Putting My 3.0 MFI Motor Back Together

[Jeff Higgins]

Originally Posted by teenerted1

did a nights sleep resolve the ignition cut out issue you were having yesterday?

or is that the next topic of discussion to see in this thread?

No need to lose sleep over it or even think about it anymore. I found it at the track before we left; ran like a champ all the way home. Loose connection; I'm going back through and soldering everything now that I've driven it and tweaked it a bit, which has allowed me to establish the "permanant" locations of all of the components. As "permanant" as anything ever gets on that car, anyway...

[kenikh]

Whew!!!

[Jeff Higgins]

Originally Posted by kenikh

Whew!!!

Yeah. Imagine the pucker factor the first time it cut out, after what I've been through. I think I sucked the seat cushion right up to my Adam's apple, the long way...

It was weird; it would cut out when I lifted and pushed the clutch in to blip the throttle for a downshift going into a corner. Soon as I let the clutch back out, it would refire and run great. After one hell of a bang, anyway. Never a problem under power, just lifting to get on the brakes and to downshift.

[J P Stein]

Here's a chassis dyno chart of my 2.7L, with Solex cams, Webers, & 10.5:1 pistons, single plug on race gas.
This is bred as an AX motor so torque is very important but with enuff revs to streach
2nd gear when required. Taking into account Jeff's extra 18 cu/in it looks like it does well. In actual AX events the grunt is there. The graph is not as professional as Jeff's....

[joetiii]

JP,

The duration of the Solex suggests the peak torque to be around 4900 RPM. Why is yours kicking in super strong below 4k?

BTW, I charted your curve, Jeff's and my stock SC cammed motor here...
dyno comparisons for 3.0 torque motors

[J P Stein]

Compression, tall aux venturi, free flowing balance tube type muffler.
The Solex cam's peak torque came at 4200 in the 2.0L. Ya start foolin' around with displacement, port sizes....plus above, "stuff happens".
If I could afford Jeff Gamroth's EFI system you'd really see something.

BTW, good chart comparo.

[Jeff Higgins]

Well, I just got back from my first long road trip since getting this thing back together and re-tuned. I ran down to Gary Emory's (of Parts Obsolete fame) camp out this weekend. That's a story unto itself, as anyone who has experienced Gary's hospitality will attest. But anyway, this is about my motor.

I managed to average just over 19, almost 20 mpg on the freeway cruise from Seattle to Portland. I was simply astonished. So, I checked again on the way home. Same thing. It appears, when cruising steady-state like that at a very disciplined 70-75 mph (gawd that's hard to do...) this thing just sips the gas. That's better milage than I got with my 2.4.

On the track, things change dramatically. Two weeks ago at its "coming out" with the local Alfa Romeo boys, it got less than 10 mpg on the track. That was taking it relatively "easy" and listening intently for anything that sounded odd. Just this last Thursday (with out local PCA chapter) I pulled all the stops and ran it for all it was worth. Milage dropped to nine mpg or less.

What a huge disparity. What a change in personality, from Dr. Jeckyl to Mr. Hyde; from Clarke Kent to Superman. This motor cruises the freeway as free from drama as my wife's Outback wagon. It rips and snorts and bellows on the track, chasing down 993's on the straights. Truly the best of both worlds.

Again, I just want to thank all of you that helped me through this. I would try to name you all, but I'm sure I would forget one or two, and I don't want to do that. This Pelican community is truly something special. I may have been the one turning wrenches and bloodying knuckles, but I would have had no idea which way to turn them without input from you guys. Thank you.

[Flieger]

And thank you for some of the best threads on the board for MFI guys. I never would have had the courage to go into the MFI injection pump like that. Very interesting discoveries.

[kenikh]

You forgot to mention the shotgun blasts you sent those following you...

[joetiii]

Jeff,

What RPMs are you running at 70 MPH to get 18 mpg?

I run 205/50/15 through a 901 trans and turn 3500 at 70mph. I think the rpms are rather high for highway speeds and am considering going up one ratio for 5th for better mpg on long cruises.

I'm getting 18 MPG around town and on highwayn trips. I Haven't been on the track but I think carbs get worse milage than MFI.

[Jeff Higgins]

It's turning about 3500 at 70 mph, Joe. 7:31 ring and pinion, 205/55 -16's.

Ted tells me Merle was particularly impressed with the blast in the tunnel...

[teenerted1]

yes that blast really caught him by suprise. started off the fourth of july panic early.

you think getting something stuck under your pedals is bad. try dealing with a dog trying to hide under your legs while doing highway speeds in traffic.

just for comparison i got @17-18mpg with my carbed 3.0, airport gearing(whatever that ratio is) and 205/50/15, 3400rpm 70mph aprox

[kenikh]

Originally Posted by teenerted1

yes that blast really caught him by suprise. started off the fourth of july panic early.

you think getting something stuck under your pedals is bad. try dealing with a dog trying to hide under your legs while doing highway speeds in traffic.

just for comparison i got @17-18mpg with my carbed 3.0, airport gearing(whatever that ratio is) and 205/50/15, 3400rpm 70mph aprox

3400 RPM at 70MPH isn't airport gearing. Your numbers pretty much dial in at stock gearing, based on my calculator for a 901 (but I think you are running a 915).

[teenerted1]

sorry yes it is a 5sp 1972 915 gearbox. i was told it has the airport gearing. was running in 5th gear. and the revs could have been a little different and not sure the mph is correct. the speedo hasn't be recalculated for the non stock tire size. usually about 10% faster and the odo is also off about 10% too.

skippy is a bastard of all sorts. i have no clue what is original to the car any more. too many owners with too many changes over the years. everyone put in their $.02 and i am already adding my own touches. after we got back from the drive i finaly put in a dead pedal of my own design. got some good ideas at Emory's, but in the end used some spare alloy from my skid-sign scraps and fabricated something up.