Time for a change

All the signs are pointing to a collapsed lifter so I recon I'll just make the swap from a flat tappet to a roller cam. I just need some opinions on which way to go. What are the pros and cons of hydraulic or solid rollers? I've looked at a Crane that has pretty close specs to the cam I have now so I might be able to get away without re burning my computer chip. Also will I need to change the valve springs and rocker arms? I have Edelbrock Performer RPM heads now. I know I will need new pushrods. Thanks in advance, Art

Get a hydraulic roller, too many headaches with durability and a solid roller. Do realize that with the same duration & LCA, because of the more aggressive lobe profile of the rolelr your overlap will actually increase quite a bit (vac. signal)

The cam I have in there right now has duration of 218/224 @ .50 with 110 degree lobe separation. The cam I'm looking at has 222/230 duration and 112 degree separation. I spoke with the people that built the FI system and they didn't think that would be a problem for the computer. More questions---the valve springs on the heads now can handle .575" max lift and have 105 lbs seat pressure. Crane cams is telling me that I will need 150 lbs seat pressure and I can just add .030" shims under the springs and all would be good? The cam I'm looking at has .539" exh lift with 1.5 rockers. Won't that be awfully close to completely compressing the springs? also how do I determine the length of the new pushrods? Sorry for all the noob questions, but I'm not an engine guru.

AJ77 said:

The cam I have in there right now has duration of 218/224 @ .50 with 110 degree lobe separation. The cam I'm looking at has 222/230 duration and 112 degree separation. I spoke with the people that built the FI system and they didn't think that would be a problem for the computer. More questions---the valve springs on the heads now can handle .575" max lift and have 105 lbs seat pressure. Crane cams is telling me that I will need 150 lbs seat pressure and I can just add .030" shims under the springs and all would be good? The cam I'm looking at has .539" exh lift with 1.5 rockers. Won't that be awfully close to completely compressing the springs? also how do I determine the length of the new pushrods? Sorry for all the noob questions, but I'm not an engine guru.

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Need more info to give good advice. I checked your profile and it says a TPI 383 so assuming that you have the OEM mass airflow on it you probably will not need to do anything to the ecm with the cam swap..

Ideally you want the springs within 40 thousands of coil bind
You won't get what the cam is capable of because your engine is induction limited. Running the TPI is like using a 2 barrel carburetor.

If this is mostly a street car you definitely want to go with a hydraulic roller cam.
.

You have a 383 with FI ? I run a Comp hydr roller cam in my 383, same Edelbrock RPM heads.... my cam has 230-236 dur , here's a link:

http://store.summitracing.com/partdetail.asp?part=CCA-CL12-432-8&autoview=sku

I asked the engine builder who did my short block to have the cam ground on 112LS and that was no problem, didn't cost more and it seems to help the idle quality.

The 383 can take more cam than a 350, I don't have a problem with vacuum and it idles fine.

Now the next question: how much are you going to safe if you use a seasoned 4 bolt main block that is already setup for the roller lifters ?
These 1986+ blocks are about $700, cleaned, magnafluxed, painted and bored .030" over.... you'll safe roughly $400 on the lifters because you can then use stock GM lifters and don't need the retrofit lifters...

If you collapsed a lifter and (maybe) wiped a lobe it might be better to start fresh....

You'll need an adater to use the 2pc RMS crank in a 1pc RMS block but I think these are only $100 or so...

The block was freshly redone when I had the engine built. It's got about 13000 miles on it now. As far as the induction being the same as a 2 bbl carb, my system is aftermarket. It has 1/2" larger I.D. runners and either a 90 or 100 mm throttle body. Way better than a stock system. It pulls like crazy up to 6000 rpm with no power loss like the stock systems. At 120 mph it is still slamming you back in the seat. Also it isn't MAF, it's MAP. I've just got to see if the change in duration from the flat tappet to the roller is enough to mess with the program they burned into the chip when they built the system. The cam I'm looking at is a Crane 119701 with 222/230 duaration@ .50 .519/.539 lift with 1.5 rockers, 112 degree lobe seperation. If the cam is wiped (I don't think it is, it didn't run more than maybe 1 1/2minutes with the lifter making noise) I will pull the crank and check the main and rod bearings. If there is any sign of damage I'll go from there. I rechecked the cam specs and also spoke with a tech from Crane and Edelbrock and it looks like the springs I have will work just fine. They will handle a cam with .036" more lift than the one I'm looking at. Thanks for the responses, Art

My largest concern is about the necessary use of those 'toggle bar' style of lifters, they tend to not do so well on longevity/street use....

if that bar ever gives, the thing flips and wipes out immediately....:shocking:

there is a good REASON GM went with that dog bone and the double D flat sided lifters, and the hold down spider.....you MAY be able to get something like that setup from the aftermarket, but you then need to machine bolts into the block for the spyder....kinda hard to do cleanly on a assembled engine....h:

AJ77 said:

The block was freshly redone when I had the engine built. It's got about 13000 miles on it now. As far as the induction being the same as a 2 bbl carb, my system is aftermarket. It has 1/2" larger I.D. runners and either a 90 or 100 mm throttle body. Way better than a stock system. It pulls like crazy up to 6000 rpm with no power loss like the stock systems. At 120 mph it is still slamming you back in the seat. Also it isn't MAF, it's MAP. I've just got to see if the change in duration from the flat tappet to the roller is enough to mess with the program they burned into the chip when they built the system. The cam I'm looking at is a Crane 119701 with 222/230 duaration@ .50 .519/.539 lift with 1.5 rockers, 112 degree lobe seperation. If the cam is wiped (I don't think it is, it didn't run more than maybe 1 1/2minutes with the lifter making noise) I will pull the crank and check the main and rod bearings. If there is any sign of damage I'll go from there. I rechecked the cam specs and also spoke with a tech from Crane and Edelbrock and it looks like the springs I have will work just fine. They will handle a cam with .036" more lift than the one I'm looking at. Thanks for the responses, Art

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Sounds like you have figured out what you want.
My comment on the TPI was based on OEM and like I said in my first post it is hard to give advice when you do not know what they have.
Each and every change makes a difference that is why I said you needed to provide more Info.

