Powerhead Swap

[iwombat]

Just double checking.

1976 85hp powerhead will fit a 1977 85hp, right?

 

[ezeke]

Re: Powerhead Swap

edit

 

[iwombat]

Re: Powerhead Swap

Yeah, I been thinking about that. I'm trying to wrangle an 85 from someone w/ 120psi in each hole for $100. I'd love to locate a 115, but a bargain is a bargain.

Which brings up a follow on question: If I can find a 115 are the 85 carb the same w/ different jets?

 

[ezeke]

Re: Powerhead Swap

edit

 

[iwombat]

Re: Powerhead Swap

Fair enough. I won't do any swapping or rebuilding until winter. I'm just in bargain harvest mode for now.

 

[samo_ott]

Re: Powerhead Swap

The fall is a good time for bargain shopping!

 

[iwombat]

Re: Powerhead Swap

amen to that. Winter ain't bad either.

 

[Dhadley]

Re: Powerhead Swap

The 76 85 powerhead will fit on the 77 as long as the 77 85hp isn't a 25" motor. I know they made a 77 85 in 25" but have never seen one.....

 

[iwombat]

Re: Powerhead Swap

Normal old regular shaft length, but good info nonetheless.

 

[iwombat]

Re: Powerhead Swap

So, I managed to get the 85hp powerhead for under $100. I'll still be hunting for a bargain on a 115 until I put the boat up for the winter. But, at least I have plan A now.

Anyone have a good way to check compression numbers on a powerhead that's not attached? I'll probably hone and re-ring unless the numbers are stellar.

 

[emdsapmgr]

Re: Powerhead Swap

These early 85 hp engines were unique in that they had a different bore than the rest of the V4's. Yours is a 92 cubic inch engine, VS the 99 for all the rest. May limit your ability to use other heads.

 

[iwombat]

Re: Powerhead Swap

Since I now have two complete sets of heads, I'm thinking that won't become an issue.

 

[iwombat]

Re: Powerhead Swap

Well I finally got information w/ the actual compression numbers on the motor. (Over 120 and even was what the seller said originally). They're 140, 140, 142, 143 respectively. Now, I don't know if that's a high reading gauge, but that seems awfully high for a '77 85hp.

Now I'm wondering if someone decked the heads along the way. Not that I'm all that worried, really. But, does that kind of compression (if it's real) warrant higher octane gas, or is 150 kind of the rule-of-thumb cut-off point?

 

[DaMightyWackO]

Re: Powerhead Swap

Compression ratio 8.0 is 125-152 PSI. Octane 89 or higher would be fine, from what i know.
91 is rated for 8.5-9 ratio.

Just out of curiosity what are the octane numbers available in your place? Here in the Netherlands 95 is normal, super is 98 and premium (shell v-power for example) is 100.

 

[HighTrim]

Re: Powerhead Swap

In Canada 87 is regular, 89 is super and 92 to 93 is premium. Id be pretty happy with those numbers. Have you used this gauge before, did it always read high?

 

[iwombat]

Re: Powerhead Swap

It's the seller's gauge, so I'm not familiar with it at all. My guess is it's reading high. The real relief is I don't need to worry about a ring job before installation. Even if it reads 30psi high I'd be happy with those numbers.

 

[DaMightyWackO]

Re: Powerhead Swap

In Canada 87 is regular, 89 is super and 92 to 93 is premium. Id be pretty happy with those numbers. Have you used this gauge before, did it always read high?

Wow thats low! I would be scared to put the in my tank.
But what is the price you are paying? (Netherlands has a super high 'Al Gore' kind of level, environment, trees, green, people-planet-profit, Prius cars, high clogging tax culture. For example most of our cars have less then a 2 liter engine and the 1 liter economic cars get subsidy).
One liter of regular fuel costs about 1.35 Euros = 1.8441 U.S. dollars. (7 dollar a gallon)

Edit:
Imagine what a day skiing at the lake cost with a larger speedboat

 

[HighTrim]

Re: Powerhead Swap

yikes, I think Id have to trade in the 200 horsie for a smaller ponie with those prices. I pay about 90 cents a litre right now, and our dollar is close to the american at the present time. Do you have a second job Although you dont see many 1 litre cars strolling around here, theyd get run over in traffic, or stuck in our Canadian snow drifts!!!

 

[iwombat]

Re: Powerhead Swap

Shoot, I don't even have a motorcycle that small.

87 is standard in the States too. It's what I use in all the outboards. Most of the bikes get 92, but they're all 9:1 or better.

 

[DaMightyWackO]

Re: Powerhead Swap

You guys, i can't believe it.
89 and 92 fuel. What about mopeds, motors, turbo-charged cars and cars like porsche. Al high compression, rpm engines?

But don't forget the Germans, Italians en Japanese manufactures these days get 100PS out of a 1.4 liter engine with turbo. And you don't want to drive a 5.7L Pick-up here cause you pay way to much road-tax for it (you pay for the weight of the car), you wallet gets empty at the gas station and last but not least..... it's to big for our average parkingplace.

But yeah a 100ps and more boatengine ain't funny anymore with those gasoline prices if you burn 50 liters fuel or more in a day skiing.