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Old 09-15-2010, 11:41 AM   #1
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Default Hard start

I have a 5.7 FWC vortec motor, Holley carb, elec. fuel pump, Mallory Distributor. I installed a pair a few years ago on my 3200SCR.

My problem is when I try to start the port motor (every time) it seems to pre-ignite or something with a grind to the starter and the Tach jumps all the way around. Then I let go of the switch and try again, then it will start.

This motor had hydro-lock in #6 cylinder from a bad head gasket which I replaced and seems to be dry now when tested last.

I've installed a new ignition switch, which it needed anyway and a new cap/rotor which made a difference when first installed. All connections have been checked to be tight and crud free.

I was wondering if the distributor was bad, or the starter. I am concerned why the Tach jumps.

Any suggestions?
Joe
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Old 09-15-2010, 01:10 PM   #2
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Joe,

Given the symptoms I'd be inclined to suspect the distributor. I assume the Mallory is fitted with some sort of electronics in lew of points and for some reason the electronics are sending a pulse to the tach and pegging it and maybe prematurely trying to fire a plug or two. Or not.

Interesting that the new cap and rotor cured it for a little while.

Easy enough to check though - since you have twins. Start by swapping the cap and rotor. If that no workie swap the distributors.

Dan
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Old 09-16-2010, 10:54 AM   #3
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Thanks Dan.
I've tried the cap and rotor swap and that is I ended up buying a new set. But it only lasted for a while and I am back with the Tach and grind issue. This is what makes me think it might be the Distributor. It does have a module in it for elec. ignition.
I'll have to try the distributor swap to see if that makes any change.
Thanks for the advice.
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Old 09-16-2010, 12:55 PM   #4
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Happy to help Joe.

To make life easier when you do the swap remove both dist caps, turn both engines over until the balancer mark lines up with the timing mark (may have to use a socket and breaker bar by hand to get it spot on) and both rotors pointing to #1...........

Wait - why am I trying all this! You apparently already know the drill..........LOL

Dan
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Old 09-19-2010, 11:08 AM   #5
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Thanks for the reminder Dan.
I'll probably do this some time next month before I take the boat out for the winter.
I'll try to post the results-if I can remember that far, blame it on old age.
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Old 12-17-2010, 12:13 PM   #6
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Default Still working on them

Well, I am still working on my motors. They have been removed and are now in my garage. I have had trouble with these motors since I bought them.

Before removal I did a leak down test and found that #5 on the starboard motor was leaking 45% with a compression of 65lbs. The port had a head gasket leak at #6 which I replaced while in the boat, then #6 leaking at 20% and compression of 115lbs. These motors have only 260 hours on them and are 3 years old. They are out of warranty and the company I bought them from said nothing they can do. I called Crusader and they are willing to send me parts. Thank you Crusader.

So I found a cracked piston in #5 right below the 1st ring, and had the heads resurfaced. I've attached a pic.

I'll let you know what I find in the port motor soon as I tear it down.

My plans are to have them Dyno tuned before reinstalling them in the boat in Spring.
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Old 12-17-2010, 02:46 PM   #7
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Pretty big bummer, Joe, but least you have something to keep you busy over the winter.

Internal problems with both; almost makes ya wonder if you simply got a couple of engines that were assembled by a knuckle dragger. Regardless, appears to be your problem now. That's a good size hunk from #5 - just under the top ring. Probably pre-ignition, but could also be the ring was too tight in the bore.

Are you sending both bare blocks out to have them checked before you go in with new parts? Might consider forged pistons as they will take more abuse than cast - especially if the engines suffer any pre-ignition for any reason. Of course, if you do go with forged slugs the cylinders need to be honed to size since forged piston grow a bit more than cast.
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Old 12-17-2010, 09:39 PM   #8
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don't forget to line bore the crank journals and have all new bearings installed on the cam...tank the whole block..repaint...it will look just like new....keep those photo's comin!!...

we live vicariously thru your photo's you know....

SP
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Old 12-18-2010, 12:32 PM   #9
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Thanks guys.

I'm not sure how far I want to take this. Money is a big issue and the dyno will cost me around $1100 to $1200.00 for both motors.

