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Time to add some ponies, whats your thoughts with this combo...

6

69vettester

Guest
The UPS Man Will be here tomorrow with my new Manifold and Holley.
Then the first of the month Im ordering heads, Cam, roller rockers, chain and gears, and Damper.

I have a M20 and 3.55 rear gear now..

Here's the combo..670 street avenger sitting on a EDL Performer EPS, AFR 190cc 68cc straight plug heads with a CC 268h cam opening the valves, CC magnum roller rockers, CC double roller chain, 6 7/8 street dampr

What do you think, will this setup get my 300-330hp vette small block up there to 400+
**What will happen to my excellent highway cruisability that I have now**
 

JHL

Senior Member
Joined
Oct 24, 2000
Messages
403
Location
Everywhere
Corvette
81 4 speed
Hi,

The comp 268 is a popular choice with quite a few people at the moment but I doubt if you will get the required 400hp with it. When I looked into changing the RPM cam in my car I had a few different cams run on desk top dyno for me and did consider the 268. It has plenty of torque but was from memory running about 375-385hp in my combo although I have the Edelbrock 64cc heads as opposed to the AFR`s you are thinking about. I also suspect that these computer simulators are generous with the numbers.

I havn`t run mine yet so I can`t report on the comp cam I installed but according to the dd numbers it comes up just short of the 400hp mark but with big torque much lower down the rpm range. So while I have given up on some of the RPM cam`s horse power the indications from the computer is that the car will be quicker in the quarter.
 
6

69vettester

Guest
JHL
Ive heard alot of guys get their numbers from desktop dyno runs..Accurate input fairly accurate results, and certainly better than no estimate at all..
I looked at the EDL rpm Power package , seems Its a real good combo with the exception of the cam, I read a few posts from disgruntled people that swapped That cam out because it killed their low end. The rest of the package is excellent, Seems your saying that too.

I dont know what pistons I have so dont know the CR but think its no more than 8.5:1
The Afr's have 68cc combustion chambers so I might not get to 9.5:1 CR with them, I would By installing 64cc Heads. Im thinking 9.5:1 CR is optimal for getting a Small Block peak on the 91 octane that we have here in the US.

I may look at the EDL 64cc heads some more..They are less expensive that the AFR's too.

Thanks..
Tom
 

JHL

Senior Member
Joined
Oct 24, 2000
Messages
403
Location
Everywhere
Corvette
81 4 speed
You are right about the compression, the flat tops I have with the 64cc heads should yield about 9.25cr and it was probably just a little short of the mark for the RPM cam. I just could not get the RPM cam to run well below 2500rpm and even with the stick shift it was hard going around town, but it did have some serious power once it was running. My car had plenty of mph at the end of the quarter - 104mph even with a slipping clutch and I felt it would have ran low 13` easily with the Edelbrock combo. AFR`s seem to be the heads of choice but I couldn`t get them over here from any of the local suppliers and the Edelbrock kit seemed good value for money. I saw a poll on an other forum of what people eventually purchased and the Edelbrock heads were way out in front. What I liked was the fit and finish of their parts, I never had to make a single mod to get any of it to fit, not withstanding the cam, it worked right out of the box. I am tempted to say that in a lighter race car with some 4.88 rear gears the cam would have been excellent it screamed between 3000 and 6250rpm, just no good in a daily driven 3500lb Vette.

Some people will undoubtedly pitch in with the crate motor idea and after I had the problems with mine I half regreted not taking that route myself it would have been hassle free and probably cheaper but not half as much fun.

I have never used DD myself instead relying on some other peoples inputs so it `s possible I am being a little unfair in my comments but reading through posts on a few other forums the hp #`s do seem a bit on the plus side in a lot of cases. Just to give some idea of what is possible with the Comp cam I fitted, I had some mail from one guy who was running it in a fairly similar combo but punched out to 383 and in a 4000lb Monte. He had tickets for 12.9 and drove it to and from the track. I will be happy if I have restored some drivability and run mid 13`s which won`t be too shabby for a 21 year old Vette, should be just enough to keep the local boy racers firmly behind me.

J.
 
I

inferno-vette

Guest
Sounds good. Need a Desktop Dyno info?
 
6

69vettester

Guest
Im missing important info about my motor, CR I dont think DD would be acurate without that?

The info Im getting in this thread will be enough to figure out what to get..
Thanks everyone:beer
 
6

69vettester

Guest
JHL

JHL, I forgot to ask If you were able to use the stock length pushrods with the combo you ended up with..
Ive heard that 1/10th longer pushrods are required to get the roller tip to center on the valve stem? anyone been there with that one..
 

JHL

Senior Member
Joined
Oct 24, 2000
Messages
403
Location
Everywhere
Corvette
81 4 speed
Tom

I used standard length pushrods and had no problems. In the Edelbrock catalogue it say`s to use +.100" pushrods if you are using the "stock" rockers. I did use some heavy duty Crane items just to be on the safe side. I also changed the original flat pushrod guide plates that came with the heads for a set of Crane stepped guide plates. On the heads they recommend using slightly longer head bolts and ground flat washers and gave a part number which I assumed was their own but when the goodies arrived I found I had paid $120 and they were ARP bolts which I could have got for less if I had bought them seperately.

The spec on the Comp Cam I used is 226*/234* & 480/498" it only gives up about 0.010" on the RPM cam but has a lot duration which I hope will give a better low end.

J.
 
6

69vettester

Guest
JHL
Looked at your motor build pics,:cool and the other pages too..whooeee..

I think Ill measure the pushrod length with the adjustable test pushrod kit, during setup and order whatever it comes out to be.

I got the manifold and 670 holley sitting on my living room floor:D
Ill take some pics and post em soon..The Edelbrock perform eps manifold is real nice, Three days ago I had the rpm airgap sitting there, its an awsome looking manifold, but on second thought , I decided not to jump through hoops to get it to fit under my 69 low profile hood, like 2" drop base and cut off the "new" holleys choke tower..:eek

The AFR heads are hard to find, There is a speed shop 150 miles from here that is a distributor for them, Ill go pay them a visit soon..
Ill have all the parts by the first of the month, but may not start the work till end of sept. or so..dont want the car down till then..

Is it getting harder for you to get parts over in the UK since sept. 11?
Ive seen some companies have stopped overseas ships because the new fed. standards make it impractical?

Hope you get the gains your looking for..
Later..
Tom
 

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