383 build...

[TUFCAT]

Ron, the 915's flow better - but I already have the 516 heads on my factory 383 HP engine. Should I be looking for 915 heads, and sell mine - - or, just spend the extra money to have these 516 heads professionally ported and polished.  From a economic point of view, which is better..... the stock 915 head or professionally ported 516's that I already have zero money in.??

[aifilaw]

you will spend the same money porting out the 516's and increasing the ex. port size to 1.81 as you will on a brand new set of aluminum edelbrock heads, and you will probably get 10+ hp across the powerband with the edelbrocks.

btw, I only opened up the exhaust ports on that set of 516's I mentioned to 1.74... and they hit the water jacket. I had a better set a couple years before I opened up to 1.81 and they didn't hit (noticeably) until after I put them on, and drove on them, then coolant out the exhaust big time... found out pressing lightly with a screwdriver showed a gaping hole into the water jacket because the metal was so thin from corrosion and rust.
These are 30+ year old iron heads guys, don't expect magic out of them too often

[TUFCAT]

Do the aluminum heads look stock on the engine in you paint them to match? Also, can you use stock valve covers? any other issues with installing these on a stock set up?

Does anyone know if the 915 castings have more meat?

[aifilaw]

piston selection isn't as horrible as you make it out to be on the 383...
there's a lot of pistons out there, and if you realize that a piston is a piston based on the bore and side-skirts, weight, and height, you will realize that a lot of other pistons that have the words "383" nowhere associated with them, work well in this block.
btw, custom pistons aren't that expensive.

[RD]

TUFCAT, here is a scenario on 516 heads

I ran 12.17 in the quarter in my 3900lb 71 charger with 516 heads that had 2.14/1.81 valves, no port or polish.  If they are capable of that, then what more do you want?

granted, I could have probably ran faster with aluminum heads, but I did not have them at that time.

[TUFCAT]

RD - that's awesome. Did you have a problem enlarging the exhaust valves?  Should I even bother with that? I 'm not using headers and wondering how much enlarging the exh valves will actually help with a stock 383 magnum cam?

[RD]

RD - that's awesome. Did you have a problem enlarging the exhaust valves?  Should I even bother with that? I 'm not using headers and wondering how much enlarging the exh valves will actually help with a stock 383 magnum cam?

any reputable machine shop can put in larger valves, but the first question is this... do you plan to drag race it or just street drive it?

[TUFCAT]

Street driving (drag race a few times).  I want it to look stock. It will have a stock 383-400 magnum cam (maybe just a wee bit bigger if it helps), 3.23 rear, and a 2k convertor.  I''ll have manifolds. I will also have the engine balanced. That's about it, othrwise, a pretty much stock rebuild. I want to make as many "unnoticeable" performance improvements as I can.,,,,,without getting too crazy with the expense like the F.A.S.T guys do. I want it to look stock, but surprise a few people with its performance at the same time.

[firefighter3931]

Ron, the 915's flow better - but I already have the 516 heads on my factory 383 HP engine. Should I be looking for 915 heads, and sell mine - - or, just spend the extra money to have these 516 heads professionally ported and polished.  From a economic point of view, which is better..... the stock 915 head or professionally ported 516's that I already have zero money in.??

Unless you're looking for an all out street/strip car the 516's will work OK on a 383. If you were building a 440 i would recommend a better head.

I would upsize to the 1.74 exhaust valve (use stainless) and have the machinist do a throat cut on the bowl whiles he's cutting the new seats for the larger valves. Then you simply blend the cut into the bowl with a die grinder and call it good. The 2.08 intake valves are fine.....just have a good valvejob done and the same throatcut/blend. 



Ron

[RD]

Ron, the 915's flow better - but I already have the 516 heads on my factory 383 HP engine. Should I be looking for 915 heads, and sell mine - - or, just spend the extra money to have these 516 heads professionally ported and polished.  From a economic point of view, which is better..... the stock 915 head or professionally ported 516's that I already have zero money in.??

Unless you're looking for an all out street/strip car the 516's will work OK on a 383. If you were building a 440 i would recommend a better head.

I would upsize to the 1.74 exhaust valve (use stainless) and have the machinist do a throat cut on the bowl whiles he's cutting the new seats for the larger valves. Then you simply blend the cut into the bowl with a die grinder and call it good. The 2.08 intake valves are fine.....just have a good valvejob done and the same throatcut/blend. 



Ron

[TUFCAT]

Thanks Guys!!! I appreciate your help and experience.  Your opinions match exactly what I was told by another trusted engine builder.....stick with the 516's, do some mild head work, add larger exh valves to match the 1968 Magnum size.... then call it done.  I don't need the car to run like a raped ape - - just an ape that's been tickled a bit   

I'm also concerned about problems with water jacket leaks after enlarging the exhaust valves from reading a previous post by aifilaw who ran into trouble.....  RD, Firefighter, or anybody else  - - should I really be worried about that? - - or is that an isolated issue?

[TUFCAT]

 

I'm also concerned about problems with water jacket leaks after enlarging the exhaust valves (after reading a previous post by aifilaw) who ran into trouble.....  RD, Firefighter, or anybody else  - - should I really be worried about that? - - or is that an isolated issue? 

[Hot_Rodder]

  I don't know what to tell you man. I pretty much have decided to go with a big block turn key crate motor. Will use a 383 block, and has aluminum heads all ready bolted on, and as for power, it's got enough to move this heavy '72 Charger on down the road, so...