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Jetting + General advice for my 2.7L Type 4

Posted: Tue Jul 10, 2018 9:57 pm
by rioprelude
I purchased a 2.7L Type4 engine from Jakob @ GetBackOnTrack about 4 years ago, and I'm finally ready to install it in my project vehicle. I wanted to verify the jetting, ignition, and steps to get it running after sitting for so long.
Engine Specs:
DPR 78mm x 105mm Duetz Cylinders w/ JE Pistons
Webcam 86C
AMC Heads 46/38 Valves + dual springs w/ matching manifolds
Full flow Oil + Electric cooler (already in car w/ type 1 engine)
Horizontal 911 cooling

Carb Specs:
Rebuilt Dellorto DRLA 48mm carbs from BlackLine Racing:
Air: 220,
Main: 200,
Idle: .75,
Venturi: 40mm,
E-Tube: #2

MSD Distributer/Blaster Coil/6A Ignition (already in the car w/ the type 1 engine)

Type 4 Sidewinder 1 5/8" from Tiger @ A-1 Performance w/ O-2 sensor bung

1. Does the jetting seem close?
2. Do you think I need to replace the valve springs from sitting so long?
3. I remember seeing an old post about building oil pressure by manually spinning the pump before trying to crank?


Re: Jetting + General advice for my 2.7L Type 4

Posted: Wed Jul 11, 2018 8:21 am
by wreck
I've a similar set up , 103x78 , scat C55 with 48 trijet Dellortos but with a bigger header , I'm still trying to find the right jet combination , right now I've 40mm vents 185 mains 195 airs with 45 enrichment jets . I've run 42mm vents with 205 mains with 195 airs with the enrichment jets blocked off ,(that had a lean midrange going from high 11's to mid 14's back to low 12s on a dyno run) all with the .2 emulsion .I've ordered .3 emulsions and will be trailing those. I'm down to a 63 idle jet with gives 13 to 1 cruise on the progression circuit .I found 75 idles way to rich and the engine would load up at idle .
I'd be inclined to remove the springs and at least get them checked for spring pressure . I spun the motor over on the starter with no plugs in it to get oil pressure , then fired it up .

Re: Jetting + General advice for my 2.7L Type 4

Posted: Wed Jul 11, 2018 9:16 am
by Steve Arndt
Jakob is very active on his personal and business pages on facebook. Ask his advice on the springs. I would say you are fine to use them as is as a guess. Get his advice on break in oil / additives as well. That is critical.

Re: Jetting + General advice for my 2.7L Type 4

Posted: Wed Jul 11, 2018 9:42 am
by rioprelude
@Wreck, I'll buy some additional jets and pick up an air/fuel ratio gauge to monitor the mixture ratio.

@Steve: I did ping him on Facebook, and he though the springs would be ok, but mentioned building oil pressure to protect the bearings.

Appreciate the feedback, just wanted to get everyone's input, since this is a pretty active forum.