11:1 compression and pump gas?

I've got the opportunity to buy a 30 over 289 Ford long block with 11:1 Ross pistons, a small RV cam and ported 302 heads to replace my blown 302. Will 11:1 be pump gas friendly? Does this sound like a streetable combination?

 

I don't think so.....unless you swap in a bigger cam to bleed off some cyl pressure......and retard the timing.........

 

THe motor in my Edsel is 10.5:1 and it barely likes 92 outa the pump...

 

1970 351W heads flow pretty well on a 289 and they would drop compression probably by a point or so over the 289 heads that those piston's compression ratio was calculated (by Ross).

 

Damn . . . this is a fresh rebuilt long block with a C4 for $1500. Seems almost too good to p*** up but won't do me any good if it runs like **** on pump gas.

 

It has lightly ported 68 302 HP heads if that would make a difference.

 

I have been able to get away with 11 to 1 compression on pump gas. To do it you have to make sure that your combustion cambers are smooth so they wont have any hot spots, you will need a cam that bleeds off some of the cranking pressure at low RPMs, flat top pistons, a really good cooling system, and a conservitive advance curve and 93 octane gas. Personally for 1500 bucks I would take a chance. If nothing else you can swap cams, dress the combustion chambers and install thicker head gaskets and still be in for less than building a new engine.

 

Any idea on how much power a setup like this would/should make?

 

Are the Ross numbers figured on 289 heads or 289hp or 302 heads?????

D3 or D5 windsor heads flow good and should help scrub off some of the comp.

Not old school... but running a MSD ignition box (6al or such) will help. Along with the other recommendations.

 

I ran a 12.2:1 468 Chevy on the street on pump gas for years without a hitch. There are some tricks to it though. As was stated already, smoothed combustion chambers and pistons, MSD ignition and a large enough cam to bleed off combustion at low RPM. There are a few other things you should be careful of. Be sure your timing curve is set up right and run the carb FAT. 11:1 is doable, but it takes some effort.

 

I ran a 350 horse 396 with a 10.5:1 ratio on regular gas for years. I used to haul a camper and tow a boat with no problem. The secret was my homemade water injection system that would add coolant (water) when the vacuum went below 5" Hg. I also installed a CD ignition system, which is the predecessor of the MSD type units. I am presently running a 454 and a Ford 390 FE ( both with 10:5:1 ) using 94 octane and octane boost. This is just adequate, but with the stock advance the engines will ping under heavy load. When I have the time, I am going to make another water injection unit.
Bob

 

11:1 is easy enough if you have good fuel and spark control. Also remember that 11:1 is advertised with a given chamber CC and gasket thickness. Do a little research and you should be able to ***emble it at 10.5:1. It will work if you pay attention to details. Add a cam with a bit more overlap for extra insurance. Also keep in mind that heavier cars aggravate the issue. Light weight cars put up with increased compression better.