Chevy Performance Tech Q&A - August 2014

Kevin McClelland Jun 26, 2014 0 Comment(s)
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Get Some Flow

Q I didn’t see any flow number listed for the Chevrolet Performance aluminum cylinder heads, PN 12363390, with 2.19-inch intake valves. These seem to be a popular head for Chevy crate engines now. It is on the anniversary ZL1 427. Thank you for any info.

Dan Howie
Chicago Heights, IL

A We just received, fresh off the press, the new Chevrolet Performance catalog, which lists the cylinder head for the ZL1 427 as PN 12363392, and it’s a fully dressed cylinder head with the 2.19/1.88-inch valve package. The 12363390 cylinder head is the same casting machined for the 2.25/1.88 valve package. This head is used on the larger ZZ502 engine that can utilize the larger valve package. Below are the flow bench numbers for the 2.19/1.88-valve-package 12363392 cylinder head flowed on a SuperFlow SF-1020 flow bench at 28 inches of water:

Lift in inches Intake flow/CFM Exhaust flow/CFM
0.100 74 71
0.200 143 128
0.300 207 153
0.400 250 178
0.500 284 200
0.600 309 218

These are decent flow numbers for a street-performance cylinder head—much better than the original iron oval-ports from the late ’70s they were fashioned after. You can pick up an easy 25-30 cfm on both the intake and exhaust with bowl work and minor porting. From experience with these cylinder heads, you will see the matching 25- to 30hp gain with the flow increases.

Hope you get a chance to score a limited-edition ZL1 427. Rat motors are very cool when they are fully dressed in aluminum.


E85 Big-Block

Q I am rebuilding a 454 and would like to run it on E85. What internal stuff has to change? Do I have to run EFI or can I run a carb? What about fuel lines, do they have to be stainless? What kind of fuel tank? What about mechanical fuel pump? Does the timing have to be different and can I run an MSD box? Thanks for your time!

Jim Sherman
Via email

A Converting a vehicle over to an E85 happy fuel system will take a few bucks. Yes, to truly make an E85-compatible fuel system, you should replace the fuel lines with stainless steel. The 85 percent ethanol that is mixed with the 15 percent gasoline is hygroscopic, meaning it attracts and absorbs moisture. This moisture suspended in the ethanol will accelerate the oxidation (rust) in the fuel system. As you mentioned, a stainless fuel tank would also be preferred. If not, you can seal your existing tank with a specific alcohol/ethanol-resistant sealer. Bill Hirsch offers a specific sealer just for this application. One pint will coat a 10- to 12-gallon metal or fiberglass tank. You can pick up what you need from Aircraft Spruce by ordering online, or calling 877.477.7823. A quart is sold under PN 09-03477. This will take care of just about any tank you have.

You can convert over to EFI, as most of the EFI injectors will support the use of blended gasoline with various loads of ethanol. The main issue you will have is if you allow the fuel to sit for long periods of time and absorb humidity out of the atmosphere, or purchase either fuel from bad tanks or old fuel. It can have high moisture levels, which will give your injectors or carburetor fits. Yes, we said “carburetor.” You can run E85-specific carburetors. This would be a carburetor that has been calibrated for the increased fuel flow and the appropriate needle and seats, accelerator pump, and gaskets to live with ethanol. Most performance carburetor builders offer E85-specific carbs. Check out Quick Fuel Technologies’ Q-750 series carb, which is E85 calibrated and specifically engineered for the use of E85 pump fuel. The main body and fuel bowls are aluminum with QuickSet sight windows on both sides that make for easy float adjustment. Billet metering blocks and throttle plate ensure leak and porosity-free sealing between circuits with unmatched adjustability. Each carburetor is hand-assembled and engine tested before it goes out on E85. Look into PN Q-750-E85 online and give them a call for more information at 270.793.0900.

Now, to feed this monster you will need an E85/alcohol-specific fuel pump. There are mechanical pumps on the market, but one of the nicest is from Holley, under the Ultra HP line. These billet aluminum pumps are constructed from CNC machined 6061–T6 aluminum to provide the utmost in strength, with a black anodized finish. The pumps were put through extensive durability testing before they were released for production. The pump comes standard with AN –10 inlet and AN –8 outlet fittings. This Ultra HP pump is rated at a max flow of 225 gph. The bases are independently rotatable from the top to fit most all applications. The pump is internally regulated to 15-17 psi, which will require the use of a Holley fuel pressure regulator, PN 12-704. Check with Holley for any question about these components at 866.464.6553. With these components your fuel system will be bulletproof.

Finally, stepping up with an MSD ignition system will help burn the high volume of fuel. With the increased octane levels of the E85, you should be able to run more spark advance over standard pump gas. Usually with street pump gas, we’re running right up against the knock limit of the fuel. With E85 we would start with 36-38 degrees of total timing. From there you may be able to squeeze in a couple more degrees if the engine performs. You will need to do some type of performance testing to land on your best spark advance.

Good luck with your conversion to E85. You’ll want to pick up an Echecker E85 fuel test tube (PN 36-E85) from Quick Fuel. With this tool you can accurately check the percentage of ethanol content in your E85 pump gas. The amount of ethanol in the fuel can vary greatly from gas station to gas station. We’ve heard of some fuel as low as 70 and some as high as 90 percent. This greatly affects your tune-up from spark timing to jet sizes. Have fun!



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