67 Coronet / Winnebago compression ratio

[67possible]

I was wondering if someone could help me figure out about what my compression ratio will be. I have a stock 73 Winnebago 440-3, engine in my car. I know these came total crap comression of like 8.2 to 1. I just ordered Edelbrock 60929 heads with 84cc closed chambers to replace the stock 452 heads. I measured my pistons, they are flat top and they are .140" in the hole. I plan to use Moper Performance P4286754 head gaskets. They are single layer steel with compressed thickness of .020"

I know the smartest thing to do would be change pistons, but I like to do things backwards. I tend to take a direction, buy everything I need for that, and then assemble. All of this is stemming from a swap to a Hughes Whiplash cam. I was just wondering if anyone can help me with a ball park compression ratio for this combination?

Thank you for your time.

 

[67 coronet]

about 8.19 to 1 for your new heads at 84cc chambers.just used a basic comp calculator.

 

[67possible]

Thanks for the information. Looks like the short block will be getting all of my attention next.

 

[YY1]

I though there was a smaller chamber option on those heads.

 

[RustyRatRod]

Put these in it.

http://www.ebay.com/itm/Speed-Pro-T...Parts_Accessories&hash=item2c6d778f20&vxp=mtr

 

[Meep-Meep]

The closed chamber Eddy heads have just about the same chamber size as the 452's so no real gain there. Also if your block has a bore chamfer resembling the one on my block that is another few cc's down the drain. If you want a cheap compression increase get a set of 516's from Rusty and use a steel shim gasket.

- - - Updated - - -

.....And you can add those pistons above with the MoPar .455" / 272 cam and really wake it up. Balancing will be required.

 

[67possible]

I bought a lot of performance junk to bolt to the engine. Toward the end of the year I will go ahead and do the engine. I bought the fuel cell, Holley black pump, -8 lines, MSD ignition, headers, 3" exhaust, 3000 converter, 3.91 rear, tunnel ram, predator carbs, and bolted all that to a stock motor home engine. I have been driving it and getting it all one piece at a time. I know its a stupid way of doing things, but it looks cool even though it really doesn't run any better than stock. And everything I have bought so far will convert over to the "real" engine I plan to make. It makes me smile and thats all that counts.

 

[67 coronet]

love the predators,prob the only reason that setup runs on a stock motor.i used to sell those back in the day,nice design,just had a tendencey to leak.

 

[67possible]

It ran great with just 1 of them. I am hoping it is better with the whiplash cam. Then I will go with a big cam when I get the bottom end to match. I am also in the process of changing to a 4 speed. I think it is going to be a handful for a street car.

 

[Meep-Meep]

We had a guy in the town where I grew up (Concord CA) with a 70 383 Challenger and a tunnel ram with a variety of carbs including the Predators. The car was pitifully slow for what was done to it (all show and no go) but I'll say this: He drove it everywhere and it did put a smile on his face, and it did look cool. He had the 2.76 gears and did everything to make it palatable to drive but I would have drawn the line on the clamp on wheelie bars (over the brake lines) and the strap on chrome rear end cover on the 8.75". We used to give him so much crap for having all that performance stuff and not being able to back it up. Damn shame. Eventually that car got a blower (under driven all to heck) and a mini tub and the gears were upgraded to 3.55's. It got in a magazine, which is what he ultimately wanted. I haven't seen him in years but heard from other sources he still has the car. So whatever you do pleeeeeaaaassseee do something to help back up all that coolness sticking out of the hood! It would just round out the package.

 

[Cornpatch MO]

The closed chamber Eddy heads have just about the same chamber size as the 452's so no real gain there. Also if your block has a bore chamfer resembling the one on my block that is another few cc's down the drain. If you want a cheap compression increase get a set of 516's from Rusty and use a steel shim gasket.

- - - Updated - - -

.....And you can add those pistons above with the MoPar .455" / 272 cam and really wake it up. Balancing will be required.

I did the cheap compression increase as above. I don't remember how far down in the hole the flat-tops were . My 516 heads were cc measured at about 74cc, steel shim head gasket, and calculations came up with about 9.4 compression............................MO