carb question on 73 SE 400 4V

[chargers_r_us]

Hi guys! I have not been on here for a LONG time! Computer crashed and I lost the address, and it took a while to find it again! I just picked up another 73 SE and it has a 400 big block. Does this have to have a spreadbore carb? I have a edlebrock 4V that came with it, and it has a plate to change it from a squarebore to spreadbore. but it was not installed. I don't know anything about this! Can anyone help? And I'm sorry for any questions for me that I did not get around to answering...been "lost"! Thanks!

[Nacho-RT74]

since 72 all 4bbl manifold are spreadbore. You don't really need an adaptor plate to fit a squarebore on to a spreadbore manifold since you already have the larger opening on manifold, EXCEPT if bolts/studs/holes don't match between carb and manifold and plate has that function too.

However you can install it if you want.

[chargers_r_us]

Thanks for the reply Nacho! All I really need, then is the thick gasket on the carb, and then to put the edlebrock squarebore right onto it ?  I "think" the holes DO line up on this one! This car is supposed to run, and he used that Edlebrock carb on it, but he ( the guy I bought it from ) told me it needed the spreadbore to run right. I would rather NOT use it, though! Will The spreadbore plate  help it run any better or be faster? Are there differences between small block carbs and big block carbs? I also have a Holley 650, but I think it was supposed to be from a small block! I'm not sure what size the Edlebrock is. I also have an old thermoquad, and it looks like it is squarebore...may have been on a small block also. I'm not sure which one to pursue insatlling so I can see how this car runs! Thanks for the help!

[max]

the edelbrock performer intakes were designed just like a thermoquad intake so it would take any carb you bolted to it.
the plate is used between 2 carb gaskets to be sure the intake and carb are sealed good.

i haven't done it but have heard the thicker carb gasket will cover the extra opening with out any trouble. i wouldn't be afraid to use the edelbrock carb that came with the car. the thermoquad carbs are good "if" they are rebuilt correctly.

[Nacho-RT74]

Ok first I'm not the expert on this, all that I can say is what I know but I can be wrong.

About questions:
-My 400 with the thermoquad does it has a plastic spacer about 1/4" that came with rebuilt kit and a gasket similar to the aftermarket exhaust manifold ones. I installed both but gasket between manifold and spacer. Don't know if any other carbs do have somekind of spacer.

-Spreadbore carbs aretipically more CFM ones because rear barrels are bigger and with maybe some gas safe since you have smaller front ones that you can control better. TQ as axemple are spreadbore carbs and PLUS they are sequential. first open front and after around 1/3 of his opening starts to open the rears. Don't know the rest. A freidn of mine has an AVS ( or is an AFB... don't remember ) on his 400. Is a squerebore one and runs alos great. Edelbrock carb is a NEW AVS/AFB carb... I mean is very similar to those.

-Use the plate will give yo more separation and that adds some "venturi" effect that will increase some HPs on your car, like an air RAM manifold. I don't know why is that.. ppl here will give you a better and more technical explanation.

-Once more, between small blocks and big blocks carbs. From Factory for example the TQ carb on SB where 800 cfms and BB were 850 cfms. Yes BB needs more cfms. I have known that a good or maybe best cfm rate would be at least the double of engine displacement. Aftermarket carbs I don't think are desigend to BB or SB just with a cfm value that you can choose to install on the engine you want all depends about performance you want to get.

-A nice TQ is one of the best carbs. the problem is to have a NICE TQ... once is damaged, is REALLY HARD to get it in good conditions again, so turns on a headache.

That's what I know.

[NHCharger]

I'm not sure what size the Edlebrock is.

There should be a number on the base of the carb on the front. Then go to the Edelbrock web site and you can find out what carb you have.