Hi all,

I'm currently building up parts for my 383 build and I just wanted to be exactly clear as to what I need to do to Retro Fit an LT1 Camshaft.

I've got a Comp Cams LT1 Cam
Comp Cams Retro Roller Lifters
Timing Set with Torrington Bearing
and a Cam Button

Pushrods - I have a flat cam standard set and a roller cam standard set -will these be OK?

Is this all I need? I beleive the LT1 Cam needs to be modified on the front to remove the pin? What is the exact procedure for the bearings and cam buttons.

I just want to make 100% sure...

 

[QUOTE=dan_t;1565467759]Hi all,

I'm currently building up parts for my 383 build and I just wanted to be exactly clear as to what I need to do to Retro Fit an LT1 Camshaft.

I've got a Comp Cams LT1 Cam
Comp Cams Retro Roller Lifters
Timing Set with Torrington Bearing
and a Cam Button

Pushrods - I have a flat cam standard set and a roller cam standard set -will these be OK?

Is this all I need? I beleive the LT1 Cam needs to be modified on the front to remove the pin? What is the exact procedure for the bearings and cam buttons.

I just want to make 100% sure...[/QUOT

I'm confused about what you're doing. If you're using a LT1 block you don't use a retro-fit cam or retro-fit lifters.

If you're using a NON LT1 block, but the block you're using originally came with a roller cam you still don't use a retro-fit setup.

Only if you are using an early block that originally came with a flat-tappet cam do you need a retro-fit setup.

Blocks that came from the factory with a roller cam don't call for a cam button or three piece Torrington bearing. Only early NON ROLLER blocks need those.

Post details of what parts you have and what you're trying to do so we can remove all the guess-work.

When building a new engine always measure and determine the specific, correct length pushrods to use. Many times you'll end up needing a pushrod length that differs from the stock length rods.

Jake

 

its a GEN1 SBC, Flat Tappet, 2pc Rear Seal, 2 Bolt Main common old school block

Orignally it was designated L83 Crossfire, but phyisicly the same as any L98 up to 1987 I beleive.

 

Then, yes, you need the 3-piece Torrington bearing to go between the timing chain gear and the block. Be sure the get the type that has the backside of the gear machined to allow for the thickness of the bearing. CompCams, and probably others, sell the correct timing chain set with the bearing included.

The thrust buttons come in basically three versions. One type is made of something that looks like nylon, another type is aluminum and the 3rd type has a bearing arrangement that spins on contact with the timing chain cover.

The third type is the best since I've seen the aluminum type drill through the timing chain cover. I don't trust the longevity of the first type. Be sure to lube the Torrington set before installing it; I use assembly lube since it won't drain away.

Another good idea is to get a timing chain cover that's reinforced with a metal tab welded on the inside of the cover in the area where the button would make contact. This'll prevent the cover from flexing when the button makes contact effecting ignition timing.

Get an adjustable pushrod length checking tool to use to determine the correct length pushrod you'll need.

The LT1 cams come with two different pin lengths. I believe, but am not positive, that those two differ from the pre-roller/retro-fit pin length. Someone else will have to chime in on that point.

Jake

 

Heres the bits I got...

Timing Set - http://www.jegs.com/i/JEGS/555/20410//-1
Cam Button - http://www.jegs.com/i/Cloyes/220/9-200/10002/-1
Cam - http://www.jegs.com/i/Comp+Cams/249/07-306-8/10002/-1

Thanks for your help so far...

 

How did you end up with a LT1 cam instead of one specifically meant for your engine?


Jake

 

I believed that the LT1 cam was only different to a normal roller cam in the respect that it had a longer pin on the front. I liked the specs so I just went for it!

Do you think its going to be an issue?

 

does it look like I've got everything that I need?

 

[QUOTE=dan_t;1565498804]I believed that the LT1 cam was only different to a normal roller cam in the respect that it had a longer pin on the front. I liked the specs so I just went for it!

Do you think its going to be an issue?[/QUOTE

No, I don't believe it'll be an issue, just that a regular SB Chevy HR could have been gotten with the same specs and, thus, eliminate the pin length issue. CompCams will grind whatever lobes you want on whatever core you choose.

They ground me one for me using custom lobes found toward the back of their catalog at no extra charge. Took only two days.

I wanted a cam with more aggressive ramps than the off-the-shelf grinds offered. So I chose two of their CRC (Constant Radius of Curveature) series lobes and got more lift in the process.

Jake

 

Correct springs, guide plates, non-self aligning rocker arms/poly-locks, and hardened, one-piece pushrods come to mind. Also valve covers that'll clear the rockers.

Jake

 

I've just got some AFR 195's so I hope that will be covered

 

Just to stress what Jake said: You will need to check push rod length. I suspect what you have will not be correct. Also take a look at the requirement for a different distributor drive gear.

 

where would i find the information for the gear? I've not opened the Camshaft box up yet. Would it be in there or could I find it online?

 

No, it won't be in the box. CompCams sells a distributor gear, but it's on the pricey side. I suppose it's designed to be compatible with the cam cores they use.

Just to give some history, I've had a few problems with CompCams camshafts and distributor gears. Each time the dist gear wore excessively and on two occasions actually caused the engine to shut down.

On the L98, once the gear wore excessively it no longer could mesh with the cam gear so ignition was cut off. On the 388 LT1 the story is different. When that new melonized gear wore (after only a couple thousand miles) the engine would continue to run since the LT1 has Opti-Spark, BUT THERE WAS NO OIL PRESSURE! Luckily the engine was just above idle and I instantly saw the bright RED Check Gauges light.

Two incidents were on a 415 L98 type engine and a third was on a 388 LT1. One incident was with a stock GM gear and two were with GM's melonized gears.

On the L98, I even ground grooves into the distributor shaft per CRANE's recommendation, but still the gear died. Now remember, this happened with TWO DIFFERENT ENGINES and on the L98 TWO DIFFERENT INTAKE MANIFOLDS.

Right now I believe the culprit was the new HV/HP oil pumps I was running in both engines. Contrary to what Melling claims (their HV/HP pumps aren't the cause) I believe IT IS the oil pump. Ask yourself "What would you expect them to say?"

From now on I plan to use the melonized gear and a standard volume/standard pressure oil pump. And, as I always do, lube WELL both the cam gear AND the distributor/oil pump drive gear before installation.

BTW, due primarily to the taller retro-fit lifters, you're probably going to need different length pushrods than the ones you have.

Jake

 

Not to hi-jack but Jake has some interesting comments about the HP/HV oil pumps and distributor gears. I an in the middle of a 383 build, think I'll swap the HV pump I have for a standard. FWIW,a bronze gear is not the answer.

 

All small block Chevy Gen I engines only need standard pressure and standard volume oil pumps.
Anything else is not only overkill, but also asking for problems, such as those described above (gear failure).
When I rebuilt a 350 for a Nova I had, my machinist stressed that high volume and high pressure pumps are not necessary.
Just my $.02.

Rich K