generalmopars

hey guys, its getting warmer out and im getting closer to swapping my 70 350 in place of the (previous owner NEVER maintained) 307 (its so bad I have to add 2 qts a week). I want to know from some peoples experience is an rpm intake worth grabbing for my set up. its pretty much a freshened up 70 350 4bbl #6 head with a mondello 20 22 and adjustable rockers. im planning on running ether thorntons or some sort of headers although im leaning more towards the thornton manifolds because I don't want clearance issues anywhere or exhaust leaks. ive already installed the stock 70 cast intake on it but I don't mind swapping it before it gets dumped in the car. also if I go with the 7111, I think I heard somewhere those manifolds like a special gasket set up. what type of gaskets do they call for and do I have to worry about the exhaust cross over not being filled / plugged? will the 7111 have its advantages accelerating on the highway. im not interested in launching off the line but more in the passing gear performance department. the car is a 1990 B Body wagon if anyones interested. and im going to be using a th350 in place of the 4r metric that has had no reverse since august... no power, no reverse, everyday...

oldcutlass

I would run the standard Performer, 2711 w/o egr or 3711 with. If your running basically stock engine, then the RPM is over kill.

Fun71

That seems to be a fairly large cam for your application.

JM-20-22
.496"/.512" lift
226º/230º duration @ .050" lift
300º/310º advertised duration

I think the Performer RPM intake would work, but again I also think that cam is a bit large.

olds 307 and 403

Hopefully you have at least 9 to 1 compression with that cam, what pistons were used? Headers and the RPM intake will work well with that combo. I hope your carbs idle circuits have been modified and you are running higher stall and gearing as well.

generalmopars

thanks for the replys. it has factory 4bbl pistons with the slight dish, not like 2bbl pistons, the cylinders were healthy so I just gave them a slight hone & new rings. the reason im asking about the 7111 is because the guy at olds rocket parts told me I should be fine with that cam but he suggested I go with an rpm intake with the set up I have. as for the rear end, its going to stay the same ratio single leger. Im aware im probably going to need a higher stall but I am going to do a little experimenting and try the stock converter at first and if it is a problem, ill take the tranny down and switch the converter. ive never had a stall converter before and I have no clue how they effect around town drivability. the thought of them is intimidating to me, maybe one of you guys can explain how they react in the city/highway? also how do you modify carb idle circuits, what will that do, deliver more fuel? im going to use a mid 70s 750 quadrajet off of a chevy with the side inlet. i feel i should be ok with the factory jets. BTW i wanted to go with the 18 20 but mondello talked me into the damn 20 22. if i went 18 20 i wouldn't have had to spend the cash on the rockers. im 24 and im still learning, had i known the inside scoop on mondello ahead of time & known about olds rocket parts first i would've just dealt with them from the start but now its all assembled and im not ripping it apart to change the cam. at this point id rather just take more time to buy the right parts to make this engine perform the best it can with the bigger cam. again thank you guys for helping me out

olds 307 and 403

A good high stall converter, I know something like the Hughes 2500 stall will act the same around town and not slip much if anymore on the highway. It will launch around that 2500 rpm when you floor it. A Transgo shift kit and something like the B&M governor kit to bring your shifts above 4000 rpm is also good. Also make sure you buy the Buick, Olds, Pontiac converter(BOP) converter. The Chevy converter has a bolt and nut set up that can hit the weights on the flywheel, do it now while the engine is out. The RPM intake needs plugs in the crossovers that need ground down and tapped tightly into your head(comes with them) or a piece of stainless steel metal to block the heat, as there is no crossover in the manifold. It sounds like you should have 9 to 1 or better compression. The only thing I would use off that Chevy carb is the electric choke coil, as you will need it. It has less cfm, looks wrong and almost guaranteed to idle terrible as is. I would either get someone like Everyday Performance build you a 800 cfm 76-80 casting, he should have a core, custom tuned to your motor or the Street Demon 750, an all new design based heavily off the Thermoquad or a Quick Fuel 750 Slayer series for a Holley style carb.

Fun71

That's just what I was going to say. The Hughes 2500 converter in my car feels the same as the factory converter during light throttle operation. Can't really tell any difference between the two.

Adam Eng

About the Edelbrock 7111, you are a bit wrong there. It does have the exhaust crossover but Edelbrock says it needs to be blocked in racing applications or warranty is void. Straight out of the manual:
"MODIFICATION FOR RACE ONLY
For boat and competition applications: Any implied or expressed warranty is void unless the special exhaust crossover plugs are used
with your engine. These cast iron plugs are furnished with each Performer RPM 330-403 manifold and must be installed in the
exhaust crossover port in each head. Use a file to fit and finish the plugs until they are a light drive fit, and with a small hammer, tap
them into each head until they are flush or a vacuum leak may occur. Extra plugs may be purchased from your local Edelbrock dealer
under Edelbrock #2733."

I'm using a 7111 on my mildly tuned -69 350 with a 2500 stall Huges converter and it's a spot on combo!

generalmopars

ok I looked into both the holley street demon and the huges converter. they do seem to be the appropriate way to go. it is expensive and out of my current budget but id rather take more time to save the extra cash vs just make it work and waste the time and money I have in it already by jumping the gun. im pretty sure the chevy 750 I have is off of a 77 van btw. id like to use the quadrajet I have but that thermoquad design looks impressive. one thing I did see with the holley is it looked like the secondary doors was one solid piece, how would that work and not crash into the divider on the intake? I don't think im going to play with the governor on the tranny because I can shift it manually if I want but I did already plan on going with a trans go kit

olds 307 and 403

I will be dammed, you are right, it does have the heated crossover, found a pic, it has been awhile since I had mine off. Still can't use the hot air choke but some heated air to the intake is nice in cooler weather. The plugs take time to grind down, especially since early heads have smaller crossovers. Either way I will stick with my Performer plans, although a 2711 non egr Performer would look stock on my 70 S but I have the 3711 EGR.

olds 307 and 403

You can notch further, many do for better fuel distribution. Just do that and use a thick base gasket to clear the back barrel on the Street Demon.

ELY442

How deep and wide did you cut the divider? Does it matter if its for street or track?

olds 307 and 403

Most cut it about 1", mine is maybe a 1/2". I also used the thick gasket to raise the carb even more. Think of it like a X or H pipe, which ever cylinder can draw more fuel can do so from both sides. Whether it does squat is another thing. I am going run a 1" open spacer on my Performer, more plenum and even distribution, similar to what German69 is doing with a stock manifold.