Hot start/Timing relation
Burning Brakes
Joined: Jul 2014
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From: Lancaster Ohio
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,806
Likes: 258
From: Dublin Ohio
Originally Posted by 67:72
Rabbit trail question... why are you so concerned about temperature? 90 isn't all that hot in the scheme of summertime temps. Just curious where the cautiousness comes from.
This is a pretty informative and not so technical you can't understand it article about gas boiling
https://www.militarytrader.com/mv-10...other-gas-woes
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,806
Likes: 258
From: Dublin Ohio
Originally Posted by Joe79Vette
I have this timing light too. It is great. I am not too far from you if you want to use mine and I can help if you need me too.
Joey
Joey
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
Are you using ethanol-free fuel? If not, try a tankful of no-ethanol fuel and see if there is any difference in the engine's operation when hot. If it improves, fuel boiling/vapor lock is an issue and heat deflector/insulator under the carb and no-ethanol fuel are beneficial.
Also, if your vacuum advance can is connected to a 'timed/ported' connection on the carb, move it over to a 'manifold' vacuum connection. With it connected as factory required, you have NO vacuum advance in lower gears and the combustion chambers will run much hotter...adding to your problem.
Also, if your vacuum advance can is connected to a 'timed/ported' connection on the carb, move it over to a 'manifold' vacuum connection. With it connected as factory required, you have NO vacuum advance in lower gears and the combustion chambers will run much hotter...adding to your problem.
Last edited by 7T1vette; Jun 10, 2020 at 10:18 PM.
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
Are you using ethanol-free fuel? If not, try a tankful of no-ethanol fuel and see if there is any difference in the engine's operation when hot. If it improves, fuel boiling/vapor lock is an issue and heat deflector/insulator under the carb and no-ethanol fuel are beneficial.
Also, if your vacuum advance can is connected to a 'timed/ported' connection on the carb, move it over to a 'manifold' vacuum connection. With it connected as factory required, you have NO vacuum advance in lower gears and the combustion chambers will run much hotter...adding to your problem.
Also, if your vacuum advance can is connected to a 'timed/ported' connection on the carb, move it over to a 'manifold' vacuum connection. With it connected as factory required, you have NO vacuum advance in lower gears and the combustion chambers will run much hotter...adding to your problem.
Also, a vacuum gauge is really necessary to correctly tune a SBC.
Race Director
Joined: Mar 2017
Posts: 11,949
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From: Virginia
It's worth the $20- to have a digital tach. And if you don't have HEI, you need the 5568 to measure dwell.
But if your tach is good, and you set your dwell by feel, you don't need those features. Please let us know how it goes!
But if your tach is good, and you set your dwell by feel, you don't need those features. Please let us know how it goes!
Last edited by Bikespace; Jun 11, 2020 at 06:36 AM.
1967 Pedal Car Champion
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From: US-PNW
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Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,806
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From: Dublin Ohio
Originally Posted by 7T1vette
Are you using ethanol-free fuel? If not, try a tankful of no-ethanol fuel and see if there is any difference in the engine's operation when hot. If it improves, fuel boiling/vapor lock is an issue and heat deflector/insulator under the carb and no-ethanol fuel are beneficial.
Also, if your vacuum advance can is connected to a 'timed/ported' connection on the carb, move it over to a 'manifold' vacuum connection. With it connected as factory required, you have NO vacuum advance in lower gears and the combustion chambers will run much hotter...adding to your problem.
Also, if your vacuum advance can is connected to a 'timed/ported' connection on the carb, move it over to a 'manifold' vacuum connection. With it connected as factory required, you have NO vacuum advance in lower gears and the combustion chambers will run much hotter...adding to your problem.
I've had a metal heat shield before and took it off because it didn't solve the problem. But that was before sending the carb to Lars.
The distributor is connected to the carb. Where is a location to get manifold vacuum? (That question probably tells you a lot about my experience level right there).
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,806
Likes: 258
From: Dublin Ohio
Originally Posted by Bikespace
It's worth the $20- to have a digital tach. And if you don't have HEI, you need the 5568 to measure dwell.
But if your tach is good, and you set your dwell by feel, you don't need those features. Please let us know how it goes!
But if your tach is good, and you set your dwell by feel, you don't need those features. Please let us know how it goes!
My tach is good but the 3568 measures rpm and dwell according to one website.
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,806
Likes: 258
From: Dublin Ohio
Originally Posted by 67:72
Are you running the Q-Jet's thick stock gasket between it and the manifold - or a similar Holley version if so equipped?
Thread Starter
Drifting
Joined: Nov 2013
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From: Dublin Ohio
Originally Posted by derekderek
You previously said it turns over very fast. Does it crank on the starter faster now than it did before?
Race Director
Joined: Mar 2017
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From: Virginia
I use a Lisle 20300 vacuum gauge, which seemed to work great, and is an essential part of adjusting the idle mixture screws.
Team Owner
Joined: Jan 2006
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From: Crossville TN
The usual 'manifold' vacuum port is the tube sticking out the right side of the Q-Jet through the choke mechanism. If that is not available, it could be connected to a vacuum feed directly off the intake manifold. I would recommend that it not be connected with the power brake booster vacuum feed, as that should be left as a 'sole purpose' vacuum line.
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,806
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From: Dublin Ohio
Vacuum line goes from distributor to the right side of the carburetor but it does go through the TCS solenoid which it appears blocks the vacuum advance while in 1st or 2nd gear and even 3rd gear on 72's.
So that makes it run hotter, eh?
(I'm clearly researching this right now).
So that makes it run hotter, eh?
(I'm clearly researching this right now).
Le Mans Master
Joined: Jun 2019
Posts: 5,481
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From: Loveland
Bypass fuel filter?
Do you have a bypass fuel filter on the car? After I installed it,,, and with the Lar's timing,, my HOT start issue was solved.
Last edited by kodpkd; Jun 12, 2020 at 12:45 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
That will definitely make the engine run hotter...especially at idle and during lower speed driving. If the TCS system is working properly, high range operation (manual or auto trans) will revert to manifold vacuum. Unless you are an avid "factory configuration' hobbyist, I would recommend that you bypass the TCS stuff with a vacuum line running from the vacuum advance can directly to that right side (manifold vacuum) fitting. You could still leave the TCS items in place on the intake; just don't connect it.
P.S. Your engine will appreciate disconnecting with TCS...
P.S. Your engine will appreciate disconnecting with TCS...
Thread Starter
Drifting
Joined: Nov 2013
Posts: 1,806
Likes: 258
From: Dublin Ohio
In regards to leaving the TCS solenoid in place - is there a way to disable the plunger in the solenoid so that vacuum is always present?
Removing the plunger?
Looks like the end of the solenoid is just crimped on.
Removing the plunger?
Looks like the end of the solenoid is just crimped on.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
You would have to test which way the TCS solenoid worked. If it passes vacuum when not powered, you could just leave it all connected as is but not put the electrical connector back on the solenoid. If it blocks passes vacuum when powered, then you would need to send 12vdc signal to the solenoid at all times. Not too sure how that would work out long-term.