Pump gas 440 advice

[Dusty997]

I'm picking up a bone stock all original 1969 Chrysler 440 motor tomorrow that is advertised as a 10:1 compression.

My plans are to run it in my duster on the street and id like to get it as pump gas friendly as possible without having to change pistons. Ive heard that certain camshaft profiles can lower dynamic compression, but im also not sure what compression translates to needing what type of fuel ext, ive always run stock 360 magnums that are 9:1

Open to all tips and suggestions, this will be my first big block ever.

 

[davek]

if its bone stock just add octane boost and you will be fine. Thats all I do to my Bee 440

 

[PROSTOCKTOM]

I run my 440 at 10 to 1 on 93 pump without issue.

What cam you have in them really makes the difference.

Tom

 

[RemCharger]

If it's all stock even with a cam, it's a good premium gas motor. I don't see anything to sweat about.

 

[Dusty997]

Great! A lot of what i was reading online was saying 10:1 was too much for pump. This is good news

 

[OMTWF-72SE]

I've found it depends on the gas. Out here where commifornia influences our gas products the blends just don't work. I went the piston route after fighting it for years.

 

[Dusty997]

I've found it depends on the gas. Out here where commifornia influences our gas products the blends just don't work. I went the piston route after fighting it for years.

I was thinking just throw the thickest head gasket i can find on it, and maybe a camshaft that will lower dynamic compression some.

 

[Jerry Hall]

An all stock 69 440 should perform good on premium pump gas. If you get any detonation you can bump the octane up a little with an octane booster or lower your timing by a degree or two. I choose to keep stock timing and eliminate any thoughts of detonation with an octane booster, or mixing some 100 octane AV gas in. The only octane booster I have found that really works is a product called Boostane. The 90 octane non ethanol that I can get around here isn't quite enough so 2 1/2 Oz. of Boostane takes it to 96 octane and problem gone.

 

[Curiousyellow71]

Most engines have less compression then what the factory rated them. You won't know exactly unless you measure. If it still has the factory piston it will be in the mid 9's give or take using a typical .039 thick head gasket. Factory used a thinner steel head gasket and will be a little more if its still running them. A Cam with a wider LSA lowers the dynamic compression and is more friendly to pump gas when you compare cams of the same size.

 

[33 IMP]

As stated above, the rated comp ratios were often a 1/2-1 point higher than actual. 9-9.5 should run okay on 91, 93 would be better.
Since stock 69 heads have no quench anyway, a thicker head gasket is an easy solution if you do have detonation problems.

 

[PROSTOCKTOM]

I was thinking just throw the thickest head gasket i can find on it, and maybe a camshaft that will lower dynamic compression some.

Putting a thicker head gasket on is a bad idea in my opinion. Adding a little more cam will help, but I see no issue with using the stock cam.

Using less cam is a waste of time.

Tom

 

[Dave6T4]

I had the heads off my '68 440 a couple of years ago. At that time, I replaced the factory steel shim head gaskets with thicker Felpro's. I could feel no difference in performance: my car is mainly a highway cruiser, and I don't race it. I can run 91 octane in it, with no detonation.

 

[Jerry Hall]

Putting a thicker head gasket on is a bad idea in my opinion. Adding a little more cam will help, but I see no issue with using the stock cam.

Using less cam is a waste of time.

Tom

I agree keep it running as good as it was when new, anything less takes the thrill out of it, and as @PROSTOCKTOM says, is a waste of time.