Anyone do just a cam swap in your LB9?

I rebuilt one, and I put a Ramjet 350 cam in it. (intake / exhaust duration @ 0.05 197/207 lift .430/.450 lobe centers 106atdc/112btdc lCL 109)

I have not done the heads yet (081 casting), but I'm just gonna re-lap and revalve with some comp 981-16 springs. Was gonna stick this in one of my boats.

Do you think it will make 260hp ?


-- Joe

 

Wheels? No

Crank, might. Most bolt on L98's which very similar cam make 240-250's whp. Lb9 would be atleast 20 less, probably a good bit less like 30.

 

I did a ZZ2 cam in a 100% stock 92 305 long block yrs ago. put it in my car and ran 13.90s with it. (the car had tons of other mods and ran low 12s with the old 350)

 

Crank. No wheels on a boat

My 260hp 350 cid split 6" crack about 1/2" below the head from freezing. I'm going to try to epoxy it since it runs, doesn't seem to have water in oil, etc. But I have a feeling the epoxy won't work.

The 260hp is flat tappet cam, whereas the LB9 I have a roller cam. So I wonder if the roller cam, and being aggressive will make up for the lack of displacement.

-- Joe

 

Hrmm. ZZ2 is quite a bit bigger cam.

-- Joe

 

The 90-92 LB9 cam IMO is a better cam than the Ramjet cam. I know it doesn't have as much lift but it does have more duration. I don't see where there will be more power to gain by going with the Ramjet cam. Maybe your LB9 cam is pre-90 though before they got the L98 cam though? Still bet it can make 220-230 HP.

 

The 90-92 LB9 cam is:

202/207 .413/.428 114.5

So it has a little more duration and less lift, but a wider LSA.

Anyway, Ramjet cam is used because it's the cam approved for marine use. I'm not sure if the L98 cam might be an issue (with exhaust sucking water).

If I had through-hull exhaust, I probably would have done something different but I'm not trying to stray too far from normal.

What is interesting is the ramjet 350 cam is 280hp with 083 heads on a 9:1 350. That is quite a bit more than an L98, so it seems to be a better cam.

-- Joe

 

I'm betting the intake is the power difference

 

Its all intake. Hsr swap on a l98 is 20-25 whp

 

Cast iron intake and 4bbl quadrajet?

I know TPI blows, but that bad?

-- Joe

 

I also believe the L98's crank rating of 230-240 hp was not really accurate and actually under rated. They will dyno 210-220 in perfect form. 80% drivetrain efficiency, thats 260-270 crank

 

Totally agree with the HP being under rated. Ive heard several guys say they will dyno 210+ rwhp. Ive also seen a guy that was having trouble with his TPI put a carb on a stock L98 down to the horrible exhaust manifolds and it hit 13.9s at the track after running 14.4s with the TPI setup.

 

Interesting..

So, with all that discussed, do you think the LB9 with the Ramjet cam, iron dual plane and quadrajet will make 260hp or do you think the boat is going slower?? haha.

-- Joe

 

I think it will be close but something like the zz4 cam would be better imo

My 91 z is terribly slow. It supposively has L98 cam. I highly doubt it would run high 14's. My guess is 180 whp at best. Intake exhaust mods may get 200-210, hard to say. More cam would help imo

 

The ramjet is rated with that EFI intake iirc but I'd bet the 4bbl Qjet would do it as well.

 

I was referring to the Mercruiser engines. The 083 (L05 head?) 350 with the roller cam is 280 hp, where the flat tappet cam is 260. Both have iron intake and a 4bbl quadrabog.

The Vortec Marine engines are 300+hp, some EFI some still carb.

I've got piles of junk in my shop, but only one complete shortblock and it's starting to get warm out

I'm going to try and epoxy this thing tomorrow, but if it fails I'm going to have to use the LB9 with the Ramjet/mercruiser cam.

-- Joe

 

083 heads were the 350 L98 iron head. Much better " according to most" than the L05 #193 swirlport head. I could see it making 280 HP with the right intake and carb. Ive heard lots of folks say even the 081 TPI 305 head is better than the old 882s and 193s. Ive seen people run the 081s and do pretty well on 350 engines.

 

I've gotta do some spring cleaning in the shop. I've got about 5 or 6 sets of SBC heads. I should start throwing out the ones that will never be worth anything. I know at least two sets are swirl port because they came off TBI trucks, so I guess those are junk. A few sets of 14096217.

I've got some L31 heads too I really need to get around to using on something..

-- Joe

 

Wish you were closer id like to get a good set they are hard to come by around here you may as well buy a new set.

 

Really? I've got some X-Rods and some GM nodular performance cranks too, but nobody around here seems to buy stock stuff.

-- Joe

 

swirl port heads = a 1 time use boat anchor

 

This happened to me. 1992 NHRA rated l98 in my camaro 285 hp for class racing