283 build questions for Don Jacks

[John1]

Looking for a little more info from Don Jacks so figured I should start my own thread. Collecting parts for a cruiser 283 build going in a 50 chevy pickup. At Don's suggestion I just picked up a set of 305 L30 vortec heads. In the build Don outlined, it sounds like the heads were left stock, there was no mention of any port work being done, is this correct? The second question is about the cam. Current budget makes the use of a roller doubtful, so I've been looking at flat tappets. I've found a Lunati voodoo grind that looks good and am looking for a little feedback. The part # is 10120700, lift is .437 and .454 , with duration at 207 and 213 at .050. The truck probably weighs 34 - 3500 lbs, has a 3.55 gear, a 2004r, and a 2400 stall converter. I plan on using the recommended Performer EPS converted to port injection run by a megasquirt controller. The truck currently is running a v6 using the megasquirt so I'm very comfortable with it. I am looking for good driveability and mileage rather than power. Any and all recommendations are welcome.

Thanks, John

 

[1961BelAir427]

That is almost the same cam specs as a stock 1988 - 89 Tuned Port 350. I think those are 207/213 @ .050" and .415"/.430" on a 117 LSA. Hydraulic Roller cam.

Your Voodoo should have no lope at all even in the little 283 unless the lobe separation is very tight.....even then it should be extremely mild.

Also, I've always heard that dual plane intakes such as your planned Performer EPS do not convert very easily to port fuel injection. The runners being on different planes make mounting injectors and fuel rails difficult.

The cam specs are what got me to thinking about the Tuned Port, but come to think of it......you could pick up a Vortec TPI base from Edelbrock and use runners, plenum, and throttle body from any TPI engine from 85-92 and have one slick set up. 19# injectors were stock with 305's......22# with 350's.......24# with the later LT1 engines.

TPI systems are notorious for being very RPM limited, but my old '89 Formula 350 ran extremely hard up to 5500 RPM. It peaked lower probably around 4500, but instead of falling off quickly after peak it would just level out and continue to pull hard for another 1000 rpm. Those same long runners that hurt upper rpm's add a ton of TQ. That thing felt like a big block in the mid-range. Much stronger pulling than either of my LT1 cars even though they are rated at 70 more HP.

On a smaller engine like your 283 the rpm range will be higher since you will be feeding the same airflow to smaller cubes.

I bet you could have a neat little engine that will pull to 6000 or 6250 rpm (which is as far as that cam will won't to go), feel bigger than it actually is in the torque department, and depending on the rest of your drivetrain....approach 30 MPG's.

The 89 Formula 350 I mentioned got a best of 26 with it's 700r4 transmission and stock 3.27:1 gears. The engine was bone stock internally with the main changes being shorty headers and no catalytic convertors. It would run 8.80 in the 1/8th mile.

 

[Don Jacks]

Okay John,we did no port work on the Vortec heads,just a valve job.Two things to note on any Vortec head,First,check the stock valves.1996,and 1997 valves didn't have the valves back cut,the 1998-2001 did.This factory modification was worth 10 more hp according to the factory.Second,Make certian that whoever does you valve job duplicates the factory valve job exactly.There are cutters for this.Some of the best head porters in the country have stated that the factory valve job is impossible to improve on,and that anything else hurts the flow.These guys are way above my pay grade,so I take it to heart,and haven't been less than amazed at how well these heads work in a mild-moderate application.They are ,by far,the best bang for the buck out there.I like Jason's suggestion on the TPI,BUT be sitting down when you price the TPI/Vortec manifold !A used TPI set up can be found fairly cheaply for the runners,plenum,throttle body,and fuel rails,and if from a 350 engine,you could get by with the stock injectors,and an adjustable regulator.Your Mega-Squirt can handle this.I think I'd go up one size over your choice of cams,but even then you'll lose about 25 ft.lbs of torque to what the engine will produce with the roller set up.With a little minor grinding,and drilling three holes,you can use the factory roller lifters from the 60 degree v6 [3.1-3.4] engines,the factory lifter spider,and,the lifter retainers,and have a lot less in the conversion.Since the engine was going to be limited to less than 6,000 rpm.that's what we did.

 

[John1]

I currently am running an Edelbrock Performer with port injection so installing injector bungs isn't a concern. I've run the current engine with both a converted single plane and the dual plane and the dual plane improved low speed driveability/torque a bunch. I actually had thought about the TPI with the vortec base, but I don't like the look or the cost. I've even considered a dual four intake with a pair of 2 barrel throttle bodies just to be different, but will probably settle on the single four intake. (easier and cheaper) I'm currently running a 2 barrel throttle body off a 5.9 Dodge pickup using a mopar adaptor to mount it on the intake. I would just move this over to the 283. I picked up the heads last weekend and already have them disassembled, the valves are backcut and the guides are tight. Should be a easy rebuild on the heads. I'm familiar with the roller cam conversion using the V6 rollers but I've never had a chance to talk to anyone who has actually done it. One source I read was concerned about the roller followers restricting oil flow to the top end but the concern wasn't substantiated. Any concerns? I'll keep my eyes open for some factory roller parts and will probably go that route. One question I forgot to ask concerned the decking of the block. With the pistons used, I'm assuming the deck height was cut to 9.005 to obtain the zero deck. If so, that means .020 was taken off the decks. Did this cause any intake alignment issues? If so, did you cut the face of the heads or the intake? Thanks for all the assistance.

John

 

[Don Jacks]

I've done this conversion on four small blocks over the last 6 years,no issues,but I use a high volume oil pump as well.What we did was mock up the engine,measure.then had the decks cut to achieve zero deck.We also had the heads lightly surfaced.No modifications were done to the EPS manifold,or seemed to be needed.The cam in the 292[.06o over 283] was a Howard's grind,number 110315.It has a duration of 262-268 advertised,209-215 @ .050.and the lift was .465 in, .470 ex.That throttle body will move all the air this engine will need with these heads,and the EPS manifold.You'll likely need to go up a size on the injectors. These Vortec heads work best with no more than 34-35 degrees at 3,000,plus vacuum advance.

 

[Don Jacks]

One more thing,if you use a .028 GM head gasket,you'll have a compression ratio of 9.5-1.That's a quarter of a point more than the common Fel-Pro gasket,and with the growth pattern and very tight piston to wall clearances [.0015-.002] used on these pistons,your .028 quench distance will not be any issue n this under 6,000 rpm engine.

 

[John1]

Thanks for the info, it's a big help. I've now got a firm plan to follow.

John

 

[Don Jacks]

Let us know how it works out for you,John.Good luck.