I am of the thinking that repair is the goal. They run real good when they start- even with the broken piston. The engines are sized perfectly for my 3200scr.
With 11 people on board, slight trim tabs and we are on plane in seconds.

With the money issue I will have to skimp on some things. Ideally replacing all piston/rings/bearings and have the block honed for both engines would be preferred.

The top of the bore (checked with verniers) is 4.001 x 4.002. I will try to borrow some bore scopes to check down further. Those numbers are typical even on bores that the compression was at 150psi.
ss3964spd the pre-ignition thing was what my machinist said as well.

I am told these motors are assembled in Mexico. My machinist said the heads on these Vortec motors have a poor mating surface and that could have contributed to the hydro-lock leak on my port motor. I am attaching a photo of when I repaired it this past summer.

I'll try to keep posting and let you know of the progress.
If there are any ideas of money savings let me know.
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Old 12-19-2010, 12:08 AM   #10
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in that case..I'd look at also have the block decked and the heads trued up.....may have to have them taken down .10 thousands of an inch to get them flat...use stronger than stock head bolts ...most are grade 8 bolts...see if you can get grade 10 or 12..most are racing head bolts and won't cost but a few bucks more...use marine head gaskets for sure.....

also make sure you torque the head bolts in 3 stages...it will ensure that they are taken down slowly and evenly......keep those cards and photo's coming......

Sp
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Old 12-19-2010, 12:09 PM   #11
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Thanks SP for the great "low cost" advice. The stronger bolt thing sounds like a winner.

I have an auto machine shop around the corner where I live. I can get the bolts from him. They are involved in track racing as a hobby/job so he's real knowledgeable. He has already resurfaced the starboard heads and checked them for cracks. They came out real nice.

Since I only had bad compression in #5 and surely found the piston cracked I was going to leave it like that and not disrupt any of the other cylinders. But a momentary jolt of wisdom came down and I decided to take all the pistons out for inspection. Good thing I did- found 2 more cracked pistons, and one more had the secondary ring crimped so that only one end was free.

I hope to start the port motor today. The only good thing about all this is that I feel that I still working on my boat even though it's winter.
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Old 12-19-2010, 03:49 PM   #12
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well...depending on where the engines were manufactured...I'd say there was an idiot involved....the engine should not have had so many bad pistons and rings...one I can see....that can happen on an engine that runs like ours do.....

one thing to concider also....don't let the shop try and get you to hot rod the engines....your boat has a constant load on it..so it's like your engine running in 4th gear up hill all the time...so..the torque should come on and stay on until almost redline....your max wot..as you know should be between 4200-4800 rpm....hotrodding the engines will shorten the life of the engines...
keep the engines right near specs...
just my 2 cents worth.....

SP
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Old 12-20-2010, 11:57 AM   #13
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Thanks SP,
That is good advise.
I did have visions of port and polish while I had things apart but my guy talked me out of it and said those motors have enough torque already. So that's two wise men that have the same advise.
Thanks again for your help.
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Old 12-20-2010, 03:53 PM   #14
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well..porting and polishing will allow it to breath a bit better...I'd do that ...I'd also have the entire engine balanced.....or what is called blue printed...balancing the engine moving parts will relieve alot of stress on the internals....the pistons won't be fighting each other as they work...so..imho...port/polish/blue printing/balancing...is something I'd really concider....I've had that done to a few engines long time ago and the difference was astounding..


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Old 12-20-2010, 03:56 PM   #15
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Having quite a lot of fun. 'eh Joe?

Steve' points are spot on - especially regarding the torqueing proceedure, but I will debate the need for stronger head bolts. Stonger head bolts are only needed if the heads are "lifting" off the decks - which is caused by high compression and typically found in forced induction engines. You have neither. Nevertheless, probably not a bad idea to replace the bolts anyway. Pretty sure I read somewhere that some are one time use only - once they've been stretched they cannot be re-used.

Have the heads checked for flatness. If they need to be resurfaced have the shop take off ONLY what is necessary. Ditto on the block decks. If you take too much off you could end up with issues getting the intake manifolds to seal against the heads. Shaving the the heads and decks will also raise your compression. You can compensate for that by using slightly thicker head gaskets. If the engines are fresh water cooled you can use automotive gaskets.

