Rubber Blocks in Crossflow Reed Chamber?

[spucky]

Can anyone tell me if all the 1.6 crossflows are supposed to have these? They are triangular blocks that wedge in beside the reeds. I am rebuilding an 1988 Evinrude 90 that was rebuilt or had a rebuilt power head installed 2 years ago, and it does not have these blocks installed. I have done 2 early 80's 1.6's and they both had them. Are they intended to decrease crankcase displacement to increase crankcase compression ratio? The engine was scary fast on a 17 foot whaler, did not seem to effect performance. Up to its untimely demise.

 

[rodbolt]

Re: Rubber Blocks in Crossflow Reed Chamber?

Hello<br /> not all crossflow engines had them. they are called filler blocks. most the i40 and some 115's had them. usually the ones with the tuned bubble back exhaust. yes it was to lower the amount of airspace inside the crankcase.<br /> good luck and keep posting

 

[Joe Reeves]

Re: Rubber Blocks in Crossflow Reed Chamber?

Various engines incorporated those rubber blocks which were designed simply to decrease the crankcase space for whatever results that item created..... apparently increasing crankcase pressure on the pistons downward stroke.<br /><br />Rule of thumb.... if they're listed in the parts manual, use them.

 

[spucky]

Re: Rubber Blocks in Crossflow Reed Chamber?

Thanks for the response. Its a flat exhaust cover, 1 3/16" carbs. I do not have an 88 manual but the 1983 1.6 Sea Drive shows them in place. I do have a set of these parts out of a 115 Johnson that has been a parts motor. Would you use them?

 

[Joe Reeves]

Re: Rubber Blocks in Crossflow Reed Chamber?

The 1988 90hp DID NOT incorporate those filler blocks. Do not install them.