE268HE from comp. From memory this is a 224/230 @.50 duration with lift the same as what you had so heads will not need mods. This is an update to the 270H ( good cam too) that has more on the exhaust with a nice ramp to it. I love the Mopar sticks but they are dated and haven't been improved on in forever. Make sure your pressures are up to snuff for the cam.

I would strongly consider a set of headers.

Big Block Camshaft And Compression Help!!
 

Thanks PK1,

I’m stuck with the pistons, but facing them down is an option.
I do like your Idea of the Steel Shim and Thick Head Gaskets, you mentioned your deck was set up for the shim? Could you explain that to me a little more?

Headers are an option, just have to wait and see what I have room for. This is a V6 truck and from what I’ve read it’s not as easy of a swap as a small block to big block, issue with the motor mount position.

I can and probably will change to an alum intake of some sorts down the road but as I’m on a budget I’d rather swap that out later than a cam. As far as the Thermo Quad I’m sold on them, I used Holley’s before and do not like them never seem work right, maybe I just got a good TQ.

Thanks again for the info.
Air Bubba

Typically you run an MLS or shim on a deck that was surfaced at half speed to give the deck an ultra fine finish. Remember the shim is not as playable and wont conform to imperfections.

Do you need it? If the block is out and they wont hit you for cleaning and all the other prep work then I would absolutely do it. Do you need it? Judgement call.

I have sandwiched gaskets too. Gasket, shim, gasket. BUT that was moons ago and it was crap gas, low compression.. beaters and it worked.

How much will the .020 head shims lower the compression?


Then how much with the addition of the thicker gaskets? (.051-.059)


I’m not looking to get to a specific number I just want to be able to run pump gas.


I have attached a picture of my Pistons.


I can face the down that is not a problem, plus it’s won’t cost anything.


Just don’t know how much to face off, any good rule of thumb?

Those are not flat tops so .. You need to check the quench area The .094 How close it is to the head.. If you remove part of it. it could cause more problems than if you left it ON that piston you could maybe cut the valve reliefs deeper or cut the piston top flat IF you do anything check the dome thickness before any machine work BEST way get some stock 9/1 pistons. then ? I would have it re balanced.

Can’t use stock pistons, these are specials so I’m stuck with them.


Stupid question, what is the “quench area”?