Thread: first 350

Tweet

hello to all, I just tore down my first 350 and planning a full rebuild, but i still need some opinions on matching some parts to get the best performance.

I just found this forum today, and already found way more info than the first one i subscribed.looking through other threads and combo 76 looks similar to what i have going so far. i already have the performer carburator and intake.

question is, this will be a street engine and would like to keep the cost down (won't sacrifise quality for cost, but would like it to be rasonable) and i would like to get your opinion on the head, they are casting #462624 come with 1.95/1.5 valves, from what i read they also came with 2.02/1.6 valves, since they are going to the machine shop, how will they do if i just put the larger valves in, i was planning on polishing the exaust ports and gasket matching too. so how good of a head do i have, or am i better off with new ones. other opinions will be thankfull too

Here's some info on the heads by another contributor....

"The 624 heads are among the worst of the worst. Don't bother spending any money on them. As already referred to, they are highly prone to cracking in critical places, and do not take kindly to port work as a result; their combustion chambers are a cavernous 76cc, and leave you with a compression ratio way short of anything resembling performance; and their flow..... well, they're part of the formula for building 180 HP 350s and 185 HP 400s because they're so restrictive."

thanks sr. that's all i wanted to hear, i'll start looking for heads, i like the world products heads, we'll see were i go from here.

Don't know much about small blocks but just wanted to say welcome aboard. I grew up in Thornton and my folks still live there, where abouts you at?

-Chris

I have the "882" heads which have been described as the "best of the worst" and I had the exhaust ports cleaned up at additional cost after a 3-angle valve job and a slight shave to achieve about 9:1 CR; they were cc-ed to 73 cc chambers with a simple milling. With hindsight I probably could have done better at only slightly more cost with a set of Vortec heads. Check the Summit catalog, it seems to me that the Vortec heads are the most bang for the buck, but of course you can easily spend more for even better heads. Check back with Tech1 and see if he will recommend intake port flow range for your application and match to your cam; very large intake ports will actually harm low rpm performance. Tell him your intended use and the specs of your cam and he can dial it in mentally. The 882 heads look good on paper but I have heard they can crack so we will see. If my heads crack I will go to Vortec heads next but the intake manifold is different for the Vortec heads so you need to decide on whether to use Vortec heads before you buy an aftermarket intake mainifold. Before the added $200 for exhaust port polishing I had the block cleaned and bored 0.030" over, the crank cleaned up at 0.010"/0.010" undersize, new rods and cast pistons with a three angle valve job, new oil pump, Crane Street cam (Z28 specs), new lifters and pushrods for $1600 assembled. With the port polishing it came to $1800. You can get a Mr. Goodwrench long block cheaper but if you change the cam you void the warranty, so I wanted to "know" what is in my engine and chose my own parts but had it assembled by a circle-track racer. I later added cheap Speedway roller-tip 1.6 ratio rockers but I may trim that back to 1.5 on the intake but keep the 1.6 on the exhaust which still adds torque but may give better mpg? Dyno runs show that with a "small" cam the torque can be increased with higher lift on the exhaust valves than the intake valves. Still the power ultimately comes from the fuel so maybe more torque/power automatically means lower mpg? Another interesting caution discussed elsewhere on this Forum is the problem that modern oils do not include the ZDP (Zinc Dithio Phosphonate) needed to lubricate flat tappet hydraulic lifters and some cams will rapidly flatten at break in. I wanted a Comp cam but my circle-track builder would not touch them perhaps because they have rapid ramp lift and may not break in well. I was disappointed but settled for a Crane copy of the Z28 stock cam which is also essentially the 300 HP cam used in the SBC327. My builder favored and recommended a Crane cam so I respected his experience. I am going to use an aftermarket ZDP additive to solve this and continue to use additives later but some folks just use oils for Diesel engines. That is a warning that if you use flat tappet lifters you need to use some additive to modern oils OR go to a roller-tappet cam (more expensive). Although I have worked on flatheads, VW flatfours and Pinto OHCfours, this is my first SBC350 and most of what I know so far has come from the very knowledgable folks on this Forum. Be polite and ask questions and you will find that this is a Forum with world class engine experts! Good luck!

