old school tunnel ram and carbs question

[whitetop]

I have set up 2 TR systems for myself and one for a friend who has a street rod. Take this info or leave it but it works. I got this info by trial and error and talking with guys who actually run these cominations on the street and who actually don't LIE to you telling how good their combination runs on the street. I think only 2 out of 10 TR systems I see on street cars actually work decent. Here is the engine out of my mustang-see attachment.

1. Get rid of the 1850 4160 carbs and the sideways linkage. They were hardly ever run on the street in the day and were mostly race car only. Those 4160 double pumpers are way too much for any small block on the street even if they are vac. sec. You will end up with gas washing down your cylinder walls and will be rebuilding the engine by the end of the summer. Run two Holley 4150 carbs with 450 cfm inline. (600x2 =1200 cfm is way too much). I had two of the 600cfm 4150 carbs on my car when I got it. It ran o.k. but the 450's were way better and the 390's I finally ended up were the best. I think the very best carb is Holley 4150 390 cfm #6299 (with no choke) and vacuum secondary. That is what is in my pics. 6299 are discont. by Holley but you can find them on ebay just about every day of the week. Do not run the 390 carb Holley still on the books. It is an emision carb. I used the balance tube kit for the v secondaries and it made the carbs run incredible-great as a matter of fact. The balance tubes were not availble in early '70's but came out in '74 ish period. I'm very picky about being period correct but would run the tubes anyway.

The trick to getting a tr to run good on the street is lots of torque. Get this by running the heaviest flywheel you can find, smallest tube headers, and highest number rear end gears like 4:11 etc. Anything less than 4:11 forget it.

I'm running an early 6530 Moroso y-block with 3/8 mainline and two 5/16 rubber lines to each carb. I've never seen guys back then run any type of OEM fuel blocks etc. Not to say that someone did. Just from looking at 5000 old magazines amd seeing original cars. Also a red Holley street electric fuel pump that puts out around 5 psi. Don't go much over that or you will be washing down your cylinder walls. The blue pump is overkill for the street. I've seen some guys just run a mchanical pump. The only problem is you will be cranking the engine alot each time to get it started. With my electric pump I turn it on for 5-6 seconds and it fills up the fuel bowels and then turn the keys and the engine kicks right off. I had the mechanical fuel pump only at one time on my car and I was always cranking the starter.

Best compression ratio for the street with a tr is 9 1/2 to 10:1. You also need to run a very mild cam that produces lots of vacuum. RV style cams work great. You need lots of vaccuum to pull that air/fuel down that long intake at low rpms. If you are running a rumpity rump cam it's probably wrong.

Also offenhauser made the best tr for the street amd most street freaks of the day (who new better) ran offie. That is what is on my mustang-which was built in '72-'74. Offenhauser Tr's for sbc and sbf came out in 1970 anyway and you can still buy them from offie through summit. I know 3 guys that run offie tr on their sb chev's and swear by them. Also a magazine did a tr comparison backin the late '70's and the offies came out on top for the street. Had to do with top plenum size and tube length and diamater.
I have to go back and see my notes etc. There is alot more info.
Dave

[budnate]

WOW..great stuff Dave..I snagged a set-up this last fall and have been wanting to read up on proper tuning...please keep sharing your "tune tips"...I really need them as I have never set one up before..

[Salvatore]

Dave, You sound right on. Small Carbs that run 85-90% efficient is much better than big carbs running 60% efficient. Need steep gears and heavy flywheel. My friend Pete used to run a 50lb. wheel with a 6.17 ring and pinnion and a 3.00 first gear in a Nash 5 speed. Car was 280 cubes in a 57 2 door wagon that weighed about 3400lbs. 10.82 @ about 130mph back in 1979. Carbs were inline (660) center squirters with an Engle roller cam. (G/MP)

[JoeG]

engine whitetop--Are you running a straight linkage ie.-1 to 1 ratio or progressive setting on your linkage

[whitetop]

I'm running Weiand straight linkage. Not progressive. I think the part number is 4011 or something like that. Both of my carbs come out to 780 cfm which even on a little 289 is more than is recommended but it is the smallest 4150 carb available from Holley.
BTW Running a Crane cam, very mild. But it produces a ton of vacuum and torque which is needed to run a tr on the street.

[musclcar]

your getting me confused now you mention a 4150 carb "double pumper" then you mention a 4160 "vacum secondary.so what is better for my tunnel ram double pumpers or vacum secondary carbs. i don't think there is room on a TR1-X for 2 inline double pumper carbs.the vacum secondary carbs i've got now the bowls are seperated by less then a 1/2 inch between the front and rear carbs. so your saying a 600 cfm vacum secondary carb will be to much and i should go down to a 450cfm vacum secondary carb for better results.i bought 2 matched 600 cfm vac sec. carbs off of ebay for a good price and all they need is a rebuild. the camshaft that's in my motor right now is the GM #140 solid lifer cam and my compression is 11.5:1 and my rear gear is 3.73.

[Salvatore]

I don't think 2-600's are too big. The cam sounds appropriate. Need some good gears. JMO Sam

[BBIGG BLOCK 396]

Correct me if I am wrong,but I always heard that vacuum secondary carbs did not work on tunnel ram setups because the tunnel ram decreases the vacuum on the engine!I remember a long time ago that my brother had to change out his carbs to non vacuum secondaries in order to get it to run correctly.

Bobby Dodson

[JoeG]

Motion had set up a 454 ZLX tr /(2)600cfm--513rear/hone---
Sam your right with the steeper gears with 1200cfm---But ....as Whitetop pointed out the smaller carbs just make life easier on the street--you could spend more time cruisin an less time tuning---JMHOX2----

VAC/MEC SEC---Would depend on cam/vac venturi size on carbs etc as whitetop pointed out and tr design--Whitetop seems to have a winning combo and you go with what works with your mods---

[whitetop]

Chuck
The 600 vac sec carbs maybe alright for your application because you have 50+ more cubes than mine. I would try them and if they don't tune out right go with the 450's. A friend of mine who built a streetrod with a 350 TR had two 600's like your but later put on my 450's and liked them better. Of course his engine was no where near as radical as yours. I think his had 9 1/2:1 Compression. The 450's are not vac secondary but the motor seemed to like the smaller cfm.

Like Sam said you need to increase your gear ratio in the rear. You may have a bog/hesitation when leaving. I can't over emphasize enough if you want to run one of these on the street you need as much vacuum and torque as you can put into the combination. You will not beleive how much torque you will loose from running a TR. Remember these were designed for the strip with cars leaving at 6-8K rpm. My friend who has the street rod only has something like 3;73(?) also but he is running a 5 speed and had a very low gear placed into it for first.