Powerhead Swap Need Information, Will it fit

[fishonboat]

I am look to purchase a 1976 (25R76E) powerhead and I would like to put this on my current motor. It’s a 1970 (25R70E). Will it work? I know that the hood is different between this two. Thanks

 

[Dhadley]

Re: Powerhead Swap Need Information, Will it fit

They use the same base gasket so the mounting bolt pattern is the same. And the cranks are the same so the splines will match. There may be some bosses that youd have to fiddle with but I'd bet it could be done.

 

[fishonboat]

Re: Powerhead Swap Need Information, Will it fit

How about the clearence on the hood and I'm not sure what you mean by Bosses, can you explain. Thanks for your help.

 

[Dhadley]

Re: Powerhead Swap Need Information, Will it fit

Many times the hoods were changed only as a styling deal. If the powerhead bolts on it will, most likely, fit under the hood.<br /><br />There are raised threaded portions on the blocks that things bolt to. There may be some minor differences.

 

[Chinewalker]

Re: Powerhead Swap Need Information, Will it fit

They should swap right out. They're both 22-cube powerheads which had their last major redesign along about 1968. Low tension magneto was added in 1974, and CDI ignition was added in 1977. Ignitions between the two were different and you may have to swap them back and forth depending on what the '76 one came with. If it lacks any igntion stuff then you should be able to just swap the '70 stuff onto it, and make sure you use the '70 point cam. If the '76 has it's ignition stuff, I'd actually recommend going with the '70 - more reliable system than the low-tension mag of the '76. Flywheels and cylinder heads would have to stay with their respective ignition system, too as they were different as well.<br /><br />- Scott