377C Freshen up, cam change.
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Author:  XAFALCON [ Sun Aug 26, 2018 2:47 am ]
Post subject:  377C Freshen up, cam change.

Hi from New Zealand!
Just discovered the forum, wish I'd come across it sooner, there's some great reading here!

I'm about to upgrade a few parts on my 377C which has only done 3500km since a rebuild. I bought the engine already rebuilt off a guy who unfortunately had to part with it (unfortunate for him, fortunate for me as the price was very good :D )
The camshaft is the main item, along with the installation of some Tim Meyer grooved cam bearings and a standard volume oil pump.
The restrictor kit and HV pump will be getting turfed.
Bottom end is nothing special, offset ground oem crank, chev rods with arp bolts, dished hypereutectic pistons, about 10.1 to 1 comp.
Heads are 2V closed chamber items, cnc ported with reworked chambers, now at 60cc.
Flow specs are..... .200" in 157 / ex 111, .300" in 220 / ex 138, .400" in 260 / ex 162, .500" in 281 / ex 180, .600" in 279 / ex 195, .700" in 282 / ex 207, .800 in 285 / ex 217. Intake runners 192cc in and 110cc ex.
Replacing the no name brand aluminium roller rockers with some compcams chromoly items and some crow thick wall 5/16 pushrods.

Right the camshaft, currently it's a crower FT item, 220/226 @ 0.050, 528/540, 112 lsa, 108 icl.
I'm going hyd. roller, so I emailed specs to a few places for custom grind, Crow in Australia came back with 232/236 @ .050, 597/598, 108 lsa, not sure what icl was. Another crowd in NZ was secret squirrel with specs and to expensive. Howards never replied but Lunati did, I asked for custom grind, they came back with 231/239 @ 0.050, 611/611, 110 lsa, 106 icl, they said that cam would be just about right for my application, even though it was off the shelf, so I bought the kit, cam, lifters, springs, retainers, locks & timing chain, $860 usd which I thought was pretty good price.
Now after reading lots of posts on here about how important it is to customise a cam to suit, I'm not so sure this cam is just right after all!
Is this at least going to be in the ball park somewhere? I don't really want to shell out for another one but I will if it's not going to cut the mustard. Hoping to get 450hp at least, any more will be a bonus.

Any advice would be much appreciated.

Other specs are:

Rpm air gap with quickfuel ss680vs
4 into 1 headers, 1 3/4 primaries, 3 inch collectors, twin 2.5 inch full exhaust with flowmaster 40 series mufflers.
T5 5 speed trans with astro performance gear set
9 inch with 3.7 gears.
Msd pro billet distributor with no vac advance and 6 al box, running 16 initial, 36 total, all in 2800 rpm.



Author:  blykins [ Sun Aug 26, 2018 5:53 am ]
Post subject:  Re: 377C Freshen up, cam change.

Thanks for joining!

When you're looking at hydraulic rollers, the advertised durations play a *huge* role. If the advertised duration is too large in comparison to the .050" duration, you may have a problem with vacuum. If it's closer to the .050" duration, then you can end up with a noisy lobe, as well as issues running pump gas.

If you were getting a cam from me, I'd be asking these additional questions:

1. Where would you like the peak hp rpm to be?
2. Are you running power brakes?
3. What are the valve sizes?
4. Is this a street car only, or will it be used on the strip?

You did well in providing the cylinder head port volumes and flow numbers. That was a big help.

BTW, remember that most hydraulic roller camshafts are billet steel cores (some are, some aren't). The billet steel core cams will require a steel distributor gear.

Author:  XAFALCON [ Sun Aug 26, 2018 8:23 pm ]
Post subject:  Re: 377C Freshen up, cam change.

Hey Brent,
Thanks for the prompt reply.

It's primarily a street engine with the odd fun day at the track.
The rpm range on the roller I have is 2600-6600, I don't really know what the bottom end is capable of rev wise but I figured it must be ok for 6- 6500rpm max with the arp bolts without stressing it to much?
I've got power brakes to think about so vacuum will play a role.
Valves are ferrea stainless @ 2.07 & 1.65.

Any thoughts on the cam I have? The advertised duration is 282/290.
Or would it be better to look at a custom job from you?
My mate works at So-Cal in Pomona and ships back here twice a year.

I'm seriously thinking about a 408 upgrade now tho after reading some of those wicked engine builds!
I'll have to wait till our dollar drags itself out of the crapper against the green back 1st tho :roll:

I did get a melonized dist. gear to suit the cam so at least I was up with the play there :)

Thanks again!

