I was checking out "how to build chevy small blocks on a budget" by David Vizard Vol 3.

He was talking about the exact intake on my car. Weiand #7525 Team-G street ram. He said it is a great singleplane intake. It also said that if I keep the cam at or below 280* seat to seat, that it will pull hard on the bottom end as well as on top end. He says I can get the perfomance of both a singleplane and a dualplane.

What I need to know is what cam should I go with? I would like to go with a comp xtreme roller grind.

How close would the LT4 hot cam be?

Maybe a dumb question, but is ADV duration measure from seat to seat? I just want to know what I am looking at when I see the specs of a cam in jegs or summit.

I will be adding this cam with new timing chain & gears, fully worked L98 heads (cast) with 2.02/1.60 valves, and a 3000 stall.
The rest is in the sig.

Also what lobe separation would be best with the carb? 110 or 108. I know the Lt4 hotcam is on a 112, would I be better off with a custom grind?

thanks for any help.

 

Yes ADV duration is seat to seat. I would look at the XR274 or the XR280. Also that book is getting kind of old, there are better intakes now, such as the Air-gap.

 

He needs a factory roller cam. the 274 is a flat tappet. The roller version is the 276, the next size up is the 282. The specs for both are as follows:

XR276hr Specifications::

* Advertised duration: 276 intake/282 exhaust
* Duration at .050 in. cam lift: 224 intake/230 exhaust
* Gross valve lift: .502 in. intake/.510 in. exhaust
* Lobe separation: 110 degrees
* RPM range: 1,900 to 5,600
* Recommended for high performance street machines.
* 2,000 rpm plus stall, gears
* Choppy idle

XR282hr Specifications:

* Advertised duration: 282 intake/288 exhaust
* Duration at .050 in. cam lift: 230 intake/236 exhaust
* Gross valve lift: .510 in. intake/.520 in. exhaust
* Lobe separation: 110 degrees
* RPM range: 2,200 to 5,800
* Great for street machines
* Needs intake, headers, stall, and gears

Both of these cams are a bit more aggressive than the HOT cam. The 282 being more so than the 276, of course. With a 3000 stall, you could probably get away with the 282. However, your vacuum acessories may take a hit for that and it may be necissary to run a vacuum canister for brakes.

Yes, advertised duration is seat to seat. When comparing cams side by side, use the .050" duration figures as the manufacturers definition of "Seat to seat" can vary from .004" to .008" of tappet lift or so. For example, Comp uses a .006" measurment for seat to seat on the hydraulic rollers, whereas Crane uses .004"

For your situation (non-cc carb) a 110° LSA is "normal." A larger LSA of 112 or so can be used, however.

Now, what valve springs are you running? I would recommend running at least the Copm 986 or 987 series if you aren't already running a spring of equivalent size.

 

The cams i quoted are solid roller cams.

 

thanks for the advice guys.

Yeah, I am looking for a hyd roller cam. I would like to use the xe282hr, but think it may be too much.

The xe276hr would probably be my best bet. I assume that these specs are with 1.5 rr's?

I have not changed springs yet. I want to match them to the cam I pic. I figure I need something bigger than the stock dia spring 1.250, so I will have to do some machining.

ME leigh,

I know there maybe better intakes out there, but I got this one for $75 and it looks brand new. Only used on a race engine. Plus it fits under the hood and has a good rpm range.

What is the adv duration on the LT4 hot cam? Would it be as aggressive as the other cams if I used a 1.6 rr?

If the other cams would be better, I will pic one of them. I am on a budget, but picking the right cam is no place to try and save money. I just want the right one for my intake.

Its not a daily driver, but it does see some road time. I would love to dip into the low 13's with this combo.

 

You don't need a huge cam and intake like that to run 13's. All you need is a good set of heads.

With stock heads a cam like that and that intake it will be slow and feel like a dog.

 

I plan on fully working the L98 heads. Full port & polish, bowl blend, 3-angle valve job, and 2.02/1.6 undercut valves.
These heads will flow much better.

I bought the intake for a 383 project, but I decided to swap from tpi to carb. So I put it on the stock L98 with the holley 750. Last time at the track I ran a 14.20 with trans problems. I could probably get a 13.99 or better out of it.

With the head work and cam swap, Low 13's should be no problem. Should be in the 12's. I just like to be conservitive on on ET guessing. I wont to see what I can do without boring or stroking the shortblock.

