Thread: 366T heads/intake

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Just pulled the heads intake and distributor off a 366t engine this afternoon, the cast iron intake is a high rise square bore intake (not spreadbore), will this have enough flow for a 500 + cubic inch engine, the heads are large oval ports but they have small intake/exhaust valves, can you have larger valves(seats)installed (2.06/1.72 or 2.19/1.88) in these heads, and will they work with the above mentioned engine size, casting number on heads 473328, date 1978, is there any way to post pic's

thanks

whats the casting number on the intake manifold? i really don't know to much about 366's, but i'm pretty sure that they did not come factory with square bore high rise intakes, but i be wrong. I'm assuming on the year (1978) of the heads that they are very similar to 049 and 781"s, which are very good heads! i would put 2.19 and 1.88 valves in because your 500 cube mill has big bores and heads would really pick up the flow. a 500 cube motor with large oval ports would make very good power especially the torque! 1992 john ligenfelter put ported 781's large oval ports on a 502 BBC and made 650 horses, just in case your wondering. I would hang on to that intake, does the intake have any casting such as HI PER(hi performance) or PASS (passenger)?

no pass or high perf , T4GM 354463, numbers hard to read, has dual thermostats and a big opening for coolant by pass(might be a problem later on), found a guy selling a 366 with the same manifold on ebay the item number is 130039812094 or 160004433844 (has better pics of intake), if you wanted to get an idea of what the intake looks like

the heads may work?? i do not know what your trying to do how much HP? i think i told you on how i have done this? the intake will not work for hp use .it is junk for that it is good for a truck that is it . 2.19 intake and 188 valve would be ok but i would go to 2.250 /1.880 11/32 stems for big cid and hp. if you do a good bowl job to .if not then do not wast you money on big valves. you do know that you can not get 500 cid you of a 366

Yep, Pat beat me to it.....you wont get to 500 cubes with that block... And my opinion is just slightly different, but I would junk both the intake AND the heads. There is just too much work to be done to get them to flow reallyl well. Money wise, Im speaking. Start with a set of 781's or something similar if you want a good GM head. John

i think you guys misunderstand me, i'm not using a 366 block, i just pulled heads and intake off a 366t, thought the heads might be large oval port heads, they are large oval port heads like a 781 head, but they have smaller valves, i thoght the intake might support a 496 500 cubic inch motor with the high rise, i listed those ebay item numbers so you could see a pic of the manifold i was taking about, i think Mr. mccarthy knows what manifold i'm talking about, and yes you did tell me how to build/stroke a 427 tall block, thanks, i'm just not to sure on what i want to do with this project yet, i picked up the heads and manifold off that 366 for 60 bucks, had to remove them my self in the RAIN yesterday, thanks for the info

Originally Posted by 1JohnnyO

Yep, Pat beat me to it.....you wont get to 500 cubes with that block... And my opinion is just slightly different, but I would junk both the intake AND the heads. There is just too much work to be done to get them to flow reallyl well. Money wise, Im speaking. Start with a set of 781's or something similar if you want a good GM head. John

whats the point of buying 781's when the heads he's got now are similar to 781's
i know for a fact that 781's can be used on 500 cube motors easily and they can be cut opened for big valves and bowl ported to flow 320CFM intake and 225CFM exhaust and still have very good velocity to have throttle response. i think if he uses the heads he would be going in the right direction, i don't about the intake, but the heads are good! good luck on your 500ci motor!

320 cfm may be a bit hard and when all said and done it would be way cheaper to buy a new set of heads that would do that out of the box .less he as a small machine shop to do all the work for free and the intake is junk and will not do any thing for hp. not all the Oports will flow that number you nail down .and a set of stock ports 781 would be hard to do them numbers

i guess i'll sell the heads and intake, I have a 427T block just to clarify, i got one more guestion for you guys, i was caught up between going with the 4.375 stroke and the 4.250 stroke, in the competion products catalog the 4.250 stroke crank(forged 5140)is $479 and the 4.375 stroke crank(forged 4340) is $599, with .060 over and 4.250 stroke i'm only getting 496, its cheaper but not in the 500ci+ range,with the 4.375 i would be in that range, pertty set on using a howards cam (lift.476/.502 duration at .050 204/214 lobe center 112) and 6.535 rods, 9:1 to 10: comp, dont know about the heads yet, had a set of 781s but one was cracked, here's my question can i use any piston as long as the compression hight fits or dose it have to match the rod and stroke i'm using? i'm just trying to put a budget together.
thanks

whats the point of buying 781's when the heads he's got now are similar to 781's

Not similar enough...they'll never come close to what you can do with a 781 casting or 049 casting.

Chevy427tall, why dont you bore it more than .060?? I think you can go quite a bit on the 427 tall blocks. You'll be over 500 easy that way.

ya i could bore it out more but after .060 over don't you get in the custom piston range,sounds expensive i haven't check out any prices, i could be wrong, just for fun this weekend i'll cc the 366 heads intake/ exhaust runners and cc the stock781 head intake/exhaust, think that might give use better insite.

CC'ed 366T heads, 250 cc intake runner, 101 cc chamber

on the customs piston and how long of the rods to use i can help maybe ? . i do not think you can beat the price on the H beam rods for the money i have used many sets and think they are a great value . on the heads they could work. here some things you may want to do first. 1wash and check for cracks. 2 do they need guides ?2 SS valves. 3get them deck .4 rotators eliminators.5 cut heads for big valves. 6 new guides. 7 set heads up for valve springs. 8 cut down guilds for PCseals and hi lift cam. 9 valve job 3+ angle .10 bowl work.this is not in the order how it would happen. this is all stuff that the heads may need. so you will have alot of money in them ? there is things i did not add in hard EX seats, spring keepers, spring retiners, new rocker studs 3/8 pushrods guilds ? it may have them on the tall decks they did have 3/8 pushrods so you will want to get a price on the work and parts. you may find out for not alot more you can buy some new heads that will make more HP and not to much more money if the heads you have need a lot of work. all parts will be the same price for the new head casting or you old casting

i called competition products tech line, they could get pistons for a 4.375 stroke and 6.535 rod, i thought you could get any piston as long as it fit the compression height, piston skirt might hit crank, i get a discount on machine shop work, my brother and I run a used car dealership/ auto service, he sells cars and i fix em, i'll probly just buy some new, set up, aluminum heads$$$ i'd trade my wife for a set of aluminum heads........maybe

thanks for your help

well there are new alum heads casting for $800 a pare? they may be junk?? have not used them . i am set up to do machine work. but still check this on any set of heads i do . i am all for saving a buck . i have had steel ground out of my eye from porting out a set of low buck heads. do you add the $400 for this little bit of fun to the cost of the heads? for the pistons hitting the counter weights this should be check on all builds with nostock parts . 4.375 crank comp sell for a 6.385 rod have used them so a 6.535 would be better. alot of pistons do not have much on the bottom of the pistons and have small skirts slippers so this helps some.it looks like you need a cr of 1.478 or 1.460 if you are down in the hole by .018 so this is not a stock shelf pistons less they are making them up for there tall deck build that comp sells ? if they do not then it is a full price custom that would be $ 800+ a set where a 4.500 crank would be a stock SRP shelf piston at about $200 less .you may want to call diamond piston and get a price they build good custom pistons