modded temp gauge for smaller sending unit anyone?????

[aaronz28]

I guess this topic comes up often -  but anyone who has later model, or aftermarket heads combined with factory guages is going o run into the temp sending unit problem...

the best solution i've yet read is to use a TS76 sending unit, and then replace the resistor on the gauge with a 150ohm resistor...

anyone done this?  how accurate?   is there another solution to keeping the sending unit in the head (do not want to go 68 style as my car is a 69 and has the harness with the shorter length)

just curious.

thanks

A

[BULLITT65]

I'm a little confused by your question. You have after market heads with a different location for sending unit?
(I have after market heads on a different small block but the sending unit boss is in the same place)

[aaronz28]

sorry - no the location is correct (between the 1-3 exhaust port -  but it has the smaller tapped hole and will not fit the OE sending unit.

I could opt to put the sending unit in the intake like a 68 car, or get a thermostat housing with the larger port -  but I have a set of Dart heads that were milled by Brzenski on the ends to look like a set of 69-70 Z28 heads -   BUT the temp sending unit thread is smaller on the Dart heads.

thanks

[BULLITT65]

Well I guess my initial thoughts if I put myself in your shoes: Since you went through time of making it look like stock heads on the ends, could you go the extra mile, and machine and retap the small hole(s) to take the stock sending unit?

If not, those original senders are brass, I am not sure how much it would affect the temp gauge if you just milled down the brass sender to fit into the smaller hole.

[aaronz28]

well the heads are on the car - so not much of a chance to drill and tap -  i do have the larger tap but i'm not sure i can fit a drill in straight - plus cleaning out the shavings in the water jacket will not be fun

i do wonder about milling down the correct size - if its possible

[BULLITT65]

I would strongly recommend not trying to drill or anything like that with the motor assembled in t he car. I have had to pull a head for a bone head mistake, it only takes about 20 minutes. Hard part is just lining the exhaust back up when I did it, (tight fit).

[aaronz28]

yeah i'm not making that mistake lol

i'll either go with trying to trim down an OE sender or go with a smaller one and calibrate

[L78 steve]

Sounds like you will have more into machining the sender than if to pull, drill and tap the head. Every Dart head I ever ran had the correct size port for the sender.
Which heads do you have? And how much did you mill off the ends? Any problem with belt alignment?

[aaronz28]

I didn't do the milling - Brzenski did the CNC work on a pair of Dart Iron Eagle 200cc heads.
they are atop a 421 small block -

[L78 steve]

Did you have to cut the drippers to get the rocker covers to fit?

[aaronz28]

yep - and dbl the gaskets

[BULLITT65]

Well it looks good. How much rear wheel horsepower have you estimated?

[aaronz28]

thats a good question -
its a 9:1  421, hyd roller cam - 236-248 at .050 with 535/518 on a 106 - Dart Iron Eagles 180cc heads
Z28 intake, AED 850 holley -
wide ratio muncie and 3.36 gears - -

if i were running headers and a good exhaust - probably a shit-ton
but i suspect the manifolds and stock deep-tone exhaust will kill a lot of the potential - especially the top-end -  but i built it to be a grunty big-block in a Z28 look-alike package.

i'll know in a few days

[BULLITT65]

Please update if you get to a dyne, or if you make a pass at the track. thank you

[aaronz28]

i will - proablby not anytime soon, but i might take it to a F.A.S.T event at some point.

i have drivin it for the past 10 years with every iteration of Z28 glory
its literally been my Guinea Pig - -  i've had 3.73s, 4.10s, and finally 4.56s in it -  the 30/30 cam, LT1 Cam, a couple aftermarket disasters, and lastly the 140 cam -
stock intake, cross ram setup,
Gardners Chambered Exhaust, and their DeepTone System, finally a true 2.5 mandrel bent system with borla mufflers and headers for the last season before pulling the 302/crossram mill out.

now, i'm shelf-ing all the original $$$ parts and will run with the 421 for a while

cheers