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Discussion Starter #1
Just got the car squared away and it feels LAZY. I think its the cam but here's some info on the car.

1984 Pontiac Trans Am about 3100 w/o driver

Engine:
-406ci SBC
-Quick Fuel Technology Q750 carb, -6AN fuel line
-Edelbrock Victor Jr. manifold
-World Products Sportsman II heads, ported and polished, 10* locks and retainers, Comp cams Springs, pushrod guides, seats. ARP 7/16" rocker studs
-Custom grind Comp cams retrofit Hydraulic roller camshaft .586/.562 lift 236*/248* duration @.050 113LSA btdc= 5 abdc=51 bbdc=57 atdc=11
-Comp cams Pro Magnum lifters
-Comp cams Pro Magnum Pushrods
-Comp cams Pro Magnum Roller rockers 1.5
-509 casting block
-Cast pistons,recon rods, stock crank
-HEI distributor
-MSD coil
-MSD supercomp plug wires
-MSD Digital 6 plus box

Exhaust:
-Hooker Longtube headers/ceramic coated 1 3/4" with 3" collector

Drivetrain:
-TH400, TCI 4200 stall custom converter, J.W. Ultra-bell, TCI transmission shield, manual valve body
-Moser 9", 31 spline axles, trac lock with 3.50's(being swapped to a spool and 4.11's)

It just doesnt want to go anywhere down low and still feels sluggish up top. I was hoping for atleast a 11.5 out of the car but it feels SLOW.

Anyone care to give some advice? I think the 113 LSA is hurting me a bit. Anyone care to give a suggestion on a new cam?
 

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Discussion Starter #3
I used the same cam in a 355 and thats what comp spec'ed me for a cam. It's pretty much the same motor except with a 406 over a 355 this time.

Forgot to mention the heads were angle milled from 64cc to 62cc as well.
 

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how high are you turning it? I would think with that duration on a for 406 it is done making power at 5600 to 5700? and the 113 lsa is more for a no2 setup.
 

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Discussion Starter #5
I spun 6300 on the old motor so figured 6k on this one but it just feels slugish throughout the band. Gonna put my LM1 on it this weekend and see what its doing too.
 

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How much compression is in the engine? With a flat top and 62cc chambers, you will have 11.25 compression. If it does, then the duration is way to short and will detonate, dropping power. If you have the reverse dome for 9.5 or so with the iron heads, you will be alot better off. The lobe seperation is way to wide, ESPECIALLY if it is installed at a 113 intake centerline. You should have run a 110 lsa but installed it at 106. I like the 108 but in basic street engines like this, a 110 is the widest, but still needs to be advanced. Otherwise the engine will be very very lazy and not accelerate at all. If you used the same cam in a 350, maybe it was installed with advance and with the shorter stroke, will accelerate faster. If the cam was installed "dot to dot" so to speak, and no advance built in the cam, it is being run at the 113. Problem is since the cam is so small in the duration, by advanceing it to 105 will kill any power and rpm up top. LMK what piston is used and where the cam is installed at.
 

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Discussion Starter #8
How much compression is in the engine? With a flat top and 62cc chambers, you will have 11.25 compression. If it does, then the duration is way to short and will detonate, dropping power. If you have the reverse dome for 9.5 or so with the iron heads, you will be alot better off. The lobe seperation is way to wide, ESPECIALLY if it is installed at a 113 intake centerline. You should have run a 110 lsa but installed it at 106. I like the 108 but in basic street engines like this, a 110 is the widest, but still needs to be advanced. Otherwise the engine will be very very lazy and not accelerate at all. If you used the same cam in a 350, maybe it was installed with advance and with the shorter stroke, will accelerate faster. If the cam was installed "dot to dot" so to speak, and no advance built in the cam, it is being run at the 113. Problem is since the cam is so small in the duration, by advanceing it to 105 will kill any power and rpm up top. LMK what piston is used and where the cam is installed at.
It's a factory style dished piston ~10:1 CR. I installed the cam "dot to dot" with 0 advance or retard per instructions. This is a N/A street motor for the most part. Looks like I'll be looking around for a new cam?

What should I be looking at for duration? I kinda figured the LSA was too wide and will look into a 108-110.
 

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I would run Comp XE hyd roller. They are at 110 with 4* built in. The 113lsa and 113ic is where your problem is. Without the dish size, I won't know exact compression, but IF it is 10.1, use the XR300R. It is a step up at 248/254 110lsa/106ic .562"/.580" lift with 1.5. A 1.6 on the intake will work well also for torque. This will work a ton better for the compression and cubic inch, and the XE grinds are more aggressive for more power. The tighter lobes will also bring that low end and midrange back that you are lacking. RPM's hould be to 6,200- 6,500 as well.
 