I dont want a mismatched cam/intake/head combo.

 

The cam is something you need to be careful with. The comp cams are measured at .006 and the standard is .0045. This equates to a 8 degree difference as best as I remember. This means the XE270hr10 should be looked at as if it were 278 degrees for this comparison and to calculate DCR.

I would use 108 degrees LSA on 3.48 inch stroke motors with 5.7" rods. 110 is OK if you pull mostly street duty or need to stretch your stall. 112 will be down on mid range torque even though it may dyno well.

I would definately get a cam rec from comp. You might collect a few from different companies and then choose something that averages what they tell you. Personally I think 282 is too big for your heads and 276 is pushing it but I can't stress enough to get a rec from the manufacturer.

I don't know what you will end up with but if you choose a 270HR-110 I have one NIB that I would like to sell but get a rec before you decide what cam you need.

HTH

John

 

Thanks john, I will keep you in mind. How much by the way?

I was planing on calling comp and see what they suggest. If I work the heads right, they can flow as much as afr 190's. Like I said if done right.

Anyone have a HP guess with this combo, using either cams?

 

Yeah but the only people that can do it right are the professionals that have been doing it for 30+ years. The average novice will only gain 10-20 cfm.

 

Well, When I said "I", I ment my machinest. lol. Sorry. Everything else, I will do. When he cuts for bigger valves, I will have him do a full port job. I dont have the tools to cut new seats and backcut the valves.

My machinest is around 65 years old and has been building motors most of his life. Round track, Street and strip, Full out drag motor. He does great head porting for a great price. Cheaper than I can buy the tools and do it myself. He has even been mentioned in hotrod and carcraft. And the great thing is, He is only about 2 miles from my house.

But I understand what you are saying. I do want the cam to match the heads.

Do you think the xe276hr cam would be too much. Even if we can get the heads to flow better? What cam do you suggest?

 

I'm not trying to be a jackass or anything here but how much are you spending on these heads. $500? That is not a good deal, for alittle more money you can get some actual performance heads. Or even some vortec that will blow the doors of those for cheaper.

 

I understand what you are saying. I have check out about all the other heads. At one point, I was going to buy some dart Iron Eagles. I still might, my machinest can get them for a great price.

If you do a search on the L98 heads/port, you will find a post on ported flow numbers.

The guys name is rhuarc30. He got great #'s that outflowed the vortecs and also flowed as well as AFR 190's. He has 4 sections wrote up about them.

I could problably get the 215 Iron eagles for around 850. Thats complete with springs to match my cam.

It bad to want to go fast on a budget.


I have always wanted to know what cam (with better spring and screw in studs) the unported L98 heads would support.

Anyone know?

 

here is what summit had on the xe276hr cam.

xe276hr


Would the stock L98 heads with new spring and studs support the LT4 hot cam? OR a cam with under .500 lift?

I would like to get 350 hp out of the modified L98 heads and a cam swap. Along with my other mods. Or am I out of my mind?

 

Absolutely not!

A decent port and polish on your L98s will theoretically support 500 hp. Follow the link at the end of my sig.

 

I know what your saying, but you can't just say he got really good numbers so i will also. To get numbers like that you have to spend close to 100 hours porting and having them tested on a flow bench. Then at the end you still have stock heads with crappy combusion chambers.

Trust me i looked into porting, polishing and setting my stock heads up for performance, or even going with Vortecs. But in the end it was cheaper and easier to just start with a aftermarket performance heads for my 383.

I will agree if you have all the tool and all the machine equipment to do head work ( cut for bigger valves, valve job, porting, screw-in studs) it may be worth porting stock heads. But if you have to pay somebody else to do the work its just not cost effective.

This is you i went with PROTopline Iron Lightining heads for about $700.

 

Yeah, I followed your link before. Real nice.

I also checked out rhuarc30. He has some good posts on the L98 head.

Im getting to the point that I dont know what to do. Maybe just slap some better springs and screw in studs on the heads. Then add a lower lift cam and be done with it.

I talked to a comp rep and they said I should be ok with the xe282hr cam. But there is nothing like real world experience.

Can I get 350 hp if I add the Lt4 hot cam, and new 1.250 springs rated for 500-550 lift. And leave the rest alone?