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ss307 04-28-2013 12:20 PM

Chevy 307 Build
 
I'm currently building a chevy 307, I dont need to hear anymore "Why a 307?" or "Better off with a 350". It's set in stone, the 307 is what I got. Heres the route I'm going- Bored .060 over-400 rods shot peened and polished-KB 3.935 Hypereutectic 4cc dome pistons-Block .025 milled off-.039 Felpro head gaskets-ported and polished 416 heads with 1.84/1.5 valves-ported and polished weiand 7504 intake topped with a Holley 700 carb. I'm debating on cam choice. I've almost convinced my self a Comp XR264HR-10 is the perfect match. I also can't decide if I'm going to have it balanced and blueprinted.Any thoughts and opinions appreciated.

tresi 04-28-2013 01:50 PM

I understand using what you've got on hand but 400 rods? are you putting in a 400 crank as well? If you're porting the heads might as well open them up to 1.94 valves. If you will be mixing up parts in the rotating assy you will need to balance it. Do a mock up assemblely before you mill the block.

68NovaSS 04-28-2013 02:35 PM

Sounds like if you cut the block .025 you'll be at zero deck with pistons. The 416, 305 heads have 56-58 cc chambers, (flowing about 175 cfm), I figure your parts list will give you 11.40 scr, high for pump gas.

I understand those heads are prone to crack, have them checked out. Keep in mind your quench as well.

ss307 04-28-2013 02:42 PM

The rods were already shot peened and polished, and I got them at a really good price with ARP studs and nuts. 307 crank, shaved .010 and .010. The heads have just been completely remanufactured, so they're done except for polishing. I've read on a few different sites that this combination should work great. I still cant decide on a cam though, If possible I'd prefer not to have to use a stall converter

ss307 04-28-2013 02:47 PM

[QUOTE=68NovaSS;1670888]Sounds like if you cut the block .025 you'll be at zero deck with pistons. The 416, 305 heads have 56-58 cc chambers, (flowing about 175 cfm), I figure your parts list will give you 11.40 scr, high for pump gas.

I understand those heads are prone to crack, have them checked out. Keep in mind your quench as well.[/QUOTE


So do you think it would be best not to mill the block? The heads have just been gone through they're ready to go except for porting and polishing. If i dont mill the block, how thick of a head gasket shoud I use to have good quench?

68NovaSS 04-28-2013 02:47 PM

You asked for thoughts and opinions, I was just pointing out what you might expect in regards to c.r. with pump gas and other items with that build. If you can live with the end product, you're good to go. Good luck.

ss307 04-28-2013 02:58 PM

I appreciate your input. I"m not disagreeing with you, I'm just trying to figure out how I need to go about this. I need to stay on pump gas. Maybe it would be better if I used flat tops. A hell of a lot cheaper i know that

tresi 04-28-2013 03:18 PM

You do understand the 400 rods are shorter than any other small block? Unless you're trying to build a short rod stroker with a stock piston they are worth $190 per ton (scrap) to you. When you mill parts before a trial fitment or specialized measurement you're very likely to get an unfortunant surprise. If it came from Detroit it fits on the outside. If it came from a hotrod catalog it fits in the shipping box. And that's all you can count on before you mock it up. If you heads are already done either used them as is or plan on another valve job. You will end up bumping a valve seat if you port them. Sounds like you'll either need to find a 307 piston with a big dish or different heads anyway. Also don't order you pistons until you get the bores measure. Boring it .060 over when .020 or .030 will clean it up is just wasting a chance at another rebuild and your machinist might want to charge you more. It will offer little if performance gain.

ss307 04-28-2013 03:22 PM

If I use flat tops my compression would be 10.56:1. Thats good for pump gas. What is considered a good quench height?

ss307 04-28-2013 03:31 PM

Quote:

