Hot Rod Forum banner

305 sbc questions

5K views 29 replies 8 participants last post by  862wdstep 
#1 ·
Greetings from Maine!
I have recently acquire a hacked up 2wd 86 Chevrolet C10 stepside. So far body and mechanical are back to life and now its time to start tuning up this motor. I have a few questions I'd like to run by some folks a little more "performance" savvy then myself. Currently the motor as it sits is a 305 bored .030 making it 310ci, it has a bone stock intake and carb that are all sorts of nasty and does not perform very well. I'm told it has a "mild performance cam" so we'll leave that subject to unknown. It has a headers and good flowing 2.5" pipes down to singular flowmasters that exit behind the cab. On the budget side this is what I would like to do to pep it up and clean it up a bit and please correct me if I should be doing something different.

Edelbrock 1405 600cfm performer carb "manual choke" (is this to much carb?)
Edelbrock 2701 RPM Performer intake
Edelbrock 1721 RPM Hi Flo Fuel pump
MSD Street Fire HEI Ignition (Will this help vs. the stock?)
8mm wire and NGK V Power 6630 plugs. (Anyone running these plugs?)

I would also like to remove the stock heads and drop a set of stock 96-00 350 vortec heads on it.
It is paired up with a bone stock 700r4 and the rear end gearing is stock but unknown at this moment.
Any helps or pointers would be greatly appreciated Ive been doing a lot of research and the opinions out there are all over the board.
The reason for all the edelbrock is I've had great luck with the carbs in the past and would like to stick with their carb and the rest I would just like to match and be built to perform with each other.
THANKS in advance for any input
Justin
 
See less See more
#4 ·
crussell85 Where is the casting number for the heads located. Is it on the flat tab behind the alternator? Or is it located elsewhere? and how do I find the compression ratio?
Greg T. Duly noted I just am in a bind for time. And as far as the parts I'm putting on this motor with the exception of the vortec heads all of these would be transferrable parts. Carb may be to little for the 350 but I can work with that. That is more of a winter time project. I'm just looking to bolt some stuff on for now to make it run well for the summer.
Thanks
 
#5 ·
You don't wanna put L31/350 heads on this motor.The 64cc chambers will kill your CR & power.If you are gonna use an iron OEM head,find a set of L30/305 heads.You will need a Vortec specific intake.The casting # for the heads is located on top of the heads.You will have to pull the valvecovers.
 
#8 ·
Has nothing to do with piston design. Choosing had gaskets is just another step in a proper build. You want the correct thickness head gasket while maintaining proper quench distance of .041 or relatively close while maintaining the desired compression ratio.

Do a Google search on compression ratios, quench distance, and head gaskets.

Here's a good place to start for info. http://www.crankshaftcoalition.com/wiki/Category:Engine
 
#11 ·
If this was an original 4 bbl truck engine,it prolly has 601 heads.The L30 head is a lot better flowing,more efficient head.Tho not as good as the L31,it will retain your CR due to it's 58cc chambers while improving performance considerably over any other previous 305 head.They can be found on 96-2000 Vortec 305 truck/van engines.Like the L31,they are crack prone,so,if you buy used heads,always have them magged to check for cracks.You'll also wanna watch the lift on the cam to make sure you have adequate retainer to seal clearance.This clearance needs to verified on any cam over .450 lift.
 
#14 ·
Well, I bought it from a 65+ year old man who hadnt run the truck in over a year he said that a year previous he just had got done putting the motor back in because he had it bored .030 and the machine shop had installed a different cam. He put about 500 miles on it the fall of the previous year and needed some money so I bought the truck.
 
#17 ·
305 Vortec head casting # is 12558059, referred to as "059" because of the last 3 digits of the casting #. Same year vehicles as the 350 Vortec heads, just used on 305's in trucks and vans.

If you already have the #062 or 906 castings 64cc chamber 350 Vortec heads, you could have them milled about .035", that would make them 5+ cc smaller chamber, and put them on your 305 using a .015" thick x 4.100" bore gasket(#1094 Fel-Pro). Good port flow without losing a bunch of compression.

059, 062, and 906 heads will all need the Vortec intake due to intake bolt pattern different than earlier SBC pattern.

Of all the new parts you listed, the hi-flow fuel pump is the least needed, a stock fuel pump should more than feed a 4-barrel on a 305 or even a mild performance 350. The distributor, wires and plugs are probably all needed on an old truck anyway.
 
#18 ·
I dont have either vortec heads yet just the stock ones that came on it which I will get casting # off from later. Thanks for the advice on the fuel pump that will save a hundred and change not getting that. I plan on just going with the same style RPM Performer intake as before just the vortec model. How does anyone feel about the 1405 600 cfm carb? to much? or should it be fine. Thanks again
 
#20 ·
keep in mind to get the most from this upgrade,you wanna have all the following critical info to choose the correct matching parts,....piston type & volume in cc's...head casting#....piston to deck hgt(this can be measured after pulling heads)...camshaft specs.All this info will let you figure your SCR & DCR & give you what you need to buy the correct parts.The 600 carb will run & run OK,but,IMO,a 650 would be a better choice.
 
#21 ·
Thank you both again. Can I measure all of that from the top side by pulling the intake and heads? And as for fuel if I just replace it with a new plain mechanical pump should I install a fuel regulator and if so what would determine the pressure I should set it at?
 
#22 ·
Another thing to keep in mind is even with the upgrades you are doing it will still probably only perform about as good as a stock 350. I would also be concerned that you don't really know what you have now. it is hard to spec out an intake and heads when you really don't have any idea of the cam specs

It would be cheaper and quicker to just swap the engine to a running junk yard 350. 6-8 hour project in an older vehicle
 
#23 ·
^^^x2 if you could track down a good used 96-00 vortec 350 you'd be way further ahead and also have a really good foundation for a decent build in the future. A stock vortec will have a roller cam with all the goodies to make it function. Plus you'll have the vortec heads you originally wanted.
 
#27 ·
Hog, do you know the full # for the newer "520" casting 305 Vortecs...as I have a set of 520's but know for a fact the ones I have are the late version 1966-67 283/327 "PowerPack" heads, with the small "Fuelie" style chamber.

GM has evidently re-used the 520 as the last three digits over again.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top