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Thinking about some power upgrades - Need some cam advice - Engine Gurus help please

Chevy305

Chevy305

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So the 355 has been treating me well, but its not enough anymore... :smokin2:


I am thinking about a conversion to a hydraulic roller cam and a 6AL box.

The current stats on the motor:
1991 350 2bolt, bored .030
9.4:1 CR
Eagle rotating assembly
Partiot Performance Freedom Series Aluminum 185cc heads
Lunati Voodoo flat hydro cam, 219/227, .468/.489
Weiand Action + Intake
FAST EZ EFI
MSD HEI distributor
Headers and dual exhaust w/ H-pipe

Can someone recomend a 6AL type box for me, there are so many and I don't understand the differences between them.

I'd like to gain a little duration and lift on my cam swap as well. Here are some cams I have picked out:
http://www.jegs.com/i/Comp-Cams/249/12-467-8/10002/-1?parentProductId=#moreDetails
http://www.jegs.com/i/Comp-Cams/249/12-466-8/10002/-1
http://www.jegs.com/i/Comp-Cams/249/08-418-8/10002/-1
 
Last edited:
Dont forget you'll need a cd trigger distributor with the 6AL box. I would suggest just a regular 6AL. Its just fancy options and such.
 
Stomis said:
Dont forget you'll need a cd trigger distributor with the 6AL box. I would suggest just a regular 6AL. Its just fancy options and such.
Click to expand...

MSD says it hooks right up to their HEI distributor :dunno:
 
Anyone with some cam advice?

My current cam has a 113 LSA, how much does that effect idle? Right now I have a pretty mild idle at 700-750rpm. The cams I listed above have either 112 or 110 LSA. Is going to give me a real lumpy idle? I still want to be able to daily drive and tow with this truck.
 
It's going to depend a lot on your preference. It's always a trade off. The cam you have has about as high of duration as I would go with the stock converter and towing. The roller cam will definitely give you more lift at that duration, for more total airflow and more power, but it may not be a night and day difference.
The 6AL is a good box, that's what I have been runnnig for years. But they changed them around recently. Do you want programmable timing, or just a multi spark CD ignition? If you don't want prommable timing just save yourself the money and get a 6A, you already have a rev limiter in your EFI.

Regular 6A

http://www.msdignition.com/Products/Ignitions/Daily_Driver/6201_-_Digital_6A_Ignition_Control.aspx

Programmable...(can replace the mech and vac advanc, may require a seperate MAP sensor for load timing control, I didn't read the instructions)

The tighter lobe seperation will give you a rougher idle, in fact, with the same duration and 110 LSA you will probably notice the idle change. Because you don't want the idle to change and you want to tow, out of those 1st cams, 12-466-8 looks pretty good for what you want. This one looks pretty good also...

http://www.lunatipower.com/Product.aspx?id=1988&gid=289

...although the comp one will have a better idle.

However, that the comp is speced with 1.6 rockers. What do you currently have for rockers? If you have factory rockers stepping up to 1.6 full roller rockers would be much easier and might give you decent gains, changing your cam lift to .499/.522". It's all going to depend on your heads and intake whether it likes it or not.

About your intake, that looks to me like a standard dual plane so so intake. I think you would see some noticeable gains going from that to say, a performer RPM, an RPM air gap would be the best. Or the weiand/holley equivalent.

If I was you, I would probably just get the 6A, 1.6 roller rockers (if you don't have them already), and a highrise RPM airgap intake with the holley flange. If you still aren't happy, then upgrade the cam and you already will have the good rockers.

If I was to change only one thing, it would be that intake.
 
I know I'm not answering your quesiont, but: How do you like the Patriot heads?
 
folkenheath said:
It's going to depend a lot on your preference. It's always a trade off. The cam you have has about as high of duration as I would go with the stock converter and towing. The roller cam will definitely give you more lift at that duration, for more total airflow and more power, but it may not be a night and day difference.
The 6AL is a good box, that's what I have been runnnig for years. But they changed them around recently. Do you want programmable timing, or just a multi spark CD ignition? If you don't want prommable timing just save yourself the money and get a 6A, you already have a rev limiter in your EFI.

