Help Frank :) - 100HP Chrysler carburettor change from wb24B to TC5D

[MickLovin]

Re: Help Frank - 100HP Chrysler carburettor change from wb24B to TC5D

Can I rejet the TC5D carbie down? it did seem to use a bit more fuel but not too bad, if I did what size, I had .080 on the wb's and not sure on the tc5d's. Also these carbs seem to leak a bit mainly after choking, but I have noticed fuel in the motor compartment below the carbs, they are clean and don't leak from the seals. Is it normal to have leakage or should I put a complete kit through?

 

[pnwboat]

Re: Help Frank - 100HP Chrysler carburettor change from wb24B to TC5D

For what its worth, my documentation shows that the TC5D carburetors used on the 1977 135 HP Chrysler motors has .096 main jets. If that's the way yours are set up, that may account for the increased fuel consumption.

It's not uncommon for the carb's to leak after choking. Also when you tilt the motor up and back down, they may leak too, but that's normal. As long as they don't leak in the normal running position, you're all set.

 

[Frank Acampora]

Re: Help Frank - 100HP Chrysler carburettor change from wb24B to TC5D

NO NO NO Do not reduce the jet size! The carbs are calibrated, vented, and jetted to deliver the correct fuel/air ratio at above idle speeds. Reducing jet size at sea level will surely melt a piston or two--or three or four! It would be the same as leaning the low speed needle excessively.

THE ONLY TIME you re-jet smaller is for high altitude where there is less oxygen available.

Remember: A two to 3 MPH gain is probably 15 extra horsepower. What does it take to make more horsepower? More air pumped through the engine and more fuel. There is no free lunch. You can not expect to bolt on a bigger carb, get more speed, and use the same amount of fuel.

When you choke the engine, a massive amount of fuel is drawn up the dip tube. Most will go into the manifold but some will splash forward of the venturi and drip out the front of the carb. There is nothing to be done for this. That is, unless you want to retro-fit for the Force enrichment valve which squirts fuel directly into the manifold.

 

[MickLovin]

Re: Help Frank - 100HP Chrysler carburettor change from wb24B to TC5D

Thanks frank and pnwboat, I won't be rejetting as advised by Frank, now that you guys have explained about choking and tilting, it makes sense as they don't leak upright and not choked. I like to keep them original Frank, so no to the force thingy .Also just as a queries I asked a bloke what it would cost to rebuild the engine and he said he would do a 115hp up instead as he said the bore sizes are bigger, would this make sense? I had 123 - 125 psi on them all, so they are pretty good, but I would like in the future to rebuild it.

 

[Frank Acampora]

Re: Help Frank - 100HP Chrysler carburettor change from wb24B to TC5D

Why are we even discussing rebuild on an engine that runs well?

The 100, 105, 120, and 125 are 3.3125 bore. All engines except the 125 and 140 have a 2.80 stroke. The 125 and 140 have a 2.875 stroke.

If you have a 4 cylinder 90, that is a downrated 105 and also has the 3.3125 bore. The 115, and 140 have a 3.375 bore and I am not sure about the 130 and 135. However, if it came with a TC carb originally, then it did have a 3.375 bore.

Force 125 was 3.3125 while the Force 120 was 3.375.

ANY of the above blocks will fit on your leg as long as it was before 1994 when the crankshaft splines were changed to accommodate a Mercury lower unit.

You can't get a rebuild for the price I do it. Here, I ask 450 labor plus about 700 in parts. A professional rebuild will cost twice that. You can certainly do it yourself. You disassemble the engine and drop off the block at a machine shop to be overbored. You buy four pistons of the correct size and install them. Then reassemble the engine. No special tools are needed except for some type flywheel puller and an inch pound torque wrench. Figure on spending about 10-15 hours total if you have never done it before.

 

[Frank Acampora]

Re: Help Frank - 100HP Chrysler carburettor change from wb24B to TC5D

By the way: Don't go chasing something that isn't there. Your engine with a 3.3125 bore and 2.80 stroke is 99 cubic inch displacement. The 115 is about 101 cubic inches as is the 125. The 140 with a 3.375 bore and a 2.875 stroke is only 104 cubic inches. Obviously only 1.3 inches more per cylinder. Even with a .030 overbore, any of these engines will only gain about 2 cubic inches. Nothing significant.

Your mechanic friend may not realize that the bigger bore really contributes nothing to horsepower.

OH, there is a theoretical advantage: The mathematical formula for figuring expected or theoretical horsepower production includes bore size. So, according to the formula, a larger bore is better than a smaller bore---but this is subject to the vagaries of the real world. In the case of Chrysler engines, bore size makes very little difference.

 

[Nordin]

Re: Help Frank - 100HP Chrysler carburettor change from wb24B to TC5D

I fully agree with Frank. Why mess with an engine that work. Leave as it is and finetune the carbs, set the air/fuel mix screws a little little rich 1-1 1/8 out from bottom. It is better to mix with the prop to get more speed. You can not get 115Hp out from a 100Hp by rebuilding it with OD pistons. If you maintain this 100Hp and run it with some care/love it will run forever.

 

[elliotlake]

Frank. Are you still out there?
Aug 5, 2016
Chrysler 140
TC5D
... your tips on fuel spill helpful.
Maybe I don't need carb kits.
Local marina searching; way up here in Canadian white north

 

[flyingscott]

Frank. Are you still out there?
Aug 5, 2016
Chrysler 140
TC5D
... your tips on fuel spill helpful.
Maybe I don't need carb kits.
Local marina searching; way up here in Canadian white north

Frank Died

 

[GA_Boater]

Frank. Are you still out there?
Aug 5, 2016
Chrysler 140
TC5D
... your tips on fuel spill helpful.
Maybe I don't need carb kits.
Local marina searching; way up here in Canadian white north

If you would start a new thread instead of hijacking a 2 1/2 year old, inactive thread by first reading the Help Tip of top of the page, we wouldn't have another reminder of a deceased member. RIP Frank.

Closed!