Help me rebuild my 1978 350 5.7

[dohcdelsol93]

I have a 26 ft flybridge I'm restoring. Haven't ever heard her run. Compression test yielded low numbers on #1 cylinder. Engine is coming out while i rewire and reseal everyting so whether its just a freshinging with new rings and a hone plus bearings she's getting torn apart.

I aleady have a set of machined vortec heads to slap on
Already have an hei marine dizzy to slap on.

What cam would you suggest? Standard oil pump or high volume? I have raw water cooling. Unless i find a boat being scrapped and get a closed system shes staying that way. Whats the best sorce for new exhaust manifolds and risers? Mine are center mount i believe. Reliability is most important. Fresh water use with maybe one to three beach trips a summer.

I plan on a regular vortec automovie carb intake ,aluminum, with zincs installed. I can buy 4 for the price of one marine.

Was Planning on rebuilding stock carb but will it put out enough cfm? I have not looked to see if carb has electric choke or if it's run from the heat off of the intake. If it is can this be adapted to the edelbrock perfomer rpm intake manifold?

Going for mpgs here not mph but woukd like to pull my son and nephews on a tube, maybe knee board.

Pre alpha with an alpha 1 slapped outside.

Also what all would you replace while it's out and outdrive removed? Im thinking minimum gaskets sealing outdrive housing to the hull. Links to said parts would also be nice. Im a sailor so i dont know specific terms for outdrive parts.

Thanks guys. Advice is welcomed.

 

[alldodge]

I would suggest picking up a newer block from the junk yard so you can use roller cam and one piece rear main seal. Unless your going to build some major power just use the standard oil pump. If your in fresh water then auto intake should work

 

[Scott Danforth]

get a newer motor. if you start with a 1988 or newer block from a truck, you get a roller motor (boats did not get roller cams until the vortec heads - same block, just not machined for roller cam retainers)

comp cams XM-270HR cam is the largest SBC cam you can run with stock exhaust. the XM264 cam is a nice cam as well.

get a marine intake. new on Ebay for $300 that has the bronze water passages. that is only $30 more than a new edelbrock intake and will not toast your motor when the non-marine intake starts to leak into the motor internally.

unless you run a heat exchanger. which I would highly recommend with a new build. with a heat exchanger, run any intake you want.

if you want fuel economy in a boat, switch to oars and a sail. a small block in a 26' fly bridge will be a heavily loaded motor. you would get better fuel economy from a bigger motor (383 stroker or 454, etc). however you have an MC transom shield and an Alpha. most you can do is a warmed over 350 or a mild 383

if running vortec heads on an SBC, you need to use LCQ style pistons to make the most power from the vortec in a marine application.

depending on your motor clearances and the oil you intend to run, you can run either a standard or high volume pump. you simply need to build the oil system to match the bearings.

 

[scoflaw]

26' flybridge sounds like a heavy boat. I'd put a big block in it

 

[FuelishBehavior]

I agree with Scott Danforth 100%! The XM270 is a great cam for torque. If you don't want to start with another block, I believe you can use "retro" roller lifters but they are on the pricey side. A standard oil pump is really all you need which for this cam application about 5200 RPM's will be then upper power band.

 

[dohcdelsol93]

The boat is not worth a bravo upgrade nor used often enough for a closed system upgrade.. This is just a take the family out boat when we want to fish or there is no wind. I have a sanjuan 26 my son and i weekend on every weekend when weather is good. This is more just a toy. When we go to the keys it will be fun expore in. Big enough where we wont have to head home for lunch or dinner or even over night in if we wonder too far. Keys is one week a year. Most use will be in lakes. We rent a canal home on the keys for a week so it will stay in a canal all week. When in myrtle it will be launched and retrieved each day.

The vortec aluminum carb intakes are about 150-160 new. Occasionally see them pop up for 50 to 75 on local craigslist. Ive yet to see a marine for less than 400. I can change manifolds yearly and be ahead on that. This boat wont be stored on water or used even on a weekly basis. Will i have issues with corrosion if I keep an eye on the zinks? Is it too much of a hassle to check them monthly? If they are in the front of the motor it isnt that hard to check while you're checking the oil.

Im just trying to justify the expense. If the family decides they prefer it to sailing and its used weekly l, well then I can always upgrade. Until then doing an intake every second year along with risers and new manifolds every 4 years seems like pretty good routine maintenance. Which probably should be at least removed and inspected every few seasons marine or not?



Is there really that big of an advantage to a roller cam engine?

Id lose my mechanical fuel pump with a newer motor, requiring an electric fuel pump 3 to 6psi.

I have a spare 4 bolt main block(70s) but it will have to be bored 30 over. Is that too much for a marine build? Cooling is what i worry about.

Is there anything particular to look for to tell if my block shouldn't be reused? I will have a race shop doing the machine work but they don't do marine builds so any info i need to relay thay they wouldn't normally look for or should do differently, I'd like to relay that to them. They are a reputable shop, worked for nascar back when dale earnhart senior was on the small circle tracks and his dad was a big time racer. Older guys that dont build many engines these days as crate motors are hard to compete with on the circle track.

Im guessing scaling and deterioration of cooling passages?

Again, if a newer roller cam will net me enough horse power to spend the extra 500-600 bucks im all for it. If its not 50 to 60 hp or a noticeable difference from idle to plane or taking me from 1.5 mpg to 2.5 mpg i wont be able to justify it. The goal is 300 hp. Im afraid after that ill eat outdrives

Isnt the rule 100 bucks for 10 hp or its not worth it? Lets just throw in inflation and say 175 bucks for 10 hp.

And if i do switch to a post 85 1pc block. Will it bolt the same to my outdrive?

Please dont hesitate to point out any flaws in my reasoning or errors in judgments.

