My rapido longblock (pics)

[FreeBeeTony]

Re: My rapido longblock (pics)

Yes Raul..........welcome!

 

[MikDee]

Re: My rapido longblock valve adjustment

Re: My rapido longblock valve adjustment

We do adjust valves here but when your lifters get charged with oil , they all change a bit differently. I would do a final adjustment after the first time out so they are fully charged. The adjustment is done by running engine at idle and loosen each rocker one at a time until it flickers or taps then tighten until it stops taping, then take it between 1/4, and1/2 turn more on all valves. thanks and good luck to all of you.. Feel free to call me...Raulll (owner)
786-663-3278 RUN-663-FAST

Raul is right on here! After doing this many times on a small block, This is the way I do it also, 1/2 turn down only from no tapping, do it slowly to let the lifters adjust in between. The engine seems to run stronger this way also.

 

[John_S]

Re: My rapido longblock (pics)

Does anyone know or want to speculate on why Merc would have one full turn? It is in numerous of their SBC service manuals, so its not a typo. Anyone know the Volvo spec?

 

[MikDee]

Re: My rapido longblock (pics)

Probably because GM has been calling for that for years 1 turn, that's the standard (book) specs. In reality the SBC runs better with no lash, but would get noisy, (get loose very soon) so 1/4, to 1/2, turn down has been found to work better. I think the reason it's there, is because complete new engines are set up at the factory that way as a standard, once everything gets worn in I'd bet that all changes, so they give you a universal standard setting to start with, it doesn't mean that's bible. Besides, how much of a turn down does it take to lift the valve off it's seat? I don't know, nor do I want to find out, but remember the longer it stays on it's seat, the hotter it gets. I prefer to err on the looser side, and the engine likes it too. I know it's messy but, the only way I'm satisfied setting the lifters is by running the engine, and tightening them down a little at a time, slowly to 1/2 turn.

 

[Rusty Boater]

Re: My rapido longblock (pics)

On the valve adjustment we found a trick on the small blocks we have built. Go get an old SBC Valve Cover and cut out a 1-1/2" to 2 strip the length of the cover with a cutting wheel. This helps to limit the oil spray and lets you adjust the valves.

 

[whywhyzed]

Re: My rapido longblock (pics)

I've started tightening my rockers with a compression gauge and cranking with the starter. Lets me see at what point the valve is staying open, then I back it up till the pushrod is just getting loose, and split the difference.

 

[John_S]

Re: My rapido longblock (pics)

OK, I thought the GM spec was less and Merc had specificly increased it above that.

 

[SuperNova]

Re: My rapido longblock (pics)

Does anyone know or want to speculate on why Merc would have one full turn? It is in numerous of their SBC service manuals, so its not a typo. Anyone know the Volvo spec?

The actual spec is 1 to 1.5 turns.
The reason takes a little time to explain, but there is a good reason for it. The internal plunger in the lifter has .120" total travel and the plunger is what allows the hydraulic lifter to adjust the valves and compensate for different operating conditions. The objective of setting the valve lash is to position this plunger in the center of its travel--appr. .060" down in its bore. The top threads on the rocker studs are 24 per inch, so 1 inch divided by 24= .041".
Therefore 1 turn of the adjusting nut move the plunger .041" down in its bore and 1.5 turns = .060" down. The reason so many people waste so much time fooling with hydraulic valve is nobody takes the time to understand what exactly is going on and adjust them properly. 1/4 to 1/2 turn will do the job of making the valve quiet, but the adjustment won't last as long as if it were done properly. And every manual you will read anywhere by anybody will tell you to adjust the valves statically(engine off) not dynamically(engine running). It a poor way of cutting corners and not taking the time to do the job right.
--
Stan
--
Stan

 

[John_S]

Re: My rapido longblock (pics)

Well, I went out on the net to get re-educated on a hyd lifter works. I like it when a forum topic does that!

Also, went reading through similiar info on car forums. From that reading, it appears that what you gain by going less than 1 full turn, is some higher headroom before valve float. You may gain a couple hundred rpms before float. I found one reference to stock floating at 5700rpms. That basicly jives with my memory of hyd lifters being OK to around 6K.

Since our boat engines won't see above 5K, I am not seeing any benefit by deviating from the Merc spec.

 

[Buttanic]

Re: My rapido longblock (pics)

I ran circle track racing engines with hydralic lifters. I would set them at zero clearence which is just taking ajustment nut to the point that there is no clearence but also no deflection of the piston in the lifter. The reason is to help prevent lifter pump up if a valve floats. If there is room for the piston to move up in the lifter then when the valve begins to bounce off the seat the lifter piston will move up to maintain zero clearence and it will hold the valve open.

 

[SuperNova]

Re: My rapido longblock (pics)

We are talking about a marine engine that doesn't see valve float rpm, but I do agree in certain race application variations from the normal procedures can have benefits. In my race engines that need to see upwards of 8000 rpm, I use a solid lifter setup with triple valve springs and can tune the power curve by varying the lash adjustment, but alas that information also doesn't really apply in this situation.
--
Stan

 

[Bt Doctur]

Re: My rapido longblock (pics)

One thing you really need to do is "pre-oil " the motor before firing it.
locate any gm v-8 dist. remove the drive gear, and innards(rotor, pickup etc.), install and spin with a drill untill oil is visably seen coming from all the rockers, also rotate the motor a few times doing this .I`ve never trusted assembly lube in a new motor.

