After replacing the EGR and PROM, the car seems to have taken to the 350 swap and most of the little bugs are worked out of it. However I still have a couple of problems I'm hoping someone can help with.

1. The car is still burning lots of oil. The guys who did the engine work think the rings still haven't sealed yet (c'mon after 2000 miles??) and suggest I drive it more. But it's burning about 1.5 quarts every 300-400 miles. That's a lot of oil. Could one of the rings be defective? As far as I know there are no leaks (none visible, no spots) unless it's only at high pressures and is leaking while I'm driving. The parts and labor are still under warranty, so I'm probably just going to take it back in and have them hunt for the leak/source of the burn. But I'd be curious to know whether there's a known offender I could track down and point out as a possible culprit.

Also,

2. Whenever I get on it and open it up WOT, there is a significant power loss around 3.5-4k RPMs. The car will shake and basically the engine is spent. This only seems to be a problem in the first 3 gears. Once in 4th or 5th I rarely get up into that 4k range as I'd be flying at 90mph and probably up to my ears in speeding tickets. What's this power loss attributed to? The engine is brand new (block, RV cam, pistons, rods, etc), but the heads, crank and intake from the 305 are all being used. Are the 305 parts limiting the overall output of the 350? Or does this thing have bigger problems?

Many thanks in advance.
Maverick

------------------
Maverick
1989 Formula 350 TPI
5spd Tremec 3550/TKO
several suspension mods

 

I'd say that yes the heads are restricting airflow into the cylinders. The RV cam might also be limited to around 4000 rpm. The RV cams are designed to improved torque on the low side. When was the last time you saw an RV turning 4000 rpm? OK, you have a 350 block, and a 305 crank. Then your motor is not a 350. Anybody know what the bore and stroke is on a 305? I think the bore is 3.865" and the stroke is 3.25", but I am not sure. If you have a 350 block with a 4.00" bore and a 305 crank with a stroke of 3.25" that would give you 327 cubic inches of displacement. Vice versa. If you put a 350 crank in a 305 then you also get 327 cubic inches.

------------------
'87 Silverado
350 4 bolt main bore .040 over
TB Injected
Ported and Polished heads
Comp cams 268h cam and top end
Flowtech headers
3.73s on Detroit locker

 

A 305 and a 350 have the same stroke. 3.48"
A 305 has a 3.736 bore and a 350 has a 4.000(4.001?) bore.

I would definately take the motor back since it is under warranty. Get what you paid for.

I would worry about the shaking. Even with 305 heads that 350 should pull more more than 35-4000 rpm. I had a 350 with 305 heads and a 204-214 cam (.420-.440 lift) and mine pulled strong to 5500.
Sorry I can't really help you with your problems

------------------
LOBC-- SS-84

92 RS Heritage package with a 305 3" high-flow cat and pipe with a Dynomax 3" in dual 2 1/2" out.

84 El camino- 383 CID, Performer RPM, GMPP vortec heads, Holley 750 D.P.(0-4779c), Crane Energizer 274,Dual 3" Flowmaster 40 Series Exhaust, TCI 2500 stall, Richmond 3.42 gears, PST Poly graphite Suspension bushings, PST steering linkage, PST springs, Monte SS sway bays, Wheels from a Third gen(does that count?)

 

Thanks. I figured as much. I'd asked around and was told that using the same crank on the new block wouldn't matter. As for the block, it's got a .030 over bore (that'd be 355?). I knew the heads were going to be trouble though.

Back to the shop I go.


------------------
Maverick
1989 Formula 350 TPI
5spd Tremec 3550/TKO
several suspension mods

 

If your engine is shaking at higher rpms, I think that it is due to the crankshaft. Although 305's and 350's have the same stroke, the cranks are balanced differently even though they look nearly identical. I don't think that a 305 crank can be balanced enought to compensate for the 350 pistons. That vibration will destroy the bearings in no time.
When I bought my formula 305 it had a rebuilt 305 in it. This engine had lots of vibration, after some fustration someone told me that a 350 crank would cause this. And sure enough, I took the engine apart and there was a 350 crank inside. I replaced it with a 305 crank and its been running smooth ever since.
I would take it back to the shop and have them put in a new crank. Hope this helps



------------------
1990 Formula WS6 - 305 - T5
14.3 @ 96.5 mph
MSD 6AL
Strut tower brace
Subframe connectors
MAC headers
Underpulleys

 

You can't tell a 305 crank from a 350 one by looking at it; they're the same casting usually (442). Some of the cranks in 305s are even the same balance as the ones in 350s, in motors like the L69 with X rods.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

One way to tell the difference is to lay a straight edge along the counterweights. The straight edge will lay across the 305, not on the 350. This is from Lingenfelters book.



------------------
Joshua Johnston
1991 Z-28
Flowmaster
K&N
305 / 5spd. (Temporary)

 

why the f&$@ are so many people giving advice that have no idea what the f$*@ they are talking about?????????????
its really pissing me off.

------------------
-Tas
'89 Formula WS-6

305, TBI, auto, 14x3 chrome flat based open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

To be installed eventually far far far into the future: Yours if the price is right and I don't have to ship :
Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248), Catco 3" cat, and injector spacer.

Super GRK_Taz World
F-Body Dual Exaust
EFI & Intake Options
AOL IM: superGRtaz

[This message has been edited by Tas (edited July 13, 2001).]