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The engine im building up is from a 1999 c1500. Its the vortec style heads and manifold. Now i know that if i put vortec style heads on it, then i need to use a vortec manifold (im going to be using a carb inplace of the FI). My questions is, can i use cylinder heads that are NOT the vortec style? Is the block the same design or whatever as the pre-vortec engines just with vortec heads on it?
Thanks
Nick
I put some older style heads on a tbi block one time. My engine spun a bearing in my truck so I picked up a tbi 350 cheap and put my heads, intake, carb and distributer on it. All I had to do was run an electric fuel pump because the tbi cam did not have the lobe for the mechanical pump.
It was not a vortec motor though.
But I bet you could run early style heads on a vortec block because you can run vortec heads on early style blocks.
Yeah i was kind of thinking that they were interchangeable also.
yes you can run older heads on that block. the only thing thats different is that your block has no provision for a mechanical pump
The vortec heads have small chambers don't they? So you would get very low compression with a different head. Or I guess if you are building it you could put pistons to work with the heads. I've heard the vortec heads are super torquey, so why would you want to get rid of them?
The coolest buy right now on heads for older engines are cast-iron "Vortec" complete retrofit heads. These heads are advertized as being intentionally configured to fit pre-vortec engines and they do require the updated manifold. I would say that if you are going the other way (vortec block/ older heads) that you will want to examine the water passages on both carefully. Another issue is the possibility of having a combination that is technically compatible and will run, but will have too low a compression ratio.
The original GM L31 5700 Vortec heads that came on that block from the factory (casting numbers 10239906 or 12558062) flow better than any other PRODUCTION head that Chevy ever produced. Combustion chambers are 64cc's and intake runners are 170 cc's. The heads can be identified in a boneyard by the sawtooth design on the ends of the heads. To use them in a carbureted build, you must use an aftermarket "Vortec" intake manifold due to the different bolt angle and number of bolts used. I think the ports are a little higher up on the heads also.
Very respected professional engine builders such as Pat McCarthy on this forum have stated that most of the boneyard L31's that they see are cracked, so you may have to go through more than one set to find a set that is valid for use.
As produced, the valve lift limit with the stock springs, retainers and seals is 0.450" according to information published by GM. The problem is interference between the bottom of the retainer and the seal at lifts exceeding that. Some amateur engine builders have applied a "ghetto grind" to the bottom of the retainers to gain more lift, but you're still stuck with the stock, weak valve springs if you're planning any kind of agressive camshaft design. Anything over about 0.480" lift will require a larger diameter spring to be fitted to the heads if you're going to do it right, so you have to bore the spring seats with a cutter. Or you can chance it with the stock 1.250" spring seat and more agressive springs. The valve guide boss in these heads is quite large in O.D., so it's tough to put a single spring with damper on the heads unless you reduce the diameter of the boss. There just is not enough room between the I.D. of the damper and the O.D. of the boss. Comp makes a beehive spring that doesn't need a damper spring, so that spring fits without doing surgery to the boss, but they are pricey.
Keeping the rocker centered on the valve was accomplished with "rail rockers" that have a recess in the tip of the rocker to keep the rocker from sliding laterally off the valve stem tip. The 3/8" rocker studs are pressed into the head. Either the stock 1.5 rockers can be used or you can purchase rail roller rockers in 1.5 or 1.6 ratio. You can either drill and pin the studs to prevent pull-out using rail rockers or you can machine the heads for screw-in studs and guide plates so that you can use conventional rocker arms.
Racing Head Service manufactures a "Vortec" style head that bypasses all the negatives of the production head and is drilled for either the conventional Gen I manifolds or the aftermarket Vortec manifolds. Part #12410 is apparently available with the original GM intake runner configuration and 1.94"/1.50" valves or RHS runner configuration with 2.02"/1.60" valves and a little better flow. Both heads use a 170cc intake runner.
If I were going to build an iron head small block Chevy street motor, I might think seriously about using the larger valve 170 RHS heads.
http://www.racingheadservice.com/Cyl...st%20Iron.aspx
What I have learned through fiddling with the DynoSim dyno software is that you have to take any head manufacturers flow data with a grain of salt. For instance, if you look at the RHS data, it says that they flowed the heads using a 4.200" pipe. When's the last time you saw a 4.200" bore on a production small block motor??????? It also states on their site that different pipe sizes will yield different results. Well, DUH!!!:eek: Anyway, for what it's worth, I factor flow figures from the manufacturer by 0.9 or 0.85, depending on how much I think they're lieing to me. I'm not particularly picking on RHS. I think all of them lie, so like I said, I just factor the flow figures.
NLMoschitta, sorry I got off on a tangent. The point is, I would not use early production heads on such a neat roller cam short block. They'll fit, but there are better heads available fairly inexpensively, considering the end results.
Here are the bare 2.02"/1.60" 170cc bare heads at Summit.....
http://www.summitracing.com/parts/CCA-12410/
I'd buy 'em bare, then use the springs recommended by the cam grinder for the cam I chose to use.
i am doing a throttle body 1990 sbc they came with a flat lifter cam but block will take Gm roller parts so i and having a very very small hyd roller cam made so the map can work and no re chip and going with a Vortec type head that PBM sell i have had good luck with them and who makes them for PBM it is a big head and block maker that starts with D:D there good out of the box just lap in the valves give them a good bath and put them together. i do cut the valve guild down to 531 for the rigid chimney viton seals for long life .they do make a cutter for the vtech heads if you need to cut them down it a part number 4716 cuts them to .630 and is in competition products page 70
Not to hijack a thread but tech where do i find these vortec rhs heads drilled for conventional manifolds?Quote:
Originally Posted by techinspector1
Summit lists them bare, but I haven't been able to find them assembled. It might require a call to Racing Head Service.
http://www.summitracing.com/parts/CCA-12410/
http://www.racingheadservice.com/Contact/
THose are the heads I thought you were talking about. But at the bottom of the page it says: Notes Requires Vortec-style intake manifold for installation. I was wondering if there was one that had the stand gen I manifold holes.Quote:
Originally Posted by techinspector1
Why not buy an Edelbrock 2116 intake....designed to fit Vortec heads? The Vortec intake gasket is vastly superior to the previous small block gaskets. The 2116 has no heat to the carb, etc....looks just like the other manifolds except for the mounting bolts.....and it is cheap.
mike in tucson
Sorry, my bad. Here are 64 and 72 cc models in straight plug design (easier to fit headers) that will take conventional intake manifolds. They're 180cc intake runners as opposed to the Vortec models with 170cc's and use 2.02/1.60 valves. Should do a great job on a street/strip 350 or mild 383.
http://www.summitracing.com/search/P...?keyword=heads
Tech i may be wrong too. I looked at the 12410's on summit and read the entire description and it said it was able to mount to all different types of manifolds. (vtec, converntional)Quote:
Originally Posted by techinspector1