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

[LockDoc]

-
Even though I don't know half of what you are talking about, it still sounds good... ..Glad you are getting the performance, and the bonus mileage too...

LockDoc

[wibilly]

good deal, what gears have you got? how do you like that tranny? gathered one of them for my next project, but never have driven a truck with one to know what i thought of one

[Green Machine]

Love the OD tranny, gears are spaced just like a standard 3 speed, but there is one more shift to over drive. We have 3.73 posi with 265/70 R17 tires all around. I think they are about 31.5 tall. 60 mph is 1700 rpm, and yes the speedometer is calibrated perfect, so I know our mileage is accurate.

[qksilver]

I had a 82 C10 with that trans........loved it. thinking of one for my 69

[Brad]

'89 305 huh? Very interesting. Thanks for the detailed write up!

[BCOWANWHEELS]

my s.b. 383 with a th350 and 3.08,s gets 17.5 if i drive it right.

[special-K]

Is the A833 the manual floor shift 3spd+o/d?

[Andy4639]

I have the 86 (stock) IROC -305 HO TPI motor in the 71 with a 700-R4 with the corvette upgrades in the transmission and driving it on the interstate I get 20 MPG. These little motors are a good choice for our trucks that aren't built for speed. I can run up to about 95 with the 4:10 gears before it starts loosing power, but it pulls good all the way.

[bad6772]

wow shure ... great write up.the 67 gets about 14 mpg with stock everything my 72 lol.....8-10mpg i got to change those 4.56s lol.....naw it pulls so good.....good job....

[Billla]

Sounds like a great build!

[tkeduk8r]

Sounds awesome... way to go guys... scary part is I did understand what you were saying.... For everyone else, I ve seen and drivien the "machine" pre engine rebuild and it drove like a dream then... wow... their engine choice is one of the best around (with the roller 305) for both performance and mileage. I have been on the look out for a roller 305 since I drove thier truck last march. Anyway, Im tired and Im rambling, but congrats on the build!!!
--Mike

[truckdude239]

only scary part to me is why did you reuse the lifters? I've always been thought in school to never reuse lifters even roller lifters

[special-K]

I wasn`t surprised to hear you had to go back and take care of the heads.Bottom ends outlast heads/top ends.The problem most have is doing the top end only to have blow-by on down the road from the rings.But,guides and cams are the first to go.

[70rs/ss]

You can reuse rollers, but never, NEVER reuse flat tappets! Sounds good, I have two roller 350 blocks, I think in a mild form such as yours 18-20 mpg may not be out of reason. Roller is a big part of that equasion, less friction. My problem and most everyone else's here is that we put our foot in it and the MPG goes down the drain!!

[truckdude239]

oh okay i was just told never to reuse them

[PanelDeland]

Green Machine, sounds like a near perfect build for a cruising engine.No radical stuff just good straightforward rebuild with some mild performance goodies and a well thought out plan to get to a defined goal.
Glad it worked so well.

[glock35ipsc]

Originally Posted by Green Machine

190 cranking PSI

Is that oil pressure, or......?

[Techy]

Originally Posted by glock35ipsc

Is that oil pressure, or......?

I would assume Cylinder pressure.


If he has 190 lbs of oil pressure, the filter will fly, and probably a lot of gaskets, too.

[Frizzle Fry]

Nice job. I'd like to build a gas sipper one day too. Maybe a destroked roller 327.

[oldgold70c10]

Wow, this is like an inspirational thread for me. Your getting better MPG than most of the new trucks, too!!!