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"Late"model intake manifold mod

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vettedog72

Jedi Knight
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Can some one tell me if a '74 TR6 intake manifold can be modified to fit up two 2" SU's? I wanted to ream out the 1&3/4" to 2" but I don't even know if the bolt patterns are the same.
Give me a clue.
 
I believe that the Skinner Union and Zenith Stromberg carbs have then same bolt pattern. One of my friends has a TR250 with HS6's mounted to a stock intake - well it looks stock from the outside - same as on my TR6.
 
Hello Vd,
the 2" and 1 3\4" S.U.'s will fit the same manifold, the pitch of the bolts is the same.
When you talk about reaming out, I assume you are refering to the manifold?

Alec
 
Right, ream out the manifold's 1 & 3/4 to 2". I want to purchase a manifold and port it out, polish and match it to the head. (I'll keep the OEM manifold for prosperity). The only mod I've done to the engine is shaving the head (I think around 9 to 9.5 compression ratio) and electronic ignition with a HV coil. I understand the clean up and manifold to head matching makes a little more power; I don't know if the dual 2"SU's will make any difference in power but it will be fun and conversational. I would like to dyno it before and after but I doubt I will have the time. If anyone has any hints on doing something with the manifold or experiences in 2" replacements for the 1&3/4's, let me know.
 
Yo vettedog, look at the manifold, while you can easily put on the big carbs you will get only the benifit of increased fuel consumpsion. Save your $$ and get a tri carb setup, the equal length runners alone are worth several HP.
MD(mad dog)
 
I did not want to hear "put on the big carbs you will get only the benifit of increased fuel consumpsion". I was thinking that an increase in compression and an adjustment to the spark advance would be like replacing a 2V with a 4V on a V8 (when the compression was increased, spark adjusted etc). At 110hp and 24MPG, I don't need more fuel consumption with out the HP kick. Usually a dual plane manifold is used (on the V8) but I don't think I will have that. Is the manifold the problem or what?

Geese, it might be moot after this storm any way.
 
The manifold is the issue. Modern dual plane manifolds on V8s are designed by Edlebrock or whomever to evenly distribute the air flow to all eight cylinders more or less equally as the demands from valve openings require, which it can do since the manifold is located in a relatively compact area between the heads. The dual carb manifolds, early or late, do not do that as well as the three carb manifold on a straight six. The tri-carb setup, because of its higher efficency, is reported to result in increased gas mileage compared to stock.
PS Hope you weather the storm OK!
 
[ QUOTE ]
Can some one tell me if a '74 TR6 intake manifold can be modified to fit up two 2" SU's? I wanted to ream out the 1&3/4" to 2" but I don't even know if the bolt patterns are the same.
Give me a clue.

[/ QUOTE ]

Just be careful when reaming that you don't break into the water passage. A local TR6 is running a 9:1 engine with 2" SU's. The combination provides easy tuning, improved performance and decent mileage. I have no figures but the owner has had zero complaints about the set up.

I have the triple carb set up on mine and I do not get better gas mileage. But that could be because it's to fun to drive it like I stole it. /ubbthreads/images/graemlins/grin.gif
 
Swift6:
Thanks for the info and if you could pass along my wishes to open a line of communication with him to see what all he did to the manifold, it would be appreciated.
 
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