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My BBC compression #s:

ndaniels

ndaniels

Well-known member
Well, I fugured I'd check it before I winterize it... looks good, 145psi lowest and 151 highest- averages out to 148lbs between all 8. I did it while the motor is stone cold. Jumps up rapidly, too.:thumb:

I haven't checked it untill now... I know the starter acted like it had good compression during the season, though.
 
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Totally unrelated, but... how much antifreeze is everyone using when winterizing?
I fogged it also.
I used two gallons of rv antifreeze. I figured that should be more than good after draining the block, hoses, and exhaust. I'm not way off in my thinking am I?
 
I use about 5 gal, BUT......I dump it in the intercooler, block, and headers seperately after draining the whole deal. I also dump AF in hoses after draining them. I don't do the "suck it in through the drive method". Your compression numbers seem OK.
 
I pulled the thermostat and poured it in the block- after draining everything... I don't trust the suck thru method.

Whats a stock gen VI 454 supposed to put down for compression- anyone know?
 
When I winterize my Persuader I put stable in gas tank and let run for 10minutes. Then I suck 2 gallons of rv antifreeze through lower unit, soon as it sucks it in I shut engine off and let sit for awhile. Then I remove block plugs and water jacket plugs. Drain and refill lower unit and I'm done. Never had any problems doing it this way.
 
ND your compression is tall calcs out about 9:1 you have no worries there.

I winterize for people in the upper elevations where it can get as low as 3 deg. As far as fuel goes, top off your tank and add stabil as mentioned run it through your pump and carb
I drain everything, block ,manifolds, pull all hoses make sure water is not in coolers or anywhere,
I then do the same as you did, pour antifreeze through the thermostat housing, I use sierra biodegradable non pollutant anti freeze and fill up the block. On those extra cold days an electric dipstick works well if you're storing outside. fogging is recommended, Seafoam is a good product or marvel oil. I store inside and it does not freeze where I keep my boat. I still do all to prevent rust in my block. But I run my fuel down to 1/4 tank and add stabil so I can add new fuel in spring .There is no condensation problem where I store,
You guys can't do that where you're at . Disconnect the battery take it out if you can and maintain it. These are the things I do.
The guys that do nothing at all are the ones that screw there boat up.
You guys know whats up. I also have tips at blog.mkhammer.com. There are other things to consider if your boat is outside.

MKHammer
 
I have just under 1/4 tank of fuel, treated with stabil, foggged the motor, and the drive oil has only 5hrs on it, so I let it go. I also got the seadoo ready while I was at it. The checkmate- I'm hoiping I can get out one last time before putting it to bed.

9:1? Hmm... Motor will spin 5700rpm and timing at 34*- I've been running 93/92octane... I was told by previous owner that I can get away with 87 or 89 if I have to- just keep rpms down. I don't know, but if I can get away with 89 all the time, that would be great! Nobody has premium at the few lakes I've been to, just ethonol free 89. Any opinions on this?

I'm keeping it in my heatead garage I had built this year- its insulated really good and the plan is to keep it at 40* this winter. The main reason I even added antifreeze is because I travel for work alot in the winter and worry about the power being off for a long period while I'm gone.

I'm in the middle of redoing the utility room on the house and moving stuff into the shop, but here are a couple of pics- its 28x40.
 

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ND, your compression is close to that there is no real way of telling the exact compression without measuring everything before engine assembly . Your compression is good. stock 454 is 8.75:1 . The ones I test that still run alright are between 110 to 130 psi they have alot of hours on them. Timing should be set to make HP without detonation, 34 deg. sounds about right. you need to be around there to make HP. I sent a boat out with a new 509 9.5:1 I built I had it set at 36 deg on premium. The owner bumped it up to 40 . I told him he is at his own risk. he said it runs good. I think he may not be able to hear or tell if it's detonating.
My opinion is everything you are stating sounds reasonable.


MKHammer
 
Yeah, I've just been worried about not being able to hear any detonation on 89octane while underway... gonna have to try it next season, I think.
 
You could tell if your engine is detonating it will not sound smooth and crisp it will crackle and ping when on it at acceleration. I think you would notice it.
 
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