New Engine Help

[Engine07]

Man this Arkansas weather has been crazy lately. Putting slow delay on my plans, lol. I went to the junk yard and pulled a rear axle from a 94 suburban for the larger drum brakes on the rear and also an 8.25 front axle so I could work in the meantime. I have my new gears in both as well as all new bearings and seals. Got 4.10 ratio g2 gears with Detroit truetrac in the rear. Have the engine block cleaned up at .030 over and about to start clearance for the stroker and measuring for the deck height. I am going to go with the bow tie heads on this build being a 383 for the slightly larger exhaust ports. I have another question now that the engine is up sized to 383 instead of 355. The original cam I was looking at was lunati 213/219 @.050. My question is will the larger cubes eat up enough of the cam that I could use the gm hot cam and still be tunable at idle? Gm hot cam specs- 218/228@.050 112lsa with .525 lift? It is also about 100 dollars cheaper than the lunati.

[lionelhutz]

I think you'll find the general consensus is that you can get a better cam than the GM hotcam. It's not a terrible cam, but I think you could get one with a better lobe design that would perform better.

[Engine07]

Along what lines would you recommend? The main goals of this engine are to be reliable, streetable, pull my lightweight boat, and have a little fun offroad every now and then. Looking for more of a torque beast than a horsepower monster. I am new to the whole tbi tuning so being within specs of what I will be able to tune is all new to me.

[lionelhutz]

As a quick pick, I'd expect something like the Comp Cams 08-423-8 to be a better cam.

[brian617]

As a quick pick, I'd expect something like the Comp Cams 08-423-8 to be a better cam.

Isn't the lobe sep a little tight for that much duration for good strong idle vacuum?

[Engine07]

I was thinking that but I'm not familiar with tuning these things yet with mods lol. I know the cam I chose would def not be my choice if I was going carb or max power but I was thinking great torque, good power, and being done by 5500. Oh and being able to tune lol. I wouldn't mind stepping up a bit if I don't lose much torque and I'm still able to tune. As of now I'm looking at 454 tb with 454 injectors for fueling. I think around 670cfm should be plenty for this engine or do you recommend a bored out 454 tb?

[Roadknee]

You won't need a lot of cam to meet your goals. Take a look at this 383 with Vortec heads.

http://www.superchevy.com/how-to/578...e-engine-test/

With the "Hot" cam

http://www.superchevy.com/how-to/148...-engine-build/

I think something in between the two would be ideal such as

http://www.compcams.com/Company/CC/c...?csid=186&sb=2

I'd run 1.6 rockers on the intake and 1.5 on the exhaust, and step up to the premium beehive springs and retainers. Even with the 110 lobe separation this cam would be compatible with your TBI.

I think the larger comp cam Lionel mentioned would be challenging to tune with TBI. I have a TBI 383 with a 223/228@0.050" mild hydraulic flat tappet and it needs 13:1 afr at idle and less than 14.7 below 1,500 rpm to run well. I've tuned a port injected 406 SBC with a Lunati 219/227 efi hydraulic roller cam. It's on the edge of being able to run closed loop idle. It runs smoother at 13.5:1 idle, but can get by at 14.7:1. Port injected can handle more cam because fuel distribution is better.

[BLG355]

I am running an Isky 211252/257 cam. Ton's of bottom end and pulls hard through the top end too. it's a great all around cam for street use, specially in my heavy pickup. it will idles super smooth too. I run 1.6 rockers and I am very happy with it. I had my shift points as high as 5800, still pulled good but was pretty much done.

http://iskycams.com/timingchart.php?...ber=210252/257

[Fast355]

You won't need a lot of cam to meet your goals. Take a look at this 383 with Vortec heads.

http://www.superchevy.com/how-to/578...e-engine-test/

With the "Hot" cam

http://www.superchevy.com/how-to/148...-engine-build/

I think something in between the two would be ideal such as

http://www.compcams.com/Company/CC/c...?csid=186&sb=2

I'd run 1.6 rockers on the intake and 1.5 on the exhaust, and step up to the premium beehive springs and retainers. Even with the 110 lobe separation this cam would be compatible with your TBI.

