dead end cruiser

I am attempting my first small block top end build on my own and I need some opinions on some parts to seal the deal.

I have a full roller 350 crate motor, I working this build around the cam kit and heads I have already purchased.

The cam is Comp Cams Big Mothr Thumpr
http://www.summitracing.com/parts/CCA-GK12-602-8/

I have also got a pair of RHS 64cc chamber 180cc intake, heads that I had milled to give me a 9.5-1cr to match the cam

I am using Lunati 1.5 Roller rockers

Breathing out of Hooker headers and 4" side pipes

Parts I am considering to go with it (feel free to leave opinions)
http://www.summitracing.com/parts/WND-7547-1/
http://www.summitracing.com/parts/HLY-0-80508S/

Is this the correct water pump? http://www.summitracing.com/parts/EDL-88124/

I also need input on what auto transmission to use along with a 2,800 stall converter, flex plate, mechanical fuel pump, All the ignition parts to make it run (HEI or points opinions?)

Help me build this pig!

Little Mouse

Well hopefully you bought the cam lifters at summitracing so you can send it back.

With that cam you sure will be at a DEAD END FOR A CRUISER.

cv67

Sorry but my opinion of those cams is.....
Youll be much happier with the way it runs with the right cam
(and it isnt from that line).


Much smaller and a good dual plane intake

Ben Lurkin

That's way too much cam for your combo. It has almost as much duration as the cam in my 540 BBC! It will be misery itsself in a street car. Send it back and get something with about 25* less duration.

dead end cruiser

Why do you suppose this cam will cause me so much misery?

Ben Lurkin

Your crate engine with those heads will probably have 10:1 comp or so. All your components are for a hot street engine. With what you have listed, everything will work well together up to 6000 rpm or so, except the cam.

Your cam is best suited for a street/strip machine and will peak at around 7000 Rpm or so. With that much duration you will bleed off a bunch of pressure at low rpm and you don't have nearly enough compression for that. It won't want to idle below maybe 1000 rpm and will be a stone when running below 3000 rpm. Your crate engine won't likely even survive at the speeds that cam is designed for. Just as the cam is starting to peak, the rest of your components will be signing off.

Match the cam to the rest of your components so they work with, not against, one another. You'll be much happier with the end result.

63mako

That cam would be closer to right in a forged 434 with 11.5 to 1 compression, 4.56 gears and a 5 speed that sees the dragstip regularly but there are better cams for that use too.

dead end cruiser

Thanks for the input Ben! My machinist, who also builds race engines told me that these components would work best with this cam set up. I am glad I asked for a second opinion though. I don't really car to turn this thing into a top speed drag car, I am really looking for something that will make a lot of noise, sound like a popcorn machine and still get me around town. Of course a power increase is expected, but I don't want to twist the car into pieces. I have watched some videos of people driving around with a thumpr cam and it looked pretty streetable. Any suggestions on a BIG but more streetable cam for this build? I'm sure if need be I can exchange the cam kit.

cv67

If you just have to have the Thumpr cam then geta much smaller one like almost 15-20 deg it will run much better. Get a good dual plane intake, Edelbrock RPM, Holley 300-36, Weiand airstrike *believe thats the name of their new one) Check for hood clearance. It will run strong and youll still hear the cam. The rumpity rump stuff to a point is overrated these days. Sure it sounds cool at a light but-

Youre machinist...240@.050 with 9.5:1 running good hell no. They all "build race motors" doesnt mean they will "run" follow?
It wont get out of its own way trust me. BTDT....

The whole "low compression/big cam" thing imo is bs magazines pump at you. sure they may get a # on theri dyno but how it works in a heavy car under load are too different things. everything has to match as a package.

