While my 83 Cordoba 390 stroker project is down waiting for the new trans to be built I was wondering how I can get more low end torque. My combo is not very radical as it is a street/strip car that will be used alot on the street. I am using a Torker 2 single plane intake that is really excellent above 3,500rpm. It really pulls great in the upper rpm range but I would like to get some more low end ooomph. Here is my combo

70 318 block 4" crank KB forged pistons,9.7 C/R .044 quench
Iron EQ magnum heads with 2.02 intakes fully ported
Cam is Comp HE-275HL series 231/237 duration @.050 .565 lift
Hooker super comp headers 1 3/4 with 3" exhaust and X-pipe
Holley 3310 750 vac secondary carb
3.73 gear 8 3/4 rear that has the 2.74 low gear A-999 trans

My limitations are the 2,600rpm stall converter that I just can't change. A higher stall will cost me over $600 and that is just not in the budget right now. I know that would solve my problem but I can't do it now. Aside from that, what is the best way to get some low end back??????

I do not have the vacuum advance hooked up now and will that help me out to get the distributor dialed in properly?
I have a 74 electronic dist with an MSD 6al box and blaster 2 coil. I also bought the secondary spring kit and have a very light spring in now. In fact when cracking the throttle, the secondaries start to open up so maybe I have too light a spring in there now.

Question, will a nice dual plane like the Edelbrock rpm air gap be a better combo for me considering the mods I have right now??? That was my original plan but I am using the stock A/C compressor and the Torker 2 and the standard performer intake are the only 2 that will fit.
( Or a stock iron intake ) However, I have researched and found a way to modify the existing AC brackets to move the compressor over about 2 inches to get the cleance needed for the water pump outlet.

I can also get the Bouchillion kit that does the same thing using a short A/C compressor and it will cost me $400. Unfortunately, I just spent $250 on a new, stock C171 compressor that I want to keep as it works great. I can sell my Torker 2 to help offset the cost of the new intake and that will be the best solution for now as far as I can see.

Can I tune this 390 better for more low end using the single plane or am i wasting my time and just get the air gap now???? Thanks TBF

You have a 4" stroker motor and you want more torque?

I say a performer RPM will get you what you want.

Also, what kind of timing are you running? I personally would start out with 15 degrees initial, but of course the slots in the distrib rotor plate need to be welded up some first to do that so the total timng doesnt get past 34ish degrees.

A dual plane will definitly help. An air gap will improve it across the board too IMO. I put a regular performer back on my 360 with Eddy heads when I put it together, just cause I had it and ran out of $. The bottom end was like but the rpm range endedbout 5000. Put an air gap on it and the bottom end was still very strong, and the rpm range went way above 6000 easy. Made 412 hp at the back wheels at right at 7000 rpms.

How is your cam installed? straight up, advanced? Advancing the cam will help and not a lot of $$. I personally like daul plane intakes. Every motor to leave the factory is a daul plane. Hemi, Six Pack, Big Chev, Fords. Big and Small block and they all ran like a scalded dog. For just straight line Single is fine but on the street. look at your rpms most of the time, will be down low. So, cam advance, timing, carb adjustment (secondaries)

Mr.Runum

tighten up the secondaries & play with your timing & get the timing right & the vac adv can be added later.

Three fixes.

1. Convertor
2.Compression
3.gear

anything else you are chasing your tail

Performer RPM should pick up the bottom without hurting the top end on your combo. Why not install a magnum serpentine setup on the front and ditch the v belts??

You know the secondaries are not right. They should not crack open ever unless you're in gear and accelerating. I would put the plain spring back in as a good starting point. NExt, you know the ignition isnt set up right. Get acurve in the distributor, and hook up the vacuum advance. You need to get what you have working, before you dump more money on parts. I don't think, afte these changes, that you will need any torque boost.

comntact board member calgecko, I gave him plans to produce some adapter brackets I designed to run an air gap on my '86 5th ave while retaining the C171 compressor.

the RPM/air gap will definitely add some bottom end

another option would be advancing your cam with an offset cam key 2-4 degrees....just be sure to check valve to piston clearance.

I'd get your carb/ignition dialed in first before tearing into the motor though.

what pistons are you using?

Hmmmmmmm......

Good info here..... maybe I should tune with what i have and take from there??? TBF

Pistons are KB forged dish.. about 9.7-1 Compression.... I would very interested in those brackets Patrick... TBF

With the weight/converter and other factors the intake is a real weak link. The tune like others have stated can really help this combo,but combined with the best intake it's really not hard to get it right.

Thanks for the good info fellas.... I think I will stay with what I have now and get the carb dialed in. I bought it off ebay and put a rebuild kit in it as the power valve was blown. It cam off a chevy 396 and it obviously did not work right. Now it works just about perfectly on my 390. I was the one who decided to put the light spring in for the vacuum secondaries. From a roll it has the response of a DP but from a dead stop I think it opens up all 4 barrels too soon and it is killing my vacuum. It does not bog at all, it just does not start pulling good until over 3,000 then it gets with the program big time. If I can leave the line on just the primaries will this give me more torque???? TBF

Pic is the KB forged pistons, quench pad clearance is .005 with a .039 gasket total quench around .044. Runs perfect on 93 octane.

Good... tranny guy says the rear clutch pack was fried....
I should have it back in next week..... TBF

I agree try a stiffer spring first and go ahaed and do the quick change diapragm conversion and a rear metering block kit too....just gives you a ton more tunability.

I'd prefer an RPM or an AIR GAP (I've never really seen an air gap make any more noticable power than the regular RPM btw....you still have water passing through the manifold) and block off one side of the heat riser (so it still works but doesn't cross contaminate the cylinders).

My old 383 750 combo was like a 72/76 jet, 6.5 primary valve, a 31 rifle shooter, pink cam in the #2 position and I think I ran the long purple spring. Don't worry about fine-tuning the spring until you get the timing and primary jetting right, just see if delatying it with the stiff black sring helps...then you know you're onthe right track and maybe don't need a manifold.....and if you're distributor isn't recurved for a stroker you're leaving power on the table, send it to Don at FBO with all your specs but I would estimate you want a mechanical conversion with about ~18 degrees initial with a 4" stroke and a decent size cam, and then a relatively slow curve to 34-36 maybe all in by 2800 or so....it's nice if you can run at or near full advance at highway speeds but that may not work in a cordoba body which is pretty heavy (I had a 77 Charger for a time so I know).

Thanks a bunch Wize... I checked out the metering plate conversion and they are pretty reasonable at under $50. I guess I should buy a box of jets as well. I also see that proform has a nice high flow main body for the vac secondary carb for $125. I also had a stumble off idle as the acc pump cam does not engage quick enough to give a quick squirt....... I see that they sell an assortment of pump cams as well so I guess I'll need to get them. I figure I could buy the new main body and all the accsessories to tune it for about the same price as a new manifold

There sure is alot in carb tuning and timing to know about to get your car in the best possible tune......... I also have a bung welded in the exhaust collector so I can borrow a buddies LM-1 and see where I stand...............

I think I will stick with the single plane and give it a proper tune first and see what happens...... TBF