350 vortex head on a 305
- Thread starter MWalker1
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Not much but you will need a different intake. You will not gain any compression because the vortec casting 906 and 062 are the only good castings. These are 64cc casting and are the same as your 305s. Some of the 305 HO casting 601 and 614 are the only HO casting with a 58cc chamber if that helps. Would I do it NO if you had a 350 and needed the compression increase and flow numbers of the vortec heads then I would do it.
if you don't have the intake for vortec heads you might at the look at World Products 305 S/R Torquer cylinder head. They come in old and new intake bolt patterns so they might be more expensive than the vortec heads but you can use cheaper intakes or the one now if money is tight. Plus to get a good compression you don't have to mill the WP heads like you do with the 305 vortec heads.
http://www.jegs.com/p/World-Product...quer-Cast-Iron-Cylinder-Heads/746698/10002/-1
http://www.jegs.com/p/World-Product...quer-Cast-Iron-Cylinder-Heads/746698/10002/-1
The 305 vortec heads are no better then the one coming off. They still have the ramp on the intake side and are no use to any one. Only the 062 and 906 heads flow the numbers you need to make power. Spending the money to make a 305 doing any thing is a waste of time and money. Do a 350 and your big money ahead.
Do you generally just want more power? Tell is more about your ride so we can have a better idea. There's probably other things that can be done, maybe for less effort.
I posted this the other day. Is your 305 a 1-piece rear main with the roller cam? If so, you can reuse the crank and rods and just get a blueprinted 350 block from Summit. You'll need pistons, rings, bearings, gaskets, but this is the best thing to do with a 305 if the emission police don't require you to keep the same motor size in your car. As a bonus, the 1-pc. blocks all come with the OEM roller cam provisions. The blocks are drilled for a mechanical fuel pump. As long as there are no flaws in your rotating parts, you should be OK up to about 300 HP.
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What are you talking about? The 059s are only second highest flow to the 062 and 906s for factory heads, they wake up any 305 by a good bit. Plenty of 3rd gen Fbody guys getting 300+ HP out of 305s with 059 heads. There are also 520, 305 vortec heads which are crap but the 059s are pretty good.
Here is the bone stock flow numbers of 059 L30 heads. 28 in/h20 pressure drop.
Lift-----Intake----Exhaust
.050------36-------28
.100------68-------47
.200-----128------103
.300-----179------138
.400-----205------152
.500-----221------163
L31 Vortec flow numbers
Lift-----Intake----Exhaust
.100------70-------49
.200-----139------105
.300-----190------137
.400-----227------151
.500-----239------160
It is a shame with 305 threads there is always somebody who has to pipe up about 350 swaps and derail the thread.
Also not all 1 piece rear seal Chevy blocks have provision for roller cams, my one piece block sure doesn't.
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Sorry I don't have a unlimited budget to spend on a 305 trying to make the power of a stock 350. I guess I missed that part in life about what works best. For me I find its easer to make 400HP with a vortec headed 350 then 300HP with a 305. Its really hard to beat the extra 45 cubic inches that come FREE with that 4 inch bore 350 block.
That extra 45 ci isn't free, you need to find and buy a good running 350 which is hardly free especially a vortec one, then have the space, parts, and tools required to swap the motors. Takes far less tools, time, and money to swap heads than to swap a whole motor. If the OP wanted to do a 350 swap he would have asked that. Many stock 350s from the 70s only made 140 HP with crummy low CR. Even the cheap base 290 HP crate 350 is really a van motor that makes 200 hp in the real world at best. It is a shame that anytime there is a 305 thread somebody always has to sour it. Plenty of F body guys just swap the 059 vortecs on and make nearly double the HP for peanuts, but it isn't cool like spending a few K on a complete engine swap to make the same amount of HP. If you really want alot more than 300 HP, than a 350 swap becomes a better choice. But by 400 HP the body and frame start to twist apart without major reinforcing, these cars were not built to be high HP cars with thin gauge mild steel.
Back on the topic, the OP will need a vortec intake, you can buy Vortec Qjet intakes with EGR from GM Performance, the direct GM part sites sell them the cheapest new. You will also need a 87-88 ECM and a ZZ4 PROM or a external EGR line kit. You will also need to run a coolant bypass to the water pump since vortec heads lack an internal bypass.
Back on the topic, the OP will need a vortec intake, you can buy Vortec Qjet intakes with EGR from GM Performance, the direct GM part sites sell them the cheapest new. You will also need a 87-88 ECM and a ZZ4 PROM or a external EGR line kit. You will also need to run a coolant bypass to the water pump since vortec heads lack an internal bypass.
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