Vortec 454 Heads and Cam
01-16-2008, 05:13 PM
#11
Teching In
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There are plenty of choices for oval-port aluminum heads for the L29. GM Performance Parts sells aluminum 110cc heads, part number 12363390. They have dual valve springs and will support more RPM with a different cam. GM heads will take a standard length set of head bolts but you mighr try the aftermarket for heads. Edelbrock's BBC heads need four different sized head bolts because they've designed the runners differently to make them flow more like rectangular port heads.
Be sure that the cam you are buying has a stepped nose for a factory roller Mark-VI block. You need this for compatibility with the thrust plate and the single-roller timing chain that leaves room for the reluctor wheel. That brings up another point - don't bother trying to replace the timing set.
Unfortunately roller rockers do not fit underneath the factory low-profile valve covers. The placement of the throttle body over the passenger side valve cover restricts the use of taller covers. In order to install roller rockers and taller covers you'd need to fabricate some plenum spacers to go between the upper and lower manifolds. I'm going to eventually be doing this myself, but it's a ways off. Keep in mind swapping the cam that the factory rockers are not adjustable. New pushrods will be required because the new cam is likely to have a different base circle diameter than the stock one. Big block have two different length pushrods, about 1" difference between the two, and are sold in custom lengths in sets of 8 for that reason.
If the new cam can better get the exhaust out you'll find it will accept a lot more timing advance in the top end. Have you ever looked at the stock timing curve on an L29? It falls off past 2400RPM and never gets past 13 degrees at WOT. Pretty pathetic.
If you're willing to run a 180 degree thermostat and Premium Unleaded fuel, I can tell you that completely stock, it will take an additional SIX DEGREES of timing in the upper kPA with absolutely no knock retard. (That's a huge increase.)
Be sure that the cam you are buying has a stepped nose for a factory roller Mark-VI block. You need this for compatibility with the thrust plate and the single-roller timing chain that leaves room for the reluctor wheel. That brings up another point - don't bother trying to replace the timing set.
Unfortunately roller rockers do not fit underneath the factory low-profile valve covers. The placement of the throttle body over the passenger side valve cover restricts the use of taller covers. In order to install roller rockers and taller covers you'd need to fabricate some plenum spacers to go between the upper and lower manifolds. I'm going to eventually be doing this myself, but it's a ways off. Keep in mind swapping the cam that the factory rockers are not adjustable. New pushrods will be required because the new cam is likely to have a different base circle diameter than the stock one. Big block have two different length pushrods, about 1" difference between the two, and are sold in custom lengths in sets of 8 for that reason.
If the new cam can better get the exhaust out you'll find it will accept a lot more timing advance in the top end. Have you ever looked at the stock timing curve on an L29? It falls off past 2400RPM and never gets past 13 degrees at WOT. Pretty pathetic.
If you're willing to run a 180 degree thermostat and Premium Unleaded fuel, I can tell you that completely stock, it will take an additional SIX DEGREES of timing in the upper kPA with absolutely no knock retard. (That's a huge increase.)
01-29-2008, 01:19 AM
#12
I found some pretty interresting information on the stock L29 heads. I don't know if this is accurate but apparently the L29 heads are the only factory heads ever to actually flow better on the exhaust than the intake. This has to do with shrounding of the intake valve I guess, the exhaust valve being smaller isn't as bad.
With that rotating assembly you'll want more RPM out of it. I think the factory rev limiter is 4800RPM and OEM shift points are at about 4500. I bumped my limiter to 5100 on a totally stock longblock but you'll want to put yours up to the maximum that the PCM supports, which is 5800, if the rotating assembly is rated for it. (The 96-2000 "black-box" PCMs do not support more than 5800RPM.) Of course in order to do that you're going to have to do something about the valve springs. They are so weak you can literally press them open with your thumbs. Valves start floating on the stock heads at about 4800RPM. Personally I'd rather just spend the $2K on a pair of aluminum heads that already have the right springs and valves in them.
The fuel injector flow rate in the PCM for a L29 is 2.804 gm/sec or 22.3 lbs/hr. They will support 415HP but you'll be at almost 100% duty cycle doing it. If you can get more RPM out of it I think you'll find 415 is a very conservative number. I think you'll be looking at more like 500HP. Luckily the injectors are standard EV1-type and easy to replace after lifting off the upper plenum. (Clean the oil out while you're in there too, it tends to pool int he bottom of the intake plenum.) You can put any injectors you want to in here. I used a few different injector types on the Whippled 383 and found that the 62# Siemens ceramic disc units support shorter duty cycles than conventional pintle-type injectors. The Siemens units even idle better. 62# is kind of overkill for this but I can tell you they work so much better than pintle injectors it's worth using them. In fact, the set from my 383 will be going on the 454 before it gets boost.
Keep in mind the OEM fuel pressure regulator is a 4-BAR unit and most injectors are rated at 3-BAR.
The intake manifold gaskets are GM part #12534412. I think Fel-Pro FPP-1071 will work for the head gaskets.
This might be just nitpicking but it seems like the general concensus on multi-electrode plugs is that they don't work well in high-swirl combustion chambers. You might be better off with a set of NGK TR-55's if you have problems with misfires.
Aftermarket billet distributors for L29, L30, and L31 are available now. This is a nice upgrade over the plastic POS OEM distributor.
What do these exhaust manifolds you have look like? I have seen a set of long-tube headers add 35HP on a stock 454. It's almost hard to believe.
Edit:
I can't find if that cam you're looking at has the smaller bolt circle and stepped nose for the factory roller block and thrust plate. If it does, cool. I've found that Crower uses "LM" at the end of their part numbers to indicate factory roller block and stepped nose. Here's a slightly larger Mark-VI cam from them: http://www.crower.com/misc/cam_spec/...rt_num=01401LM
This is what the thrust plate looks like:
With that rotating assembly you'll want more RPM out of it. I think the factory rev limiter is 4800RPM and OEM shift points are at about 4500. I bumped my limiter to 5100 on a totally stock longblock but you'll want to put yours up to the maximum that the PCM supports, which is 5800, if the rotating assembly is rated for it. (The 96-2000 "black-box" PCMs do not support more than 5800RPM.) Of course in order to do that you're going to have to do something about the valve springs. They are so weak you can literally press them open with your thumbs. Valves start floating on the stock heads at about 4800RPM. Personally I'd rather just spend the $2K on a pair of aluminum heads that already have the right springs and valves in them.
The fuel injector flow rate in the PCM for a L29 is 2.804 gm/sec or 22.3 lbs/hr. They will support 415HP but you'll be at almost 100% duty cycle doing it. If you can get more RPM out of it I think you'll find 415 is a very conservative number. I think you'll be looking at more like 500HP. Luckily the injectors are standard EV1-type and easy to replace after lifting off the upper plenum. (Clean the oil out while you're in there too, it tends to pool int he bottom of the intake plenum.) You can put any injectors you want to in here. I used a few different injector types on the Whippled 383 and found that the 62# Siemens ceramic disc units support shorter duty cycles than conventional pintle-type injectors. The Siemens units even idle better. 62# is kind of overkill for this but I can tell you they work so much better than pintle injectors it's worth using them. In fact, the set from my 383 will be going on the 454 before it gets boost.
Keep in mind the OEM fuel pressure regulator is a 4-BAR unit and most injectors are rated at 3-BAR.
The intake manifold gaskets are GM part #12534412. I think Fel-Pro FPP-1071 will work for the head gaskets.
This might be just nitpicking but it seems like the general concensus on multi-electrode plugs is that they don't work well in high-swirl combustion chambers. You might be better off with a set of NGK TR-55's if you have problems with misfires.
Aftermarket billet distributors for L29, L30, and L31 are available now. This is a nice upgrade over the plastic POS OEM distributor.
What do these exhaust manifolds you have look like? I have seen a set of long-tube headers add 35HP on a stock 454. It's almost hard to believe.
Edit:
I can't find if that cam you're looking at has the smaller bolt circle and stepped nose for the factory roller block and thrust plate. If it does, cool. I've found that Crower uses "LM" at the end of their part numbers to indicate factory roller block and stepped nose. Here's a slightly larger Mark-VI cam from them: http://www.crower.com/misc/cam_spec/...rt_num=01401LM
This is what the thrust plate looks like:
Last edited by James B.; 01-29-2008 at 01:50 AM.
01-29-2008, 08:51 PM
#13
Rockers:
I found a thread from some off-road guys running a Vortec 454 that were able to fit aluminum roller rockers under stock valve covers using only thick gaskets. The stock covers have a channel in them with a silicone seal but they just used older-generation bigblock gaskets. Since the aluminum ones required such a small amount of additional clearance, they believe that stainless steel rockers with their smaller bodies might actually fit.
Maybe something like Comp Cams part number 1120-16
http://www.compcams.com/technical/Ca...106-07/271.pdf
I found a thread from some off-road guys running a Vortec 454 that were able to fit aluminum roller rockers under stock valve covers using only thick gaskets. The stock covers have a channel in them with a silicone seal but they just used older-generation bigblock gaskets. Since the aluminum ones required such a small amount of additional clearance, they believe that stainless steel rockers with their smaller bodies might actually fit.
Maybe something like Comp Cams part number 1120-16
http://www.compcams.com/technical/Ca...106-07/271.pdf
02-01-2008, 12:01 PM
#14
Staging Lane
Join Date: Apr 2007
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Hey guys
For some reason after doing my cam on the 454 theres a stupid code about the cam sensor and crank sensor not synced or something. I found out that the Cam retard on the tech2 should be at 0 but when i put it there car runs like Crap.But on the dyno it made 300hp 400 torque and the cam retard was at like -32 or so i dont know what it is.
For some reason after doing my cam on the 454 theres a stupid code about the cam sensor and crank sensor not synced or something. I found out that the Cam retard on the tech2 should be at 0 but when i put it there car runs like Crap.But on the dyno it made 300hp 400 torque and the cam retard was at like -32 or so i dont know what it is.
02-01-2008, 03:58 PM
#15
did you do a CASE Re-Learn with the new cam? You can do that with the Tech2.
What "stupid code" is it? If it's code P1345 then the distrubutor just isn't installed right.
Why would you run up an engine on a dyno that you know is having timing problems? You say 300/400 like that's something to be happy with. The L29 makes 290/410 STOCK, so all that work and money you just put into it is wasted until you FIX the timing problem.
What "stupid code" is it? If it's code P1345 then the distrubutor just isn't installed right.
Why would you run up an engine on a dyno that you know is having timing problems? You say 300/400 like that's something to be happy with. The L29 makes 290/410 STOCK, so all that work and money you just put into it is wasted until you FIX the timing problem.
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