Rebuilt the engine in Green Machine - now 20 + MPG & more power !!!

[Green Machine]

A little background - we "rebuilt" an 89 Camaro 305 roller motor during the build of the 1970 and installed it last summer. The "rebuild" was just rings and bearings and gaskets, tchain, oil pump etc. Did not touch the heads as there were no leakers. Had to put in a good set of used roller lifters because they were all stuck from the PO's bad oil change habits and reused the stock roller peanut cam.

Results were pretty good - nice power and 18.5 mpg with the overdrive A833 4 speed manual, but we developed a miss the first part of August this year. Compression test showed 50 psi on hole 5, suspected valves, but the motor had always sounded plenty loose and getting worse with a suspected loud piston slap on at least one hole. We were not going to mess around this time so out it came. Yes I know you should remove the ridge when attempting a re-ring job but we did not have access to one then.

Number 5 piston had a stuck top ring and so did one other hole, with evidence of the fire sliding down the side and melting some aluminum away !! All pistons were loose enough in the bore that its is a wonder they did not swap holes !!! Thats the bad.

Now the good -

Had block decked about .010 to square it up an bored .030 over. Got some Silvolite rebuilder hypereutectic 4 valve relief pistons (destroked .020) to replace the slight dished stock pistons. Had engine balanced , new slugs were a bit heavier than the the old ones. Had heads shaved enough to clean, all guides were good yet but stems were wore on exhaust, so new exhaust valves went in to tighten that up and a set of "Z28" springs with the rotators retained to make sure the bigger cam won't bounce the rollers when we get rowdy. Opened up the top ring gap. +004 to .020 per conversation with Silvolite tech to avoid any possibilty of ring butting.

Pistons ended up about .035 in the hole, with a .040 gasket about .075 deck (yeah, I do know about quench but.. compression ratio is about 9.3 with this set up and we want to run 89 octane.

Got new takeout HT 383/Ramjet 350 roller cam (has fuel pump lobe) from Ebay for about 65 bucks, reused the used roller lifters again with stock rocker arms and pushrods and resused the performer intake and carb and HEI that was on there. Installed cam 4 deg retarded to reduce dynamic compression and vacumn a bit, keep the push on the piston a little longer, and extend the top end.

Engine fired up first turn over - ran about hour put on about 50 miles and dumped oil and filter.

Results- Lot more power than before - 190 cranking PSI (ouch - more than we we hoping) Had to redo the dizzy, only 4 initial plus 20 in the dizzy all in by 3200 with stiffer springs an 10 in the can to eliminate pinging on 89 Gasohol. Now I know we violated a few engine building rules here, large quench distance, retarding the cam and using "doggy" swirl port TBI heads, but the proof is in the pudding. It will surely spank any stock 350 an get better mpg to boot.

Went to a car show and cruise 100 miles away last Sunday, engine only had about 300 miles on it when we left so it still may be a little tight. Drove down 100 miles pushing a slight headwind and then drove another 65 miles thru some parks and scenic areas, lots of idling, stop and starts, hills 2nd & 3rd gear, never got into overdrive. Got 17.5 on that leg of the trip. On the way back with a slight tailwind, lots of stops and starts, (not a straight shot) we got the 100 miles done on 4.9 gallons !!! And we still don't have headers on yet.

We be smilin now