You and I have very similar engine setups. I don't have any
overheating problems (except for last year, but that has been traced to
a gummed-up radiator), so maybe I can help. I run 10BTDC static
timing, no vacuum advance or retard. I have a 12" Hayden electric fan,
no crank fan. I run 50/50 in the rad, no water wetter. No oil cooler
(in my opinion, these are only necessary on full-race engines, but I'm
sure there are others who would disagree). I don't think an oil cooler
would help you anyway, since they probably aren't very effective at
idle (since there's no airflow through the heat exhanger). I run a 165
degree thermostat. Anyway, with this setup, I have no overheating.
The car seldom gets even up to 1/2 on the gauge, it usually runs around
3/8. I've heard good things about water wetter, but have never used
it.
I would be suspicious of the vacuum advance/retard units. These are
going to see different vacuum signals since you have an aftermarket
cam. Try disconnecting these and plugging the pickups. Other than
that, I would say it just sounds like you don't have enough airflow
through the radiator. Do you have a good shroud? I believe the TR6
one was of better design than the 250, better ducting. Or maybe you
need a bigger electric fan. How big is the one you are currently
using? There are bigger rads available, but it really shouldn't be
necessary....
Tim Holbrook
1971 TR6
--- Peter Macholdt <vze2846b@verizon.net> wrote:
> Date: Mon, 01 Jul 2002 12:26:58 -0400
> Subject: Timing and overheating
> From: Peter Macholdt <vze2846b@verizon.net>
> To: 6pack list <6pack@autox.team.net>
>
> After my winter program of modifications, I now find that the 250 is
> overheating in warm weather. It is fine at cruising speed, but at
> idle in
> traffic the gauge begins to creep up to red. I've got a electric fan
> that
> helps, but not enough. The cooling system is free from crud (only
> about 8K
> on a rebuilt engine. I'm running at GP2 cam, 9.5:1 compression with a
> sport
> header and 2 1/4' pipe out the back.
>
> The timing is set at 10 degrees BTDC (about 2 degrees ATDC with the
> retard
> connected). I'm wondering what will happen if I retard the timing to
> say 5
> degrees BTDC. What will it do to my performance (which is great now)
> and
> will it help in any significant way with the overheating.
>
> Follow-up questions:
>
> Does Water Wetter do anything to reduce temps (in practice, not
> theory)?
>
> Is it possible to have the stock radiator re-cored to provide more
> cooling
> area?
>
> Why doesn't an oil cooler cool the engine? I thought that one of the
> primary functions of oil was to transfer heat, yet I've been told
> that an
> oil cooler doesn't cool the engine much (street car).
>
> TIA,
> Peter
> '68 TR250 (love the performance, tired of planning routes to avoid
> sitting
> in traffic)
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