So unless there is justification any recommendations for a good non roller cam for a vortex head swap?

And were the pistons you recomended compatible for both roller and non roller cams?

 

[dohcdelsol93]

Sorry for the typos. This phone hates me

 

[dohcdelsol93]

Lets keep cam options mild. I don't want to have to worry about water intrusion so i want to keep it safe.

If i do go roller i will need new rocker arms and push rods correct as well as more head work to clear them?

 

[dohcdelsol93]

So lcq style pistons, can you please link me to some examples? Im seeing reverse dome, d dish, dish, flat top and dome as well as hybrids but im not coming up with much.

 

[alldodge]

You can just rebuild what you have and .030 is standard first bore, no issues.

Would not suggest roller unless you change blocks

Don't use anything aluminum in salt unless you have to.

If you don't keep it in the water, the zincs will not tell you anything about what is going on inside.

Since you don't know if family is going sailing or power boating, I would spend as little as possible.

Either year motor will hook up to the drive

 

[dohcdelsol93]

Most uses will be along the lines of dropping it in on a Friday and towing back home on Sunday. On occasion it would be nice to explore other local lakes on a whim which is too time consuming to do with a large sailboat.

Again, we dont know how the family will like it.

Also is there any advantage to having ceramic or powder coating done to the intake to protect it? Its about 80 bucks to have it done. 40 if i wait until someone else is also getting the same coating and a prep it myself. (Bead blaster at work)

 

[dohcdelsol93]

https://m.ebay.com/itm/Cast-Iron-VO...%3A735f35f115f0ac8074cd9564fffad886%7Ciid%3A1

I did find this which is an intake well within budget. Granted 100 more than the jegs intake but cast iron should net me 10 years life. I will be happy if the motor lasts that long.


So no roller cam. What standard cam would work for me?

I dont really want to invest in another block just for a cam if mine is reusable and i have a good truck core in the storage shed.

 

[alldodge]

Coating the inside of the manifold will help it last, and ceramic will (IMO) last longer.

If you use your old block you cannot use the intake in your post 12 because its Vortec. Need the Edelbrock 2504 (or other manufacture) intake or find a fresh water used one. Might find one in a junk yard in a truck.

If your cam is within spec (machine shop will advise) use it, otherwise, use a standard truck cam. The truck cam is the same as what is in a boat

 

[Scott Danforth]

xm268h is the largest flat tappet cam from comp cams. I used the XM264H in my vortec headed warm over of my motor.

you should be able to find a complete running late 90's motor and drive in a junk boat on a semi-good trailer for close to $1000 or less on CL. that is the route I would go

 

[dohcdelsol93]

The heads i have (already rebuilt and ready to be installed) are 96 vortec heads.

I knew getting this boat the motor would probably need to be pulled apart and examined. When i spoke to the race shop next door and i asked them about head work and they told me they had a set i could have for 200 i paid and left before they could change their mind.

 

[Scott Danforth]

Vortec heads are $500 a pair new, so a set for $200 is an average price. As stock, they are limited on valve lift. If the have not been machined for more lift, stick with stock cam, or look into beehive springs.

Have your heads been modified for screw in rocker studs?

 

[dohcdelsol93]

They are unmodified. Only a valve job, guides and seals

 

[boatman37]

no HV oil pump. they take way too much horsepower to turn and aren't necessary. they can also empty your oil pan if it doesn't drain back quick enough. either go with a stock pump or high pressure. i used to buy a stock pump then pull the spring and add a small washer between the spring and cotter pin to add a little pressure. did this for years on several race engines with no issues. did burn up 2 drills though trying to prime high volume pumps

 

[Scott Danforth]

no HV oil pump. they take way too much horsepower to turn and aren't necessary. they can also empty your oil pan if it doesn't drain back quick enough. either go with a stock pump or high pressure. i used to buy a stock pump then pull the spring and add a small washer between the spring and cotter pin to add a little pressure. did this for years on several race engines with no issues. did burn up 2 drills though trying to prime high volume pumps

You seriously do not understand how an oil pump with an internal regulator operates, or how clearances in an engine are what control pump output. it has been proven time and time again that a high volume oil pump can not pump a pan dry - Smokey Yunick proved it years ago with high speed cameras. A seriously sloppy motor with crap bearing clearances and plugged oil drain-backs and the wrong viscosity oil, maybe. however if your motor has that much oil coaking to plug the drain backs, the motor has been neglected.

a high-volume BBC oil pump takes about 1.5 hp to operate. a standard SBC pump takes about 1.2hp to operate. A high pressure/high volume pump is about 3hp.

a high PRESSURE pump will increase pressure, therefore increasing HP. putting the washer between the spring increases pressure in the regulator.

the way a pump internal regulator works, it pumps oil until the outlet pressure hits the spring pressure, then the regulator piston opens up and pressureized oil is routed to the pump inlet (effectively making a loop). with healthy bearing clearances and a good oil , no oil squirters (pistons, lifters, timing chain, etc.) then you only need to flow about 20% of the pump's capability. increase RPM and temperature, the oil viscosity drops a bit, and you are using about 60% of the pump's capacity

add oil squirters, a few other system mods, open the clearances a bit for lower drag (faster spool) and you are needing a high volume pump.

on a stock-ish motor with standard clearances and running under 7000 RPM, a stock oil pump will suffice. a high volume oil pump is over-kill, however will not, I repeat, WILL NOT suck a pan dry or increase power requirements enough to notice.

 

[Bondo]

on a stock-ish motor with standard clearances and running under 7000 RPM, a stock oil pump will suffice.

Ayuh,.... This is where I am in this debate,....

Our boat motors only need the stock oil pump,....
Anymore is money better spent elsewhere,....