I am new to y blocks and have a 1962, 312 powered inboard boat. I am planning to replace the twin sidedraft intake with an automotive 4bbl intake. The intake I have uses a modern holley carb. I have a couple of queastions.

First, I hear the exhaust crossover can be blocked off to prevent paint burn on the intake. Being on a boat, I dont think I need to worry about warming up the intake? If it can be blocked, what is the best way to do this?

Second, The intake has a "mushroom looking appendige" on the left side of it...looks like some kind of a vent. What doesit do? Does it have to be there?  Can it be removed and plugged?

Here is a pic I found of one like mine that shows what Im talking about .....

Thanks!

.

You can block the heat crossover with a couple of pieces of tin or aluminum.A little silicone or similar to hold them in place and then put your gasket in place.The other item is the old leftover heat pipe for the choke.They go right through the manifold to pick up heat.They corrode inside the manifold so you plug the ends when no longer required.You can change it to something neater if you want.

  

Thanks oldcar,

Does the heat pipe press fit into the manifold? Will it pull out? / or just cut it off flush? Since there is no heat, ok to plug it with an epoxy?

64 Inboard,

Hello and welcome to the site.  I have a 1955 272 in a mid 60's clinker skiboat and had never heard of a YBlock before this site and have learnt heaps from these wise people.

I already had a 2 barrel intake for a 350 holley and since upgraded to a 4 barrel to fit a Holley 570 Street avenger which increased the take off torque alot, great for pulling skiers out of the water.

When I fitted the 4 barrel intake I did exactly what you propose and covered both the heat cross overs with some thin steel sheet and plenty of gasket sealant around the new gaskets.  Try to keep the sheet as thin as your game as if it's too thick the manifold will rock on it and you may suck air from somewhere else!  I had no worries at all and clamped it all down as per torque specs and never looked back.

I also sealed off a spare old threaded hole (vacuum in my case) and mixed up some of that 2 part metal putty and pressed it in (make sure you don't push too far as it might end up anywhere) and smoothed it over and gave it a light sand and can't even be seen now the whole manifold was repainted. 

Good luck.  Whitey (Down Under)

My first V8!!

Brisbane, Australia!!

The pipe is just pressed in.Cut it flush and plug it works fine.

  

Marine carbs are slightly different from automotive carbs, I think mostly the bowls are modified to prevent sloshing of gas while bouncing around on the waves to prevent fires and lean conditions if the gas bounces up off from the jets. Don't know all the specifics but you may want to look into a marine carb when doing the conversion. I had a boat with a 302 SBF that had a 4bbl marine Holley carb, so they should be available somewhere.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

Thanks to all for the input!!!  I sandblasted the intake and will plan to cut and plug the heat valve, as well as plug the crossover.

Whitey, Does your boats engine run a RH rotation as mine does/ or standard automotive LH rotation?

Billy, I got a Holley 4160 marine carb from a  friend. I think it is a 600. Was kinda looking for a 450,but will give it a try. What CFM are most of you running? Any tips on tuning the 600?

One other thing.. I gotta fess up.... I am a diehard Bowtie boy, but now have two Ford books in my library. The How to Repair and Rebuild the Y Block and the Falcon 6 Performance Handbook. I just got my 64 inboard running. It is powered by a flywheel - forward , 170CI Falcon inline six.  I would NEVER tell any of my Chebie buddies, but I have some kind of wierd fondness for the old 6 banger... hopefully this Y block will also find a spot in my heart!??!

64, Yes the motor is mounted backwards and runs right hand rotation.  I have a dog clutch fitted which is helpful when skiing as it's not such a drain on the starter turning off and on.  I researched my carbies when I replaced mine and was told by many persons (ski boat people) re marine carbies of the pros and cons.  The biggest worry is re fire and spend the money for a really good quality air cleaner to stop any back fires from exiting the carby.  Mine is just an automotive carby (with a good air cleaner) and I don't have any trouble with fuel slushing around, leaking, starving, floats etc and it gets quite rough where I go due to all the boat traffic, plus getting thrown around when skiing.  I planned as well to get a 450, but could get a 570 street avenger (exact same carby specs just updated technology for floats etc, check holley site) for the same price new as a refirbished 450, hence I went that way and been really happy with it.

Cheers Whitey

My first V8!!

Brisbane, Australia!!

The mushroom like valve is the inlet side for the hot air source going to an automatic choke.  It is attached to a tube running through the manifold crossover, with the tube ending at a port on the opposite side.  You can just plug the port on the opposite side and leave the "mushroom" alone.  For block off use what is available.  The hardware store has some brass shim stock that could work.  Cut to fit.  I would only block off one side.

Wow, didnt see all the other responses before posting.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

I will throw this out for consideration.  For a period of about 2500 miles I used a Rams Horn on PS and a front dumping crossover on the DS, setup as dual exhaust.  To compound the differences from one side to the other, the DS was 1.75 in. tubing, and PS 2.00 in. tubing.  I figured the resulting pressure difference would be pushing exhaust gas at a fair rate through the crossover.  Not something wanted but expected until the mismatch could be corrected. 

On teardown there was no inidication any exhaust gas had entered the crossover. 

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.