[Bob Moore]

Hi
What do you guys think about using these heads , I have a couple lying around so they cost me nothing , I thought I could put in bigger valves , and screw in studs and port them a bit
Because they have large chambers I could use them on a 400 block with stroker crank to make 455 , what c/r would these be on a 455 ?

[steve25]

I think those heads are of the large valve type already, although being used They are probibly worn over .001 on the stem and need replacing.

If not re-fitting them with the big valves durning the rebuilding process is cake.

If the machine shop you use has a 75 degree bowl hog type cutter sized to work on the intake side you porting work will be cut by some 75%.

Compression wise with a stock bore 455 ( .030" over 400) you should end up with about 9.5 if the heads are not milled more than .005" and the block does not need to be decked any more than that same .005"

On any web site you might find to figure out compression ratio add in 1.5 more CCs into what you input for the chamber volume as this is the average piston ring land volume that no one seems to add in to the total.

[moontower69]

i can give a yes vote on #11s (i think they were originally on high compression 350s in 1968 or 1969) -- marcel at SD Performance did a street port on mine and put 2.11/1.77 valves on them

i now use the #11 to get pump friendly 8.7:1 compression, he milled them to 91cc

they run great on my 389 tripower driver with a very mild crower 60240

[Bob Moore]

Thanks
They have 1.96 intake and 1.66 exhaust valves , pressed in studs , but the stud bosses are flat with a screw hole in between them so should be easy to convert to screw in studs and guide plates , a couple of the valves are missing so I would be replaceing them anyway

what valves should I use / there seems to be different p/n 2.11 in 1.77 ex for different years

[moontower69]

depends on intended use of your combo (and size of cam, etc.) -- others on PY would have more expertise than me but i think its generally good to have the bigger valve sizes for better head flow, esp with a big cam -- but if you have just the stock cam, then not as necessary, bigger valves might even hurt low end torque a little

[PONTIAC LARRY]

The valve length could be 4.98" like a 6X-4 as the chambers are similar sized. You could just put the 2.11 intake and a bowl blend afterwords. Keep the 1.66 size exhaust. They are a 1970 400 2 barrel factory rated 8.8:1 compression so yeah probably cc in th low 90's.. I would CC the chambers to be sure... pressed studs not a big deal , save money and pin them dirt cheap. Its old school and it works , mild street hyd cam under .500" with some better stock sized springs.

[PONTIAC LARRY]

the normal 2.11 valve lengths are 4.89 , 4.98 and 5.09 , RAIV 5.21 or so..

[Formulas]

I have 11`s they are right at 85 cc 70 2bbl low compression 350 head and sometimes used on the 2bbl 400 same year..

Might want to look at longer than stock SBC. valves,

And prolly to much compression on a 455 with flat tops... small 10-15 cc piston dish would work ..

[PONTIAC LARRY]

just put a 4" crank in that 400 with flat tops 428-440 ci about 9.2-9.5:1 then and no block grinding for the crank

[Bob Moore]

Thanks
I know of a 421 bare block down here for sale , what do think would be a fair price to pay ? I would still need crank and rods and pistons etc , but a 421 would be rather cool

[INJUNTOM]

I'm pretty sure the #11 will be a lot of compression on a 455, and also pretty sure they were small valve.

Don't have my info handy right now though..

[thadeal4real]

Originally Posted by INJUNTOM

I'm pretty sure the #11 will be a lot of compression on a 455, and also pretty sure they were small valve.

Don't have my info handy right now though..

x2

[PONTIAC LARRY]

just 10:1 if the 85 cc is true on a factory deck 455...

[Stuckinda60s]

Originally Posted by Bob Moore

Thanks
I know of a 421 bare block down here for sale , what do think would be a fair price to pay ? I would still need crank and rods and pistons etc , but a 421 would be rather cool

It would be very difficult for us to give any kind of guess as to what that block's worth, given your location. What it's worth and what you should pay for it are two different things.

Unless you can get it very cheaply, cost wise, with that being a bare block (w or w/o caps?), it would be probably be as cheap or cheaper to use a stroker crank in a 389-400.

If it was me, I'd use a 400 block and use its heads.

[INJUNTOM]

I'm showing them to be off a 1970 350 with a chamber in the 72-73cc range.

[Formulas]

READ post #8

How many charts are flat out wrong on Pontiac head cc`s ?

Let me help you ---> most if not all