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Discussion Starter #12
I would run Comp XE hyd roller. They are at 110 with 4* built in. The 113lsa and 113ic is where your problem is. Without the dish size, I won't know exact compression, but IF it is 10.1, use the XR300R. It is a step up at 248/254 110lsa/106ic .562"/.580" lift with 1.5. A 1.6 on the intake will work well also for torque. This will work a ton better for the compression and cubic inch, and the XE grinds are more aggressive for more power. The tighter lobes will also bring that low end and midrange back that you are lacking. RPM's hould be to 6,200- 6,500 as well.
I was just looking at that cam and one of the Magnum cams with 252/252 .600/.600 on a 110/106. Those are the top 2 on the cam quest I downloaded a while ago. Swapping to 1.6's would suck since I would need to elongate the push rod holes. For this Mild of a build is it worth getting a custom cam from Bullet etc.?

And its a 113LSA/ 113ICL cam Hotrod 36
 

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I custom design almost every camshaft and have Bullet grind it for me, but for this, you wouldn't need to. OTS cams work just fine in these applications, and I wouldn't spend more just for a custom grind. Be throwing money out the window. I don't like the Magnum single pattern designs, kind of old school and won't be optimized. The XE grind is the much better choice. I have run this cam in the 383/406 and it works very well. Stick to the 1.5's then if you don't have the clearance, it will still be night and day from what you have, trust me. The current cam is way too small and mismatched. The converter you have is perfect for a street car and the gear swap is the way to go with the 4.10's and a 28" tire. This car will feel like a whole different car with the cam and gear swap. I would also run the 950hp with the HVH spacer for even faster e/t's...
 

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right now you have waaaaaaay too much lsa, find something in the 106-108 range and your engine will be much happier. you said they were ported, any flow numbers or other details on the heads? duration in the 250's will work well paired with some 1.6 rockers.
 

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my suggestion is also get another cam. SBC's love a 108 lsa cam. I would not recommend installing 1.6 rockers on the exhaust, intakes would be OK if heads called for it.
If that cam was spec'd for a 355 ci engine, remember when you increase CI the cam spec's increase with the CI. That 406 see's that cam much smaller than the 355 did.

Blessings..........Ron.
 

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Discussion Starter #17
Nothing real special with the heads just some clean up work really. Still 2.02/1.6 valves which I know dont help either. I've thought about sending them somehwere for more porting and 2.08/1.6 valves but thats probably a waste of money.

Heres flow #'s though:
Lift /Int. /Exh
.200 / 127/ 116
.300 / 186/ 155
.400 / 227/ 183
.500 / 254/ 204
.600 / 265/ 213

Like I said nothing great but I've used them for 3 years now.

Thanks for the help Kris and everyone else, I'll swap to that cam ASAP and see how it works out. Probably be a couple weeks. I was planning a Head/Cam swap next year but with how it acts this year it's pissing me off too much.
 

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I custom design almost every camshaft and have Bullet grind it for me, but for this, you wouldn't need to. OTS cams work just fine in these applications, and I wouldn't spend more just for a custom grind. Be throwing money out the window. I don't like the Magnum single pattern designs, kind of old school and won't be optimized. The XE grind is the much better choice. I have run this cam in the 383/406 and it works very well. Stick to the 1.5's then if you don't have the clearance, it will still be night and day from what you have, trust me. The current cam is way too small and mismatched. The converter you have is perfect for a street car and the gear swap is the way to go with the 4.10's and a 28" tire. This car will feel like a whole different car with the cam and gear swap. I would also run the 950hp with the HVH spacer for even faster e/t's...
"""


x2
 

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Ron- These engines with the 3.750" stroke LOVE the 108, you are right. But, since it is a basic street engine, the XE grinds work very well, and give ample vacuum for power accessories with the 110 and have the adv built in. I just didn't see anyreason to go custom for this just to have a 108lsa. The 108 I run in more of a modified combination.

84ta- Just swapping the gear, and camshaft, will make you go much faster. An alum head swap will net you a bigger port with bigger valves, and the ability to run more compression on 93, in which case I would step up the camshaft considerably and go solid roller. The cam I suggested works very well with the smaller 200cc runners and low compression. An Air Gap dual plane may even make more power down low and mid range and accelerate the car faster than that Vic Jr., But the camshaft is more important. Let us know how you make out.
 

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Those heads are not a bad head for a street build .I know a lot of dirt track guys that still use them as well. I think if you go witha cam a long the lines that kris speced you well be supprised at how much it will wake up. Good luck and keep us posted on how it go's
 
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