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454 with 292 / 820 heads, bigger valves?

7K views 20 replies 7 participants last post by  Geo71 
#1 ·
My 454 has a set of the 292/ 820 heads. Used the Vortecpro videos and tried alittle porting on them. Didnt go too nuts on them. Dropped them off at the machine shop yesterday and he is looking them over, then installing new guides, seals and valve job. We talked about going to the bigger intake valves...worth it to put the 2.19’s in them and leave the 1.72’s alone? There is a xe262 comp cam in it, which I may reuse or maybe try the Summit 1302 cam....

Shortblock is all Original stock as far as I can tell, hoping to be able to just hone it and maybe find some higher compression pistons or run it as is. Block has some kimd of valve reliefs in the bores.

Years ago had a 402 out of a Monte Carlo, pretty sure they were the same heads...
 
#2 ·
We do tons of those heads on our 100% stock-appearing builds. About 95% get SBC intake valves (2.125"/2.150") and some Mopar (Indy) exhaust valves (1.810"), all are 11/32" stems which also help some with the final flow numbers!

These heads can produce upwards of 525 HP (no real porting) on these stock-appearing builds!

Thanks, Gary in N.Y.

P.S. Am still keeping my posts a bit short due to some health issues, still only half-way out of the woods so far!
 
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#3 ·
Thanks for the info. Sounds like it’s probably not worth messing with. Unless the stock valves are bad? Maybe the little bit of porting/ clean up and valve job is enough. They will be getting new guides I am pretty certain.
 
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#4 ·
Never had good luck with larger valves in closed chambered heads. I only use the stock size now with them.
 
#6 · (Edited)
They aren’t closed chambered heads. Alittle weird shaped though.
 

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#7 ·
Yeah I was just thinking the intakes only, if anything. Pretty sure these were the same heads on my 402 back in high school, (80’s). Just ran stock valves and a magnum 292 cam...it went to 7500 rpm often only 13.88@105 with alot of wheel spin. It needs guides, so could go to 11/32 with new valves if I had to....or just stay with the 3/8 and reuse my valves.
 
#9 ·
The 820 heads were used on the 1971 Corvette LS5 engines and are a good head to start with.Someone flowed ALL the production cylinder heads on EVERY engine and listed all the findings.And I think the 820 heads had the largest oval intake port of all the BBC ovals.Somewhere there's a link to that list but I haven't been able to find it.
 
#11 ·
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#14 ·
Dropped the heads off at machine shop...no cracks, exhaust valves were bad. Had comp double springs good for .600 lift. We decided on new guides, 2.19 and stock size ss exhaust valves, valve job and backcut, machine for better valve seals and 10* locks and retainers.

Next to decide if I want to change the cam, and do anything with the shortblock.
 
#15 ·
Any idea what a good piston to use with these heads? Any open chamber piston ok? Thinking 9.0-9.5 compression ratio to run pump gas. May or may not stick with the comp xe262.
 
#16 ·
Are you going to use 11/32nd stem valves ? I would since your changing guides unless your not changing int. guides, exh. side goes through water IIRC, I had new 2.19/1,88 SS valves & guides put in a set of 063 semi open chamber heads and wish I would've used 11/32 stems instead of the 3/8ths, lighter & a little better flow
 
#17 ·
No I kept the stock valve sizes. I looked into it, but the 11/32 stuff was too expensive for what I wanted to put into these heads.
 
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#20 ·
I ended up sinking $1,100 in to my 063 heads, $300 for decent heads that had some port work (by who Joes Plumbing?) Comp. Products SS 3/8 stem 2.19/1.88 valves & .550 lift spring kit was $2xx then 1st machine shop screwed up even though I gave them the cam card but don't remember $$ amount, 2nd shop fixed 1st shop screw up for $xxx LOL, it's good your keeping them on a budget I was half way to a prime set of aluminum heads :thumbsup:
 
#21 ·
It is easy to wrap up some $$ in this stuff. I kept thinking in the back of my mind what a set of aluminum would run. Maybe should have gone aluminum, but really just want a nice cruiser with power to have some fun. Keep telling myself, NOT A RACE MOTOR THIS TIME! :D And it's kinda cool the heads are 72 to match the 72 wagon. Not that that really means anything, just kinda cool..

These wouldn't have been too bad $$ wise if the exhaust valves and seats weren't shot. At least the springs were already Comp 924's, so that saved a bit. Upgraded the locks and retainers to 10* which added alittle and the rotator eliminators.

Basically, new Erson SS valves, guides, machine for the better seals, machine for the bigger valves/ seats, valve job, backcut, mag, pressure test and mill .008 to clean up the deck was about $800.00. Still need new rocker studs and maybe guide plates if I go bigger pushrods. Could have shaved a few bucks here and there, but I don't have alot of luck cheaping out :) He put a fair amount of work in them and got them done in a week, can't complain about that.

Will drag the block up to him this week and see what we can do with that. Hoping a hone/ deglaze is all that it needs, with my luck it will need bored. :grin2: Tried that with my 6.0L...of course it needed bored.
 
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