Help! Thermoquad gasket 71 340 - which one?

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GY3 71 Demon

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A little help here from the experts - which gasket is correct OEM for mounting the thermoquad on a '71 340?

If either gasket can be used, which is best and why?

Car has the stock Mopar manifold #3512100.

As always - any help is appreciated.

Thanks. :cheers:
 

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Are those the thick insulating gaskets? I believe 71 is a one year only setup. 71s take two gaskets with a metal plate in between the two. Let me see if I can find some more info.
 
I think the open element would act like the LD340 plenum notch and provide a little more top end while the closed one would idle better. No expert though.
 
It depends on if your using the stock aluminum spacer or if your going right on the manifold.
 

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if on the original spacer or the plastic one in the kit go open if directly on the intake which i wouldn't do go 4 hole
 

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Thanks for all of the excellent responses - looks like I've got a problem...

I do not have an aluminum spacer. When I bought the car it had an Edelbrock carb on the stock manifold (using a carb adapter.) One good thing was the seller gave me the correct 71 t-quad carb, but one bad thing - it has a cracked "ear" on the plastic part so I can't used the carb at this point.

I ended up buying a replacement thermoquad, but didn't know which type of gasket to use. According to the photos I have the early manifold not the "spring" one. The car was built in 11/69 so I guess that's why it's got the early manifold (at least that seems correct!)

Any suggestions on where to get an aluminum spacer or should I simply use the thick open style gasket pictured above?

Thanks.
 
I found the aluminum and phenolic style spacers at a couple of the major supply chains.

Regarding the above gaskets, the Fel-Pro 1905 (4-hole gasket pictured above) is 1/4" thick and is sold as a heat insulating gasket. I have one of those lying around so I may give it a try.

But before I did, I'm looking for some opinions - has anyone else used this 1905 style gasket on a 340?

Pros / Cons?

Thanks.
 
the correct set up is in the pic above the spacer with two thick asbestos gaskets, if your not doing a 100 point resto i would use the thick gasket or the plastic spacer with two thin gaskets under the carb, you can paint the plastic spacer aluminum! The stuff in the pic took me a couple years to find and now would be over $500 for the solinoid, spacer and choke, if you can find it. Scott has made spacers in the past you would need to call him for pricing.. heres the link
http://www.harmsauto.com/iHarms_Carburetors.html
 
i would use the open, i would not want a unsupported gasket over the intake opening. It might be rare but there is always a chance of a piece of the gasket cracking off and heading down into the engine,,,,, just my two cents...
 
EL5DEMON340 said:
i would use the open, i would not want a unsupported gasket over the intake opening. It might be rare but there is always a chance of a piece of the gasket cracking off and heading down into the engine,,,,, just my two cents...
Click to expand...

Good advice - and it makes sense.

I'm not after the 100 point resto - so I'll order the open 1/4" insulating gasket. If I remember properly, I think it's Fel-Pro 1908.

Thanks again for the advice. :prayer:
 
I always get the absolute thickest baseplate gasket I can find if it's something I plan on actually driving.
 
WOW! I learn so much from you guys. I have a friend who will give me a stock 1971 intake if I don't use the LD340. I didn't know about the carb spacer. I don't have the correct 1971 carb that is rarely available and is priced like it is gold plated whenever it is for sale. A correct original solenoid seems to be priced like it is high purity silver. I have a 1972 TQ that I will be using after I rebuild it. I am trying to decide between using the stock manifold or modifying the LD340 to accept the TQ without an adapter.

I do know that phenolic gasket/spacers are heat insulators and I was planning on using one. Decisions, decisions.
 
Not only is the 71 TQ priced like gold, it runs like ****. They were all supposed to be recalled and replaced with the 72 and up unit. I wouldn't even dream of running the 71 carb. Don't waste your money. Cause that's all it will be. A waste.
 
If your using a choke you can't go much taller than stock on the spacer, also the little solinoid is more $$$$ than the carb IF you can find one. Got to disagree on the carb being junk no one would be paying $300 if they were unusable, I know several guys running them with no problems and the fastest 340 F.A.S.T car just ran in the 10's with one.
 
