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Old 10-13-2012, 09:24 AM
Jaykobo Jaykobo is offline
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Quote:
Originally Posted by oldbogie View Post
For a TBI engine not much of what you bought is a very good solution. Let's start with the cam, TBI doesn't like and will not work with much cam timing. The one you bought is more for a Tuned Port Injection (TPI) at that a TPI with a Mass Air Flow (MAF) sensing rather than Manifold Absolute Pressure (MAP) sensing which is what your TBI also uses to determine fueling requirements. MAP sensed systems need a lot of manifold vacuum which gets smaller as the duration and lift at the valve get bigger. The Edlebrock 3702 cam with durations/lift for the intake of 194/.398" and exhaust 214/.442 at the valve is about all TBI will tolerate without needing special, and often quirky, custom chip burning. Lookie here <<< TBI CHIPS >>> the other problem with TBI is that it cannot inject enough fuel to sustain more than about 290 horses. This would be with the larger 670 CFM throttle body with the largest injectors that will fit which are rated to 88-90 pounds of fuel per hour. Your stock 305/350 TBI ain't even close to that they will do about 220 horses before they are out of injector capacity.

Compression, you didn't sight what head you've got if original the 1993 TBI engines use the Swirl Port head, these are not very high RPM heads as the vane that creates the swirl obstructs the port preventing revs over 4500 RPM regardless of the cam used. The Swirl Port head comes in two casting with different size chambers the 14102191 has a low compression 74cc chamber while 14102193 has the high compression 64cc chamber. So before you bought pistons you needed to pull a rocker cover to find the casting number of the heads on your engine. A 12cc domed piston is likely to cause compression ratio problems with a super tight tune and iron heads with 91 octane fuel about 9.5 to 1 Static Compression Ratio (SCR) with a mild cam is about as far as you can go without encountering detonation. Go here when you know what head you've got <<< United Engine & Machine Co. Incorporated >>>.

Pushrod length is determined by how the roller on the rocker tip traverses the valve stem tip; you can't determine this till the engine is assembled up to the and including the heads. Then with an adjustable pushrod you place a mark on the stem tip and turn the engine over by hand to get a witness mark of the roller on the stem tip, using this technique the proper mark will determine the pushrod length. Changes in build up from block decking, head milling, head gasket, stack-up changes of the type and manufacturer of heads and certainly changes to roller rockers will affect the needed pushrod length. Follow the instructions found here >>> COMP Cams® - Sorry... >>>

The SCAT stuff is cast or forged in China and finish machined in the USA and is priced likewise. Most of the high priced brands are also made in China and finished here but are sold at made in America prices. The SCAT stuff is damn good stuff we use a lot of it from street rods to full up race engines. I happen to like and use the SCAT 2-ICR5700 for 5.7 inch rods and really make use of the 2-ICT6000 6 inch rod, these are made from forged 4340 and use capscrews rather than bolts. They are plenty good for hot street engines and Claimer race motors. Capscrews make for a stronger rod as the compromises made in the shape of the shank to allow a headed bolt are avoided. The capscrew rod also gets around the issues of clearancing for a stroker which compromises the bolt head. These rods use a capscrew that passes through an alignment dowel that insures the cap and shank make properly, they also provide an extra step outside the fine-line of the cap and shank interface which is a great help in reacting the tension loads put on the cap when the rod assembly is jerked down on the intake stroke. This is a movement that wants to egg shape the cap which pinches it in at the interface line with the shank. This movement pinches the bearing taking the oil wedge off the rod journal, spinning the bearing and finally failing the rod. the design that SCAT uses along with the capscrew mounting hardware goes a long, long way toward eliminating this most common of rod failures. A bushed rod with floating pins is the only way to go. This eliminates making mistakes disassembling and reassembling pressed pins that can bend and twist the rod and in the case of alloy steels like 3140, 5140, or 4340 unlike the factory mild steel of 1046 or 1053 the alloy steels do not like to be heated and many shops heat the pin end because this is fairly safe to do with mild steel, but with alloy steel it's a disaster in the making as it modifies the molecular structure and destroys the heat treatment of these materials. Stay away from 5140 rods, this stuff is advertised as having the same tensile strength as 4340 at a lower price. While this is true there’s more to the performance of a chunk of metal than its tensile strength. In the case of 5140 it is brittle compared to 4340, refer to the Izod Impact Test numbers for these metals, For a connecting rod where the load constantly changes from compression to bending to tensile and repeat again a more brittle material is asking for trouble. 5140 is OK for a crankshaft when running an automatic on one end with an expensive/effective damper on the other. Unfortunately, you've made some really big decisions before coming here first and you have stuff like the pistons that in the first place aren't a good street piston and secondly have defined the rods and crankshaft for you.

Actually the best way to get power out of a TBI engine is to make it bigger a 383 being the way to go, use less cam, use a 670 CFM TBI from an older mid 80's to mid 90's 454 or get a new one from Holley and use a custom chip with the higher manifold vacuum that comes from the milder cam. This makes a much more stable and predictable engine. For about the same cost as what you've sunk this would have been a lot less painful. Now you've got these pistons which have you locked into the 5.7 inch rod. Short of sending this stuff back I don't know what you're going to do about compression especially if you've got 193 heads.

The other way to get more power out of the TBI engine is to replace the heads. The Vortec is always a good choice for these. This type head gets much better power by improving the burn rather than using more fuel and air to burn. This again lets you get away with a milder cam and fewer, if any, changes to the injection programming. Against the very mild OEM cam that the TBI engines use the Vortec head will pick up an easy 20 horses. Given the Edlebrock 3702 cam that will go to 30-40 horses with a like amount of torque increase in both cases. These do get you into some plumbing headaches with the EGR which are not too difficult to solve or with a custom chip the EGR can be eliminated. Don’t just disconnect it as this will cause the mixture to go lean more than the LEARN function in the computer can compensate for and you may just toast the engine as a result. There are aftermarket Vortec type heads from many sources in iron and aluminum. For a mild 350 these from Skip White are pretty decent and let you use your current intake <<< White Performance Detail Description >>>.

Frankly, I’d send everything back and completely rethink this project and certainly come here for advice.

Bogie
Thanks guys for the the sufficent and quick answer

I belive now that I was trying to build the engine with a blind eyes and tight brain....I think I was easy.

I already check the heads and the #14102193 which have a high comperssion and 64cc head chomber.

I read the instruction of the -14 cc and it required 2-4 dgreeing less timing.

I now make a mistake and want to correct the stuation now.want your help guys.

the most important and hard quiestion to me.......will the engine run with this piston or not......need more dgreeing for less compession ratio?I just read on the net pages that.


I will try to buy the 2inches intake and I read on google that you can bore the stuck monifold and just buy a 454 thottle body for more breathing...is it ok?


the chip....I know about it but like to hear which is recommended for the use?

with intake I think I need headrs exhust.

and I,m a little shy about asking....I think I asking much...be pationt with me

the engine is now for racing use??can't be used on high ways?the normal octan here in my country is 95 will it work well or need to increase it?

I won't run a high RPM......mixmum 4000

please recommend the parts needed to correct my mistake.....and would like to thank you guys for all answers
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