I think the larger comp cam Lionel mentioned would be challenging to tune with TBI. I have a TBI 383 with a 223/228@0.050" mild hydraulic flat tappet and it needs 13:1 afr at idle and less than 14.7 below 1,500 rpm to run well. I've tuned a port injected 406 SBC with a Lunati 219/227 efi hydraulic roller cam. It's on the edge of being able to run closed loop idle. It runs smoother at 13.5:1 idle, but can get by at 14.7:1. Port injected can handle more cam because fuel distribution is better.

I had 232/240 @ .050 on a 110* LSA in a 10.5:1 Vortec head 383 with a highly modified TPI setup on it. Never had an issue getting it to idle in closed loop. Had to adjust the o2 windows and what not to get a clean idle, but it would run in closed loop at about 14:1 air/fuel ratio. The more overlap you have the lower your target o2 voltages need to be set to get the same air/fuel mixture.

[lionelhutz]

I think Roadknee picked the better Comp cam. Your initial Lunati pick should be good too.

You'd probably find the XR276HR is too much in the truck. I was suggesting that as a Hot cam replacement but looking again, I now think the XR270HR is a more comparable but better replacement for the Hot cam.

Just to throw another cam out there. What does everyone think of the Comp 266HR-14? - http://www.compcams.com/Company/CC/c...?csid=213&sb=2

[Roadknee]

Just to throw another cam out there. What does everyone think of the Comp 266HR-14? - http://www.compcams.com/Company/CC/c...?csid=213&sb=2

i think either of the comps, the lunati, and the hot would all work well. I like the shorter duration and tighter lsa of the comp for better low and mid range. Should pull strong well past 5k and have great drivability.

[Engine07]

I appreciate all of you guys help on here, especially with what can and can't be tuned. I'm thinking whenever I get the engine finished, having it dyno'd so we can put the results up here for what can be achieved with tbi vs carb and maybe coming up with a list for guys like me that aren't very familiar with tbi tuning such as what duration and lsa can be tuned on tbi vs the engine displacement that makes them seem smaller. I'll update with specs and pictures on the engine build too so anyone who searches and finds this in the future will have all the specs and final hp, tq, and driveability. Just got finished running the final pattern on my rear gears and getting it buttoned up so the shop is about to get cleaned in prep to start the engine. Crank and pistons should be here Wednesday!!

[Fast355]

I appreciate all of you guys help on here, especially with what can and can't be tuned. I'm thinking whenever I get the engine finished, having it dyno'd so we can put the results up here for what can be achieved with tbi vs carb and maybe coming up with a list for guys like me that aren't very familiar with tbi tuning such as what duration and lsa can be tuned on tbi vs the engine displacement that makes them seem smaller. I'll update with specs and pictures on the engine build too so anyone who searches and finds this in the future will have all the specs and final hp, tq, and driveability. Just got finished running the final pattern on my rear gears and getting it buttoned up so the shop is about to get cleaned in prep to start the engine. Crank and pistons should be here Wednesday!!

I am not sure if Lunati still has these on closeout but I bought one of these improved Hotcams for $70.00+shipping from Lunati and have it in my closet for a future project.

http://www.lunatipower.com/Product.aspx?id=2607

[Engine07]

Awesome!! I emailed them just now to see if any more are available. Hopefully I can get lucky too.

[Engine07]

Ok guys, another question...looking around for parts and I located a holley 670 throttle body for pretty cheap. What are you guys experience with quality of these? I have heard about injector seal issues and such but is that just with the throttle body casting or is it only a holley injector issue? Will it be ok if I get this and change out to a set of flow matched 454 injectors, or is it worth messing with?