It's time to change my Crane roller race cam (290/300 dur and .680/.708 lift), for a more 'decent' one.

Now have I ordered Comp Cam 288AR with new springs, valve steam seals, chain and rollerlifters. (288 dur and .623 lift).
The engine is 454 bored +.030, 11.2 comp rate, .990 rec heads (slightly ported), Torker singelplane manifolder, Holley 850DP, Hooker 2" headers with 3" dual pipes and flowmaster mufflers. MSD6AL box.

- Special things to think of during the swap?

- Can the match be much better?

- Which jets to start with?

- Is the filter area of K/N 14x3' filter enough?

Thanks in advance!

 

How does your car act down low in the rpm range? Might want to look at a dual plane or an air gap manifold to make it a little more friendly at lower rpm's. I guess you are changing cams to make it more streetable. With that bb you don't have to worry about torque down low. :)

 

The Crane cam has a range between 3500-7000, while the Comp cam has 2200-6500, as spec. I must say that the Crane are very hard to drive in normal traffic and also impossible to run when cold. I expect from the new cam to have a much more matched engine for a street machine.

 

Lasse,

Im going to go with a Crane Powermax hyd. roller cam # 139731 , which i think is the one you are going with also.

My current setup is a 460 cid , dual plane Air Gap Intake with Speed Demon 850 dp/mech. secs , 4 speed, with Edl #6045 oval port new Heads and Headers. The cam i have is a mild Edl .553 lift 232 dur. 110 deg. lobe center. SO....im coming from the other end than you are ; im looking to get a bit more radical for street use than what i have.

If you go with a dual plane, youll notice a much better warmup period with your engine.

Dave

 

Well, lets see... Why are you replacing the lifters? Unless there's something wrong with your old ones, they can be re-used. One of the nice things about roller cams.

It will still be a rather high-strung engine. The smaller cam will build more cylinder pressure and you will likely have to run higher octane fuel.

If you want a really nice street engine I would lower the compression to 9.5:1, with a slightly smaller dual pattern cam on a wider lobe separation and use a dual plane manifold. You can fit a Performer RPM under the L88 hood.

The 14x3 filter is more than enough.

 

After spending 20 hours changing my cam, I would not want to do another ever, not a fun job.

 

Lasse,

Please keep me posted on how you like the CompCam solid roller. I have been giving more than a little thought to changing to either that cam or one very similar to it. The factory L88 cam has even more duration than your current one; but, not as much lift. I've noticed that Crane also has a cam similar to the 288AR and that they have a lightweight roller lifter. This brings the lifter weight down to that of a normal solid lifter, approx 100 grams. This should allow less spring pressure, longer life of the lifters, and all araound less stress and wear on parts.

Jetting seems to be high 70's or low 80's if your using an 850-950 cfm carb, but I would get it dialed in with a dyno and A/F sensor to perfect.

Chuck

 

Chuck, how do you think the L88 cam compares to the 294S Comp cam 294/294 .595/.595 lift cam. What are the spec on the L88 cam?
:cheers:

 

Corey,

The L88 has very long ramps. The advertised duration is about 347/359 degrees. At .050 it is about 262/273. The .540/.560 lift, once considered pretty extreme, is quite tame by today's standards.

The 294S measures about 248 degrees measured at .050 so it is much more mild by comparrison.

Chuck

 

The summer has hit Sweden, so the reply took a while....

Zwede - I had one lifter which locked last summer, and now when I swap the cam, I don't want to take a chance with the others.
I want a high-strung :smash: engine, the petrol price are high here, so I want to get the most of it, when I take a ride. :yesnod:

The only thing that worries me, are if the octan (Swedish 98) aren't enought. What to do then, change pistons? But Comp cam support say's that it will work. Hope they know...

Dual plane, yes I have thought of Performer RPM 2-R or RPM Air-Gap 2-R. Will they fit under L88 hood? I try with this setup first.

73-454 - Not fun :D :(

Chuck - I post you the results. Now I waiting for the parts to arrive.

 

Lasse,

I have an L 88 hood on my 1970 BB. I have the EDL Air Gap with 1/2" wood spacer, and Speed Demon 850 Carb.....still room left, but not much.