Regular 6A

http://www.msdignition.com/Products/Ignitions/Daily_Driver/6201_-_Digital_6A_Ignition_Control.aspx

Programmable...(can replace the mech and vac advanc, may require a seperate MAP sensor for load timing control, I didn't read the instructions)

The tighter lobe seperation will give you a rougher idle, in fact, with the same duration and 110 LSA you will probably notice the idle change. Because you don't want the idle to change and you want to tow, out of those 1st cams, 12-466-8 looks pretty good for what you want. This one looks pretty good also...

http://www.lunatipower.com/Product.aspx?id=1988&gid=289

...although the comp one will have a better idle.

However, that the comp is speced with 1.6 rockers. What do you currently have for rockers? If you have factory rockers stepping up to 1.6 full roller rockers would be much easier and might give you decent gains, changing your cam lift to .499/.522". It's all going to depend on your heads and intake whether it likes it or not.

About your intake, that looks to me like a standard dual plane so so intake. I think you would see some noticeable gains going from that to say, a performer RPM, an RPM air gap would be the best. Or the weiand/holley equivalent.

If I was you, I would probably just get the 6A, 1.6 roller rockers (if you don't have them already), and a highrise RPM airgap intake with the holley flange. If you still aren't happy, then upgrade the cam and you already will have the good rockers.

If I was to change only one thing, it would be that intake.
Click to expand...

I think you're right about the intake. It was a leftover from my 305 and I was on a budget building my 355 otherwise I would have upgraded. I'll make sure to add an Edelbrock RPM Air Gap to the list.

I have 1.5 comp cams roller tip rockers because again I was on a budget and couldn't spring for the full rollers. I was planning on upgrading to the full roller rockers with the cam swap. Should I bump up to the 1.6 with a new cam or stick with the 1.5?

I'm pretty dead set on a cam swap and I really like the Lunati you listed. Funny how that one never came up in a search at either Jegs or Summit :dunno:. That 60111 Lunati seems almost like the roller version of my current cam. I'm definately going with that one :waytogo:.



Keitha said:
I know I'm not answering your quesiont, but: How do you like the Patriot heads?
Click to expand...

The Patriot heads are the shnit! Great craftsmanship and dead on casting. The power is great out of them, I really think they are the biggest power upgrade over stock. But to be honest they were a bit of a compromise between a set of vortec heads (cheapest) and a set of AFR Eliminators (most expensive). The AFR Eliminators flow slightly better but at something like $1400 for the pair I figured the Patriots were right up my ally. Don't get me wrong I am definately happy about choosing them and I'd recomend them to anyone else.
 
Chevy305 said:
I think you're right about the intake. It was a leftover from my 305 and I was on a budget building my 355 otherwise I would have upgraded. I'll make sure to add an Edelbrock RPM Air Gap to the list.

I have 1.5 comp cams roller tip rockers because again I was on a budget and couldn't spring for the full rollers. I was planning on upgrading to the full roller rockers with the cam swap. Should I bump up to the 1.6 with a new cam or stick with the 1.5?

I'm pretty dead set on a cam swap and I really like the Lunati you listed. Funny how that one never came up in a search at either Jegs or Summit :dunno:. That 60111 Lunati seems almost like the roller version of my current cam. I'm definately going with that one :waytogo:.
Click to expand...

Well, since you are definitely getting the new roller cam thats a tossup on the rockers. Its going to depend on your head flow numbers and valve springs, etc. You lift isn't extremely high so it could benefit, but it's hard to say. I would probably look at your head flow numbers and see if there is a significant difference between the lift at 1.5 and 1.6 with that particular cam.

