View Full Version : Cleaning Up A Poncho 400

03-19-2006, 05:31 PM
I just bought a bare 400 block. Just wondering approx price of how much you guys would think it would cost to have it cleaned up and all. I'm not sure of all the proccesses they go through, I know it needs to get hot tanked and checked for cracks, I also wanna have it bored .030" over. What all would they have to do to ensure the block is like new? I also heard of filling the block, what exactly does this do? I know it is to strengthen the bottom end of the block, but what exactly do they do? Any info would be of great help.

03-27-2006, 09:34 AM
Filling the block is a way of stiffening the bottom end. A pourable block filler is poured into the freeze plug openings and fills the water jackets up to the bottom of the freeze plugs. I dont really think you need it unless you are doing a really high HP rebuild. By then the power would probably be hard to put to the pavement in a pro-touring app. otherwise a poncho buildup is not that hard.

04-03-2006, 11:39 PM
are you signed up here?


04-08-2006, 10:17 PM
Our engines run notoriously hot, some people have had success combating the heat by block filling. Search around on the Performance Years forum for more info. If you plan on block-fill, be sure to fill it before you have it bored, otherwise you may end up with ovaled cylinders (block-fill gives off a thermal reaction).

05-04-2006, 10:13 AM
i don't think block filling is going to help a cooling problem, other than by fooling the temperature sensor. filled blocks have less cylinder surface area, and less coolant volume, which means more cooling problems. that's ok for a drag racer who can cool the engine down with an electric pump in-between runs, but bad for anyone else.

flimsy blocks like Buicks and Fords can be stiffened by filling the water jackets, but from what i've seen Poncho's are pretty damn stout. follow the performanceyears.com link above, and get advice from people who specialize in Pontiac motors.

Skip Fix
06-29-2006, 07:29 AM
With a good radiator and thermostat I've never had a heating issue. My current low 11s @ 122 455 is still only 190 at the end of a pass.A body GTOs especially older mid 60s have a poorer designed downflow radioator and no shroud have more of an issue.

Block fill "theory" for cooling is less cylinder flex at the bottom of the cylinders, reduces flex reduces friction reduced heat buildup.

Mine isn't filled, but my next heavy hitter wil be.

The main bottom end strengthening would be the addition of 4 bolt main caps on the senter three mains.

Also there are crank kits to drop in a 455 length stroker crank in the smaller 3" main bearing 400 blocks.

Tom Welch
06-30-2006, 06:16 PM
Try, Pontiac Street Performance. Several guys that frequent this site have major experience with building Pontiac engines, Jim Hand, Jim LeHart, Cliff Ruggles, Rocky Rotella, Ken Brewer, Many others, no nonsense, no flame, just good info.

Skip Fix
07-10-2006, 01:46 PM
You can see my car there with the old 400 RAIV motor in it that ran low 12s.
The new 500" motor is at the machine shop now for another project as the Trans Am is going back to cornering.

Skip Fix
07-13-2006, 07:37 AM
If you wait long enough Allpontiac will have their forged 3" main cranks out.

07-14-2006, 03:38 AM
or i can sell you mine that was built.. :twothumbs :)