Smokeram or STR10?

[mtrhead]

My build viewtopic.php?f=69&t=3024 is progressing I've aquired 4.155 Block, 210 70cc Pro-filer Heads, STR 10 Cross Ram, 3.8 stroke Crower ultra light crank, Crower 6" rods, 11-1 Mahle Pistons. TKO600 with a 3.90 gear, Crower shaft rockers.

I have now gotten my 1.75 headers with extensions to make them up 40" primaries if needed. I also picked up a mechanical flat tapped cam that is almost 100% identical to the one you recommend by Crane. My cam came from Crower (Buddy is sponsored so we had them make one for my combo) it came up with a degree here and there and within .005 on the lift.

I've also purchased a SmokeRam this week which came in the original box with all the spare parts/paperwork and I have the STR10 Crossram with one 600DP. I've been reading the "negatives" on both for the street but I'm determined to make it work. I do have a small distributor. The Smokeram is the latest with the notch in #8 for the distributor base. Either way short term I have to buy either another 600DP for the crossram or a 830DP? with mods for the SmokeRam.

Which one would you start with for 100% street based on my build so far?

 

[grumpyvette]

Ive used BOTH cross ram designs on several builds in the past but Id say that the SY1 is preferred in any street application because its easier to tune a single carb vs twin carbs


these related threads should help

viewtopic.php?f=44&t=623&p=834&hilit=+crossram#p834

http://www.wallskid.com/c/small-block-chevy-cross-ram_|rKmBts5HrkD7LgWJ4o2CXBYhxN0k*|5qQiC0m3AGdg/

http://web.archive.org/web/200603220017 ... tallation/

viewtopic.php?f=55&t=444&p=20301&hilit=dual+quads#p20301

viewtopic.php?f=55&t=4617&p=12350#p12350

viewtopic.php?f=32&t=1148&p=2330&hilit=crossram#p2330

http://www.hotrod.com/how-to/engine/1311-cross-ram-manifold/
STR-10 BELOW

SMOKEYRAM (SY1)BELOW

OFFY BELOW

lets clear a few things up

first theres a common plenum in the offy intake

OFFY BELOW

Offenhauser part numbers are: Base--5893 Single four top for 4150/Q-jet--5901 (possibly discontinued) Single four for Dominator-- 5948 Dual-quad top--5903 Linkage kit for dual-quad--5902 3-Weber-top--5899 (no longer available) 3-Weber linkage kit--5900 (no longer available)

next, both carbs basically feed the opposite bank of cylinders on the engine but the common plenum allows some cross feed flow to the other engine side cylinders

next both carbs should be identical
and the linkage set up so both sides open at the same rate

if your having problems getting an ignition to fit a crossram or tunnel ram intake due to clearance issues a couple detailed pictures of both the intake and distributor , and distributor mounted in the intake showing the interference would help,look at the picture and youll see a large coil in cap HEI will never clear.

generally youll need a small base HEI with remote coil or vertex magneto to get clearance

viewtopic.php?f=70&t=1320&p=16925&hilit=vertex#p16925

viewtopic.php?f=55&t=444&p=20301&hilit=dual+quads#p20301




next

the carbs you want to use will be in the 450cfm-600cfm rated range but will NOT FLOW near 600cfm on that intake because the reduced vacuum the venturies see will reduce the flow to about 400-500cfm each MAX, (not necessarily a bad thing in this case)

read the links I posted, a properly set up 383 with good heads and that intake with a matching cam should have little problem making over 450-500hp plus
youll want headers with about 37"-39" primarily tubes in most cases and a 16"-18 collector to match the intended power band
youll NEED heads that flow about 250cfm at .500 lift MIMIMUM to get the full benefit from the intake design

cross rams like the offy need about 10.5:1-12:1 compression,a cam on a fairly tight 105-110 LSA and about 245 duration to operate in the intended rpm range & power band of about 3700rpm-6400rpm on a 383 sbc

viewtopic.php?f=55&t=3431&p=9088&hilit=crossram#p9088

viewtopic.php?f=44&t=623&p=834&hilit=+crossram#p834

viewtopic.php?f=55&t=444&p=20301&hilit=dual+quads#p20301

http://www.camaros.org/crossram.shtml

 

[mtrhead]

Thank you -

Today I picked up a 830 Annualar booster Holley DP. I also got the paper work in the original box with the smoke ram. I'm going to make the air modification deflectors they say to put in with the instructions.

 

[mtrhead]

Update - modified the smoke ram - added the deflectors and radiused all the entrances to the ports. Also opened up the ports to the 1206 gasket (my pro-filer heads). I came across a thread about running the smoke ram on a healthy SBC. The owners "carb guy" used the 830 I have but, changed just about everything. New boosters, new 1.75" throttle plates, off-idle circut mods, 1-1 linkage.

Is this intake that sensitive to carbs?

 

[grumpyvette]

Update - modified the smoke ram - added the deflectors and radiused all the entrances to the ports. Also opened up the ports to the 1206 gasket (my pro-filer heads). I came across a thread about running the smoke ram on a healthy SBC. The owners "carb guy" used the 830 I have but, changed just about everything. New boosters, new 1.75" throttle plates, off-idle circut mods, 1-1 linkage.

