i just picked up a 16 foot glasstron type boat with a 140 merc 4cyl in it. the boat is a 1976 with very low hours on it and in great shape. what can i do to get alittle more HP out of this thing? i believe is known as an iron duke 4cyl (?). not looking to replace the motor but i will have it out this winter and thought i'de try an wake it up a bit. was thinking about upgrade on the ignition(still has points) and carb. maybe a cam if i can find one.


does sterlling offer a replacment for this engine

thanks all

That engine is based on the eary 60's Chevy II engine. If it is the iron block version, there are lots of hipo parts made for it. Later, Merc made some changes to it and casted it out of aluminum. Those may be harder to hot rod.

GlassDave

A great little engine and yes there are parts as they are used in dirt track racing both back in my home country (Australia) and yours.
If you like driving at WOT all day a couple of things are required.
1. Oil cooler and pay close attention to the oil level, too much and the crank will whip up the oil and aerate it.
2. Have the head machined for screw in studs as it has quite a large rocker arm ratio and I know they will pull out after a while.

Pay attention to the history of the engine re salt water use as the cylinders are very thin especially No 1.

If you want a reliable ignition just use the late model distributorless version.

The engine can use much larger induction but I dont know where to go for that.
With some head work the numbers are close to a small block chev but you need some creativity to enlarge the stock manifold and carb.


PatriYacht, what model is the version you refer to that is aluminium?

Regards

CJ

Try to find a complete 165hp 6 cyl and replace the 4 or a good 170hp 4 cyl. the 165 will fit with little mods and can be made to 200hp or so. good luck

The aluminum version was called the 470. 4 cylinders, 170 hp. I think it was stroked to 3 liters.

The 470 was an entirely different animal. It was an aluminum Merc block (3.7 litre) that used a 460 Ford cyl head, 460 pistons and rods and closed cooling.

The 470 was a prone to failure. With the different rates of heat expansion between the alum. block and cast iron head, the deck would warp quite easily, weep antifreeze down into the cylinders and seize up the wrist pin.

If you ever see one, take a close look at the head. Chances are you'll see traces of coolant weeping down the side if the block.

They did make great power for a 4 cyl. It was also offered in a 190 hp version with a 4 barrel.

Kurt

good info guys. thanks.

campbell- this engine has very low hours, under 200. i am going through it this winter and will probably do a few of the thing you suggested. the screw in studs sound like a good idea.

Ironman- are refering to a V6 or straight 6. i have seen both. i know i dont have room for the straight one.

Mr.P- is this the engine that was called the iron duke. it is the cast iron one by the way.

The only engine that I know of called the Iron Duke is the Pontiac 4 cyl. used in the Fiero. I believe yours is the Chevy II motor. My dad had 2 of them in a 26 ft skiff in 77.

The inlin 6 cyl 250 cu in motor. I had done one of theese upgrades for a customer years ago and it was super easy. However if you do not have room in front of the 4 it will not fit. I thought that some of the glastrons came with inline 6's mostly volvo's though.

These people once had performance parts for that motor, I dont know if they still do, you might have to call them. http://www.cliffordperformance.com

Years ago I had a 16' Glasstron with a 120 in it, went about 40 or so. I wanted to speed it up a bit... wound up putting a warmed up 350 in it, went about 65 after that.