Lifters ticking
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Instructor
Joined: Apr 2018
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From: Buxton ME
OK, I get it, no worries. You're right, no substitute for experience, which I have more of now that I went through several exercises chasing this problem. You offered a lot of info for this thread and I appreciate it.
Drifting
Joined: Jun 2025
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Moreover, there's no substitute for being there in-person.
Thread Starter
Instructor
Joined: Apr 2018
Posts: 165
Likes: 92
From: Buxton ME
Thanks OCB, but it gets worse - I looked online to see if there was a factory cover plate, and now that I see it, I realized that I already own it! It must have come with the manifold, and I hope it's still in a box somewhere in my shop...
Drifting
Joined: Jun 2025
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OP Scottinmaine:
Dunno which P/N TFS heads You have ? It seems your TFS aluminum heads have exhaust Xover ports ? Yes or No ?
If you do not want super-heated fumes coursing across & through intake (and directly beneath plenum); suggest you block those ports in your heads. It's clear you no longer have a heated divorced choke or choke stove; but have fitted an electric choke. That decision to block is yours.
Intake manifold gaskets with integral metal blocking plates are widely available. I've also cut my own plates from thin stainless; ubiquitous in race classes requiring iron OE GM production heads.
*the factory choke stove eliminator cover plate Does Not affect hot exhaust fumes coursing across intake plenum.
Dunno which P/N TFS heads You have ? It seems your TFS aluminum heads have exhaust Xover ports ? Yes or No ?
If you do not want super-heated fumes coursing across & through intake (and directly beneath plenum); suggest you block those ports in your heads. It's clear you no longer have a heated divorced choke or choke stove; but have fitted an electric choke. That decision to block is yours.
Intake manifold gaskets with integral metal blocking plates are widely available. I've also cut my own plates from thin stainless; ubiquitous in race classes requiring iron OE GM production heads.
*the factory choke stove eliminator cover plate Does Not affect hot exhaust fumes coursing across intake plenum.
Last edited by Rebelyell; Sep 10, 2025 at 09:25 AM.
Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
The fabbed up one you have now might just be riding high on that unmachined area across the top of the mounting boss. A few moments with a grinder would allow the plate to clear the raised area. It would sit flush to seal the passage. Probably a 5 minute deal here.
Can't wait to hear how you like driving it.
Can't wait to hear how you like driving it.
Thread Starter
Instructor
Joined: Apr 2018
Posts: 165
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From: Buxton ME
Dunno which P/N TFS heads You have ? It seems your TFS aluminum heads have exhaust Xover ports ? Yes or No ?
Exhaust crossover hole
The blue area is what I would have had to gouge out if I wanted the choke tube to fit. Trickflow said don't do that. I do have the thin blocking plates, would there be any benefit from a slightly cooler intake manifold?
Also, it does look like my fabricated plate hits a high spot, I'll look at that when I get home.
Drifting
Joined: Jun 2025
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Most motors prefer a cooler-denser fuel-air charge. Blocking Both Xovers will help provide a cooler-denser fuel-air charge; greater efficiency.
Any tradeoff may be a little slower warmup during colder months.
If you successfully block off Both heads' Xovers, that will make having a choke stove cover moot; it'll be sealed anyway, although I guess a bug could nest there.
In my region, those race classes that mandate OE iron heads w/ Xovers, Also mandate performer 2101 intake. Some cover choke stove but most don't, because their heads' Xover ports have been blocked. Those are race motors; not street motors and, of course, no chokes at all.
I also have a carbed street sbc with GM 487 heads; both Xovers are blocked And its Qjet's choke assembly's been deleted; warmer in my region than in yours and I can pat the gas for minute or two and it's good.
Any tradeoff may be a little slower warmup during colder months.
If you successfully block off Both heads' Xovers, that will make having a choke stove cover moot; it'll be sealed anyway, although I guess a bug could nest there.
In my region, those race classes that mandate OE iron heads w/ Xovers, Also mandate performer 2101 intake. Some cover choke stove but most don't, because their heads' Xover ports have been blocked. Those are race motors; not street motors and, of course, no chokes at all.
I also have a carbed street sbc with GM 487 heads; both Xovers are blocked And its Qjet's choke assembly's been deleted; warmer in my region than in yours and I can pat the gas for minute or two and it's good.
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Thread Starter
Instructor
Joined: Apr 2018
Posts: 165
Likes: 92
From: Buxton ME
Just to close this out, it was an exhaust leak at the choke plate, but it was not the plate. I cut a heavy paper gasket (again, thinking this was a water crossover) and it lasted through the cam break in period and then the heat got to it. I put the real cover plate on with high-temp RTV and no gasket and the noise was fixed.
Drifting
Joined: Jun 2025
Posts: 1,603
Likes: 564
Just to close this out, it was an exhaust leak at the choke plate, but it was not the plate. I cut a heavy paper gasket (again, thinking this was a water crossover) and it lasted through the cam break in period and then the heat got to it. I put the real cover plate on with high-temp RTV and no gasket and the noise was fixed.
This will prevent exhaust from heating intake plenum; thereby improving-lowering air-fuel charge temp. This may also slow warm up sequence.