Also, isn't your block new enough you can use the roller spiders and slab side lifters? Lifters may be cheaper if they aren't the retro fit style. Don't forget, with a roller cam you need a cam button to set camshaft endplay, and preferably a torrington bearing behind the timing chain, although not required. Roller cams have a flat parallel lobe surface and don't have any means to hold themselves in position axially, and if they float around in the block it can cause erratic timing, or worst case, catastrophic failure if a lifter body contacts an adjacent lobe or the chain hits the cover. So make sure to at least use a cam button and set camshaft endplay by bending the timing chain cover in that spot if you have to. Don't forget to include the gasket dry when you measure. I usually set it at the high side with the gasket in and snug (.009"), and when I install the timing cover and tighten it down properly I am at the low end of the endplay tolerance, your results may vary. I measure endplay with a caliper, I just pick a spot in the lifter valley where I can consistently measure from the block to one of the lobes sticking up, and then move the cam back and forth while I measure.

On MSD. Did you want programmable or just leave the timing up to the dizzy? I forgot to link the programmable unit. This unit can be programmed for timing (you would have to lock your distributor solid), then the timing can be programmed with a computer. Mechanical advance could work easily, however, vacuum advance would require a MAP sensor to use. Not sure if you could splice into the EFI map sensor signal or if you need a seperate one. I am not running the programmable, once I have my timing curve set I never change it anyway.

http://www.msdignition.com/Products/Ignitions/6530_-_MSD_Digital_Programmable_6AL-2.aspx

The 6A would give you all the benfits of the CD ignition and multiple sparks without the extra cost of the rev liimiter (6AL) or programming features (linked).
 
Chevy305 said:
The Patriot heads are the shnit! Great craftsmanship and dead on casting. The power is great out of them, I really think they are the biggest power upgrade over stock. But to be honest they were a bit of a compromise between a set of vortec heads (cheapest) and a set of AFR Eliminators (most expensive). The AFR Eliminators flow slightly better but at something like $1400 for the pair I figured the Patriots were right up my ally. Don't get me wrong I am definately happy about choosing them and I'd recomend them to anyone else.
Click to expand...

Good to hear on the Patriot heads. Same scenario I am in. I am finding it hard to justify the price of AFR heads. I plan to swap a 6.0 LS into the Sub in a few years. The rebuild I am planning is just to tie me over until then.
 
folkenheath said:
Well, since you are definitely getting the new roller cam thats a tossup on the rockers. Its going to depend on your head flow numbers and valve springs, etc. You lift isn't extremely high so it could benefit, but it's hard to say. I would probably look at your head flow numbers and see if there is a significant difference between the lift at 1.5 and 1.6 with that particular cam.

Also, isn't your block new enough you can use the roller spiders and slab side lifters? Lifters may be cheaper if they aren't the retro fit style. Don't forget, with a roller cam you need a cam button to set camshaft endplay, and preferably a torrington bearing behind the timing chain, although not required. Roller cams have a flat parallel lobe surface and don't have any means to hold themselves in position axially, and if they float around in the block it can cause erratic timing, or worst case, catastrophic failure if a lifter body contacts an adjacent lobe or the chain hits the cover. So make sure to at least use a cam button and set camshaft endplay by bending the timing chain cover in that spot if you have to. Don't forget to include the gasket dry when you measure. I usually set it at the high side with the gasket in and snug (.009"), and when I install the timing cover and tighten it down properly I am at the low end of the endplay tolerance, your results may vary. I measure endplay with a caliper, I just pick a spot in the lifter valley where I can consistently measure from the block to one of the lobes sticking up, and then move the cam back and forth while I measure.

On MSD. Did you want programmable or just leave the timing up to the dizzy? I forgot to link the programmable unit. This unit can be programmed for timing (you would have to lock your distributor solid), then the timing can be programmed with a computer. Mechanical advance could work easily, however, vacuum advance would require a MAP sensor to use. Not sure if you could splice into the EFI map sensor signal or if you need a seperate one. I am not running the programmable, once I have my timing curve set I never change it anyway.

http://www.msdignition.com/Products/Ignitions/6530_-_MSD_Digital_Programmable_6AL-2.aspx

The 6A would give you all the benfits of the CD ignition and multiple sparks without the extra cost of the rev liimiter (6AL) or programming features (linked).
Click to expand...

For the 1.5 vs 1.6 rockers: i looked at the flow numbers and I'd only gain 2-3 cfm with the increased lift. That being said I don't think the 1.6 would be worth it, plus it would push the valve springs closer to their .575" lift limit.