R.R.

 

Lasse: Swedish 98 octane is not the same as US 98 Octane. In Europe octane is measured according to the "research" standard. In the US, octane is measured as the average of research and motor (R+M/2).

What all this means is that Euro 98 is about equivalent to US 93. So if you called Comp Cams and said you're running "98 octane", they probably thought you had access to race gas. Ask them how it will run on 93, and you may get a different answer...

 

Thanks Zwede!

I will ask them, at ones!

 

Unfortunately, I've lost all faith in the Comp tech line. Two weeks ago I faxed a cam recommendation sheet to them, then after not receiving a response for 3 days, I called them. The tech on the other line had no idea where to find my fax, so I gave him all the information again and he then recommended a certain cam for my new engine. A few days later I receive the response to my fax in the mail, and the cam recommendations are so much different it's rediculous. I'm talking around 25 degrees and .1" lift difference. Not even close! It's obvious that when you call them you simply get one person's opinion, not a decision reached by their combined experience and research. I'm done with their tech line, the guys here on the forum are much more knowledgable overall. :mad

Joe


[Modified by Flareside, 3:03 PM 5/13/2002]

 

I`m going to follow this thread closely,as i will change my cam to a roller this winter.
Lasse:Kanske syns på någon corvette träff i sommar... :cheers:

 

Flareside - Sad to hear that! I have mail them two times and they have recommended 288AR both times. Can I trust them? :confused:

Is it someone here, that have time to check this setup:

Size: 462 cui
Original Stroke and Bore +.030
Comp ratio 11.2
1.7 roller rocker arms
Holley 850DP (modified, without choke-thorn)
Edelbrock Torker manifold (singel plane)
GM Hi Perf rectangular iron heads #6272990 (118cc, IP 325cc) ported and machined for larger springs.
Original valve sizes.
TRW l237F030 power forged pistons, dome volume +38.5 cc
4 speed manual with 3.55 rearend, 26" wheel
Hooker 2" headers, dual 3" exhaust with Flowmaster 50-series mufflers.

Application: Performance street

Current cam:
Crane 138091 cam
.680/.708 lift
290/300 adv dur
252/262 dur .050

Recommneded from Comp Cams:
Comp Cams 288AR
.623/.623 lift
288/288 adv dur
246/246 dur .050

What I can see as an amatuer, is that the intake figures (times) are near each other, but the lift are much smaller.

Will the 288AR cam fit my engine, on 93 octan as Zwede say's.

Thanks!


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Lasse, I think that cam sounds great for your engine with the possible exception of your compression ratio. With 11.2:1 compression and iron heads, you may be on the ragged edge of detonation with any cam more mild than the crane you're currently running. We'll need to hear from someone else who's run a combo similar to yours.

 

Lasse,

I'm afraid that pump gas will not work with a smaller cam. You have over 11:1 CR with iron heads. That's... alot! I'm surprised you didn't have detonation with your current cam. I would recommend you inspect your main and rod bearings. You could have detonation and not know it.

Now what would be a nice cam for you? I would recommend something around 235/245 @050, on a 112 or 114 lobe separation. You should consider a hydraulic roller unless you want to inspect the engine about once a year. Solid roller lifters are supposed to be rebuilt every 10-15k miles. They are also marginal if the engine is idled for any time. With hydraulic rollers you install and forget for the next 100k miles or so.

With the above cam you should get about 12-13" vacuum at idle. It will idle decently at 850 rpm. It will still have a lope, but not too bad. Torque peak should come in around 3800-4000. HP peak around 5800. Redline at 6300.

How does that sound?

 

I've got an answer from the previous owner of my Corvette, who built the engine. He said that the Crane cam is just as Flareside said 'on the ragged edge of detonation'.

I have also got an new answer from Comp Cam and they say that they recommend the 288AR to be custom made with 108 LSA. Thanks for the useful info Zwede.

I go on your path Zwede and will look after an hydralic roller and change the comp with new pistons.

Thanks pals! I will open a new topic for that part. :cheers: