Tim H

Your "Irish style diplomacy" isn't flattering.
Anyway I'll let it go because if it takes someone 19 pages of nonsense and gibberish to get a street engine built then so be it for them but not me.
Good luck.

jotto

wtf does that mean?

C3Paul

Hi,

I took the engine and rotating assembly to the machine shop yesterday and should have it back in about couple of weeks time.

When I walked to the shop they had a small block ford on dyno screaming its nuts out.

WOOW, what a noise.

This engine is going in to a REAL GT40 (Race car) worth about £1.6 mil.

The shop is busy with final tuning on Ford and Chevy engines destined to race in historic cars at 12 hr race in Spa.

I know it looks like an organized chaos crossed with Aladdin’s cave but I am in safe hands.

C3Paul

Hi

All the rotating kit has been balanced now without needing any Mallory metal, but I am still waiting for the engine to be machined.

Should be ready on Friday.

BUT: Need a help with camshaft, please.

Spoke to Comp Cams and gave them this info for my cam:

Little problem with the Camshaft CORES at this moment so I was offered exactly this same cam spec, but on 07 (91-98 LT1/4) Core

Apparently the only difference will be slightly larger hole in the cam for the Optispark, but my engine will not know any difference

The cost is the same $334 free shipping within US.

Again, Billet core with Iron gear

Can I order it?

Tim H

Specs look like an extreme 4X4 truck cam.
If you going that big on lift maybe a roller cam would be better?

C3Paul

Yes, this is roller cam in a roller block

Little Mouse

Think maybe your being lied to on the cam core.

C3Paul

In what way?
Shortage of suitable cam cores
Or
LT1/4 retrofit/substitute for non Optispark application

Tim H

I hit that nail on the head!

C3Paul

I had another chat with Comp Cams Tech and was told that the LT1/4 cam will work in my block with no problem.

The only difference between LT1/4 cam and early cam is a button on the nose of the cam but this can be machined with suitable dowel pin to work with early pre LT1/4 engines.

I do not know any better to make a decision.

What do you think?

Found this as well:
http://forums.corvetteforum.com/c4-t...-cam-core.html

gkull

it is worth the money to buy a billet core and pressed on sleeve. They don't fail. I went out on the Comp Cams site and found this similar cam. If they have the lobes you want go ahead and order it.

http://www.compcams.com/Company/CC/c...csid=1111&sb=0

Our owner just sold the GT-40 for something like $2.5 million USD. the cheater motor came out and a more to spec 300 ci 4 Webber went back in. The power limitation was the ZF transaxle We kept breaking the cases at the mid 500 hp level. The original type motors are only mid 400

63mako

I am not sure if the LT cam has a fuel pump lobe since they were all electric fuel pump engines. Better check if your using a mechanical fuel pump. Since Comp has a shortage of cores have them do the necessary machining needed to make this work in your engine at no charge. If they do the work and guarentee it will work in your application I would order it.

PS: the LT1/4 cams lift numbers are all figured with 1.6 rockers so don't let them change that lobe profile or your actual lift numbers at the valve drop.

C3Paul

What is the difference between 5150 and 8620 steel?

Ordered the cam and depending on what is available it will be either 5150 or 8620 core.

BTW, the problem with suitable cores is because Crane cams went out of business.

Also, I am going to collect the block and rotating kit tomorrow.

Little Mouse

Paul

I had a crane catalog there roller cams were listed as being made out of 8620 or 9310.

Here is what "xenginebuilder" wrote

In my " experience " the comp 5150 cam cores would perform poorly in endurance type aplications compaired to proper 8620 cores. In all cases 5150 would pitt out after say 150 to 200 laps in a circle track engine. 5150 material is induction hardened which makes production much cheaper and easier then the process of copper plating and carburizing 8620. 9310 is also a carburized steel. Anything copper plated will usually be 8620. I have seen 5150 cores run ok in drag racing environment where you don't care so much about endurance, but in my opinion they are truly inferior to 8620.

There are several companies that supply cam cores. Crane going out or back into business had no real effect on anything.

Just some BS your being told to get by with selling you an inferior cam core. Like i said in my earlier post be carefull of being lied to on the cam core. Personally i would call comp back tell them its on a 8620 core or i'm going elsewhere for my cam.

C3Paul

Good news,

Spoke to Comp Cams and the cam is being grind on 8650 steel core. (Not 5150 or 8620)

The block and the rotating kit are at home now, but I have a question about balancing.

My Scat crank has to be balanced Internally front and Extarnally rear.

All is good but:

I am using Mcleod flywheel with bolted in (removable) weight on the flywheel itself.

In order to balance the rotating assembly the machine shop drilled the last counterweight (Rear main) and the flywheel itself.

Why did they drill the flywheel and the counterweight, rather than replaced or removed the flywheel bolted in weight all together?

DRIVESHAFT

Good question. Now your married to that flywheel.
If you ever have a problem with it you better have the balance numbers written down somewhere or your going to be in trouble.

Little Mouse

8660 is what your getting still not as good as 8620/9310 but better then 5150.

tekvette

They are externally balancing your rotating assembly?
I didn't think anyone did that anymore.

C3Paul

Ok,

I am building a one piece rear seal roller engine and using one piece rear SCAT forged crank.

Scat one piece rear seal crank has to be balanced Internally front and Externally rear.(Single piece rear crank has lot less meat at the rear than two piece rear crank. I am not trying to teach you how to suck eggs)

I spoke with the machine shop owner this morning and was told that they have tried to take off the weight and internally balanced the rotating kit, but in order to internally balance they would have had to use LOT of Mallory weight and/or turn the flywheel in to a Swiss cheese.

In his best effort to balance the kit he went with Scat recommendation and balanced the kit Internally front and Externally rear.

Also I have the balancing card and should I ever have to replace the flywheel I have the weight figures to sort out replacement parts.

I guess, I was surprised to see the weight still on the flywheel with drilled flywheel and crank.

BTW:
I read few books and researched How to build SBC, but there is LOT LOT LOT more to it than I imagined.

jackson

all OE iron block-iron head sbc having one-piece rear main seal (begin about 1986) are a "hybrid" ... GM supplies them with only Neutral front damper And only Counterweighted flexplate-flywheel ... all 49 bazillion of em. When you build a custom motor you can skin that cat several ways ... but OE GM are hybrid since about 86. This sub-7K rev street motor will never know either way.