Author:  XAFALCON [ Sun Aug 26, 2018 8:34 pm ]
Post subject:  Re: 377C Freshen up, cam change.

Strip not track.

Author:  blykins [ Mon Aug 27, 2018 6:02 am ]
Post subject:  Re: 377C Freshen up, cam change.

I think it will be ok, especially since you already have it. Should be done at around 5800-6000. 66° of overlap, so you'll have vacuum for your brakes. Duration split is ok.

If you have access to 93-95 octane gas, I'd put it on a 104 ICL instead of a 106.

Keep in mind that a 408 will want more camshaft to peak at the same rpm.

Also keep an eye on the distributor gear. If it's a cast core camshaft, a cast gear will be ok, but if it's a steel core, I've never had any luck out of anything but a steel distributor gear.

Author:  XAFALCON [ Tue Aug 28, 2018 3:21 am ]
Post subject:  Re: 377C Freshen up, cam change.

The best fuel we have here is 98 ron, which is about your 93 and it's not sold everywhere, most common is 95 ron (your 91).
I do mostly use 98 as the local servo sells it but will probably have to use 95 at times so not sure how well that'll go with the 104ICL?
Lunati matched the cam gear for me, it's one of theirs so hopefully it'll work ok, but I'll confirm if the cam is cast or steel and get a steel gear if I need it.

Thanks for the advice and will be in touch when it's time for the 408 upgrade. :D

Just quickly, would my current heads and manifold be useful for 408 time or CHI all the way?


Author:  XAFALCON [ Mon Oct 08, 2018 7:23 pm ]
Post subject:  Re: 377C Freshen up, cam change.

Hey Team,

So the cam kit arrived a couple weeks back and I've since read a few posts on here regarding valve spring pressures so thought I'd check what they included, and now I'm a little worried they may be a little on the puny side?

Lunati 73124 springs and 75741 steel retainers 1.550

Dual with damper 1.510 od
Bind 1.175
Seat load: 118lbs@1.880
Open load: 355@1.200
Rate 348

231/239@0.050 611/611 lift, it's only mild for a hyd. roller, but I'll be a little pissy if they aren't going to cut it, another few $$ on kit price and they could have included something up in the 150 seat and 380-400 open range if that's what's required.



Author:  blykins [ Tue Oct 09, 2018 12:44 pm ]
Post subject:  Re: 377C Freshen up, cam change.

So if your install height is actually 1.880", you have ~118 lbs at seat and 330 lbs open.

Your cam with only a 51° split between advertised duration and .050" duration (this is called hydraulic intensity) is actually on the aggressive side. That cam is more on par with something like a Comp XFI lobe, etc.

It will probably be a little noisy and IMO, I wouldn't trust it with only 118 lbs of seat pressure. Keep in mind that the seat pressure is what shuts the valves and if you hang an exhaust valve open at high rpm, you're gonna introduce it to the piston.

I'd like to see 140-150 seat and about 375 open on this one.

It looks like if you set them up at 1.880", you're gonna have about .095" coil bind clearance. You will need to carefully measure your install heights and adjust them. If you could use a .030" shim and get them closer to a 1.850" install height, you'd gain about 10 lbs of spring pressure. Not exactly making everything right in the world, but if you're stuck with them, I'd do it and try to help yourself.

Author:  XAFALCON [ Tue Oct 09, 2018 2:38 pm ]
Post subject:  Re: 377C Freshen up, cam change.

Hey Brent,

Thanks, I figured this may be the case.
It amazes me when they have such a selection of springs, they include items that are either inadequate or barely adequate at best!
For the princely sum of $11.25 extra they could have included the set with 1.540 od, 142lbs@1.940 seat, 402lbs@1.250 open which I'm picking would have done the job?

For the sake of a couple hundred bucks I'd rather get a new set than have the thought of an inconvenient marriage between piston and valve hanging around every time I gas it.

Any recommendations? Maybe some Isky 8005a items? Maybe some tool steel retainers while I'm at it or is that a bit overkill for my application?



Author:  blykins [ Tue Oct 09, 2018 3:18 pm ]
Post subject:  Re: 377C Freshen up, cam change.

What bugs me is that they include a universal spring kit and they don't know the valve sizes, install heights, or anything about the engine.

I'd run more spring and I'd run a tool steel retainer, but keep in mind that some of the tool steel retainers add .100" in install height. Before you do anything else, I'd measure what your current install height is and then we can go from there.

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