505 build up

I'm currently in the process of putting together parts for a 427 tall deck i plan on building into a 505.
I'm going to use a set of large oval port open chamber heads that the motor originally came with. I am going to have bigger valves put in these heads, will i need to have hardened seat inserts intalled for the intake and exhaust valves or just the exhaust valves? i plan on running this engine on 92 octane.
Another question, I want to use an HEI distributor to simplify this project. Can anyone recommend an aftermarket HEI distributor that i will be able to run up to 6000 rpm? I have read that factory HEI' sare only good for about 5000rpm.
Thank you

yes you can run hardened seats and i have not used them to. but i now put them in all my gm head builds when i run the biggerEX valves you will not need them for the intake. with this engine i would run at least a 2.190 intake to . hey i have some killer rect port iron grumpy J heads that would work nice and they are for sale . use a msd or a hop up hei with a coil and module

hi pat, can you email me all the info on these heads including how much you would want for them?
email to mike_kgvk@hotmail.com

you might check about the hei , because it dont have a slip collar on the dist. it might not work with a tall deck motor .

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Originally Posted by kennyd

you might check about the hei , because it dont have a slip collar on the dist. it might not work with a tall deck motor .

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yes this will have to do with the intake it may be bored down the dist well or some intakes are set up for a short style dist or you can turn off the collar and make or buy one from msd have done all of it any way you go you will need to check for fitment

What are the casting numbers on your heads? If they are the stock heads on a tall deck truck block, they are not going to be the best heads for performance use. Also, what is the intended use of this engine? You dont need hardened seats at all unless this is going to be a daily driver. You'll never see the deterioration unless you're going to drive this thing about 30K miles. And if you get a good GM hei distributor (not one of the aftermarket ones from China), it will be fine for 6K. Lots of my friends are running them in a drag/street car, and they are just a stock HEI....no break up at 6500 RPMs going thru the traps. Post the numbers on those heads. John

Hi, the casting numbers on these heads are 343772. They are large oval port open chamber heads with 2.06/1.72 valves. I want to replace these valves with 2.19/1.88 valves. This engine will go into a vehicle that at most will be driven twice a week on the street and an occasional 1/4 mile run, but I intend for them to be very hard miles on the street. As for the issue of the hei distributor and the tall deck block, i have a weiland team g tall deck oval port intake that i plan on using which will allow me to use a standard height distributor.

Hi Mike I also have a 427 tall deck and plane on making it a 525 but are those heads large enough. Just my thought. keep this thing posted I would love to here how it turns out. I set my build back for a 396 build. Never enough money or time for all my projects. HaHa!

head size has a lot to do with what you are doing RPM and TQ low rpms you will not need big heads but if you are going past 4500 to 7500 then big heads will help

Agree with Pat....those heads are not a familiar casting num. to me, and I have been around GM big block heads for awhile. Mortec doesnt list the runner size on them, so I would be concerned about that part. You can put the larger valves in them, but if the intake runner size is small (peanut port heads), that won't do any good. Are they the heads that came on the block originally? If so, you might as well forget about using them, they wouldn't put anything but a small runner head on a truck engine. They would be great for lower RPM, and have great torque...you would smoke the tires for miles with that engine...but you wouldnt have any top end. So if you want to use those heads, I wouldnt even do the larger valves, it wouldnt do any good. If you want to stick with GM heads, (good idea by the way) look for a set of 781's...they make a great performance head...put in the larger valves, have some mild port work done, and you'll be good to go. They were very common on 454's throughout the 70's, and there are lots around...049's are basically the same casting, but they only used them one year, so not as many around. On the hardened seats, if you would be more comfortable with them, go for it...but it's not really a 'beat on it' issue, it's durability, so with the amount of driving you'll be doing, I still dont think they're necessary...but that's up to you. I have had my Chevelle with non-hardened seats on the road since '98. I drive it several times a week during the nice months, run on 91 or 93 octane. I run it very hard quite often. I pulled the heads for a new engine that I built 2 years ago, and had them freshened up while they were off. The machine shop said there was no indication of any seat deterioration due to the no lead factor. But like I said, if you would feel better doing them, go for it for peace of mind. What are you doing for pistons and rods, compression ratio, etc? Good luck with your build, and keep us posted. John

Hello gentleman,
First some of the other details of my project, for my rotating assembly i plan on going through ohio crankshaft and purchasing a complete assemby. I want to use a forged 4.25 crank and a 6.8 inch H-beam rod. The pistons are available with the correct compression height for this combination to work in my tall deck motor. The pistons have a diamater of 4.35 which is .100 over, this would give me a total displacement 505. This will give me an extremely good rod ratio and will give some added strength to the bottom end of my motor, plus hopefully give me a few extra horeses by giving the bottom end a little extra mechanical advantage with the 6.8 inch rod. I am hoping to keep compression around 9 to 1. I have a weiand team g oval port tall deck intake and also a holley 850 dp to top things off.
As for my heads, i wouldn;t have believed it myself if someone had told me a 427t truck engine came with large oval port heads, but it did. I was extremely suprised to find this out when i tore this engine down the day i brought it home; i bought the engine whole, carb to oil pan. In fact i didnt even look at the heads when i pulled the intake off, i only realized it a few minutes later in passing, and was i ever suprised!!. I am currently in the process of porting these heads. Attached are a few pictures of my engine and the heads that it came with.
thanks everyone

yes the old tall decks are good for stroking did one to 525 why use a rod that long? on 4.500 strokes i have used 6.535 and 6.625and have used6.135 and 6.385 on 4.250 and 4.375 with the 6.385 and the 6.700 rod for 4.750 stroke all of them are still out there .you can use CH 1.520 with the 6.435 rod cut the deck .020 or CH 1.645 with 6.385 rod and cut .045 if you want O deck

As for my heads, can i get these heads to work in these engine?

What do you mean, work in these engines? As in high RPM, no, not really. In lower to mid rpm, probably up to 6K, there are lots of guys running oval ports on drag cars. What are you going to be using this car for? You certainly dont need high rpms with a big block stroker....my 505 has all the torque anyone can possibly use. If they are true large oval ports, they will work fine on your engine.

yes they will work like jonny said for low rpm BUT you will have some money in them and for all the grinding and cutting out for the big valves guides mill heads it may be better to get some bettter heads if you are looking for big hp and rpms

My primary use for the engine would be cruising the streets and laying tire. I am not planning to run engine past 6000 rpm, in fact 6000 rpm would be the outer limits that this engine would ever see. To be perfectly honest, my goal with this engine is 550 hp, and lots of torque. I am not looking for high RPM's and massive horsepower numbers, just a good running street engine with lots of torque.
How much does a machine shop usually charge to grind bigger valves into a set of heads and do a valve job? How much to install new valve guides?
thanks,
mike

well i am a machine shop and i just did a set to 2.190 and 1.880 and the $$ has alot to do with the shape of the guides and if you want harden ex seats you can not cut them out for big valves if the guides are loose so then you need new guides and they will have to be bowl out to if not done the big valves will not do much. if you want low end why not put a 4.500 crank in it 535 cid this will roast your tires to the rims and would cost the same or use a 4.375 crank 520 cid

Ya know, if you wont be spinning this engine that high, you probably wont even see the advantages of the larger valves. With a stroker of any size, be it 505 or 540, you will likely meet your 550 HP goal, and the same or more torque, so Im sure you will be happy. I dont know that I would even go thru the expense of installing bigger valves. Yes, the bigger cubes will need more air, but at cruizing rpms, and up to 5K or even higher, I dont know that it will matter. Maybe Pat can shed more light on this aspect. At any rate, I had a set of 781's done a few years ago, larger valves, 3 angle valve job, new guides, cut the guides down for higher lift cam (you might have to do this also), milled about .020, a little bowl blending. As I remember, it came out to around $750.00, and I supplied the new valves. He supplied anything else, and of course the machine work. Remember, you can buy a new set of aftermarket iron heads for 1G bare, or about $1350 or a little more, complete. So think hard about putting money into those GM heads. Pat, what do you think about the valve size? Im assuming stock valves are in there, 2.06/1.72's....they still flow pretty good as is.

2.06/ 1.72 yes that sound right .the big valve size at very low speed will not do to much i think .on a small bore engine BUT if you are going up on cid i would at least run the big valves2.190-1.880 with the bigger cid on the smaller396- 454 i have not seen much with the bigger valves. but a good bowl job and back cut valves will help alot with small valves. so this is for me hard to say i will put it like this bigger valves help with doing the older heads if the seat are hammer out or you need to put a new guides in the heads not a liner or a thin wall guide if i put new seat in the ex side i go right to 1.880 ex and use a seat for that valve and rework the short side radii what you have to do is see you much money you want to put in them $500to$700 i would say you could be at . for me all of machine work is free .i do it so only coast me my time. but it gets old picking iron out of your eyes or lifting them heads up and down all day when you can go out and by some heads that will do the job and have a better Ex port

pictures of my intake

ok looks good. maybe we can do something