Recommended maximum overbore in 218

[Hemibear426]

Machine shop just called and recommended .080" overbore on my D14 218. Sounds like a huge overbore. Can the 218 take such an overbore and be okay cooling and strength wise? Looks like I can get the "80" over pistons from Egge.

Thanks MIke

 

[Dozerman51]

Do not let them bore it. .060 is the max I would go on a Mopar flathead. At .080, you stand a better than even chance of cooling problems. I would try and find some sleeves and bring the specs. back to standard. Just my opinion and as they say “Opinions are like a......., we all have have one”. LOL. 

[55 Fargo]

.080 is fine heck .125 can be done.

.060 is not the limits for these engines.

They have very thick castings.

.080 cooling issues not likely.

Piston availability is an issue, Egge has them some say there pistons are marginal but your not building a race engine.

Is this a USA short 218 or Canadian long 218?

The Canadian 218s can overbored right to 3 7/16 ( .0.60 over) and fitted with standard sized 251 pistons .

Or find another block or resleeve every hole.

Gove George Asche a call 814 354 2621he can give you the straight up on this.

Edited March 5, 2018 by 55 Fargo Spitfire

[dpollo]

I do not think you will have any troubles but the larger the bore, the narrower is the gasket surface between the siamesed cylinders.

so make sure the block and the head have been resurfaced.

[DJ194950]

Have your machine shop use sonic cylinder bore thickness first . If thick enough your good to go.

 

A friend has a 1950 Plymouth 25" 218 bored +0.070 has never had problems.

 

DJ

[Hemibear426]

55 Fargo Spitfire,

 Thanks for your guidance. This is a 23" flathead out of a 1940 Dodge I believe. 

On ‎3‎/‎5‎/‎2018 at 4:44 PM, dpollo said:

I do not think you will have any troubles but the larger the bore, the narrower is the gasket surface between the siamesed cylinders.

so make sure the block and the head have been resurfaced.