Thanks for the advice on the cam end play. I'm not sure if my block can use the regular roller lifters or if they have to be the retrofit style with the bridge. The block is '91 and came factory with a flat tappet cam. I believe some engines came with factory rollers at that point but I'm not sure if they are transferable. I will try to google it as Lunati's retrofit lifters are more expensive than the cam at $369 :eek1::eek1::eek1:.
Also Lunati's website recomends one set of lifters and Summit recomends a different set :confused: :screwy:

For the MSD, I'd rather stick with the mechanical/vacuum advance. The digital ignition seems a bit more complicated than I need it to be. I'm going to go with the first one you linked, the 6A. But as my MSD HEI sits now it still has the factory set timing curve, which might not be optimial for my engine, so I need to get on that. What should I set my timing curve to? A quick advance or a slower one? I think you might have answered this question for me in a previous thread but I can't find it :doah:.



As far as the question about the Patriots, they cost me something like $815. Here's a link to the set I got:
http://www.jegs.com/i/Patriot+Performance/723/2168/10002/-1
Also they have provisions for both style valve covers and can accept both carb intakes and the TBI intakes from '87 up (just not vortec intakes). They come in both angle and straight plug too. I got the angle plug because the straight plugs were back ordered when I bought mine.
 
Sounds like you got it under control then, 1.5 rockers will work well, you can't go wrong with a 6A, and an RPM air gap is a definite improvement. Don't forget the cam button, depending on your timing cover, there are two length cam buttons to choose from. If your timing cover has the raised ribs trhough the center you need the longer one.

Yeah, hydraulic roller lifters are expensive, but they are worth it. The different types are probably the different levels. Most hydraulic lifters in the US are all made by one or two companies for the aftermarket. However, there is a new design that is manufactured differently and less expensive, they work very well, up to around 6000 RPM or so. I think Lunati calls them the street series or something. You start getting above that and you need the more expensive lifters that can rev to 6500 or so. After that, it's time to go mechanical. I have the better ones in my 388 in my regal that is 14 years old with a comp hyd roller, however, I just used the street version in my 489 because I have the rev limiter set at 5900. With that cam and the lighter SB valvetrain I think you would be fine with the street version.

For the timing curve. I usually put the lightest springs in they offer. I like the timing to come in fast for more throttle response and more power. It's only too fast if it starts to detonate under load at lower RPM, which could happen easier if you start towing or start in higher gears. If you do any heavy towing you might want to try the medium springs. Or you could use one of each for a 2 stage ramp up. I'd set your timing at 36 deg at 4000 RPM (just make sure the mech timing is all in, with the lightest springs it will be in by 3k RPM) with the vacuum advance disconnected. Then reconnect it and measure the timing of your vacuum advance. You want to try to limit it so that the timing at cruising RPMs with vacuum is about 50 - 52 degrees. You could try 38 WOT degrees as well and see if it runs better without detonation. As always, back off the timing if you are getting detonation. Down low = heavier springs, at WOT = turn dizzy, and reajust the vacuum can to put it back at 50 - 52 for cruise.
 
With a 1991 block, he won't need a cam button. It will be a roller block. He may have to tap some holes though. Instead of using a roller button, it has a thrust plate that bolts onto the front of the block, behind the timing gear. That holds the cam from coming forward. The distributor pushing the camshaft forward will prevent it from going towards the rear of the block.

He will also be able to use a set of OEM roller lifters with factory link bars and a spider. He may have to drill and tap the pedestals in the lifter valley to bolt the spider retainer down though. Some early roller blocks are not drilled and tapped.

Martin
 
Thanks for clearing that up, I knew the spiders and crossbars could be added but didn't remember the cam retainer plate behind the sprocket. Although if he is working on an assembled engine in his truck and the block isn't drilled and tapped it may be easier to just use all the retrofit stuff at that point, unless they don't clear the taller lifter bosses. If the block is drilled and tapped its a no brainer. Drilling and tapping is easy enough but I would be concerned of leaving metal chips in there in that scenario.
 
Shouldn't be hard to do if a guy is really careful. Lots of rags, and then a layer of grease covered rags on top of them.

