Hi guys, I have a junky rebuilt 305 roller motor in a 1983 TA that I am going to slightly upgrade until I can replace it with a non-craptastic motor. Although it's a roller block, I have the stock 83 Qjet, and all emissions equipment, on top of it. I have a whole bunch of very low mileage flat tappet cam and lifter sets that I have pulled from other cars, one of which I want to replace the tiny roller cam in the 305 with. I normally would keep a roller block roller because it's a much better cam design, but in this case, with a 305, I am not too worried about it because I know it's not going to really be fast enough to worry about.

I have a flat tappet Comp 275 DEH 219/229 @0.05 0.462"/0.482" cam, 110 LSA, that I was running in a 327 for about 1000 miles, w/ numbered and matched lifter set, that I'd like to use in the 305 for now. The 327 was MAF EFI and I burned my own chips for it. This cam ran fine w/ computer control, except for fooling the O2 at idle due to the overlap. I would have to over-enrichen the mix at idle to get the narrow band O2 to be happy, because the overlap was pumping extra intake charge past the O2 and making it think it was lean.

I am worried about how the way more primitive CCC system will handle this cam. I am also worried about how much bottom end the 305 will have. I hate 305s, it is just too small of a bore to be worth making power with, but anything is going to be better than tha 0.350" peanut TPI roller cam in it, for now.

Thanks

 

Hi 327, I dunno how close my setup is to what you're looking for but I'm running an XE262H-4 cam in my 350, CC-Qjet and 3.73 gears. I used to have the peanut cam the universal 350s came with. The XE262 computer cam specs out at 218/224 @.05", 262/270 adv. duration, .464/.470 lift, & 114 sep. I love this setup. At first I was disappointed in the (little) loss of low end torque, but it pulls so much harder past 3500rpm that I forgot about it quickly. It still has plenty of low end though, lugging around town is no big deal I usually am in 4th gear @ 35mph.

 

The key to all computer cams CCC, TPI or otherwise is the separation angle... 112 is the minimum 110s will probably cause issues regardless of the duration... I know that 216's@0.050 and 112 separation angle will work... I also know that most 110 cams will cause the stock computer to have fits.

Cams with 113* or 114* will work even better with the computer.

The other thing to focus on with CCC is your compression ratio... Any change? If you have, run a ECM and PROM from a car with a similar compression ratio. This will give you optimal timing... If you have gone hog wild on the compression and are picking a 110 cam to bleed off some cylinder pressure you will need to re-program your PROM.

 

Stab it in and find out. I've run cams as big as the mid 220s with CCQJets on a 350ci engine (can't remember if the cam was 110 or 112 LSA, but it definitely wasn't any wider than that). That was definitely borderline before the O2 sensor starting acting up in a similar way to what you describe in your fuel injected engine.

 

Thanks guys. Yeah I know 114 LSA's are more computer friendly, but they also make the cam very lazy. I just bought a comp cam retro roller on a 112 LSA for my MAF EFI'd 327.

But for this budget 305, the flat tappet cam I have is on a 110 LSA. I know it will be borderline w/ the O2. I have run 232 @0.05 cams in a MAF efi'd car with 108 LSA and it drove great, but idle was very difficult to tune.

I probably should buy a different cam but I have 3 near-new flat tappet cams in the garage! I hate to throw them on ebay and get $30 for them when they are so new...

Oh well I'll figure it out. THanks for the input

 

Someone will probably disagree with what I'm about to say.. but the wider LSA's don't make a lazy cam... They just put more emphasis on the quality of flow of your heads...

Tight LSA cams with 108-110* are becoming somewhat "old school". The "tight" cams were used to help bleed off cylinder pressure on old school combustion chambers. But new "kidney bean" chambers will run low 10's:1 on even crummy 87 octane. With modern heads you actually want a wider LSA and build pressure not bleed it off. Tight LSA also increased the valve overlap that helped fill the cylinders over 4000 rpm... But the great flowing heads they make now don't need this help.

If you have crummy flowing "dog dish" chambered heads then ya you need a tight LSA... Modern "fast burn" heads will work better with 112-114*

Just my opinion.

 

I've run the xe256 in an LG4 with a 110 separation with good idle. Maybe not a 'stock' 500 rpm idle, around 700 rpm if I recall correctly. I was concerned as well, but the dwell readings at idle didn't 'hunt' anymore really than the stock setup. It was actually pretty tight.

Wasn't stock exhaust, of course and a lot of other factors may come into play.

Like you, I had the cam already with nothing else to put it in. Who really 'plans' a build? We just stick parts we find in and see what happens.

 

I planned the current roller upgrade and new heads on my 327 and matched all of the parts. The 305 I am working on w/ the LG4 CCC carb on it just isn't worth the thought, though, because it is a short-term engine. It is getting replaced at some point, but it's my brother's car, so God knows when he will actually do anything about it. I put the 305 in the car Until then, the awful 0.350" TPI cam that is in the 87 305 in the car must come out at all costs.

Naf, the XE 256 is a lot smaller than the Comp DEH 275 cam I intend to put in the 305, especially in the duration department, (mine is 219/229 @0.05, the XE 256 is only 212/218). I have run this 275 cam and it idles choppy, it is not a smooth idle by any means. It lopes quite a bit. I probably should just stick the LT1 roller cam in the 305. The only reason I wouldn't go this route is I hate having to run an inline electric, and I am sure as heck not going to drop the tank on the car to install an in-tank electric (plus I don't know that a 5 psi intank electric exists for a 3rd gen).

I have 3 barely used flat tappet cams including the 275, but they are all probably too big for the 305. LOL Actually this is telling me that the 305 is too small for what I want to do, but I knew that anyway. Thanks for the advice guys.

 

Yeah, that's one of those 'other factors that may come into play'. I was still pleased with the way the ccc-qjet handled the tight lobe sep, as I was told by many that it wouldn't work.

If you've got the pusher pump in the tank (later LG4) an in-line pump wouldn't be bad. I ran my '87 camaro's 350 with a little fenderwell mounted pusher that came with the motor when I bought it used (no fuel pump bore). Since swapped out for something better mounted in the rear. Run it through a stock replacement mech fuel pump (not operating) for return using the stock lines.

 

The car is built on an 83, so there is no pump in the tank. The LT1 cam I have has no fuel pump lobe, so it would have to be handled entirely by an inline electric. I hate having to hang an electric under a street car.

 

Saw it was an '83 but remembered something about an L69 from before?

Kinda agree, by the time you pay for (and install) an in-line pump you could have just spent the $ on the cam you really want.

 

The engine is a 1987 305 TPI that was transplanted into the 1983 Firebird, previous V6 car. I took all of the engine wiring and emissions equipment off a donor 1983 LG4 car, so the 1983 Fierbird is now all-stock appearing underhood, with a roller 305 long block. It's still nothing to write home about, at all. The 2.8 is such a god awful engine that I could not respect myself if I had to drive a 3rd gen with a 2.8 in it, so I put the 305 in to move the car around while I was doing body and paint, and driving the car between states. It is grunty off idle but is a really wheezy engine. Good enough for now though.