Guinns Engineering
CROSS RAM FAQ's

The following is a list of common, most frequently asked questions (FAQ's) presented to Guinns' over the years. The intent of this page is to edify the enthusiast and dispel some myths regarding Cross Ram characteristics and performance.  

Q: Is a Cross Ram equipped 302 engine temperamental? I've heard it's hard to start due to the absence of chokes, difficult to get rolling off the line without a real high rear gear ratio and ton's of rev's and it has no power/torque on the bottom end.

A: Chevrolet Engineers designed the the Cross Ram Package to be an extremely flexible power plant over a broad power band.   Design specifications for the Cross Ram Package were based on the following criteria:

* NOTE: I refer to the Cross Ram as a "Package". The Cross Ram itself was only part of the HD 302 race engine package designed to accomplish the above goals.  The Cross Ram Intake, "140" Cam, Special Valve Springs, Cold Air Intake System, Headers and TI ignition system were all part of the comprehensive Trans Am "assault" engine package.

Bottom line is... The 302 Z/28 engine, when prepared correctly and in the proper state of tune, is an extremely flexible and powerful engine. Start-up is trouble-free due to the double pump carburetors which provide adequate cold start fuel richness, and once warmed, the engine is stable at idle without an over-richened fuel mixture. The power band is strong across the entire operational rpm range creating a tractable vehicle from "off the line" to the upper limits of operation with no higher than 3.73:1 rear axle and 2:20:1 first transmission gears. The Cross Ram equipped 302 is one the most exciting engines you can experience. The power derived from the Cross Ram equipped 302 is simply amazing. Guys who are experienced with big block power will swear that in the upper rpm ranges the Cross Ram 302 feels stronger than most race prepped big blocks, and once you reach 7,200 rpm, it just wants to keep going. One last comment regarding the power on the low end... The Cross Ram 302 produces an additional 35 hp over the stock single four 302 in the rpm range that gets you rolling. There's certainly no "hole" in the bottom end, so let's put to bed that "Hard to get rolling and slow off the line" myth and let the take-away be this: You can have all the above but...  The key to it all is in how the 302 Cross Ram Engine is prepared

Q: How much horsepower is a Cross Ram 302 capable of making? 

A: Depending on the component choices and level of tuning, a Cross Ram 302 can produce 550+ hp. Keep in mind however, the 302 Small Block Chevrolet Engine has inherent limitations using stock components. With all stock components (excepting our roller rockers) we have been able to get upward to 470 hp and the durability is un-compromised. The signature Guinn's Engineering build for the Cross Ram 302 is 465 hp (see our Air Cleaner decals). This is a heritage based build made famous by TRACO Engineering in Culver CA for use in TRANS-AM competition cars such as Rodger Penske's '68-'69 Sunoco Camaro . We are proud to keep the heritage alive by reproducing the exact head porting techniques that to this day remain the standard for Chevrolets 202 inch felly heads.

Q: Can I keep the SMOG Pump and Cast Iron Exhaust Manifolds with the Cross Ram?

A: I won't tell you to not use the Smog Pump but please read the following VERY CAREFULLY

Most guys who ask us about running the Cross Ram with the SMOG pump and Cast Iron Exhaust Manifolds are under the impression that it is "correct:" after having read the 1969 Car Life Article and or having seen several period  Chevrolet Press Release photos showing Engineering's  Mule Car (Press Car) with SMOG equipment and Cast Iron Manifolds. The intent of the article was to showcase the Z/28 High Performance equipment, but the trade off was... it that had to shown on a Camaro that was fully compliant with the law. 

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.

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.

Copyright Wayne D. Guinn, 2006
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