Martin
 
It is a pretty old cam now but the LT4 hot cam used to be a pretty good runner for cheap. For sure change the intake. Honestly the ignition will make a very small difference and I would spend my money somewhere else first. I have run a good gm HEI to 7 grand so many times at the dirt track it isn't funny. It isn't holding you back. I didn't read the whole thread but what are you looking at for rpm range?
 
folkenheath said:
Sounds like you got it under control then, 1.5 rockers will work well, you can't go wrong with a 6A, and an RPM air gap is a definite improvement. Don't forget the cam button, depending on your timing cover, there are two length cam buttons to choose from. If your timing cover has the raised ribs trhough the center you need the longer one.

Yeah, hydraulic roller lifters are expensive, but they are worth it. The different types are probably the different levels. Most hydraulic lifters in the US are all made by one or two companies for the aftermarket. However, there is a new design that is manufactured differently and less expensive, they work very well, up to around 6000 RPM or so. I think Lunati calls them the street series or something. You start getting above that and you need the more expensive lifters that can rev to 6500 or so. After that, it's time to go mechanical. I have the better ones in my 388 in my regal that is 14 years old with a comp hyd roller, however, I just used the street version in my 489 because I have the rev limiter set at 5900. With that cam and the lighter SB valvetrain I think you would be fine with the street version.

For the timing curve. I usually put the lightest springs in they offer. I like the timing to come in fast for more throttle response and more power. It's only too fast if it starts to detonate under load at lower RPM, which could happen easier if you start towing or start in higher gears. If you do any heavy towing you might want to try the medium springs. Or you could use one of each for a 2 stage ramp up. I'd set your timing at 36 deg at 4000 RPM (just make sure the mech timing is all in, with the lightest springs it will be in by 3k RPM) with the vacuum advance disconnected. Then reconnect it and measure the timing of your vacuum advance. You want to try to limit it so that the timing at cruising RPMs with vacuum is about 50 - 52 degrees. You could try 38 WOT degrees as well and see if it runs better without detonation. As always, back off the timing if you are getting detonation. Down low = heavier springs, at WOT = turn dizzy, and reajust the vacuum can to put it back at 50 - 52 for cruise.
Click to expand...

Thanks for the advice on the timing :waytogo:. I'll make some adjustments as my work schedule allows which would be in about 2 more weeks :doah:.


82355 said:
With a 1991 block, he won't need a cam button. It will be a roller block. He may have to tap some holes though. Instead of using a roller button, it has a thrust plate that bolts onto the front of the block, behind the timing gear. That holds the cam from coming forward. The distributor pushing the camshaft forward will prevent it from going towards the rear of the block.

He will also be able to use a set of OEM roller lifters with factory link bars and a spider. He may have to drill and tap the pedestals in the lifter valley to bolt the spider retainer down though. Some early roller blocks are not drilled and tapped.

Martin
Click to expand...

Thanks for the clearification. I googled it and it seems like I might as well flip a coin to tell if I have a ready machined roller block or if I need a few holes drilled/tapped. Just let me make sure I have it right, to go roller I need the cam, facotry roller lifters, spider thingy, and a thrust plate?

EDIT:

Ok I found a pic of when I assembled the engine, it appears that I don't have any holes for the spider retainer:

355build011.jpg


355build005.jpg


355build001.jpg


355build002.jpg


80' 427 said:
It is a pretty old cam now but the LT4 hot cam used to be a pretty good runner for cheap. For sure change the intake. Honestly the ignition will make a very small difference and I would spend my money somewhere else first. I have run a good gm HEI to 7 grand so many times at the dirt track it isn't funny. It isn't holding you back. I didn't read the whole thread but what are you looking at for rpm range?
Click to expand...

The LT4 hot cam is way over priced and isn't what I'm looking for in a cam. I'm looking for about 1500-6000rpm. A pretty broad power band is what I'm looking for.
 
Oh and for those asking about the heads, hear are some pics of when I got them:

355build021.jpg


355build022.jpg


355build023.jpg


355build029.jpg


355build030.jpg
 
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