Chrysler did not issue a recall on them for nothing. That's all I know.
 
Sorry for going a bit off-topic, but...

The idle solenoids are repopped and run around $100 brand new. The chokes a re repopped also. I just bought a solenoid about 3 months ago. It is a really, really close match to the original and it actually works properly. IMO, anyone that would spend that kind of money on a small, used electrical part is crazy. For me, if there is a better part, especially an electrical part, that appears and functions the same as OEM, for a fraction of the price - well, that's a no-brainer. You know, if my alternator burns up - I'm going to the local parts store an buying a replacement. As long it appears the same and works like OEM, I could care less that the # stamping is different!

I continue to win car shows with my Demon and I use repop parts all the time. Most judges have no clue what the subtle differences are regarding Mopar parts - heck, half the time most Mopar folks argue over what is or isn't correct...
 
I have never seen the recall on them, can you show me the recall? I do know when they came into the dealers back then with carb problems they would just swap them for 72 73 74 or whatever carbs. The 71 is the fastest 800 cfm carb out there as far as factory t quads due to the air metering, but vey hard to get jets and rods for. There may have been manufacturing problems with this first year carb but I think calling them junk is a little extreme.
 
GY3 71 Demon said:
Sorry for going a bit off-topic, but...

The idle solenoids are repopped and run around $100 brand new. The chokes a re repopped also. I just bought a solenoid about 3 months ago. It is a really, really close match to the original and it actually works properly. IMO, anyone that would spend that kind of money on a small, used electrical part is crazy. For me, if there is a better part, especially an electrical part, that appears and functions the same as OEM, for a fraction of the price - well, that's a no-brainer. You know, if my alternator burns up - I'm going to the local parts store an buying a replacement. As long it appears the same and works like OEM, I could care less that the # stamping is different!

I continue to win car shows with my Demon and I use repop parts all the time. Most judges have no clue what the subtle differences are regarding Mopar parts - heck, half the time most Mopar folks argue over what is or isn't correct...
Click to expand...
you got lucky on the repop solinoid! Most are to week to hold the throttle open, there was a side by side comparisons on them and the original has three times more copper windings! Most guys with 340 a body's worth 20k are not going to spend the money on the original solinoid but this was also used on 440 6 pack and Hemi cars those guy want the #'s solinoid since the car is worth 80k to 200k
 
EL5DEMON340 said:
I have never seen the recall on them, can you show me the recall? I do know when they came into the dealers back then with carb problems they would just swap them for 72 73 74 or whatever carbs. The 71 is the fastest 800 cfm carb out there as far as factory t quads due to the air metering, but vey hard to get jets and rods for. There may have been manufacturing problems with this first year carb but I think calling them junk is a little extreme.
Click to expand...

I've never actually seen it myself, just read about it. I'll see if I can find it.

My understanding is that they actually run better than the later carbs.......but at WOT. Their idling and part throttle characteristics weren't good at all.....again from what I've read. It's a one year only carburetor. Had to be a reason.
 
Yes I have read and been told the 71 carb is slightly faster, it has the same air metering as the 1969 to early 70 competition 1000 cfm race quads and those carbs are in high demand!!
 
Absolutely. It's not that they are necessarily junk.....just even more difficult to tune and get right.............as if they are not already. lol
 
EL5DEMON340 said:
you got lucky on the repop solinoid! Most are to week to hold the throttle open, there was a side by side comparisons on them and the original has three times more copper windings! Most guys with 340 a body's worth 20k are not going to spend the money on the original solinoid but this was also used on 440 6 pack and Hemi cars those guy want the #'s solinoid since the car is worth 80k to 200k
Click to expand...

No doubt there are some repop parts that are inferior to OEM parts. But the opposite is true too- there are repop parts that are superior to OEM - especially electrical parts.

My idle solenoid works perfectly. You know, sometimes I wonder if "comparison" articles aren't written by hobbyists (car owners) that have a vested interest in keeping all prices high.
 
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