Let the regulars here guide you some more

63mako

If you want that thumper sound and decent performance this one matches your build specs better.
http://www.compcams.com/Company/CC/c...csid=1258&sb=0
Low compression, small heads and a too big cam is a recipe for disaster.
I would also look at an rpm air gap dual plane. Hood clearance is always an issue so study before buying. The vacumn secondary holley is a good choice with your automatic. You need all your power by 6000 RPM because your bottom end is built for that and the heads are going to be done about then. You have to match your components to get the best results. The thumper cams use a big exhaust duration and tight LSA to get more overlap to get the sound. This is counterproductive, especially with a lower compression, automatic car as the cam bleeds of cylinder pressure and narrows the operating range of the engine, so with the thumper cams you are trading performance for sound somewhat

anips

I'am thinkin the carb is a little big also, my guess would be a 600-670CFM street avenger would work better go to http://www.gtsparkplugs.com/carbcfmcalc.html. there is a formula fill in your spec's and it will recomend the correct carb

dead end cruiser

Thanks for the input, as for trading sound for performance that is fine with me, I have a few other vehicles I use for the performance aspect. More or less I am only using the Vette as an obnoxiously loud poppy cruiser... Not really interested in hauling *** with it. But if this gigantic cam is basically going to grenade my engine then I don't want it. I plan to ultimately sell the Vette but I cant really get a penny for it as it sits blowing smoke as if it were a crop duster, so I decided to pick up a crate engine for cheep and build the top end to get a little bit more performance then stock.

Little Mouse

The thumper cam 63mako put up has the same tight LSA to help give that rumpity rump you want without all the unrealistic high duration. Be a much better cam for what your wanting to do.

scottyp99

As soon as you hear someone say "I build racing engines" or "I am a racer", start taking their advice with a grain of salt. Race cars and street cars require completely different approaches.


Scott

dead end cruiser

Thanks guys! If it wasn't for your responses I probably would have built a disaster. I just got off the horn with my machine shop buddies and they agree with what you are all saying... They suggested if I want a ratty choppy rough sounding car and still want to drive it, to go ahead and use the thumpr cam as opposed to the motha thumpr or the big motha thumpr ( the smaller of the 3 cams ) and it would be much more practical for my build. I'm putting my return slip on the box now and going with the more mild cam. Any other input for this build?

Now which cam should I order? I notice the lift is different and under the notes section, only one mentions that it is for an OE roller engine such as my crate engine

http://www.summitracing.com/parts/CCA-GK12-600-8/
and
http://www.summitracing.com/parts/CCA-GK08-600-8/

Little Mouse

Make sure the RHS heads you have are set up with springs for a hydraulic roller cam.

If you have an OE hydraulic roller block you want the second cam that comes with the correct cam and lifters for that block.

You have a 79 with plenty of room for a high rise dual plane RPM edlebrock as long as you use a drop base air cleaner. If you want to keep the original air cleaner and cowl hood function then just go with a performer edelbrock.

dead end cruiser

Yeah those heads are set up for the hydraulic roller, those springs would handle the original cam I had intended using no problem so I am sure they will be fine with the more mild cam.

The car is actually a '78 silver anniversary but I am assuming the hood clearance would be the same

Little Mouse

I had a new L/82 1978 and a new 73 with the same hood. Someone has painted the windshield trim on your 78 black like the 79 had lol.

63mako

Your original cam was this one.
http://www.summitracing.com/parts/CCA-GK12-602-8/
It has the link bar lifters. These are not right for your roller block. You can use your original spyder, bolts and lifters. All you need is the camshaft and probably pushrods if the RHS heads have the +.100 valves most aftermarket heads have. I didn't realize you had a roller block. Get a pushrod length checker for $20.

Edit: Here is the right cam for your application.
http://www.compcams.com/Company/CC/c...?csid=216&sb=0

dead end cruiser

No, the one I am sending back is the GK-08-602-8 I got the correct set up for the roller block, but as everyone has said it will not be drivable at all, so I am exchanging it for the GK08-600-8 which is the smallest of the thumpr cams....