well i almost have everything to finish my iron l33 anyhow what heads were ran on the 5.3 H.O. , still trying to decide if i want to take the cheap way and re use my 862's or buy another set of heads

 

799's or 243's, it'd be ideal if GM made a set of 317's with smaller combustion chamber as the 799/243 heads have larger port volumes than the 317's (or so I have read) and the smaller volumes would help the 5.3 out a bit.

 

You could just send your 862's out for a bigger intake valve. I had a set done for the wife's 6.0L Tahoe that I put 862's on and for a few hundred bucks I got a beautifull job done with 2.00" stainles Ferrara intake valves and a full freshen up. The intake ports don't flow quite as good as the 243's, but they are close and with a bit of port work they can be better than a set of 243's. I'd also have them milled .015. That would push your compression up well into the high 10:1 area which would really help out a 5.3L.

 

I have looked into this and no one has been able to see a difference in the ports of 317's compared to 243's as far as I know. I do know the ports are the same sizes on these heads.

 

TurboGibbs, Thanks for the info you posted!!! If you don't mind my saying, I noticed you listed the 5.3L rod length of 6.098 as a 4.8 in the 5.3L numbers... I am sure it was just an over site. As I said Much thanks! You seem to be the most interested in having something positive to add, So again I Thank you as should those who were looking for this info. With out it I would not know how to figure out pin height and I would probally just have to call a friend or ask my engine machine shop.

I hope No one minds but this is the info I have... I will copy/re-format TurboGibbs post with my numbers... I am sighting from several sources, but the best one on online is: http://www.enginebuildermag.com/Arti...all_Block.aspx

4.8 Specs
4.8 stroke: 3.268
4.8 rod : 6.275
4.8 deck height: 9.240

5.3 Specs
5.3 stroke:3.622
5.3 rod: 6.098
5.3 deck height: 9.240

Now do the math: The centerline of the crank is half the stroke of course and the deck height is measured of the centerline of the crank.

5.3 Stroke 3.622/2 = 1.811
4.8 Stroke 3.268/2 = 1.634

5.3:
1.811 + 6.098 = 7.909
9.240 - 7.909 = 1.331 Pin Height

4.8:
1.634 + 6.275 = 7.909
9.240 - 7.909 = 1.331 Pin Height


Looks like it works out to the same exact pin Height. As Zippy Said, they use the same flat top 4.8L pistons in the 5.3L L33 optioned engines...

 

Thanks for sharing that link it is very informative. The only thing I noticed odd is that it states 862/706 heads have a chamber of 71cc while I thought it was common knowledge that these chambers were 58cc. Also it lists 243's as 61cc chambers when I believe they are 65cc. Other than that the info seems very usefull.

 

Its an old link and No, the head info Is not correct... If you need that info Look in this link...
https://www.performancetrucks.net/fo...6&postcount=17

While technology has gotten much better and the heads are all cast fairly consistant for each type of casting number, you will find very small differences if you actually cc Various sets of heads with the same casting numbers

862/ 706 Heads have a 61.15cc Combustion Chamber Volume Not a 58cc

243 Heads are supposed to have a 64.45cc Combustion Chamber Volume.

Hope that helps...

 

Thanks for the catch. I was in a hurry when I did it, just going by memory mostly.

 

Thanks guys, great info.

 

so will any 6.0 or LS internal parts work with a 5.3 ? found cheap 5.3 wanting to put 6.0+ parts in it?