Don Shillady
Retired Scientist/teen rodder

Here's a good "wish list" to start you off. For a street motor, look for the highest torque at the lowest rpm's.
http://www.ryanscarpage.50megs.com/combos1.html

Originally Posted by skids72

Don't know much about small blocks but just wanted to say welcome aboard. I grew up in Thornton and my folks still live there, where abouts you at?

-Chris

I'm at 104th and Colorado, i just moved here though from Aurora about a five months ago, nice area, so far i'm very comfortable here, it seems it's growing a lot. how long ago did you move out?

techinspector1:
thanks for the link, i had already seen you recomended it to several others so i looked it over and added it to my favorites folder so that i can look it over. i like combo 76, maybe it's just because i already have the edelbrock intake, carb and i was looking at a cam similar to that, maybe a little more lift. i'm still tinkering with what heads to use, now even more knowing i kneed better heads...

Don, thanks for your reply, it sounds like you're making sure you get what you want with your engine, its fun that's why i'm doing this project, because i will know what's inside and i'll be the one picking out the parts. also thanks for going over the break in of a flat tappet cam. I was looking at a cam from comp but i stoped because i'm still not sure if i want to dish out the money for a roller cam or get a flat tappet for less and be super carefull during break in, since i have never done a flat tappet, and from what i hear it scares me that i'll end up ruining it before i enjoy it. when i rebuildt my ford 302 it had a roller cam...

76 looks like a weak-suck combination to me. I'd be lookin' for at least 400 ft./lbs. of torque under 4000 r's. You don't have to settle for 8.5:1 compression ratio either. If you run a tight (0.035" to 0.045") squish, you can operate on pump gas up to 10.0:1 or more with no problem, even with iron heads.

If you liked ryanscarpage, you're gonna love this link. In order to make any sense out of comparing one head to another, compare them at 0.400" lift figures. Trying to compare them at every lift will only confuse you (at least it did me).
http://www.purplesagetradingpost.com...fo/heads1.html

I grew up around 120th and Colorado... you're in my old stomping grounds. Of course back then all that was at 104th was a 7-11 and a fishing hole. Things have changed a lot the last 20 years... lived around there from 81~93 lived around 104th & Huron for a few years before that.

I'm with techinspector.... especially at our altitude we can get by with higher compression. I was racing 10.2:1 iron head BBC on 91 premium with 42* timing lead... so I probably could have run on 87 at more reasonable timing. If you shoot for 10-10.5:1 you'll have no problem with 91 octane. Aluminum heads you can run almost a point higher. On the other hand if you're not looking for tons of power and want to run on regular cheap gas you can go lower.... I'd probably even go at least 9:1 at that.

-Chris

i too just built my first 350 but im shootin for something a little higher...whether ill get there or not im not sure but i have to buy a new top end because of my CR and seen you were looking for heads...i have a set of headds for sale here that u might be interested in looking at. i think theyd be great for ur plans. just go to the classifieds and itll be under top end kit for sale. worth a look anyways good luck and let us know what kind of numbers you come up with

those look very nice, and while it would be a wet dream of mine to get some heads like that, i think i'll pass on your offer for now. i'm trying to be a little more conservative with my engine, plus while i'm still in the planning stages, i'm still figuring out were to spend my money. i baught the same book you have when i got my engine. nice book i like it. of course by now i have more and tons of reading material from this website. 10,000 rpm, that's has to sound amazing, when you get it running post some sound clips. one of my favorite sports is F1, high reving engines are music to my ears. what are you putting it in?

ha ya it sounded great but i had to tear it down early and get what i really want out of the motor. i didnt even expect that kind of rpm out of this motor but im not complaining. alot of the guys ive talked to say all the power is in the heads and thats where you should spend the money but like you said there is alot to the planning stages and alot of money going every which way. im puting it in my 91 camaro ive had it since i was 15 and its come quite a ways sometimes i wish i wouldve bought a 70's monte but im happy oh just in case u were wondering im only asking 700 for the heads...assembled good luck with your project