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Installing new starter

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1503652 by bcbennett Vance, this is a very wonderful list of things to check; I have checked, rebuilt or repaired some of them, but will check and double-check.

I really appreciate your taking the time to write it all down. Merry Christmas!

Brad

I should mention a personal story regarding vacuum leaks.

If the engine has been modified at some point in its past, it could be much more sensitive to leaks than an unmodified engine. Why do I mention this?

The factory deliberately installed a couple of "leaks". The carbon canisters trap gasoline fumes, and then the engine is running manifold vacuum is applied to the canister to draw off the fumes and burn them. It turns out that evaporating gasoline is more than half of the hydrocarbon emissions of an uncontrolled car. Anyway, the hose going to the carbon canister is pulling unmetered air into the engine.

After I installed a warm camshaft in my car, I had a terrible idle - much worse than I felt the camshaft could possibly cause. I sprayed propane, starting fluid, set the timing blah, blah, blah until I was ready to turn into a clock tower sniper. I finally pulled and plugged the hose to the carbon canister, and voila! smooth idle. The air coming from the canister was enough to disturb the idle of the new camshaft. Rather than toss the carbon canister (we get tested and inspected here) I created a restrictor and inserted it in the hose to reduce the rate of fumes being pulled out of the canister. Worked great, and all my emissions stuff was in place and working.

My point is, any hose or line connected to the carbs and/or manifold should be pulled and plugged for testing. Then reconnect one by one and see if one of them disturbs the idle.

You never know what previous owners have done to the car, and if the cam (for example) is not stock then everything is a potential culprit. Keep it in mind as you step through the diagnostics. Don't assume that anything is doing what it is supposed to just because it "looks" original.

Potential sources of vacuum leaks - EGR valve/fittings, distributor vacuum line, carbon canister hoses, crankcase breather lines, intake manifold gaskets, vacuum lines to thermostatic switches (TR7 has one in the air filter housing, IIRC). And 40 year old hoses and vacuum lines have been known to fail eye popping smiley

And if the PO capped off some of the fittings, don't assume the cap is leak free. Sticking a bolt in the end of a hose to seal off a fitting is not an effective seal.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

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bcbennett Avatar
bcbennett Silver Member Brad B
Abilene, TX, USA   USA
OK. Updated data:

I started, let warm up and choke down, and as before, the idle was moving up and down, almost dying on the down. I limped it out of the garage and drove my nearby 10-mile loop, mostly at 70 mph. No cutting out at high revs--that must have been a fluke. But when I got home and let it idle in the driveway, it settled in just above 1,000 and seemed fine. So, it seems to be a "garage-warm-up" phenomenon.

I examined all vacuum hoses; all seem fine.

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