Originally Posted by tresi (Post 1670905)
You do understand the 400 rods are shorter than any other small block? Unless you're trying to build a short rod stroker with a stock piston they are worth $190 per ton (scrap) to you. When you mill parts before a trial fitment or specialized measurement you're very likely to get an unfortunant surprise. If it came from Detroit it fits on the outside. If it came from a hotrod catalog it fits in the shipping box. And that's all you can count on before you mock it up. If you heads are already done either used them as is or plan on another valve job. You will end up bumping a valve seat if you port them. Sounds like you'll either need to find a 307 piston with a big dish or different heads anyway. Also don't order you pistons until you get the bores measure. Boring it .060 over when .020 or .030 will clean it up is just wasting a chance at another rebuild and your machinist might want to charge you more. It will offer little if performance gain.


Yeah I know they're short, but If there's no clearance issue they're staying. I plan on having someone professionally port them, if they bump em they buy em lol. Thats what it took to clean it the cylinders up, it had been sitting in a barn for a long time. Actually its not quite .060 yet, after I get the pistons, the cylinders can be honed to fit the pistons. What about my cam choice?

ss307 04-28-2013 03:32 PM

Quote:

Originally Posted by tresi (Post 1670905)
You do understand the 400 rods are shorter than any other small block? Unless you're trying to build a short rod stroker with a stock piston they are worth $190 per ton (scrap) to you. When you mill parts before a trial fitment or specialized measurement you're very likely to get an unfortunant surprise. If it came from Detroit it fits on the outside. If it came from a hotrod catalog it fits in the shipping box. And that's all you can count on before you mock it up. If you heads are already done either used them as is or plan on another valve job. You will end up bumping a valve seat if you port them. Sounds like you'll either need to find a 307 piston with a big dish or different heads anyway. Also don't order you pistons until you get the bores measure. Boring it .060 over when .020 or .030 will clean it up is just wasting a chance at another rebuild and your machinist might want to charge you more. It will offer little if performance gain.


Yeah I know they're short, but If there's no clearance issue they're staying. I plan on having someone professionally port them, if they bump em they buy em lol. Thats what it took to clean it the cylinders up, it had been sitting in a barn for a long time. Actually its not quite .060 yet, after I get the pistons, the cylinders can be honed to fit the pistons. What about my cam choice?

gearheadslife 04-28-2013 03:34 PM

as others have said..
the 400 cid rods are shorter than the other small block rods you need the 5.7" rods..
the other is yes to balance blueprint, not needed but if they are decking the block they'll need to do some of it anyways..
if they line hone the mains remember you'll need a shorter timing set..
if the heads have the valve job already done. leave them be..it's to late..
save your time and money and start saving for a set of vortec heads (299 each complete)
with your rods your pistons going to be so far down the bore, decking the block would do zero..
I know you want to use what you got, but you need to go over this build again..


your rods are 5.565" way to short

vinniekq2 04-28-2013 03:39 PM

test the heads for flow and or measure the deck height/CR of pistons used"""then""" choose the cam.I'm guessing you are trying to make over 200 HP?
Not sure what 307 pistons work with short rods?

tresi 04-28-2013 03:49 PM

A set of vortecs will be cheaper than having a pro port your heads and another valve job would just be part of any good port job even if it shows up on the invoice so upgrading to 1.94's would only up the price the cost of the valves.

DoubleVision 04-28-2013 04:35 PM

The 5.565 rods are fine to use in a 307 with the 3.250 inch stroke.
This gives it a rod ratio of 1.7:1 which is good for a street engine.

If you went with Vortec heads, had the block decked .012 and used a GM 4 inch bore .028 compressed thickness head gasket you would land right at 9.5:1 compression ratio which is ideal for the street on pump gas.
It would also put the quench distance at around .041 which is also ideal.
Run a dual plane Vortec intake and a Quadrajet on top, with small tube headers and a summit hydraulic flat tappet cam with .214 Duration @.050
and .440 lift, tune it up with the best pieces you can afford.
What you'll have is a strong running street 307 with outstanding throttle response and good fuel economy to boot.


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