Thread:

Need engine build advice on a 460

Going to dump some money into my engine after a head gasket blew last summer but dont know which way to go. I have plenty of experience building big blocks for automotive but no jet experience. Decided to tear down the block to verify parts that the owner said were there.

Here's what I have now:
'77 Tahiti 18' with I think 12jc with A impeller. not positive on the jet info though

Engine:
460 bored .060
Cast crank and rods fully balanced
Flat top pistons
d3ve-a2a heads
Clay smith cam: 244 int/exh duration @ .050, .570 lift, 108 lobe center
Dual plane intake and 850 cfm Holley dp
Current setup was running 69 mph on gps

Already purchased a tunnel ram and want to run that.

Option one I am looking at is:
4.5" stroke rotating assembly with dished pistons to put it about 10:1
Porting the D3VE heads (have experience doing this already)
**Cam choice I am clueless on. Clay smith says I should not be running a hydraulic cam meaning switch to solid lifter. It would be nice to save money and run my cam I have now.

Option two:
Edelbrock rpm heads
once again Clay Smith says use a solid lifter. They suggested a .258 duration (@.050), .615 lift, 108 lobe center. To me this seems to low of a cam to even really make use of a tunnel ram.

Question is what would be best bang for the buck to get all around better performance and a bit more top speed. Obviously I'd like to do both but that's just not in the budget. Seems to me the stroker would be all around more fun.

first off the 69mph is not bad for the set up you explained! If you lifted a head and hurt more stuff then by all means go thru it. If not, alot depends on the pocket book! I would start from the hull and work up. the older hulls (no offense) have alot of hook at the transom and a rocker that may need adjustment. Then starts the pump work! At what RPM were you seeing 69 mph and how did it leave out of the hole? You can toss a ton of money into a motor and then put into a heavy bad bottom boat and end up with alot of power going nowhere. Put a straight edge on the bottom, check the intake, get a ride plate and shoe, do a qwik rebuild on the motor and see if it is close to what you want out of the boat. ALOT depends on intended usage! JUST MY LAME ASS OPINION

Originally Posted by ol guy

first off the 69mph is not bad for the set up you explained! If you lifted a head and hurt more stuff then by all means go thru it. If not, alot depends on the pocket book! I would start from the hull and work up. the older hulls (no offense) have alot of hook at the transom and a rocker that may need adjustment. Then starts the pump work! At what RPM were you seeing 69 mph and how did it leave out of the hole? You can toss a ton of money into a motor and then put into a heavy bad bottom boat and end up with alot of power going nowhere. Put a straight edge on the bottom, check the intake, get a ride plate and shoe, do a qwik rebuild on the motor and see if it is close to what you want out of the boat. ALOT depends on intended usage! JUST MY LAME ASS OPINION

I second this opinion. Luckily, my hull was fairly true for being a '78. while it did take me a couple seasons to build my pump with all the goodies, it was worth every penny. Then I built the engine to make a decent amount of power - solid roller, tfs streets, etc. (466 BBF) . The last trip out everything kinda came together, and it was a blast. I can't count all the boats with WAY more motor than me that didn't quite shine after running me...
my very humble advice is, if possible build the boat and pump first, then make the power.

Unfortunately I dont know what rpm I was at. First time I had the boat out after buying it and I put a new tach in it but couldnt get it working. I plan on doing the shoe and ride plate as well and probably some pump work later on. I was just thinking while the motor is out and completely torn apart I'd like to start there. Same as from my automotive stuff where racing is from the firewall back really. Also explain "hook at the transom" and "rocker adjustment" please... new to boats.

Originally Posted by zacho!

I second this opinion. Luckily, my hull was fairly true for being a '78. while it did take me a couple seasons to build my pump with all the goodies, it was worth every penny. Then I built the engine to make a decent amount of power - solid roller, tfs streets, etc. (466 BBF) . The last trip out everything kinda came together, and it was a blast. I can't count all the boats with WAY more motor than me that didn't quite shine after running me...
my very humble advice is, if possible build the boat and pump first, then make the power.

