Inline 6 questions

[Hooligan71]

Have a 250 I6 in my 71. It came with a 292 originally but the person before me swapped out motors for one reason or the other. My question is this, below the thermostat housing is a housing with the temp sending unit and heater hose openings on the passenger side and a 1" 1/4 opening on the other side, that opening has been blocked off. I assume it is a bypass but I can find no where to hook it back into the block. Any pictures or part #'s or anything like that would be helpful. Winter is coming and would like to be able to warm up a little. Not a huge deal since I live in Arizona but would like to get things where they are supposed to be. Thanks for your help.

[zeeklu]

The outlet on the drivers side goes to the waterpump on a 292. Chris

[Hooligan71]

So I guess parts are interchangeable on 250 & 292"s. Can I put a 292 water pump on the 250?

[tecky11]

sorry to hijack, but does the 250 have a timing chain or gears?

[Hooligan71]

I would suspect a chain.

[Hooligan71]

Looked at autozone.com, no listing for a 250 timing chain, so Gears? I'm new to these I6's but I have heard alot of great things about them. Had a 53 chevy 4 door b4 this truck traded it for the truck. It had a 235 I6 in it. I was going to get performance parts at cliffords for it.

[Shyguy]

I am pretty sure that 250's have gears and not chains, at least that is what my repair manual shows.

The water pumps for the 250 and 292 are not interchangeable.

Danny

[tecky11]

alright thanks much

[Hooligan71]

I have the hole plugged right now and running with no thermostat to keep flow. Does the 250 need a bypass or does it rely on the heater core for flow when the thermostat is closed. Or does anyone know where I can get the correct part that mounts to the head? Thank you all for the help. and Danny you are right it is timing gears.. Thanks again... Tom..

[MudBug]

The 250 I had, I ran the heater hose inlet from the adapter and outlet to the pump.When I swapped to a 292, I ran the heater hose from the adapter to a Clifford intake ,then to the heater,and then back to the pump. I used the same 250 pump on the 292 with no problems.If you can get one , an adapter from a late model I-6 with three ports will let you hook up a sender for electric fans.

[Hooligan71]

putting electric fans on is a good idea. I still am curious about the flow without this bypass? Thanks for all the help.

[MudBug]

The hoses to and from the heater acts as the bypass.You dont need the big 292 bypass hose.With a 160 thermostat,I had heat pretty quick.I never had a flow problem with this set-up in the 250 or 292.

[PanelDeland]

Oops, I mixed up threads while looking for the link to add to this post.Please disreguard this unless you need the info.



http://67-72chevytrucks.com/vboard/s...d.php?t=148346

That link is the best HEI specific to a 250 6 there is.

You may need to rebuild the carb and replce the filter in the carb itself.You also should know the intake and exhuast manifolds are connected under the carb.The heat from the exhaust warms the intake.The 6 has an open design intake and the fuel can condense in the intake.This heat exchanger helps warm the mani to prevent(somewhat) the condensation of fuel.There is also a heat riser in the exhaust system,usually between the exhaust manifold and the exhaust pipe.It is a spring loaded damper which helps keep heat in the exhaust mani at start-up.It has a bi-metal spring which expands/contracts with temp change.As the engine warms the spring this heat riser opens allowing exhaust to flow more freely.Make sure the heat riser will open/close by hand(you are less likely to get burned if you check this while the engine is cold.Then warm the engine and make sure it is actually changing position as it warms.
After my HEI swap I haven't had this problem but then I did it in early spring so the temps did not eaffect the mani temp as much.

[Hooligan71]

Thanks Mudbug, 160 seems pretty low, can I use a 170 or 195?

[MudBug]

170 will give you alittle less heat in winter,195 gives great heat but might be to much for summer.I used an alumnium stockcar rad.because it was cheap.

[Hooligan71]

Where did you get the radiator? Are they good for 105 degree summers? I'm in AZ. Cool pic of my Rat Truck at www.flcaz.com in the blog..
Thanks Mudbug...

[Hooligan71]

Ok, got a 195 thermostat this morning. will use it for the winter. Next summer will put a 170 in maybe. I plugged the large 1 1/4" hole with a rubber expandable plug, will this hold under the pressure. If not any suggestions? Thanks for all the great help!!

[ChaStur]

Originally Posted by PanelDeland

The heat from the exhaust warms the intake.The 6 has an open design intake and the fuel can condense in the intake.This heat exchanger helps warm the mani to prevent(somewhat) the condensation of fuel.There is also a heat riser in the exhaust system,usually between the exhaust manifold and the exhaust pipe.It is a spring loaded damper which helps keep heat in the exhaust mani at start-up.It has a bi-metal spring which expands/contracts with temp change.As the engine warms the spring this heat riser opens allowing exhaust to flow more freely.

Hyjacker here.

I dont have my heat riser spring hooked up. It's actually removed but does this effect my exhaust in it's "neutral" position?

[john]

Heres some pics that might help your bypass hose question.

[MudBug]

There are two different style thermostat housings,one for the 250 and one for the 292.I looked at the first post and sounds like you have a 292 housing.If you have a plug that tightens up, should work with a light rad.cap (12 psi I think is stock).I got a 292 to take out next week,I'lll look at the Thermostat housing.If you get a chance, stop by a junkyard or Pull-a-part and find a Thermostat housing off a 250.

You can find the radiators at Speedway,Jeg's,Summit,Day's Motorsport,basically at anyplace circle track parts are sold.I got mine from Performance Bodies in Iowa.The reason the are a bit better is the have two flues 1"or 1 1/4" wide for more surface area for the fins.The radiators come in three flavors,single,dual and triple pass.The end tanks have baffles in them to force the coolant back across. Coolant goes across the top, down, and back across the bottom on a double pass.Triple flow, the coolant crosses the radiator three time.You can get by with a single flow on a 250.Single flow cost about 160$ or so. The triple flow is a bit more expensive.We hotlap at temps up to 100 plus in summer and the temp runs about 200 degrees when he parks the car afterwards.

spring being gone on the exhaughst would just cause it to take a bit longer to warm up.

Nice bikes,can you put a suicide shift on any bike?

[Hooligan71]

Mudbug thanks for the info those pics tell the story for me. I have a 250 with 292 thermostat housing. Thanks. I'll look up the radiators. FLC can suicide shift your lawnmower if you want! You name it they chop it.

[Hooligan71]

Ooops, forgot to thank John for the pics. If I would have only seen them 3 days ago.. lmao.. would have prevented a lot of head scratching. No worry the hair will grow back!

[Hooligan71]

mxmaniac needs a 292 thermostat housing and has a 250 housing. I am considering trading. Thanks for all your help..

[Hooligan71]

Well, in the process of fixing this problem I broke both the housing and the outlet. I remembered a old friend had a junk yard so I went over and found the correct pieces for my 250 for only $20.00. Although this set up has no place for a water temperature sending unit. Is there any where else I can put a sending unit? Thanks to all for the help.

[MudBug]

Found the answer to my origanal question from the other thread.I think there is a port on the intake side of the head.I'm going to do some junkyard diving tomorrow and I'll see what I can find.