Join Date: Sep 1999
Location: Vancouver, Washingon
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Vortec Head Conversion (Info)
It's been many moons since I last posted here. I'm building a 1992 Police 350 TBI engine for an older GM 4WD pickup, and thought it might be a good idea to share some of the information about the engine build. The stock TBI heads are being replaced with Vortec heads. There are a couple things about Vortec heads not usually talked about, so I'll mention them here. The Vortec head uses only 8 bolts to hold the intake manifold onto the engine, while older SBC engines use 12 bolts to hold the intake manifold onto the engine. The valves sizes for a Vortec head are 1.94 intake / 1.50 exhaust. The combustion chamber size of a Vortec head is only 64cc's. The stock valve springs on a new Vortec head limit cam lift to just .450 / 450.
For the engine I'm building, I'll be using new pistons +.030", rings, roller cam / roller lifters, timing chain / gears, re-sized connecting rods, and a crank that is going to be turned -.010/.010. As luck would have it, this Police 350 has a steel crank. I'm going to keep the compression ratio close to 9:1.
I decided to use a set of new bare cast Vortec heads because of the lift limit of the factory Vortec springs. I will be using a Federal Mogal roller cam (part # CS1065R) with a lift of .471 intake / .490 exhaust. I could have used a new pair of Vortec heads and just replaced the factory springs, but I decided to use new Elgin undercut valves (part #'s HPV34 intake / HPV35 exhaust). The springs I'll be using are Elgin (part #'s RV-1943X) which are +.100 longer than factory springs. The seat pressures for the Elgin RV-1943X springs are 125 lbs. @ an installed height of 1.750" and 325 lbs. at a compressed height of 1.200" with coil bind at compressed height of 1.160". The max lift limit of the Elgin spring RV-1943X is .550". Because the Elgin spring is +.100" longer than the factory spring, I have to use the Elgin valve spring retainer which is a 7 degree machined retainer which is available in a retainer / lock kit (part # ER-3976K). These retainers adjust for the installed height difference using the longer spring.
Just incase someone is wondering, the engine parts total, including a new Edelbrock 4 barrel intake manifold (part #2116) is just over $1600, add the cost of the machine shop fees and the total will be close to $2100. Some people might say, I could have had a crate engine for that kind of money, but I'm a Burger King kind of engine builder, I like things my way.