Smart man!!! You can drop a diamond in a pile of dog shit and all you end up with is a shinny pile of shit. If you want to go fast, start from the bottom up in a jet boat. MLAO Mark

Originally Posted by Squirtin Thunder

The only thing I would do is put screw in studs and guide plates at which time you can switch to 1.8 rockers and get a little more lift to the existing cam, which will help with the T-ram. I would also make sure you have a double spring set-up, but not too much pressure, 150 or less on the seat, your existing cam will work well. Are you going to go CJ size or leave it 429/460 port ? The BBF cast crank is very strong, I have never broke or twisted one yet. Circle racing in CompJet is very hard on engines.

Your talking about just using the d3ve's? What do you think about switching to solid lifters like suggested? If I did new heads I was gonna go with stock 460 ports.

Originally Posted by Squirtin Thunder

The only thing I would do is put screw in studs and guide plates at which time you can switch to 1.8 rockers and get a little more lift to the existing cam, which will help with the T-ram. I would also make sure you have a double spring set-up, but not too much pressure, 150 or less on the seat, your existing cam will work well. Are you going to go CJ size or leave it 429/460 port ? The BBF cast crank is very strong, I have never broke or twisted one yet. Circle racing in CompJet is very hard on engines.

Another great idea! the lock down valve adjust is a BIG BIG and if I didn't say Large draw back on the heads on a bbf! Leave the bottom end alone for now. Pull both heads, have them machined for adjustable rockers, pick-up a set of chevy rockers (at this point) yes you will lose alittle lift but you will gain big time in the overall. Learn to adjust valves and just see how much the engine wakes up. With stock rockers you will go from a 1.73 lift ratio to a 1.70! big friggin deal. Yes I know everybody and there mother is going to say "why not just spend another thousand+ dollars on aluminum heads" My response would be "spend it on the bottom and pump first" This all go's back to my past post. I run over 80 mph in a heavy P.O.S. as we speak with a stock 454 cast motor, just by alittle of this and alittle of that. PLEASE THINK! I ran over 90 mph with a P.O.S. 429 Ford in a tunnel hull building MAYBE 550 h/p. All bottom and pump work. JMLAO M

Originally Posted by ol guy

Another great idea! the lock down valve adjust is a BIG BIG and if I didn't say Large draw back on the heads on a bbf! Leave the bottom end alone for now. Pull both heads, have them machined for adjustable rockers, pick-up a set of chevy rockers (at this point) yes you will lose alittle lift but you will gain big time in the overall. Learn to adjust valves and just see how much the engine wakes up. With stock rockers you will go from a 1.73 lift ratio to a 1.70! big friggin deal. Yes I know everybody and there mother is going to say "why not just spend another thousand+ dollars on aluminum heads" My response would be "spend it on the bottom and pump first" This all go's back to my past post. I run over 80 mph in a heavy P.O.S. as we speak with a stock 454 cast motor, just by alittle of this and alittle of that. PLEASE THINK! I ran over 90 mph with a P.O.S. 429 Ford in a tunnel hull building MAYBE 550 h/p. All bottom and pump work. JMLAO M

Adjustable rockers is a given. I'm a professional mechanic so adjusting valves is no big deal ha.

The hacker has not yet posted up the budget and intended usage so all the advice in the world is a waste of time. Alot of good budget advice here but maybe a waste! Who knows!!!? If it were me! I would have the heads done, machined for adjustble rockers and spend a buck or two on the pump and a few hours on the bottom. M

Originally Posted by ol guy

Smart man!!! You can drop a diamond in a pile of dog shit and all you end up with is a shinny pile of shit. If you want to go fast, start from the bottom up in a jet boat. MLAO Mark

Ill say. As far as everything else goes, Id say build the pump-shoe-rideplate first. It worked for me, and I certainly am no expert. BUT a properly loaded pump is pretty impressive outta the hole. And in my case, my pyle runs ok - 90ish with 550- 600hp.

Originally Posted by ehacker01

Adjustable rockers is a given. I'm a professional mechanic so adjusting valves is no big deal ha.

Glad to hear it! So why don't you just give the bottom-end a re-fresh, have the heads done as is and try it from there, after taking a look at the bottom? If the pump seems okay just straight edge the back 6 feet of the bottom and go from there! those hulls have a major hook at the last 12 or so inches, take a look and maybe sand it down a pinch and see how it acts on the water. I don't think anybody is trying to kick you in the balls here, just adding advice. Certainly not me ! Good luck and hope it works for you! M