Well, I found the bad news last night. The #8 intake lobe on the cam is wiped. I spoke with a guy locally who builds circle track and drag engines and he said he will completely go through the engine and rebuild with whatever parts I want and give me the parts at Summits price. I've been to his shop and you could eat a meal off the floor. I've also seen some of his work and it's top notch. Pretty hard deal to pass up. Hopefully I'll be back on the road in a couple of weeks. Just a little less in my bank account.:crap: Oh well, that's how the phrase "money pit" came to be.:thumbs:Art

OH HELL, oh well, time to rollerize....

maybe pick up a later block with factory rollers in it already, bolt in swap with your stuff.....

:smash::smash::fishing:

Then again, Art, I have essentially a ZZ4 engine...maybe check into that also....

mrvette said:

OH HELL, oh well, time to rollerize....

maybe pick up a later block with factory rollers in it already, bolt in swap with your stuff.....

:smash::smash::fishing:

Then again, Art, I have essentially a ZZ4 engine...maybe check into that also....

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I'll see if he has a later block we could work a trade on maybe. If not, I'll just get the best retrofit lifters money can buy. My wife's already said she doesn't give a shit how much I spend. Can't take the cash with me, right??

You can buy a brand new 1pc rms block from Summit for $700 - or a used one for much less... keep in mind you safe roughly $350-$400 on the lifters ... put that money towards a newer block instead of retrofitting the old one....
The old block still has some value if it can be bored to the next size, ask your engine builder if he takes it as a partial trade, sounds like he's willing to work with you.
IMO it just doesn't make sense to use a 2pc rms block and retrofit the lifters if you need to have the block machined anyways....

I'm curious as to why you think the block I have now needs bored? I only have 13000 miles on it since it was built it in the first place. All I should have to do is polish or possibly turn the crank journals and replace all the bearings. I understand the value of using a later block and will definitely talk the shop owner about that possibility.

Well.... I often expect the worst case so I can only be surprised positively:

When a cam lobe goes you have a lot of junk (metal particles) going thru the oil passages, I'd expect the bearings to take the first hit, then the cylinder walls if you run the engine for too long after the lobe is wiped.

If the cylinder walls look fine and if you want to use this block with the pistons that are installed right now it'll be most likely fine. If you want to use this block with a different set of pistons I'd go to the next size so that the bores can be matched to the new pistons.

Best case scenario you only need to replace the bearings. Still I'd suggest you have the block hot tanked so you can be sure all the metal junk is removed from all hidden spots....

Cleaning your old block alone is going to cost you a few $$ and the rotating assembly must be removed... now you want to magnaflux the block before you re-assemble with fresh parts.... now add the extra cash that the retro lifters cost you and the new 1pc rms block is only a few bux more

The new block can be machined to fit your pistons as I assume those are .030" over. Unless I am missing something you only need the rear seal adapter and your good to re-use the existing 2pc rms crank.

Pulled the rotating assy last night and the crank journals look real good. No signs of scarring( at least to my old eyes). Cyl walls still look good too. It's going to the engine builder tomorrow so I'll hold my breath for his verdict. If we decide to go with a late block I'll have to get my cam custom ground. I can't find one for the late block that has specs I like. I'm somewhat limited with the EFI computer, can't get to radical or the computer will go postal on me!

Dropped off engine parts Thursday and they said all looked good. No damage to crank!:bounce: Going to be back on the road in about 2 weeks.

Well, it's been five weeks, but I got my engine back from the shop on Sat. and fired it up yesterday. Went through the two heat and cool cycles like the builder suggested and it sounded great! Will take it for a test drive after work and see how the new roller cam feels. I can't wait till 5:00 tonight!!:yahoo: Art

Did you survive the test drive?



.

Yea, but somehow a pin in the connector on the back of the computer decided to open up, lose contact and make the check engine light come on and the car run like shit! It took me two days with the help of some fine people here to find it. Just got back from another test drive and holy shit that thing has got some power!! Very noticeable difference from the flat tappet cam that was in there before. I don't know how much, but I have a substantial power gain with the roller setup. Waiting for thr wife to come home and help me put the hood back on so we can go burn some more gas. Whoopee!

AJ77 said:

Yea, but somehow a pin in the connector on the back of the computer decided to open up, lose contact and make the check engine light come on and the car run like shit! It took me two days with the help of some fine people here to find it. Just got back from another test drive and holy shit that thing has got some power!! Very noticeable difference from the flat tappet cam that was in there before. I don't know how much, but I have a substantial power gain with the roller setup. Waiting for thr wife to come home and help me put the hood back on so we can go burn some more gas. Whoopee!

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Aside from the obvious friction losses being regained from rubbing a flat tappet cam, the lift ramps can be much more steep and there fore knocking the valves off their asses for a more open average flow over a longer duration at the valve....so there is more room for air....can't be done on a flat tappet cam due to the edges of the lifter hitting the cam lobe, and overloading the dynamics on the rub surface....wear and crap....

it's just what I have read...makes sense...

I hear it's like 15? hp gain just for the roller cam....I believe it....
screw the other gains from durations/ramps....

:beer: