header help, need to make sure i don't melt my motor Options

[werd]

hey everyone I'm new to the forum and 914's. I recently got a 1974 914 1.8.
Iv never owned a 914 but when I saw this one i had to have it. The car has headers and exhaust on it and it sounds great. my concern is is that all of the heat exchanger stuff is gone and I'm not sure its okay to just leave it disconnected. Is there anything i need to do or block off to make sure there is enough air blowing across the motor to keep it cool?
I did check the thermostat thing to make sure its working.
There are 2 rectangle flaps on the bottom of the fan housing that are missing. Should i block these holes off? Thanks for any help you can give me. I live in nc and its hot!!! I don't want to mess anything up.

[era vulgaris]

(IMG:style_emoticons/default/welcome.png)

You're fine. There's plenty of air making it to your engine with the heat tins removed. The same amount of air is making it to your engine whether or not you have heat exchangers. The air that exits on the bottom of the fan shroud destined for the heat exchangers has no part in cooling the engine anyway, and simply gets expelled to the atmosphere if you don't direct it into the cabin for warmth.

The most important thing you need to know to not overheat your engine is to cruise between 3k and 4k rpm. Extended cruising below 3k rpm will eventually cook your heads. The cooling fan is bolted to the crankshaft, so more air moves at higher rpm. The sweet spot is between 3k and 4k. Your ideal shift point for normal driving is between 4k and 4.5k rpm.
Much different than a water cooled car.

Btw, where in NC? I'm in Raleigh.

[werd]

(IMG:style_emoticons/default/welcome.png)

You're fine. There's plenty of air making it to your engine with the heat tins removed. The same amount of air is making it to your engine whether or not you have heat exchangers. The air that exits on the bottom of the fan shroud destined for the heat exchangers has no part in cooling the engine anyway, and simply gets expelled to the atmosphere if you don't direct it into the cabin for warmth.

The most important thing you need to know to not overheat your engine is to cruise between 3k and 4k rpm. Extended cruising below 3k rpm will eventually cook your heads. The cooling fan is bolted to the crankshaft, so more air moves at higher rpm. The sweet spot is between 3k and 4k. Your ideal shift point for normal driving is between 4k and 4.5k rpm.
Much different than a water cooled car.

Btw, where in NC? I'm in Raleigh.

thanks thats good to know. I'm in pittsboro just down the road. I just put mine on the road yesterday and made a semi sucessful trip to work in cary. I did find out that I'm going to have to take my trans back out and realign the shift forks. 4th gear is not working correctly.

[bdstone914]

You should block off the flaps at the bottom of the fan shroud to not loose cooling air. Also block off the round holes where thr J to tubes gothrough the top cylinder tins.

[jcd914]

You should block off the flaps at the bottom of the fan shroud to not loose cooling air. Also block off the round holes where thr J to tubes gothrough the top cylinder tins.

OK, the engine sitting out in my garage has plates riveted over the cooling fan outlets since the engine has a header.

But I read a post in the past where Jake Raby described testing the air flow out of the fan housing with the heater outlet left open and with them blocked off and blocking them decreased the air flow. So you where better off leaving them open rather than blocking them off.
His determination was that because of the interior shape of the fan housing, blocking the outlets created a turbulence that decreased the air flow.

So it seems logical the blocking them would be best but we all know Jake tested the heck out of just about anything and everything.

Jim

[era vulgaris]

I would agree with Jake. Blocking any aspect of the cooling air flow that isn't normally blocked seems unnecessary. What does it matter if the air exits the fan shroud straight to the atmosphere; or if it exits the fan shroud, moves throughout heat exchanger, and exits to the atmosphere via a closed flapper box? I don't see a difference, and if Jake has the data to prove it then that's good enough for me.
I would agree with blocking off the top of the J tubes to prevent hot air from entering the engine bay. But the OP said he has no heater tin or heat exchangers, so that's a moot point.

[rhodyguy]

Make some covers for the j tube holes on the engine tin. If not done, cap the heat ducts that run thru the longs.

[r_towle]

You should block off the flaps at the bottom of the fan shroud to not loose cooling air. Also block off the round holes where thr J to tubes gothrough the top cylinder tins.

To prevent mice from moving in also.
As many of us know too well, rodents can move in and after making a nest they will block air flow and cause overheating issues and with the piss will come corrosion and smell