I'm buying an lo5 tomorrow morning, has less than 80k miles.... I wanna upgrade my cam and keep it mostly stock til I get some money. I have a performer rpm intake to go with it. I also wanna run 1.6 roller rockers...

What cam could I use, SAFELY, with the 1.6 rr without having to mess with the heads, for now?

The lt1 cam maybe? Thanks guys

 

An LT1 Cam part # 12551705 and has I/E .447/.459 valve lift with 1.5 ratio rockers (.298/.306 cam lobe lift). It is a roller camshaft.

Depending on application the LO5 may have either flat tappet cam (majority of LO5 were in trucks) with I/E .385"/.403"; . A small number of LO5 produced were rollers and between 1987 to 1995 can be found in B-Cars with similar cam shaft profile. However the same swirl heads (14102193) were used in either flat tappet or roller engines.

When you get your LO5 make sure that is roller cam ready and has spider bosses in the lifter alley - '880 blocks have these features cast or otherwise take intake off. Spider, dog-bone plates, roller lifters, cam retention plate can be sourced.

With 80k on the clock I would replace springs and seals. Installed pressure and max valve lift should be checked to make sure that coil does not get into a bind. It is better to yank heads off and take it to machine shop to be checked - you already removing intake manifold to install LT1 cam. Head gaskets are not that expensive.


//RF

 

I will check, definitely. But I thought all lo5's were set up for roller cam, just that not all came with the roller cam (truck applications). I'll probably change springs definitely, what would be the best for these heads (without being too bad)?

Are you saying, if the motor isn't roller ready, the lt1 camshaft won't work?

Would the heads accept 1.6 rr with the lt1 cam if it were roller ready? And would I need taller valve covers?

 

In 1986 SBC transitioned from 2 piece RMS to 1 piece RMS, but provisions for roller cam did not appear until 1987. Even after 87 truck LO5 could potentially use blocks that were cast in 1986 and thus did not had provisions for roller cam spider bosses.

Do yourself a favor pull intake and make sure that LO5 has cast bosses. Even if the LO5 is equipped with a flat tappet cam it can be converted (drill and tap bosses) to a roller - LT1 cam - provided that it has bosses for "a spider".

This is what a roller block with a spider should look like (photo of '97 L31 short block):

 

This is out of a 95 truck, so maybe it will... Thanks

 

Ok new question, lol

Just bought my intake-$75 (rpm brand new. Installed once, never used)
Motor tomorrow-$400 (95 suburban)
Heads tomorrow-$75 ( support .550 lift, new springs, 2.02/1.60 valves, new valves, screw in studs)
Roller rockers-$25 ( from guy I got intake from, brand new never used, selling all his sbc stuff for BBC)

Now what cam would be best if roller motor?

What cam if not roller?

I'd prefer to go roller, but it is what it is, thanks

 

Also forgot my main question... I have a tbi car, wanna keep it that way at least for now. What mods to my tbi do I need to support those mods?

Would just my injectors need to be changed? Would I need the computer or a computer from a similar lo5 car? This is my first build.

 

That's what my engine looks like

 

What pistons are those and are they good? That's what mine look like

 

You're going to need headers as well, otherwise a cam with 1.6RR's is just going to bog you down. Look for an LT1 cam- that should take care of your needs. If you want to stay with the TBI you're going to need to either program or run EBL Flash. If you run EBL Flash it would be in your best interests to upgrade your fuel pressure regulator to a vacuum referenced unit (or fabricate one from your current FPR like I've done). That way you'll still have good idle qualities while getting a sufficient amount of fuel under load. Right now you have 55 lb/hr injectors. You can either keep those or move up to 61 lb/hr injectors from a Caprice cop car. If you decided to stay with the injectors that come on the motor you'll want to get them cleaned, as often these engines go their whole lives without having the injectors cleaned and flow matched.

 

I have headers already, so covered there.

I don't understand the ebl flash and stuff.
Is there a link to modding the FPR?
The engine I bought comes with the 350 injectors, should I go bigger?

I'd go carb, as they are abundant here for cheap, but I don't wanna go through the hassle of modding my fuel pump system and everything linked to it. I now have two tbi, one on my 305 one on my 350.

 

You don't have to mod your fuel system really, just add an adjustable FPR. I would keep TBI if I could though, for sure.

 

That's what I was hoping to do, I don't wanna get rid of the tbi. I'm sure there is somewhere on here that shows or explains the FPR making it adjustable? I'll look, thanks

 

The Lt1 cam is probably about as big as you wanna go with your TBI for now. Adding roller rockers will just increase the lift by about .30. That would then exceed the lift of your springs. Lt1 cam on its own with stock 1.5 rockers is already pushing it.

 

Not sure, but you may wanna get a custom chip burned for that thing now that you have a 350. As for the cam, you can either put 1.6 roller rockers on with the stock cam or use 1.5 stock rockers and the Lt1 cam. 1.6's will fit under the valve covers fine if you use certain brands. I know comp cams roller tip work fine.

 

I'm not goin to use the lo5 heads anymore, I have a set of 67-75 350 heads. Valve job, ported/polished, 2.02/1.60 valves, and brand new seats and springs... They were made to hold a .550 lift, I don't wanna go that high though, I'm looking for a total with rr's to be at .500, no higher, so the lt1 cam with 1.6rr would be perfect, right? That should be .495 right?

 

Bigger injectors if you don't want to spend $350 on EBL Flash (which is awesome, I highly recommend it)- you can't program a chip to accept a VAFPR/VRFPR. In my thread you can see a schematic I drew up for a Vacuum Referenced Fuel Pressure Regulator, I'll be updating it shortly with pictures of my finished unit. It's really not that hard

https://www.thirdgen.org/forums/tbi/...tbi-vrfpr.html

Edit: Here's my build thread which might help answer some of your questions (mainly the first page).

https://www.thirdgen.org/forums/tbi/...ld-thread.html

 

Awesome, yeah my engine came complete, brackets/pulleys/tbi/ etc. So I have the injectors for a 350.

 

It will run better with an AFPR than with bigger injectors. You have better fuel atomization with smaller injectors anyway. If you add bigger injectors you WILL NEED a tune. No way around that.

 

yes

 

Sweet, that's what I will do. Thanks guys!!

 

I read that article and got to the quote: "curse this auto transmission, if I had a manual...", I have a manual, what the deal? Tune or no tune? What is the reasoning behind the quote?

 

Get a tune after you put in the 350. You will need a 350 chip anyway or a retune of your current one. 350 cars did not come with a manual transmission because of the amount of torque the 350 engine produced. I would be easy on your car after the engine swap.

 

That was the plan, not too beat on it, I was also going to get a pro 5.0 shifter, to help in lengthening the tranny. It's low mileage tranny with new clutch and all.

 

Ok, now that I know my block is a roller block... Lifters: are they reusable with an lt1 cam, or need I replace them with a specific type?

 

re-usable.

 

Cool deal, thanks

 

I have a oppturnity to buy the same at 500 bucks with computer, the fuel pump crashed on the guy shortly after it crashed and is in need of money. there is a tag soddered on the block saying referbushed. I pulled the valve covers off in it was like new in side. what would you do