Compression ratio help

[Anonymous]

I will be taking my head tomorrow and wanted someone to look at my numbers so I don't make a unrepairable mistake.1978 head, 1969 200 block bored .030, milled to get a deck to piston of .015, dished pistons, fel pro head gasket .050, and I will be telling the shop I want 50cc combstion chambers to get around 9 to 1 compression ratio. I checked numbers on calculator but would feel better if someone else had a look. I hope I put enough information and thank you for any help.

 

[wsa111]

Your compression with the spec's you gave figure out to 9.1:1.

If you zero the deck & use a napa victor .044 compressed thickness & take the cc's in the chambers to 49 this will pop up your compression a little more.

The main ? is your camshaft choice. the more duration the more static compression you can crank in.

What camshaft are you planning to use?

More power to you. William

 

[Anonymous]

I ordered a comp cams 252H-10, the mustang is a daily driver.

 

[wsa111]

The comp 252 is a very weak cam, very slow rate of lift, its just an antique cam profile. With that cam 9:1 would be your max.

That cam is just a little better than a stock cam.

You really should purchase a cam from Mike @ www.fordsixparts.com

His cams are designed with a modern profile, such as a faster rate of lift & higher lift. Even for a daily driver I use a FSPP 264 with a 112 lobe center & 9:5 compression & its probably 20 HP stronger than the comp cam.

Unless you buy a cam from comp cams that was designed recently you are using an out dated grind such as the 252 or the 260, they just don't produce the power of a newer design because of the rate of lift. When you have a cam which requires only 50# of spring pressure on the seat you have a very weak profile designed camshaft. William

 

[Anonymous]

Thank you for the help, I will be giving the car to my son in about 6 months as his first car and I did not want it to be too powerful. Later when he is a better driver we might try something else.

 

[CobraSix]

The Comp 260 is a very nice cam for the 200, no experience with the 252. I have the 260H with 9.1:1 CR.

Slade

 

[mustang6]

I'm running a 252H and would agree it's only a slight bump above stock, idle is still pretty smooth but it sounds slightly throatier through the dual exhaust than the stock cam did. Mileage really wasn't affected, nor was low end torque, although it did gain a little topend.

 

[wsa111]

I can see your reason for using the comp 252 with your son being the primary driver.

Another nice camshaft if FSPP does not stock this mild of a cam is the crane H-194/265-2S-10. the intake duration is 256, exhaust 264. the duration @ .050 is 194 intake, exhaust 202 degrees. It requires 80# seat pressure springs.

Im sure FSPP could order a mild camshaft matching those specs. William