The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by tjm73, Apr 9, 2008.
I recall it's 8.8:1 stock
I have a 470 in my '84 4Winns 195, and I have to say that I'm not too impressed. You have to run a fairly steep pitch prop to get the damned boat on plane, and then you don't have enough ass to cruise above say 25mph. I've pushed it to about 40mph, but even then that was well above 5000rpm and it sounded like the valves were starting to float. It sounds like hell, the charging system (stock) is a joke, and it shakes like a dog shittin' razor blades. And that's running good!
If anyone wants to trade me even up for a nice 350 marine motor I'd be all for it.
what bellhousing/clutch set up is these little mtrs
Bellhousing dowels and 3 bolts are Chevy. I used Chevy to Ford Lakewood bell and cut and moved starter pocket, then made thick flywheel as engine has extended bellhousing flange and put adapter pilot bearing in flywheel. Flywheel was lightened on backside and drilled for 10-1/2" Mustang clutch pattern in std. and metric.
My buddy had one in a 1977 Reinelle 18ft boat. Delco dist with points, 1973 casting date 460 head, 460 pistons 2 bbl 170hp.
I've been way off in my thinking.
Does anyone know the stock deck height?
You are absolutely right, I called mercruiser tech support. A dealer here had misinformed me.
How much decrease in CR is best?
[I'm about to buy dished pistons]
just posting to stay in the loop......
Which head casting and what is the intended use?
Hey Big Chief! What's up? I read these threads everytime they come up and I continue to be interested in doing one of these for a bucket. I've seen two or three on the local Craigslist in the last year. One I nearly called on.
Do you happen to know what the deck height is on these blocks?
.050" less than a 460 so piston compression height is same with a .100" shorter stroke crank.
Head : D3VE A2A
Merc470 replacement motor for a 1800lb replica of a 30's indy car. (I worry that its present motor will blow up as I've run it up to 3600, double its design rpm).
Will drive it in rallies on quiet country roads and hill climbs and will drive to some of the events.
Volume data is on the internet for most of the ford pistons except those with the bathtub-shaped dish, so I don't know if the bathtub style is even worth considering. It would seem that both the "bathtub" and the "D cup" dish would add volume but not increase the squish distance as a broad shallow dish would. (If the squish is already too thick, I guess it wouldn't matter)
ps: I am very grateful for your help on this.
Wouldn't swapping an aftermarket alloy 429/460 solve the compression problem? You may raise the static compression a little but the head would lose heat to the coolant much quicker making the engine more compression tolerant. Not to mention you would possible solve the head gasket issues mentioned earlier....I would think you could have some dissimilar expansion rates between the cast iron 460 head and the alloy Merc block. Now that I think about it, you would also shave about 30lbs off the weight of the motor with an alloy head.
Something makes the mercruiser 470 combustion different from the Ford 460 combustion even though they have the same head:
1. you can rule out head shape & volume as it is the same head.
So what is left:
1. use as a boat motor at prolonged open throttle
2. squish distance
the aftermarket alloy heads are said to combust better. and yes the weight is an advantage. I'm doing this on the cheap tho. but may resort to an alloy head later .
I also had one in a mid 80's Four Winns and had the same experience. The guy I sold it to hates me now because he puts at least a grand into the boat every year. Not to say it won't make a great rod motor though. I'm interested because I can get a couple of these motors for next to nothing but have been shy due to the boat experience.
Don't sweat the extra compression on a street motor. Run pump premium and you'll be fine with the flat tops. You'll have soooo much fun with that motor in an 1800lb car.
Yes, swapping to an earlier 429/early 460 head or better yet an aftermarket aluminum head would be better (with a flat top or a reverse dome slug...not the bathtubs) for improved flame front travel and squish area.....especially helpful for performance applications.
Mostly the application is the issue. The main issue was that these motors literally do a dyno pull as the boat is planing off and they are under a constant load when the boat is moving. Couple that with detonation prone chambers, poor gas and dealers/boat companies/owners trying to get every last MPH out of the boat (incorrect propping at the expense of low end grunt) all adds up to a pinging, overheating pig.
I cc'd my head and it was 100 cc. Aftermarket are all 20cc less except Blue Thunder.
Thats kind of on the big side.....let me guess....D2VE-A2A castings?
keeping in the loop...
I measured my merc 470 head and it was 91 or 92 [too hard to tell them apart without a plastic plate] So if your volume is more than that it is all to the good as far as avoiding pinging. I'd better measure my "new" head tomorrow as if it is 100cc my anticipated compression ratio problems are pretty much over.
Of course unanticipated problems bite harder. :0)
The load is very different in a car, few extended open throttle runs. but on the other hand, transient heavy load on the engine can result in severe pinging [I can still hear my mother driving years ago, she never downshifted unless the car was bucking] Vacuum spark retards were made for drivers like her. Now since merc retarded the spark 2 degrees in boats, I'd like to advance it and not have knocking in my little car. Is my discretion with the throttle enough or is a vacuum pullback better?
Ok no bathtub pistons, it looked as if their compression was low enough to burn crude oil.
Watch craiglist and racingjunk.com for the FMS Cobra Jet alloy heads. These have been on the market for about 20 yrs, maybe more, and you will find them pop up for sale because someone is swapping on some of the numerous newer, better, racing heads. The alloy CJ is a great street head and flat out performs any stock head straight out of the box. If all that I'm reading on here is correct, I'm going to talk to a buddy of mine that is a tackle rep and have him keep an eye out for as many of these motors as he can find. For the few problems mentioned, these sound like there is a boatload (pun inteneded of potential. The problems all sound like easy fixes. Boy, bolt up a T5 and drop this into something small like a track-t and have fun.
I was reading an older thread and one of the posters mentioned milling down the mounting surface so you can use a standard flywheel. I don't recall which one they used but I thought it was a Chebbie flywheel with a Ford clutch/PP.
BTW, anyone know if these use a Delco or Motorcraft dizzy and if so, does it interchange with any GM or Ford 4cyl cars?
the distributor has a hex drive running out of its drive gear down to the oil pump.
I just measured* my "new" head [ a D3VE] it is 103 cc.
* this time I did it right, greased down a Plexiglas plate to the head. The plate had a 5/16"hole on its higher side near the combustion chamber edge through which I filled it with a 60cc horse syringe. a second #50 hole near the larger hole made vent for the air to exit.
Today I measured my old "mercuruiser" head 100cc.
So deck height is 10.322-0.050 = 10.272" and the stroke is 3.750". And for anyone not in the know and who might care, the OE 460 bore is 4.360".
A little math tells us the rod would be about 6.641" assuming an OE Ford piston pin height of 1.756" and a zero deck height. However, the 429/460 BBF has a 6.605" rod.
Did the Merc use the Ford rod as well? That would put the piston pretty deep down in the bore at TDC. I'd be around 0.036" below deck height.
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