 

[Don S]

Re: My rapido longblock (pics)

Since our boat engines won't see above 5K, I am not seeing any benefit by deviating from the Merc spec.

It gives the tinkerers something to do. It also won't hurt anything.
My guess is between Mercruiser, Volvo, OMC at one time and GM itself, they are doing the best the can to get the most power out of the engine while keeping it reliable. They also have to warrant what they sell.

 

[KaGee]

Re: My rapido longblock (pics)

One thing you really need to do is "pre-oil " the motor before firing it.
locate any gm v-8 dist. remove the drive gear, and innards(rotor, pickup etc.), install and spin with a drill untill oil is visably seen coming from all the rockers, also rotate the motor a few times doing this .I`ve never trusted assembly lube in a new motor.

AUTOZONE lent me the tool for free!

Well, you had to buy it and then return it.

 

[EricR]

Re: My rapido longblock (pics)

A long, flatblade Craftsman screwdriver works, take the handle off and chuck it in a drill. Or I scrapped a worn out HEI distributor so I used the shaft as a tool to reposition the oil pump drive shaft to drop in the distributor.

Also- the stock intake and heads even with that cam they installed won't let the engine hit 5700 I would bet.

 

[delsol]

Re: My rapido longblock (pics)

i brought a 5.7 motor from raul. he's got a nice shop. i was at the shop. he's a real nice guy who stands behind his engine's
bob

 

[Daddy O]

Re: My rapido longblock (pics)

I worked at a GM engine lab testing engines for a few years, and they taught me to turn the push rod between my fingers with the valve closed and engine not running until the push rod stopped turning. Than one complete turn. This was done on all V8's. Also this was where they built the engines until they closed the plant down.

 

[erikgreen]

Re: My rapido longblock (pics)

Okay, here's the pics from our first day of assembly - we almost got the whole thing put together!

We started at 1pm and finished at about 8:20, with about a half hour dinner in the middle.

Everything went smoothly, with just a few notes:

1) We didn't notice the intake manifold gasket restrictor inserts until the intake was already on (dumb us).. fortunately we don't seem to need any?

2) We couldn't find the proper bolts for a lot of things because I didn't label them properly, so we ended up wasting time finding bolts that fit

3) The rapido block was painted as part of the reman process, and paint and gunk in a few bolt holes caused us to scratch our heads a few times wondering why bolts didn't fit - if you assemble a block like this, I suggest you clean the bolt holes with an appropriate tap first - don't re-tap, just gently clean the holes.

4) There were a few spots of rust on the block after sitting outdoors (under a tarp) overnight - it looks like they are a few difficult areas on the block to spray with paint, so they probably got missed when the block was painted (see pic below). Not a big deal, a quick touch-up was all that was needed.

5) Some of the bolts on my old motor's intake were too corroded to use, so I replaced them with new grade 8s.

6) The oil pan gasket supplied in the gasket set for the motor was ok, but had the dipstick hole on the wrong side - putting in on the other way made it fit poorly, so I went and bought an appropriate gasket at checker auto that fit better.

7) The oil pan that I had didn't have an included windage tray... it mounted to studs in the old motor. I elected not to install it at this time, as I didn't want to remove and mess up the main bolts.. I am pretty sure I can pick up and install an oil pan with a built in windage tray in the future. For now I'll run it as-is. Comments?

Questions: Does anyone have a pic of the hose routing for the power steering pump? I can't for the life of me remember which was it goes, nor find an easy reference in my manual (seloc, I know.....).

Second, can anyone confirm that I don't need a restrictor in my intake gasket?

Here's the pics:

Bit of rust:

Oil pump installed with sump tube from old 305, that's Shawn and David helping:

Valve covers going on.. I'll do something about the labels later:

Intake on.. a bit more rust than I'd like, but we did clean out the passages to make sure there's nothing big enough to fall through to the cylinders:

Distributor and coil on:

Carb on and thermostat housing mounted:

So far so good. Tomorrow we'll find the other bolts for the water pump and re-verify we put it together right. Then I need to mount the transom plate and bell housing on the boat before I can put the motor in.

All in all, I'm happy so far with the rapido motor. I didn't expect to get so far so fast on this build, but thanks to my helpers we got a lot done in 7 hours.

Erik

 

[FreeBeeTony]

Re: My rapido longblock (pics)

Looks good eric...........keep up the good work!!

I puleed my engine out yesterday.........Raul said sholuld have my longblock before the w/e.

 

[wca_tim]

Re: My rapido longblock (pics)

I just got through the break-in period on a 4.3 that I ordered for a 1988 boat from Rapido. Everything looked good up front, they were easy to deal with, etc... I wound up ordering an older style block, changing to an electric fuel pump. We went with vortec heads and a new edelbrock intake anc carb. First oil change looked very good, and now that jets are close to right, hit 57 on GPS last night on the river and it wasn't all that calm. I'm thinking it'll be ca. 10 mph faster than the original 88 4.3 2bbl by the time the set-up is done. That's based on what the previous owner said. I "acquired" the boat with blown engine in it. I broke my shoulder right after I ordered the engine and so had a local shop (marks marine in Grimesland, NC - were great to deal with and did a great job for reasonable labor rate) put the engine in, and I finished up some of the details. After the experience I've had so far, would definately go with rapido again... especially after the way the boat ran last night... and I still need to go up to the next richer metering rod for the carb to be just right... may be even better than it looks now! Good luck...