Sleeper Engine

ed455

OK, been putting this . . . um . . . 290 AMC engine together. Building this motor to LOOK like a completely stock 290. No chrome. No billet. No bare aluminum. The performance parts that are obvious are at least partially hidden. A passing glance will say: "stocker."

The following are assembly pics with the (nearly) final appearance at the end.

Block machined and painted (.020" overbore). It was assembled with Milodon main studs.

New Venolia 10.5:1 pistons.

Degreeing the cam:

Fresh, ported 090 heads with SBC 2.05"/1.650" valves. ARP studs, Comp Pro Magnum rockers. 8.250" chromoly one-piece pushrods, etc. All being assembled.

The Holley 750DP built be ME. How do I hide it without sacrificing performance?

Here's how I hide it.

Carter High Performance fuel pump (M6906) modified by me. Inner passages opened, inlet and outlet drilled and tapped to 3/8 NPT. They come with 1/4 NPT inlet and outlet (too small IMO).

Here it is almost finished. I'm still waiting for my Bulltear 7.5 quart pan which, of course, I will paint stock AMC blue.

dwg86

Just some info on the main studs. I used main studs on my 401 with a Milodon iol pan(dual external pick-up). The pan wouldn't clear the hex nuts. I had to buy 12 point nuts for the rear main cap.

jeepsr4ever

Awesome!

ed455

dwg86 wrote
Just some info on the main studs. I used main studs on my 401 with a Milodon iol pan(dual external pick-up). The pan wouldn't clear the hex nuts. I had to buy 12 point nuts for the rear main cap.

I'm using the Bulltear pan, so we'll see. Back in my Oldsmobile days, we would ding the pan with a ball peen to clear studs.

Ibby

Wicked looking motor. I'm curious, where does a person get the stock AMC engine paint? I can't seem to find it anywhere.

tufcj

For 1968-1972 it's Seymour EN-66. You can get it in a spray can from Eastwood and several other suppliers. This is the Aqua (I think is was Alamosa Aqua Metallic). Ditzler # DQE2005

http://www.eastwoodco.com/jump.jsp?itemID=138&itemType=PRODUCT

For 1973 up, it was the same as the Caravelle Blue body color. Any automotive paint shop should have the code and formula, most can put it in a spray can for an extra charge. Any lacquer will do, it doesn't need to be high temp. Ditzler # DQE13730

Bob
tufcj

ed455

I bought it direct from Seymour. Pretty cheap too.

AMX69PHATTY

Looks good. Better have some really good mufflers trting to claim a 290. Would think the 401 could handle an 850 cfm carb. The 850 is the only double pumper with all 4 butterflies at 1-3/4" dia. All other DP's have all 4 butterflies at 1-11/16 dia. except the smallest one, 600 cfm, which has all 4 at 1-9/16 dia.

ed455

Could probably handle an 850 BUT, the Holley 850 is one of the poorest Holley carbs made, especially for velocity. Yes, I have run them. The big venturi used to get 850 CFM is a POOR venturi. The velocity needed for a carb to run properly is attained by a venturi. This is, of course a smooth, necked down, section in a tubular opening. When it comes to holley 4150 carbs the smaller the carb, the tighter the venturi. The 600-800 DP carbs all have 1-11/16 throttle bores. The flow change is from the size of the venturi (necked -down section). For that reason, smaller Holley carbs have stronger signals to the booster. Testing has shown that in some circumstances, a a small and a big carb will ultimately give the same horsepower, but bottom end response is better with the small carb. The 850 has the bigger throttle bore as an attempt to overcome the poor velocity. The venturi that would allow 850 CFM to flow in a 1-11/16 bore would kill the signal to the boosters because if would be virtually non-existant. 850's on the street frequently have problems with loading up, because of the poor signal to the booster at idle. My 530hp 427 SBC only pulled 675 cfm on the engine dyno, but made the most power with an AED 850 double pumper (modified holley). The 750hp holley and the 950hp Holley each made exactly 3 hp less than the 850. The 750 made 18 more hp at 3000 RPMs. All this rambling tech stuff is to say that a 401 really only *needs* 650CFM +/- and I have found that 75-100 CFM over actual NEED, usually works well in a real life situation. Long story short (too late): I think the 750 will be about right AND driveable.

AMX69PHATTY

Follow what you're saying. Have ran an 0-4781 850 on a 360 for a long time, couple weeks ago freshened up a 0-4779 that was on the shelf and tried it. Lower end is better, but from 3k up there's no comparison to the 850. From 3k up it climbs slower and slower with the 750, the 850 is like it's unleashed. 750 punched at highway speeds, ~3.5k, does almost nothing, the 850 jumps. Torker, 1" 4-hole, headers, auto, 3k stall, 3.73's Know what you're saying, it's such a drag cause the 750 is better for low end and the street but it just doesn't go gangbusters at WOT like the 850 does. What's a hotrodder to do ? :-| That "290" oughtta be sweet. :t: :-|

ed455

How much tuning did you do on the 750?

AMX69PHATTY

Ran pretty well in stock configuration. Pri - #70 jet & 6.5 P.V. & #28 Shooter Sec - #80 jet & no P.V & #31 Shooter Did try jetting up to Pri #73 Sec #83. Idle vacuum is 15 inches so think the 6.5 P.V. was about right. Adjusted Both Pri & Sec Idle speed screws for balance and to ensure Pri was not opened too far or too little. Used #330 Pink pump cams in hole #1. Throttle response was good, but the top end seemed choked off. Did not confirm fully opened at WOT, no one was available to help. Have put the 850 back on, may tweak the 750 some more. Unable to afford a nice ProForm main body like yuors at this time. Would that be one of the things you'd suggest ? The carb you built has a lot of nice improvements.

ed455

Two things, cheapest first.

1" open spacer with the 750, increases your plenum volume. Small plenum volume can make it seem like your carb is too small. I'm assuming you're running a dual plane like an edelbrock Performer or Air Gap, but even a Torker has only a small to moderate plenum volume.
EITHER rework the main body you have, or go Proform. I scored mine on ebay for about $90. However, the factory main body can be reworked in such a way that you still have the good 750 venturi but the carb will flow 30-40 CFM more. If this is an untouched factory body, cut off the choke tower. I use a 4.5" cut off wheel in my drill press. If you decide to do this, there are a couple of other minor details I can help you with (use PM). Once the tower is cut off, then get out the dremel or die grinder (I prefer the dremel because this is fine work) and contour all the sharp edges . I cut off the remnants of the choke horn. A faster way to do this is by the simple installation of a K&N Stubstack:
http://www.knfilters.com/search/product.aspx?Prod=85-0500

Hint: NASCAR makes 800hp with a Holley 830.