Is this intake that sensitive to carbs?

its not super sensitive to carb size, IE a 650cfm -930cfm Holley can be made to work reasonably well.
your 830cfm should work great once correctly tuned.
but it does require you to know how to jet a carb and match the accelerator pump,power valves, squirters and linkage adjustments and ignition advance curves,to your application,and it sure helps to know how to accurately read spark plugs, a vacuum gauge, timing light, and use an infrared temp gun on the headers, etc.

read all the sub linked info

viewtopic.php?f=55&t=109

viewtopic.php?f=55&t=211

viewtopic.php?f=55&t=1639&p=4545&hilit=+power+valve+vacuum#p4545

viewtopic.php?f=55&t=1442&p=5524&hilit=accelerator+pump#p5524

viewtopic.php?f=81&t=1189&p=2447&hilit=+infrared+tuning#p2447

viewtopic.php?f=50&t=383&p=1637&hilit=+infrared+tuning#p1637

viewtopic.php?f=70&t=202&p=5344&hilit=+infrared+tuning#p5344

viewtopic.php?f=55&t=635

viewtopic.php?f=70&t=3438&p=10844&hilit=power+valve+vacuum#p10844

 

[mtrhead]

Changed gears a little bit - first the smoke ram's quality was poor when lining up with the heads. need lots more welding to fit 1206 heads. Starting porting the STR10 Crossram to match the 1206 gasket minus a touch and found out I had to weld the manifold on the tops to seal and get a good port match and flow back into the intake runners. I also picked up a RPM AirGap for the initial startup and break-in of the new car before attempting the cross ram. Boy did that need porting to match up to the 1206 intake. Not much info on the net, with pictures, of the amount of porting a manifold needs to get to 1206. Pictures are initial rough dimensions before finishing

 

[mtrhead]

Also, I did the internal mods to the smoke ram that were recommended. Don't find too many pictures of these wet flow mods. I had a file that Edelbrock sent out as a fix and copied.

 

[grumpyvette]

thanks for posting,the info and pictures, its always great to see projects as they progress, and get info on solving the glitches we all find in the process


OFFY CROSS RAM BELOW
yes they are still available new, yes they work rather well once the engines above about 3500rpm if properly set up and tuned
and Ive used them in several engine combos

AND YES CHEVY AND EDELBROCK USED TO SELL VERY SIMILAR CROSS RAM INTAKES

BTW heres the cam I usually use with a CROSS RAM APPLICATION
http://www.cranecams.com/product/cart.p ... il&p=23968
the cross ram intake REQUIRES an engine with about 11:1-12:1 compression,good headers with a low restriction exhaust, a manual transmission and 3.90:1-4.56:1 rear gears to work correctly, Ive used them mostly on 377 and 406 and 383 displacements with two identical 600cfm carbs, but I know other success full cases using two 450 cfm carbs , just be aware this intakes designed to run in the 3500rpm-7000rpm power band all the time, on a engine with open or low restriction exhaust and a solid lifter or roller cam and heads that flow a minimum of about 250cfm at .500 lift
The Engineering Truth..

The Cross Ram was never intended, nor was it developed (tuned) to be used with the Smog Equipment. The only reason it appeared in the Car Life article (and others) was to satisfy the Corporate mandate to pre-empt any negative connotations derived from the article that might imply Chevrolet was not in sync, or worse yet, ran counter to the Government mandated SMOG laws. It was a risk that Chevrolet could not afford to take for political reasons.

The true intent by Chevrolet was to have the tuner build the Cross Ram equipped 302 in the "recommended" tuned state it was developed for using Chevrolets Tubular Headers with specific timing and tuning considerations - never with the Smog Pump since it was counter indicated for performance which was implied and understood by all race tuners and street racers back in the day.

PERFORMANCE FACTS:

The SMOG Pump is actually a centrifugal AIR pump that forces compressed air into the exhaust manifolds to decrease the hydrocarbons by DILUTION. A totally ineffective smog reducer and supreme power waster that adds extra weight. In fact, you could make the argument that it actually increases pollution due to its inefficiency. No one was fooled by it back in the day.

The Smog Pump will cost you 15 important hp in the lower rpm ranges that you will not want to lose
Use of the equipment prohibits optimum jetting and timing and therefore;
The optimum power/torque distribution curve is not achievable and at best you will end up with a de-tuned 302

Bottom Line - The only reason the 302 appeared in some publications with the Smog Equipment was to appease Corporate Management and placate the Government. Understanding that, if you go with-out the pump as intended, you will benefit from maximum power which is consistent with Chevrolets true intent for the Cross Ram and from a pure nostalgic point of view be in sync with what everyone actually did back in the day. That is the true spirit of the Cross Ram equipped 302.

YES READ THE LINKED INFO ITS WORTH THE EFFORT

http://www.vintagemusclecarparts.com/pa ... sram1.html

http://guinns-engineering.com/Cross%20Ram%20FAQ%27s.htm

http://www.superchevy.com/technical/eng ... index.html

http://www.carcraft.com/techarticles/03 ... index.html