I wouldn't think that those engines will need any bottom end work; IE; bearings, etc, because of the low hours. Regardless, if detonation did take out that one piston and cracked the others, it might have been bad enough to beat up the bearings so inspect them carefully.

Do these engines use roller lifters? If not, and if you are going to re-use the cams and lifters, I trust you bagged and labled the lifters so each goes back into the same lifter bore it came out of. Flat tappet cams/lifters develop a wear pattern that is unique to that particular cam lobe and lifter combination and mixing them up is almost inviting a cam lobe/lifter failure. Be sure you also use the same timing chain/gear set from each engine.

Be sure to either mic, or feeler gauge, the piston to bore clearances. When short blocks are assembled the cylinders are bored to their rough dimention and then honed to their final size - which is dependent on the pistons being used, so you need to know what the finished bore size is supposed to be from the piston manufacturer. At least that's how it's supposed to be done. Be certain to install the rings into the bore - about an inch down from the deck, and check the end gaps against what the manufacturer specifies. Once the rings are on the pistons check the ring land clearance. If you are only replacing the damaged pistons and rings, the bores will need to be honed a bit so be sure the finish is correct for the type of rings you are using (different ring material, chrome moly vs. iron, for example) require different finishes. A light coat of oil on the walls and on the pistons and rings - don't dunk the assembly in oil. If assembled correctly the rings will be almost completely seated within a few revolutions of the crank.

Hope your garage is heated!

Dan
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Old 12-20-2010, 04:21 PM   #16
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While typing my missive above Steve was also hard at work and his comments about balancing jogged my memory.

Since you are replacing pistons balancing will likely be necessary, especially since you really don't know how well the engines were assembled the first time. The shop will (or should) want the harmonic balancer from each engine but the balancer should be balanced independently of the rotating assembly. Doing it that way ensure that the balancer does not end up being specific to a particular engine, also ensures that the balancer itself isn't used to balance the rotating assembly.

Since you are working on a budget I'd ensure the rotating assemblies are balanced way before I spent money on port and polishing. A P&P job is expensive so if there's room in the budget I would change the cams before port and polish - much greater bang for your buck as an even modest bump in valve lift and duration is going to have more impact in the RPM range you'll be running than will a P&P job, IMO. If you do swap the cams be careful - Vortec heads can only take just so much valve lift - .470 I think, without needing to machine the valve guides. You'd want to know the specs on the existing cams before selectin replacements.

I love building other peoples engines.

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Old 12-20-2010, 05:39 PM   #17
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although our esteemed Mr. Dan is correct on a few things..I would think he's just going to replace the bad pistons and thus the balance job would be required...
as for the cam change out...I wouldn't go much bigger with the cam lift due to complications of clearances...on top of the lift to the valves....there is also clearance of the pistons to valve.........I also would check the crank bearings as well as harmonic balancer.....
but P/P is cheap horsepower....the engine breaths better and thus free's up hp...

SP
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Old 12-20-2010, 06:52 PM   #18
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Thanks for thowing me a bone, Steve! LOL

True, need to look at P to V clearance when doing a cam change - and is but one reason it would be good to know the specs of the current cam(s), but it's almost a given that the current cams are so mild that bumping lift another .20 or .30 thous of an inch and duration 10* won't be a prob.

Suggesting cams over P&P was based upon budget. When I had the port work on the heads for my 489 done the cost was over 700.00 for the two heads (porting and polishing cast iron is very time consumming), whereas a cam and lifter kit can be had for probably less than 200.00 each if they are flat tappets. If a roller then Joe can re-use the lifters and a roller cam is still likely to less than head work. Vortec heads flow pretty well for factory heads and finding a porter that knows how to work them - without screwing them up, is important.

Agree with the balance job, but if Joe is just replacing bad pistons, and if he finds exact replacements, he can weigh the new and old to see how close they are. If real close he won't need to rebalance if money is the main issue.

Lots of options - all of which are dependent on money, of course.
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Old 12-20-2010, 07:18 PM   #19
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Horsepower is the square root of the dollar!!

SParr
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