Installing 4bbl and manifold on (2001) 4.3LX Thunderbolt V Alpha one

[aayjay]

I am going to replace the 2bbl carb and manifold to a 4bbl. i have a new rochester 4bbl and a marine intake from michiganmarine. I checked the timing, and it appears to be a few degrees before tdc. Where should I set the crank before removing the distributor? Will the timing be the same more or less with the new carburetor i.e. Should I use current timing as a benchmark? What should I be concerned about when doing the work?

 

[bruceb58]

Just mark where the rotor is pointing and put it back in with rotor pointing to that same mark. As long as you don't rotate the engine during your intake manifold work, it will be about in the correct spot. Then retime your engine when you are done.

 

[achris]

Be aware, TB-V requires the module to be set in 'base mode' for timing to be set.

Chris......

 

[jimmbo]

Unless the stock 2bbl was a very small carb, don't expect a huge performance increase. The Q-jet is probably the best choice of a 4bbl on a small engine, actually on most engines.

 

[Watermann]

When cleaning up the mating surfaces on the heads be sure to use something other than a wire brush or wheel so you don't loose a bristle inside the motor. Plug all the runners with shop towels. Make sure you have the torque specs and pattern correct for your motor. Use thread sealer on the intake bolts so you don't end up with an oil leak.

Use a piece of cardboard to draw out the intake and the bolt holes and punch the bolts though along with any brackets that they hold on the motor. This will keep you from getting it back on and having to pull bolts back out to put the bracket on. It's also nice to be able to return the bolts to their original holes.

You're linkage for the choke may be different too between the 2 and 4.

You're new set up with the 4bbl should take your HP up over 200. :joyous:

 

[drun_trucker]

I too did the 4bbl upgrade. Currently I am having a heck of time getting the boat to run WOT. Not to mention I can't get RPMs over 4200. I got screwed buying a boat with a repaired crack on the internals so I picked up a remaned long block and decided to upgrade. Got the new intake, Holley 650, and spark arrestor.

I can get good power and what not and it runs good up to 3/4 throttle(3500 RPM) but after that performance goes out the window. I need help with ideas that might be causing my problem. Oh, and this unit now runs an electric fuel pump.

Oh and one more thing...the stupid timing chain cover leaks like a sieve. It's the plastic one that I heard horror stories about. Which makes me wonder if I got it too tight causing it to warp and leak.