Oldwolf

Hi
I am trying to get i decent idle with this setup but its hard. I want to use the car for som trips to town (not far) to bye a hot dog or something and back.
I am wondering if it´s any use trying to get the idle lower. 1500RPM idle 30, degrees advance. The engine is a 351c 4V ,1970 with 12.5 static compression and 308R Comp cam (mec roller). Stock 4V quench heads with aluminum exhaust plates (raised ports) (old technology, but cool)The induction system is a Weiand tunnelram and two brand new 650 Holley double pumpers.
Have somebody tried this type of setup, with any luck? I need some advise.

regards

davis

When I first read your post, I couldn't figure out whether you were seeking attention for having such a "lively" beast of an engine, or whether you were sincerely looking for a way to make it more moderate for the occasional trip to town.

Comp Cams' catalog describes that cam as follows:

MECHANICAL ROLLER-Ultimate Pro Street cam. 4000+ stall or 4 speed 11:1 compression, radical race idle.

With the following stats:

RPM Range: 3000 to 7000
Dur @ .050" 262/262
Lift .651" .651"
LSA 110°


Then, you top it with an "old school" Weiand tunnel ram with a pair of dual fours on it that add up to 1300 CFM of air flow potential...for what? A 357 CID engine?

Considering that you have 4V heads with exhaust port plates, your camshaft choice will work better than other engines without a typically recommended dual pattern camshaft. By work better, I mean in its intended RPM range.

Do you have a vacuum gauge? Have you used it to set up your idle mixture?

Considering that it is "idleing" at 1500 RPM, I'd say that you're about as close as you're going to get with this build. If you want it to be more docile on the street and still be wild when you're on the throttle, then you need to pull out the bottom end and go back in with a 393 or 408 stroker combination. The extra inches will mellow out that camshaft considerably, while giving you much better bottom-end response than is possible in what is now configured as a high-RPM engine.

Otherwise, you're running a "nasty boy" engine...you appear to have to live with exactly what you wanted.


:davis:

TruBlu351

With the locked out timing of 30*, is there scope with this "nasty engine" to drop the idle a tad with a timing control device?

Might just give you time to get the drive thru hotdog and donuts before the plugs foul up

__________________
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393 Tremec TKO 9"

Oldwolf

Hi Davis
Thank you for your answer. I´m not jokying. You have to excuse me for my spelling. The engine was built in the early eightees and was built for dragracing in Sweden. It´s been parked since then. I have´nt decided yet if I should change the engine to a more useful setup, change cam and induction, but that involves a lot of work with the other parts that are setup for competition, gearing 5.14;1, ladder bars,big wheels etc. I will not compete with the car (not competitive). I havént checked vacuum reading, but i suppose its low. I started the engine last week, it run good but the idle was rough and hi. The carbs are stock from the boxes, chokes and all. I will will try once more after checking vacuumreading and after I get some information about dual carb tuning. Otherwise I just have to live with it as it is. I will atleast try before I give up. I send you a photo of the engine so that you believe me.

Regards

Attached Images

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	351c2.jpg (29.2 KB, 16 views)

Oldwolf

Thank you, That is a good idea. I will look in to that.

Regards

davis

Something that may be an easy solution would be to get a single 4-barrel top and use only one of the carbs for "regular cruising" and put the duals on when you feel a need or want to go to a show.

I never suggested that I don't believe you or the engine build...nor do I think that I implied that in any way. The language barrier may be a contributing factor, if that is what you thought I meant.

The combination is certainly "exciting," though rather impractical for your apparent intended uses. A set of flat tops and a 393 stroker would do a world of good for it in terms of mellowing it out without really reducing the power levels.

You may want to try restricting the carburetion. One choice is to purchase a pair of plastic 4-hole spacers and then cut out a set of ~15mm holes centered on each of the 4 holes from a piece of sheet metal. Make a pair of these "restrictors" and simply remove them when you're looking for more top end.

Another choice might be to purchase a couple of very small 4-barrel carbs with vacuum secondaries and use them most of the time, switching to the dual mechanical 4s whenever the mood strikes you.

Something else that you can try is to simply remove one air filter element from each carb. Keep the smallest volume options. Not as good as restricting from below the base of the carb, but it may be a very simple way to try to increase your vacuum signal.

Another option for restriction may be to build a restrictor that fits between the top and the bottom of the manifold.


:davis:

Oldwolf

Thank´s for the useful tips about the restrictor plates or the smaller carbs. I will try the plates or the plate first. Ím sorry about the missunderstanding (my fault) and it is the the language barrier that is the problem. You are right about the show factor, the car is nice as is and the dual setup is the "thing" about the car. Whitout that is´s just a hopped up mustang coupe. The sollution with a stroker kit is to expensive for me, so it has to go. I will keep you informed how the project continous.

Best regards an thanks again.

rbohm

my suggestion would be to use a pair of 390cfm or 450cfm holley carbs. these are vacuum secondary carbs, and will help tame the idle. the problem though is the tunnel ram intake. it really wasnt designed for street driving.

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